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  • Chemical Engineering  (366)
  • pharmacokinetics
  • Wiley-Blackwell  (366)
  • Springer  (23)
  • 1980-1984
  • 1975-1979  (389)
  • 1976  (389)
Collection
Publisher
  • Wiley-Blackwell  (366)
  • Springer  (23)
Years
  • 1980-1984
  • 1975-1979  (389)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 10 (1976), S. 55-58 
    ISSN: 1432-1041
    Keywords: Penicillin V ; bioavailability ; pharmacokinetics ; dose ranging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary An absorption study was performed in ten healthy volunteers to test the bioavailability of various doses of two penicillin V-K preparations: Isocillin® (Hoechst AG, Federal Republic of Germany), — tablets of 600 000 and 1.2 Mega U; V-Cillin® (Eli Lilly, USA), — tablets of 200 000, 400 000 and 800 000 U. The serum concentrations and elimination of the active substance in urine were measured for six hours after administration. Independently of the source of the preparation, a strict linear relation between the dose and the area under the serum curve (AUC), or between the dose and the urinary elimination, was demonstrated by regression analysis. The dose-dependent increase in the AUC was highly significant (p〈0.01) in the range tested, i.e. between 200 000 and 1.2 Mega U. The relative elimination of active substance in urine lay within narrow limits for all doses (35.7–41.3%). Thus, both compounds proved to have the same bioavailability.
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  • 2
    ISSN: 1432-1041
    Keywords: Ampicillin ; bioavailability ; pharmacokinetics ; branded products ; proprietary preparations ; capsule formulation ; tablet formulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics and bioavailability of three different brands of ampicillin were studied in 10 volunteers. After intravenous administration ampicillin can be described adequately by a two-compartment open pharmacokinetic model. The half-life during the α-phase was 9 min and the β-half-life was in the range 50–60 min, independent of the mode of administration. Absolute bioavailability was determined from the ratio of the areas under the serum concentration curves obtained after oral and intravenous administration of equal doses. Bioavailability was also estimated by analysis of variance. The results indicated absolute availability of the three products of 39–54%. One of the products, a capsule formulation, showed a significantly lower bioavailability than the others, which were tablet formulations.
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  • 3
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    European journal of clinical pharmacology 10 (1976), S. 257-262 
    ISSN: 1432-1041
    Keywords: Anti-inflammatory and analgesic drug ; indoprofen ; pharmacokinetics ; bioavailability ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In a pharmacokinetic study of the new analgesic and anti-inflammatory drug indoprofen, plasma levels and urinary excretion were determined in four healthy volunteers after 100 mg and 200 mg iv, and after 100 mg (capsules) and 200 mg (tablets) oral doses. After iv administration, the mean biological half-life (t1/2 β) was about 2 h (range 1.4 to 3.2 h). The apparent volume of distribution Vdβ ranged between 11 to 17 % of body weight, indicating its limited extravascular distribution. Most of the drug was excreted in urine as glucuronide and a smaller proportion as unchanged indoprofen: the 24 h urinary excretion of these compounds accounted for 67 to 95 % of an iv dose. Peak plasma levels occurred between 30 and 120 minutes after oral administration of 100 mg as capsules or 200 mg as tablets. The mean biological half-life was about 2 h, as after iv administration. The bioavailability of oral doses was assessed using both plasma levels and urinary excretion data. The absorption of capsules and tablets was practically complete, that of the former being faster.
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  • 4
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    European journal of clinical pharmacology 10 (1976), S. 263-271 
    ISSN: 1432-1041
    Keywords: Butobarbital ; pharmacokinetics ; plasma concentration ; oral administration ; accumulation ; enzyme induction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A method is described for the assay of therapeutic levels of butobarbital (5-ethyl-5-n-butylbarbituric acid) in human plasma, which involves a single extraction step followed by gas chromatography with alkali flame ionization detection. The pharmacokinetics of butobarbital were studied in five healthy volunteers after oral administration of 200 mg. Plasma concentrations were determined at regular intervals up to 96 h and the data were fitted by non-linear, least squares regression analysis according to one-compartment kinetics. The average lag time was 0.11 h and the absorption half-life 0.21 h. The elimination half-life varied from 33.6 to 41.5 h with an average of 37.5 h. Four of the volunteers participated in a study of multiple dosing (every 24 h) during which substantial accumulation of butobarbital was observed. The elimination half-life after termination of drug administration had decreased to about 20–25% of its initial value, probably because of enzyme induction. It was concluded that butobarbital could not be regarded as a suitable drug for treatment of insomnia, since CNS depressant effects were likely to persist into the following day. Repeated administration of butobarbital should be avoided and its incidental use restricted to patients who require day-time sedation.
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  • 5
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    European journal of clinical pharmacology 10 (1976), S. 293-295 
    ISSN: 1432-1041
    Keywords: Bendroflumethiazide ; diuretics ; GLC ; thiazides ; plasma level ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A GLC method for determination of bendroflumethiazide has been developed, using extractive methylation. Cyclopenthiazide was used as internal standard. The maximal plasma concentration (56–107 ng/ml) after bendroflumethiazide 10 mg given orally to four healthy volunteers was seen at 2–2.5 h. On the slope between 4 and 10 h T1/2 averaged 2.7 h.
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  • 6
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    European journal of clinical pharmacology 10 (1976), S. 337-341 
    ISSN: 1432-1041
    Keywords: Amitriptyline ; pharmacokinetics ; intravenous infusion ; two compartment model ; biological half-life
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Amitriptyline was given to four male volunteers by constant rate intravenous infusion. Blood samples were collected before, during and at various times after the infusion for estimation of the serum concentrations of amitriptyline. The level of nortriptyline never reached a detectable level. A two compartment open model was shown to be applicable to the data obtained. The meaning of the parameters obtained by a non-linear, least squares curve fitting procedure is discussed and the values are compared to those recently published for nortriptyline. The calculated biological half-life of amitriptyline was about 17 hours, a figure which differs considerably from previously calculated values for volunteers, but is in accordance with some newer results from patients.
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  • 7
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    European journal of clinical pharmacology 10 (1976), S. 63-68 
    ISSN: 1432-1041
    Keywords: Phenazone ; pharmacokinetics ; injuries ; surgery ; operation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The elimination rate of phenazone after a single oral dose has been studied before and after elective operations. In a group of patients with different illnesses the elimination rate was increased on the fourth to seventh days after operation but was unchanged on the second and third days. The change in elimination rate was highly significant in a standardized group of nine patients with a ligament injury in one knee studied on the fourth or fifth postoperative day. Possible reasons for the changes are discussed.
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  • 8
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    European journal of clinical pharmacology 10 (1976), S. 251-256 
    ISSN: 1432-1041
    Keywords: Sisomicin ; pharmacokinetics ; bioavailability ; two-compartment analysis ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of sisomicin, a new single component aminoglycoside antibiotic related to gentamicin c1a, were determined in four healthy volunteers after intravenous and intramuscular administration of a 1 mg/kg dose. The elimination profile of this antibiotic follows two-compartment model kinetics after I.V. administration. The fast (α) and slow (β) disposition rate constants averaged 0.072 and 0.004 min−1, respectively. The volume of distribution at the steady-state averaged 0.185 liters/kg which approximately corresponds to the volume of extracellular space. The physiological availability of an intramuscular dose appeared to be complete. A method of administration adapted to the kinetic properties of the drug is proposed.
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  • 9
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    European journal of clinical pharmacology 10 (1976), S. 183-187 
    ISSN: 1432-1041
    Keywords: Hydralazine ; bioavailability ; pharmacogenetics ; first pass effect ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary After oral administration of a single 50 mg dose of hydralazine (Apresoline®), the serum half-life (T1/2) and bioavailability (AUC0−∞) were assessed in 16 healthy volunteers. The half-life was 2.57±0.14 h (S.E.) in 10 slow acetylators of sulphadimidine, and 2.18±0.15 h in 6 fast acetylators (difference not statistically significant). AUC0−∞ was significantly higher in slow acetylators, at 1.04±0.10 µg·hour·ml−1, compared to 0.66±0.12 µg·hour·ml−1 in the fast acetylators (p〈0.025). Treatment with Apresoline® 25 mg tid produced minimum serum concentrations at steady-state of 57.3±7.3 ng·ml−1 and 33.4±4.2 ng·ml−1 in 8 slow and 5 fast acetylators, respectively (p〈0.05). The corresponding maximum concentrations were 228.8±20.3 ng·ml−1 and 147.6±15.0 ng·ml−1 in slow and fast acetylators, respectively (p〈0.025). First-pass metabolism of hydralazine could explain the difference in bioavailability of the drug between fast and slow acetylators, without any corresponding difference in the elimination rate of the drug in the post-distributive phase.
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  • 10
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    European journal of clinical pharmacology 10 (1976), S. 121-126 
    ISSN: 1432-1041
    Keywords: Diazepam ; pharmacokinetics ; subchronic dosage in man ; desmethyldiazepam
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In seven healthy male volunteers the effects of the pattern of dosing on the pharmacokinetics of diazepam have been studied. A cross-over design was employed that consisted of three parts: a single intravenous dose (0.1 mg/kg), and oral dosing (10 mg/day) for six days followed by an intravenous bolus (0.1 mg/kg) on the seventh day, followed by re-examination of a single intravenous dose after diazepam (D) and its major metabolite desmethyldiazepam (DD) had been completely eliminated. Plasma levels of D and DD were monitored by a specific, sensitive GLC-method. In younger patients (n=5, age 29 – 35 years) the elimination half-life, T1/2 (β), of D was 33.9±10.6 h (mean±S.D.) after the single dose. The control study gave an almost identical result (35.7±12.1). After subchronic dosage in all patients T1/2 (β) showed a modest but significant prolongation (paired t-test p〈0.01) to 52.9±17.4 h. It was caused by a significant decrease (p=0.016) in total plasma clearance ( $$\overline {\user1{Cl}} $$ ), from 26.0±10.8 ml/min to 18.2±7.0 ml/min. Older patients (age 43–60 years) showed the same phenomenon. Blood/plasma ratios remained constant indicating no change in protein binding. Biliary excretion of D was measured in five patients with a T-tube. Only negligible amounts (0.3–0.4%) of administered D were excreted within 3 days after subchronic dosage, which demonstrates a lack of enterohepatic cycling of D. After multiple administration of D, there was accumulation of DD to levels approximately five times higher than after a single dose. The possibility that the slower elimination of D after subchronic treatment might be caused by DD was also supported by experiments in dogs and rabbits. After pretreating rabbits with DD and maintaining a high DD plasma level, there was prolongation of T1/2 (β) from 2.7 h to 5.2 h, with a corresponding decrease of $$\overline {\user1{Cl}} $$ from 101.6 ml/min to 23.4 ml/min. Similar results were obtained in dogs. It is concluded that the disposition of D is altered by subchronic use and may be regulated by the plasma DD concentration.
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  • 11
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    European journal of clinical pharmacology 10 (1976), S. 311-317 
    ISSN: 1432-1041
    Keywords: Hydralazine ; instability of impaired renal function ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Following a single 50 mg dose of hydralazine (Apresoline®) in 13 patients with impaired renal function, a decrease in glomerular filtration rate (GFR) was correlated with an increase in serum half-life (T1/2) of the drug (r=−0.69; p〈0.01). The T1/2 was 15.8 h in one patient with a GFR of 16 ml·min−1, as compared to a T1/2 of 1.7–3.0 h found previously in 16 healthy volunteers. In 49 patients on long-term antihypertensive treatment with hydralazine, the ratio between the minimum steady-state drug concentration and the daily dose of hydralazine (C SS min : Dose) increased as the GFR decreased. This accumulation of the drug was particularly evident in patients with a GFR less than 30 ml·min−1 (r=−0.63; p〈0.01; n=19). As renal excretion of unchanged hydralazine is generally regarded as unimportant, the slower elimination rate in chronic renal failure was probably caused by a slower rate of metabolic conversion. It was found, however, that the renal excretion of hydralazine could easily have been underestimated, as only 12.7% of an initial hydralazine concentration of 200 ng·ml−1 in urine could be recovered after storage of the samples at room temperature for 24 h.
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  • 12
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    European journal of clinical pharmacology 10 (1976), S. 325-330 
    ISSN: 1432-1041
    Keywords: Flutiorex ; pharmacokinetics ; sex ; anorectic agent ; sympathetic stimulation ; CNS stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effects of flutiorex, a new anorectic agent, and of a placebo on food intake and the activity of the sympathetic and central nervous systems have been compared in a double blind trial in two groups of healthy volunteers, one of five males and the other of five females. Flutiorex 20 mg orally had a significant anorectic effect both in males and females, the observed reduction in food intake being 34.0 and 27.5%, respectively. It caused α-adrenergic stimulation (blood pressure and pupil diameter) and central nervous system excitation (critical flicker frequency), both of which were more marked in males than in females. Flutiorex was better tolerated by women than by men. Measurement of the blood level of flutiorex and its de-ethylated metabolite, norflutiorex, showed that both compounds were detectable in four of the five male subjects, but in only one of the five females. Sex-linked differences in the pharmacokinetics of flutiorex may explain the greater intensity of its effects in males.
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  • 13
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    European journal of clinical pharmacology 10 (1976), S. 343-347 
    ISSN: 1432-1041
    Keywords: Methaqualone ; hypnotic ; pharmacokinetics ; combination formulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Concentrations of methaqualone have been measured in the serum of five male human subjects receiving five consecutive evening doses of a combination formulation containing methaqualone (250 mg), carbromal (300 mg) and benactyzine (0.33 mg) in each tablet. After administration of the first dose, mean peak serum concentrations of methaqualone (1.2 µg/ml) occurred at 3 h. After obtaining peak levels, mean concentrations of methaqualone declined rapidly during the next 6 h and there-after more slowly during the next 18 h. After administration of the last (fifth) dose, mean peak serum concentrations of methaqualone (1.9 µg/ml; 1.5 µg/ml above the predose level) occurred at 2 h. After attaining peak levels, mean concentrations of methaqualone declined rapidly during the next 6 h, and thereafter more slowly, with a half-life of approximately 10 h. Mean concentrations of methaqualone in serum samples 24 h after the second, third, fourth or fifth doses were not significantly different (0.3 µg/ml – 0.6 µg/ml) during this period of dosing. This suggests that significant accumulation of methaqualone in the serum did not occur during a period of five consecutive evening doses of the combination formulation.
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  • 14
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    European journal of clinical pharmacology 10 (1976), S. 25-29 
    ISSN: 1432-1041
    Keywords: Digoxin ; exchange transfusion ; pharmacokinetics ; neonates ; 86Rb assay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary By means of an86Rb-uptake inhibition assay, changes in the plasma concentration of digoxin and the amount of the glycoside removed during exchange transfusion have been studied in two newborns. For comparison, the exchange procedure was simulated by a computer on the basis of a two-compartment open model and available pharmacokinetic constants. A rapid decrease in plasma digoxin concentration during exchange transfusion was found when the glycoside was administered intravenously or intramuscularly within 60 min before the procedure. The amount of digoxin removed by the exchange was less than 6 per cent of the given dose. Computer simulation of the procedure also showed removal of only a minor amount of digoxin. It is concluded that the decrease in plasma concentration and the removal of only a small amount of glycoside by the exchange transfusion can be attributed mainly to extensive tissue distribution of digoxin. The results imply that replacement of digoxin after an exchange transfusion seems unnecessary.
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  • 15
    ISSN: 1432-1041
    Keywords: Diabetes mellitus ; drug interaction ; phenprocoumon ; pharmacokinetics ; pharmacodynamics ; sulphonylureas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The influence of various antidiabetic treatments on the kinetics and efficacy of a single oral dose of 12 mg phenprocoumon were studied in 71 hospitalized patients, 58 with adult-onset diabetes mellitus and 13 non-diabetic aged patients, and 13 healthy young volunteers. Treatment for one week or longer with insulin or the antidiabetic sulphonylureas tolbutamide, glibenclamide or glibornuride, altered neither the plasma level (1.29 – 1.40 µg/ml at zero time) nor the half-life of phenprocoumon (5.2 – 6.8 d) compared to treatment by diet alone. The mean half-life of phenprocoumon was significantly shorter in non-diabetic aged patients (4.2 d) than in diabetic patients of the same age (5.1 – 6.8 d), or in young healthy volunteers (5.7 d). The efficacy of a single dose of phenprocoumon (maximal reduction of Quick-values by 34 – 47% after 48 to 72 hrs) in diabetic patients treated with diet, or diet and antidiabetic drugs, was the same as in non-diabetic aged patients. In healthy young volunteers phenprocoumon was half as effective as in aged patients.
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  • 16
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    European journal of clinical pharmacology 9 (1976), S. 327-332 
    ISSN: 1432-1041
    Keywords: Antipyrine ; pharmacokinetics ; half-life ; blood ; plasma ; saliva ; individual variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A previously described GLC method has been modified and applied to measurement of antipyrine levels in plasma, blood and saliva of man following administration of a single oral dose (10 mg/kg). The levels in blood and saliva were comparable to those in plasma at every time studied. The half life of antipyrine determined in blood, plasma or saliva in any given individual was similar. The intersubject variation in half-life was about two-fold (n=5). Antipyrine levels in saliva were not affected by the rate of saliva flow when collections were made continuously for 20 minutes. This study has demonstrated that kinetic data about antipyrine comparable to that from plasma may also be obtained from readily accessible tissue fluids, such as saliva and capillary blood.
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  • 17
    ISSN: 1432-1041
    Keywords: Chlorthalidone ; diuretics ; drug plasma concentration ; protein binding ; red blood-cell concentration ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A gas chromatographic method has been employed to determine chlorthalidone in plasma and whole blood after therapeutic doses. Radioactively labelled chlorthalidone was used for in vitro studies of the uptake of chlorthalidone from plasma by red blood cells. Chlorthalidone was markedly concentrated in red cells and as a compartment they would account for at least 30% of total drug in the body after multiple doses. The ratio between the plasma and red cell concentration of chlorthalidone varied between individuals. After a single oral dose of 50 mg in 6 healthy volunteers chlorthalidone was eliminated with a half-life of 51 to 89 hours. The apparent volume of distribution varied between 3 and 13 1/kg and the clearance between 53 and 145 ml/min. The mean steady-state plasma concentrations during treatment with a standard dose of 50 mg daily (n=10) varied 5-fold between individuals. During the steady state approximately 50% of the daily dose was excreted unchanged in the urine during 24 hrs. The plasma levels observed in patients were higher than those predicted from the single oral dose studies in healthy volunteers.
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  • 18
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    European journal of clinical pharmacology 9 (1976), S. 367-372 
    ISSN: 1432-1041
    Keywords: Sotalol ; β-adrenoceptor blocking drugs ; exercise tachycardia ; efficacy ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effects of sotalol after oral administration were measured on the tachycardia induced by strenuous exercise in normal subjects. Plasma sotalol levels were also determined. The oral administration of sotalol (50, 100, 200 and 400 mg) to 6 subjects produced a progressive reduction in the tachycardia induced by severe exercise. This was similar to the effects of 25, 50, 100, 200, 400 and 800 mg given to different subjects. Each increase in sotalol dose produced a successively greater reduction in exercise tachycardia. This did not appear to be maximum even with 800 mg. Oral sotalol was rapidly absorbed and produced peak blood levels in 2 – 3 hours. The plasma levels of sotalol measured 2 hours after the oral administration of 25 to 800 mg showed never more than a six-fold variation between different subjects. The half-life of sotalol in plasma was 12.7 ± SE 1.6 hours. There was a significant correlation between the logarithm of the plasma sotalol concentration and the percentage reduction of exercise heart rate. It is concluded that the oral administration of sotalol either once or twice daily (depending on dose level) will provide satisfactory 24-hour blockade of β-adrenoceptors.
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  • 19
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    European journal of clinical pharmacology 9 (1976), S. 443-450 
    ISSN: 1432-1041
    Keywords: Cyclobarbital calcium ; pharmacokinetics ; plasma concentration ; relative bioavailability ; oral administration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics and relative bioavailability of cyclobarbital calcium have been studied after oral administration of Phanodorm, of tablets according to the Formularium Nederlandse Apothekers (1968; FNA), and an aqueous solution. Six healthy volunteers participated in the investigation on three occasions and each received the three preparations. The dose administered was 300 mg cyclobarbital calcium. Plasma concentrations of cyclobarbital were determined at regular intervals. Absorption from the three preparations was rapid and was faster from the solution. Peak concentrations were usually attained within 1 h. The elimination of cyclobarbital could be described by a single first-order process with an average half-life of 11.6 h (range 8 – 17 h). There was little intra-subject variation of the half-life. Relative bioavailability for each volunteer was estimated by comparing the areas under the plasma concentration curves. The FNA-tablets and Phanodorm exhibited similar bioavailability, whereas the average bioavailability of the solution was 78% of that of FNA-tablets; the reason for this unexpected finding is unknown. It was concluded that cyclobarbital cannot be regarded as a uniformly suitable drug for the treatment of insomnia. The long half-life that was apparent in some of the volunteers (15 – 17 h) creates a substantial risk of residual effects on the following morning. In principle, however, the calcium salt of cyclobarbital may be used for induction of sleep, because of its rapid absorption.
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  • 20
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    Journal of pharmacokinetics and pharmacodynamics 4 (1976), S. 199-230 
    ISSN: 1573-8744
    Keywords: disopyramide ; antiarrhythmic ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pharmacokinetics of the antiarrhythmic disopyramide, 4-diisopropylamino-2-phenyl-2-(2-pyridyl)butyramide phosphate, and its monodealkylated metabolite were investigated in seven volunteers after intravenous (1 and 2 mg/kg) and oral (3 and 6 mg/kg) administration. Unchanged drug (52%) and the monodealkylated metabolite (25%) were renally excreted on intravenous administration. The pharmacokinetics of disopyramide were first order and dose independent only when referenced to the drug not bound to plasma proteins since this binding was dose dependent. The apparent half-lives of the α and β phases on intravenous administration were 2 min and 4.5 hr, respectively. The apparent volumes of distribution of the central and peripheral compartments, referenced to unbound disopyramide in the plasma, were 9 and 80 liters, respectively. The half-life of absorption of oral aqueous disopyramide phosphate was 30 min with a lag time of 16 min and an apparent first-pass metabolism of 16% of the absorbed dose, consistent with the hepatic efficiency of 14%. The renal and metabolic clearances were 125 and 111 ml/min, respectively. Graphical and computer analysis of the plasma and urine data showed dose-independent first-order pharmacokinetics of plasma unbound drug in a two-compartment-body model to give two metabolites and a first-pass transformation of a fraction of the oral dose. The absorption efficiency of unchanged drug was 83%.
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  • 21
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    Journal of pharmacokinetics and pharmacodynamics 4 (1976), S. 337-353 
    ISSN: 1573-8744
    Keywords: bioavailability ; pharmacological data ; pharmacokinetics ; modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The use of data deriving from monitoring the time variation of the intensity of pharmacological effect(s) following dosing can often present an advantageous alternative to the more conventional approach of using chemical or radiological assay of blood and/or urine level data for bioavailability evaluations of drug products: bioavailability studies can be performed with drugs where no assay exists. A relatively simplified discussion of the general theoretical principles on which the use of pharmacological data is based and a stepwise description of the approach for its routine application in bioavailability studies are presented. Approaches for computing rates and extents of drug bioavailability vs. time profiles on analog and digital computers are qualitatively described and quantitatively presented in a subsequent report. The concept of preabsorption (gastrointestinal bioavailability) is introduced and biophasic availability of drugs to local sites of action is discussed.
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  • 22
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    Journal of pharmacokinetics and pharmacodynamics 4 (1976), S. 355-375 
    ISSN: 1573-8744
    Keywords: deconvolution ; bioavailability ; pharmacokinetics ; modeling ; pharmacological data
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Mathematical expressions and approaches to the computation of rates and extents of drug bioavailability for implementation on analog and digital computers are derived. The equivalency of expressions derived on the basis of assuming compartment models to an approach based on using experimentally determined weighting functions is demonstrated. The relative merits of the two techniques are discussed: their application for use with temporal pharmacological data is emphasized. The applicability of the computational techniques to determining the availability of drugs at local sites of action (biophasic availability) and to computing preabsorptive drug release into the gastrointestinal contents (gastrointestinal bioavailability) is pointed out. An approach to computationally predicting in vivo blood level or pharmacological response vs. time profiles from in vitro dissolution testing results is presented and its limitations are discussed.
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  • 23
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 16 (1976), S. 742-746 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Mold flows and melt viscosities of an incompatible bi-component EPDM and “Viton” fluoroelastormer system were examined. A marked reduction in the melt viscosities of either component was observed when a small amount of the other component was present. It was speculated that the phenomenon was a result of a slippage between the polymer and the coated capillary surface due to the presence of a minor amount of the incompatible polymer. Evidence is given to indicate that this effect cannot be accounted for using the “melt structural heterogeneity” mechanism proposed for a different system by Andtrianova.
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  • 24
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The Part I paper described the mechanochemical basis for achieving high adhesive strength in bonds between polymeric surfaces such as polyethylene, polypropylene, and Teflon, using the SABRA method (Surface Activation Beneath Reactive Adhesives). This paper gives a brief survey of bonding techniques as well as results of shear tests of simple lap joints and scarfed tube joints. They compared favorably with other methods such as CASING, Peeling test results are also presented. Mixed systems were examined such as glass fiber reinforced polyester bonded to polypropylene and aluminum with thin films of polymeric material sandwiched between. A start was made towards of optimization and exploration of primer specificity for different materials, The implications and further applications of the SABRA method are discussed.
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  • 25
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    Polymer Engineering and Science 16 (1976), S. 771-776 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Various blends over extended compositional ranges have beer, prepared for combinations of a thermoplastic urethane elastomer with polystyrene, a styrene-acrylonitrile copolymer, a polyhydroxyether (Phenoxy A), and poly(vinyl ethyl ether). The thermoplastic urethane elastomer was based on a polycaprolactone diol of approximately 2100 number average molecular weight, 4,4′-diphenylmethane diisocyanate and 1,4-butanediol at a molar ratio of 1/2/1, respectively. At ambient temperature, the tensile properties of the blends typically are intermediate between the values of the two separate components. Characterizations of the dynamic mechanical properties of the blends show the relative degree of compatibility for the thermoplastic urethane elastomer and the respective polymers. Two separate glass transitions are obtained for blends of polystyrene and the styrene-acrylonitrile copolymer with the thermoplastic urethane elastomer. This behavior demonstrates that these blend systems are incompatible. The blends of Phenoxy A and the thermoplastic urethane elastomer exhibit a single glass transition for which the temperature is dependent on the respective concentration of the components. These mixtures are considered to be compatible in nature.
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  • 26
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    Polymer Engineering and Science 16 (1976), S. 803-810 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Trifunctional poly-ε-caprolactone polyol was polymerized with a chain-extended 1,6-hexane diisocyanate, and the rheology followed by cone and plate flow. Viscosity was found to be independent of shear rate up to at least 102 N.s/m2 (103 poise) and 30s-1. Extent of reaction was monitored by a periodic titration for isocyanate groups. Using branching theory, viscosity was related to extent of reaction and temperature. Such relations should be useful for process models. Normal force data for the curing system are also reported.
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  • 27
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    Polymer Engineering and Science 16 (1976), S. 811-816 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Melt How data has been determined for a series of fractionated and whole low density polyethylenes which has been characterized in terms of their molecular weights and degree of long-chain branching, (LCB). The resulting data indicate that low LCB influences melt flow both through a reduction in molecular size and an increased level of intermolecular interaction. Die swell measurements on whole polymers indicate an increase in melt elasticity with increase in degree of LCB for samples of similar melt flow (MI). Comparison of GPC data with observed die swell characteristics indicates that die swell is a molecular size dependent property and independent of intermolecular entanglement effects, suggesting that the measurement of elastic properties of LDPE melts will provide a means of determining relative degrees of LCB for commercial resins.
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  • 28
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    Polymer Engineering and Science 16 (1976), S. 15-24 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Articles with increased rigidity can be obtained by compression molding at high pressures as shown by experiments with five types of linear polyethylene. The materials, with weight average molecular weight ranging up to 1,000,000 were molded at pressures as high as 80,000 psi. The material temperature was 149-204°C, and the tooling was at 38°C. The duration of load was typically 3 mins, and the thickness of the molded disks was 12.7 mm. The results show that at high molding pressure the tensile modulus of the material is nearly twice that of materials molded conventionally at low pressures. This increase in modulus occurs for all the materials studied and even for a duration of load of only one min. The causes for this large increase in modulus were investigated with the help of density and melting point measurements and optical and electron microscopy. It was observed that the spherulites showed a distinctive and systematic change with the forming pressure. A hypothesis is proposed to explain the high modulus phenomenon on the basis of the kinetics of spherulite formation.
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  • 29
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    Polymer Engineering and Science 16 (1976), S. 87-92 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polymer blends and composites are composed of two different components, and usually, two different phases. Sometimes one phase is continuous and the other clearly discontinuous. Often, however, both phases retain some degree of continuity, as in certain fiber reinforced composites, block copolymers, materials composed of alternating lamellae structures and interpenetrating networks. A semi-empirical theory is developed to express mathematically not only the known structures, but also two-phase morphologies not yet synthesized or characterized. Many structures both real and proposed are shown to exhibit dual phase continuity, although for most systems, one phase can be said to be “more continuous” and the other “less continuous”.
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  • 30
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    Polymer Engineering and Science 16 (1976), S. 82-86 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: For fabrication processes such as blow molding, vacuum forming, film blowing and fiber spinning, extensional flow is the dominate mode of melt deformation. Under these conditions, extensional viscosity is a significant rheological property. Thus, the biaxial extensional viscosity was measured for several samples of polypropylene. A technique based on the bubble inflation method of Denson and Gallo was used. Experimental values of biaxial extensional viscosities ranging from 1014 to 1010 poise as a function of strain rate, 10-5 to 10-2 reciprocal seconds, were obtained at 25°C. The technique used was critiqued and found to be useful in characterizing unoriented and biaxially oriented films, Uniaxially oriented films gave unsatisfactory results. It may be possible to use this testing method to assist in materials selection decisions.
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  • 31
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    Polymer Engineering and Science 16 (1976), S. 138-144 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper points out that interpretations from stress changes alone during oriented crystallization have led to widely different proposed chain conformations and consequently very different crystallization mechanisms for strain-induced crystallization (SIC). Many of the proposals, including the one by Keller and Machin which takes into account some electron microscopy and X-ray observations, show varying degrees of incompatibility with existing stress relaxation, kinetic or morphological data on SIC. Another problem lies in the difficulty with proper interpretation of observed morphology on samples which have been Subjected to additional thermally-induced crystallization (TIC) after SIC, especially, in the absence of prior characterization of SIC crystallites, the finding of a fibrillar-to-lamellar transformation in stretched polymers upon additional TIC (Part H) also indicates that the generally-observed oriented lamellar morphology has a much more subtle origin than-that depicted by most crystallization models. Part I discusses our previously published morphological data on the characteristics of SIC crystallites from the melt, which includes: (a) their melting point elevation, (Tm » T°m), (b) their nearly perfect crystalline orientation function (fc ∼ 1), (c) their fast rates of crystallization (t1/2 〈 1 sec), and (d) their fibrillar morphology and limited dimensions along the fibrillar stretch axis (∼100Å). Examples of morphology of SIC from the glass and from stirred solution are also included to show the overall similarity of fibrillar morphology brought about by stretching.
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  • 32
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Stress-induced crystallization may be studied by the birefringence technique and by low-angle light scattering. From measurements of the change in birefringence and stress during the crystallization of a polymer above its Tg and from a calculation of the intrinsic birefringence of a polymer crystal, the change in volume fraction crystallinity may be calculated. The technique is illustrated for several polymers and found to give values in reasonable agreement with other methods for the study of crystallinity. Crystallization is also accompanied by the development of a low-angle light scattering pattern, the size and shape of which is indicative of the amount, size and morphology of the crystalline superstructure.
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  • 33
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    Polymer Engineering and Science 16 (1976), S. 158-162 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Several observations are made regarding the role of the fluid mechanics involved in the process of flow-induced, fibrillar crystallization from solution. Computational evaluation and discussion of various flow effects in the nucleation step, including combined shear and extensional flows, are presented in terms of the elastic dumbbell model. These results indicate the important role extensional kinematics in the growth process. A qualitative evaluation of concentration effects is also given. The evaluation of facts concerning the growth morphology is presented in terms of a model for the growth process along with data concerning rinsing and quench rate effects on the morphology and inciting behavior of shish kebab crystals.
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  • 34
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    Polymer Engineering and Science 16 (1976), S. 168-175 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A theory of crystallization under stress is developed about the premise that the direction a chain takes through a crystallite, relative to its end-to-end vector, is determined by the first few links of a chain that initially deposit onto the crystallite surface. Since these few links are quickly trapped by subsequently crystallizing chains, their orientational probability prior to deposition governs the chain direction through the crystallite, and the properties of the system depend upon a statistical distribution of all vector orientations. Such a model leads to a relationship between the melting temperature and the degree of network orientation, and relates the retractive force to temperature in the crystallization region. The theory appears to adequately describe some of the published data on rubber and polychloroprene networks.
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  • 35
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    Polymer Engineering and Science 16 (1976), S. 204-211 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This study demonstrates that it is possible to extrude highly oriented polyethylene fibers using only a plasticating single screw extruder, specially designed and operated dies, and a simple take up mechanism. The degree of orientation achieved is as high as that achieved in solid state extrusion studies but accomplished at a fraction of the pressure. The degree of orientation is significantly greater than that of commercial grade fibers. The orientation is developed in the elongational flow of the “wine glass stem” region preceding the die entrance and is retained by crystallization in the die. Crystallization is inhibited in the pre-die region by maintaining a temperature above the effective melting point of the flowing, oriented (hence lowered entropy) melt.
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  • 36
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    Polymer Engineering and Science 16 (1976), S. 229-234 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This article describes a new experimental and analytical method for determining the specific heat and thermal coductivity of plastic materials. This method arrives at these temperature-dependent properties by analyzing the thermal history of a slab of the plastic material. The procedure is as follows: 1) A partial differential equation model of the heat flow through the slab is established a priori. 2) A varying heat flux is a applied to the slab, and temperature readings throughout the plastic are recorded at fixed time intervals. 3) This temperature data is fed into a digital computer (along with the established mathematical model) and the required specific heat and thermal conductivity values are extracted. The extraction is done by using the maximum likelihood system identification technique.
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  • 37
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    Polymer Engineering and Science 16 (1976), S. 240-245 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A method is described to predict the time-temperature behavior and hence thermal stability of PVC melts in a Brabender Plasticorder torque rheometer from basic rheological data(flow and thermal stability observations) obtained on an Instron capillary rheormeter. The predicted and experimentally determined values of the Brabender thermal stability are shown to be in good agreement.
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    Polymer Engineering and Science 16 (1976) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 39
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    Polymer Engineering and Science 16 (1976), S. 270-275 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The inflation and growth kinetics of bubbles in thermoplastic structural foams are discussed in some detail using a model which assumes the initial existence of very small voids in the pressurized polymer melt. The effects of a drop in external pressure, the presence of a distribution of bubble sizes, and the diffusion of gas between neighboring bubbles are considered. It is shown that at a given pressure the number of growing bubbles present in the melt at any onetime depends on the ratio of the critical radius to the average radius of the microvoids assumed to be present in the melt It is also demonstrated that gas diffusion between neighboring bubbles reduces the growth rate appreciably only when the interbubble distance is reduced to a micron or less.
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  • 40
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    Polymer Engineering and Science 16 (1976), S. 276-283 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper concerns the action of plasticizers and nucleating agents on the crystallization of bisphenol-A polycarbonate. The influence of plasticizers is to increase the rate of crystallization to a great extent using 10 percent of a plasticizer such as trimellitic acid, tridecyloctyl ester. The influence of nucleating substances on plasticized and undiluted polycarbonate is investigated. A large number of substances have been found capable of nucleating polycarbonate crystallization. The un-plasticized semi-crystalline polycarbonate is characterized by a much higher melting point (300°C) than the plasticized semi-crystalline systems (210-245°C). The stability of bisphenol-A polycarbonate in the presence of nucleating salts is also examined. We observe a substantial decrease in the molecular weight in the presence of a great number of nucleating substances. The modulus-temperature curves of two semi-crystalline polymers are reported in the last series of experiments.
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  • 41
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    Polymer Engineering and Science 16 (1976), S. 294-297 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 42
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    Polymer Engineering and Science 16 (1976), S. 318-322 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polyphenylquinoxalines (PPQ) were crosslinked with a tris-benzil comonomer, to alleviate the inherenthigh temperature thermoplasticity, and evaluated as matrices in graphite reinforced composites. The room temperature flexural strength/modulus of Modmor IJ laminates were as high as 245,000 psi/16,6 × 106 psi. Essentially 100 percent retention of ambient mechanical properties was obtained at 371°C using a PPQ matrix from the fully-crosslinked polymer prepared from 4,4′-bis(4″-oxybenzilyl) benzil (BOBB) and 3,3′-diaminQbenzrdine. The degree of high temperature thermoplasticity in the composite was found to be more closely related to the final postcure temperature than to the BOBB crosslink density. The thermoplasticity essentially disappeared when the BOBB comonomer-PPQ laminates were postcured at 482-510°C in nitrogen. Substitution of DMAC for the commonly used m-cresol solvent system allowed facile preparation of prepreg to fabricate low-void laminates and NOL rings.
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  • 43
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    Polymer Engineering and Science 16 (1976), S. 327-333 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: By combining quantitative molecular, microscopic and macroscopic information from an oriented crystalline polymer, it becomes possible to unify, predict, and explain not only processing behavior but such important material properties as failure, shrinkage, modulus, yielding, melting, and storage and loss moduli. Among the advantages gained by this approach are the ability to: (a) identify the particular phase of the two-phase system which controls a given property-(b) correlate internal structure quantitatively with a large number of seemingly different types of properties; (c) identify quantitative behavioral rules which are generally valid for Very different crystalline polymers; (d) clarify component roles such that new techniques and processes result; and (e) predict the properties of a crystalline polymer for structural states not previously tested. Using two dissimilar crystalline polymers, isotactic polypropylene and poly(ethylene terephthalate), as examples, the general validity and unifying power of the structural approaches is demonstrated.
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    Polymer Engineering and Science 16 (1976), S. 334-343 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Constitutive relationships are presented to relate the directional dependence of the mechanical properties of anisotropic, partially crystalline polymers to (a) the percent crystallinity, (b) characteristics of the crystalline and amorphous orientation distribution, and (c) the mechanical properties of the crystalline and amorphous components. These relationships were tested with structural and dynamic mechanical data obtained for isotactic polypropylene films in various states of crystalline and amorphous orientation. The dynamic mechanical properties of the crystalline and amorphous components were treated as parameters and evaluated from dynamic mechanical measurements along the longitudinal and transverse direction of three different film samples. These mechanical parameters, and the associated structural parameters, were in turn used to predict the dynamic mechanical spectra for a fourth, independent, film sample. The predicted values for the storage and loss modulus, along various directions of loading, were within 10 percent of the measured values over the temperature range of -80°C to 80°C.
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  • 45
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    Polymer Engineering and Science 16 (1976), S. 344-352 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The Halpin-Tsai equations are based upon the “self-consistent micromechanics method” developed by Hill. Hermans employed this model to obtain a solution in terms of Hill's “reduced moduli”. Halpin and Tsai have reduced Hermans' solution to a simpler analytical form and extended its use for a variety of filament geometries. The development of these micromechanic's relationships, which form the operational bases for the coniposite analogy of Halpin and Kardos for semi-crystalline polymers, are reviewed herein.
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  • 46
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    Polymer Engineering and Science 16 (1976), S. 465-472 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of annealing on the microstructure of commercial grade poly(vinyl chloride) was investigated by calorimetric, X-ray and viscoelastic measurements. The degree of crystallinity increases with increasing annealing temperature from above the glass transition temperature up to 130°C, at which point the degree of crystallinity takes on a maximum value. Also, the crystal melting temperature increases with increasing annealing temperature. Thermal analysis and X-ray study suggest that the crystallite of poly (vinyl chloride) decomposes by thermal degradation when annealed, above 170°C. The isothermal crystallization process is analyzed using Avrami's equation employing the degree of crystallinity as a function of annealing time at various annealing temperatures. The crystallization rate has a maximum value at around 140°C. It is expected that the crystalline texture grows in the shape of a lineal-like habit, judging from the magnitude of Avrami's constant and from a study of the X-ray intensity distribution. The αf-transition was observed to occur at temperatures 5 to 10°C lower than the crystalline melting temperatures for annealed specimens of poly(vinyl chloride) using a dynamic spring analysis. The αf-transition may be attributed to thermal molecular motions with a long time scale, resulting from the cross-link points introduced by the small crystallites.
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  • 47
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    Polymer Engineering and Science 16 (1976), S. 473-479 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The chemistry of p-xylelene and of its analogues has been reviewed. Its modes of formation and polymerization to poly-p-xylelene have been described, and the initiation and hypothetical termination steps have been discussed. The reactions taking place in the gas phase and in the deposited film are contrasted with those taking place in solutions. The problems of crystallization of the polymer simultaneously proceeding with its growth have been stressed. Finally, the properties of poly-p-xylelenes and their application in the coating industry have been described in some detail, emphasizing the special advantages of gas-deposition leading directly to a solid and coherent film. Some future fields of application of this technique have been outlined.
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    Polymer Engineering and Science 16 (1976), S. 490-495 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Two kinds of thermodynamic theories, which seem to be applicable to polymer deformation and flow, have been developed in the recent literature. One of these approaches utilizes entropy far from equilibrium as a primitive undefined concept. The alternate kind of theory involves the idea of a quasi-static process as a primitive concept. In this work, an approach based on internal state variables (specifically, the micro structure of the polymeric material) is used to argue that both primitive concepts are in some sense legitimate on physical grounds. In particular, the legitimacy of the quasi-static process concept is related to the smoothness of the function delivering the rate of change of the microstructure.
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    Polymer Engineering and Science 16 (1976), S. 480-489 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new apparatus has been constructed to measure the thermal conductivity and the thermal diffusivity of reactive and nonreactive liquids and solids. The method used consists in suddenly subjecting the test specimen to a thermal flux and measuring the velocity of the heat wave across the sample. Maintaining the heat flux leads to a steady thermal gradient across the sample from which the thermal conductivity can be determined. The test duration is short relative to durations employed by existing conventional techniques and thus causes only a small thermal disturbance to the sample of the order of 1 to 2°C. Thermal properties of liquids and solids, including thermoplastics and a typical epoxy resin during cure with different equivalents of an aromatic diamine hardener have been measured near room temperature. Experimental data compare favorably with literature values for similar systems. Variations in thermal conductivity and diffusivity during cure have been obtained through a series of individual discrete measurements to cover the whole isothermal cure history. The results have been analyzed and discussed with respect to the cure characteristics of the resin and the nature of the physicochemical changes the material undergoes during cure.
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  • 50
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    Polymer Engineering and Science 16 (1976), S. 507-509 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In a previous paper, results of morphological studies using electron microscopy and X-ray diffraction were reported concerning random and non-random olefin copolymers of ethylene. As comonomers, relatively low concentrations of n-alpha alkenes and 5-methyl norbornene-2 were used. It was tentatively concluded that one possibility for morphological changes observed in the n-alpha alkene copolymers was a change in direction of chain folding. These studies have been continued with copolymers of ethylene and acenaphthylene. The intent was to pursue effects of vicinal substitution; however, the result was to produce ethylene copolymers of quite high comonomer content which were crystalline and showed no evidence of an independent beta mechanical transition. Further, definite evidence was found to indicate a change in the direction of chain folding in the polymer crystals.
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  • 51
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    Polymer Engineering and Science 16 (1976), S. 496-506 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Incompatible blends comprised of polystyrene and various high density polyethylenes were processed into tapes, in which both the phase and molecular orientations were parallel to the machine direction, by a combination of extrusion and mechanical stretching of the melt prior to quenching. Machine direction tensile yield strengths and ultimate elongations were found to be considerably higher than those obtained for comparable compression molded samples throughout the range of blend compositions and processing conditions investigated. Transverse tape properties were consistently poor due to poor interfacial adhesion. An optimum in machine direction properties was observed as the stretch ratio was increased at various melt temperatures. This optimum is likely due to a competition between morphological and molecular orientation rates during the stretching process and is a complex function of stretching rate and melt temperature as well as blend composition, relative phase viscosities, polyethylene crystallinity, and interfacial adhesion. Tapes stretched at high melt temperatures tended to show decreasing ductility and increasing tensile strength as room temperature storage time increased. This is believed to be due to secondary crystallization of the polyethylene phase. Oriented tapes were found to be easily fibrillated by mechanical heating to form a pulp. This material may prove suitable as a high grade replacement for cellulose pulp in paper making and could be formed at low cost from waste plastic feed stock.
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  • 52
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    Polymer Engineering and Science 16 (1976), S. 510-511 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polyolefins are generally known either as partially crystalline thermoplastics or as elastomers. With the finding in the ethylene-acenaphthylene copolymer system of the unusual properties of high crystallinity, high modulus, and no independent beta thermomechanical transition at high comonomer contents, it appeared that it might be possible to prepare a block polymer system which would retain the desirable low temperature transition near -110°C and “hard” acenaphthylene copolymer segments as well. Attempts were made, and the resulting terpolymer is described. An intermediate crystallinity polymer of apparently broad composition distribution was obtained with the modulus of high density polyethylene but the elongational characteristics of low density polyethylene.
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  • 53
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    Polymer Engineering and Science 16 (1976), S. 512-525 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The phenomenon of flow-induced crystallization was investigated using a linear polyethylene above its normal melting point flowing continuously in a Biconical Rheometer. It was found that the resin crystallized in the superheated state at rates which increased with increasing shear rate and decreasing temperature. A method of analysis of the temperature dependence of the various stages of flow induced crystallization is proposed. It deals with and attempts to explain the experimental fact that a higher viscosity enhances the rate of flow-induced crystallization in contrast to the effect of viscosity on the rate of quiescent crystallization. Some of the flow-induced crystallization samples were transparent and exhibited a high DSC thermogram “tail”.
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  • 54
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    Polymer Engineering and Science 16 (1976), S. 529-536 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: It is the objective of this paper to demonstrate the applicability of cold compaction molding followed by a sintering treatment to the processing of polystyrene powders. The influence of pressure, compaction speed, and peak pressure dwell time on the green (as compacted) density and the green tensile strength, as well as the effect of sintering on the tensile strength and dimensional change, were evaluated. The resulting data indicate that room temperature compaction alone is insufficient to provide adequate tensile strength for the compacts. Sintering the green compacts at temperatures of 150 to 173°C markedly improves the tensile strength while simultaneously causing a thickness change in the compacts. This thickness change results from gas evolution, pore shrinkage, and viscoelastic recovery of the residual stresses induced by pressure. For compacts of 0.225 in. thickness, an optimum sintering treatment of 173°C for 30 mins is recommended to provide a tensile strength of 4,000 psi and a thickness change of less than + 7 percent. Coining (repressing) the green compacts does not appreciably affect the sintered strength. However, a finer particle size improves the sintered properties. A review of the literature on the flow behavior of polystyrene suggests that a non-Newtonian viscous flow mechanism is followed by a Newtonian one as sintering progresses.
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    Polymer Engineering and Science 16 (1976), S. 575-578 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The ultimate strength of polymer concrete was investigated utilizing epichlorohydrin/bisphenol A-type epoxy resin. Parameters were tested in an effort to conclude how variation of a specific parameter would affect the compressive strength of the polymer concrete. The parameter testing included studies to determine the effect of the polymer loading; the catalyst; the exothermic reaction; aggregate type, gradation and moisture content; curing age; and aggregate additives of portland cement and lime-stone powder.
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    Polymer Engineering and Science 16 (1976), S. 567-574 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The solid-state extrusion of polypropylene by hydrostatic pressure has been investigated at four different temperatures: 25, 50, 75, and 100°C. The pressure to effect extrusion was found to be essentially a linear function of the extrusion ratio at each temperature, while the magnitude of the extrusion pressure, for any given extrusion ratio, decreased appreciably with increasing temperature. With increase in extrusion-ratio, the polypropylene extrudates became increasingly transparent. After passing through the extrusion dies; the Sample showed some elastic recovery. The amount of this recovery decreased with increasing extrusion ratio, X-Ray diffraction measurements taken before and after extrusion showed reduction in sharpness of the crystalline Peaks. Differential, scanning calorimetric measurements, on the other hand, indicate that the relative heat of fusion of the extrudates increases with the extrusion ratio at each extrusion temperature. It also increases with extrusion temperature for a given ratio. Tensile stress-strain tests were made at various hydrostatic pressure levels on the extrudates obtained at 25°C and the extrusion ratio of 2.8. Unlike on the virgin sample of polypropylene, ho yield maximum was observed on the extrudate sample at all pressures investigated. However, the effects of pressure on the relative increase in the yield stress-and the modulus of the extrudate are comparable to those of original, unoriented samples.
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    Polymer Engineering and Science 16 (1976), S. 593-601 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Previous work has shown evidence that PMMA and PEMA are miscible with PVF2. The present paper examines in detail the behavior of PEMA/PVF2 blends by thermal analysis and dynamic mechanical testing. All transitions and relaxations are affected by blond composition but in a complex manner owing to the crystallization of PVF2 from blends rich in this component. Inadequacies of the simple two-phase picture of semi-crystalline polymers is believed responsible for some of the transitional behavior observed here. The melting point depression observed for PVF2 was found to be consistent with an exothermic heat of mixing for this pair comparable in value to that found for PPMA/PVF2/All evidence here are consistent with the previous conclusion of miscibility for these systems.
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    Polymer Engineering and Science 16 (1976), S. 602-608 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Experiments are described which show that stresses in amorphous polymers can be measured by diffracting X-rays at high Bragg angles from a filler consisting of crystalline particle or powders. The method is applicable, when calibrated, to both applied and residual stresses, to stress relaxation studies, to both tensile and compressive stresses, to both interior and surface positions in an object, and to composites of various types as well as to polymers that are substantially homogeneous. In the lower (Hookian) range, strains and stresses in metallic embedded particles increase linearly with applied stresses and strains in the matrix. When applied stresses exceed an apparent yield point, which correlates with the yield strength of the metallic filler, the elastic strains in the particles increase only slightly or even decrease as the matrix strains are increased, and with constant applied strain, the particles reveal changes due to relaxation. Strains in the particles are found to be smaller, and stresses higher, than in the matrix. Tests of graphite-fiber epoxy composites with embedded filings of silver or aluminum alloy show that compressive residual stresses from curing at 350°C and cooling to room temperature are registered in the particles as well as stresses externally applied to the cured composite. Precision of the order of 1000 psi (0.7 kg/mm2 or 6.9 M Pa) was obtained with measurements made and evaluated rapidly and simply; with more refined techniques, much higher precision would be possible.
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    Polymer Engineering and Science 16 (1976), S. 609-614 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Characteristics of the fracture of fiber reinforced plastic composites are described in terms of the elastic stress distribution at the crack tip, the mechanism of crack tip damage, and the modes and conditions of final fracture. The three-dimensional, stress field at the tip of a sharp crack in a laminate is presented and contrasted to traditional two-dimensional models. The response of the material in the form of inter- and intraply damage formation and growth under increasing load is characterized, and its effect in blunting the main crack is examined. The final fracture conditions, which may range from quasi-brittle to notch insensitive, are discussed and related to the damage zone extension. Observed and anticipated effects of various material and geometric parameters are also discussed.
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    Polymer Engineering and Science 16 (1976), S. 626-637 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An extensive set of rheological data, including steady shear, normal stress, and oscillatory response functions, have been obtained for several polyethylene melts, and a modified form of the Spriggs nonlinear co-rotational model has been used to represent the data. The resulting model was used to predict the transient stress response of the melts in a simplified model of the extrusion process, with a resulting criterion for the onset of melt distortion in terms of readily evaluated rheological parameters. The predicted occurrence of melt distortion based on this criterion agreed well with observations for the polymers in this study as well as for a variety of other polymers reported in the literature.
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    Polymer Engineering and Science 16 (1976) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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    Polymer Engineering and Science 16 (1976), S. 638-644 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This report describes the influence, of (a) degree of biaxial orientation, (b) stretching rate, and (c) stretching temperature on the tensile, dynamic mechanical and dielectric properties of non-impact modified PVC. A new parameter designated “planar strain” is used to correlate anisotropic property values with both equal and unequal biaxial stretching in a single two-dimensional plot, thereby providing a direct comparison of the effects of two or more biaxial stretching ratios. It is shown that optimum stretching conditions depend to some extent upon end use and that a 2 × 2 stretch ratio is optimum for impact resistance. The actual property/processing condition relationships exhibit very complicated interactions and are correlated empirically in this study. The dynamic measurements suggest that overall local segmental beta motion is increased after orientation but that the relative chain alignment makes it more difficult to activate this motion.
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  • 63
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    Keywords: Chemistry ; Chemical Engineering
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Based on an understanding of the basic mechanisms and governing laws for liquid mixing, a new concept for increasing the efficiency of laminar mixing is advanced. The new concept is motivated in part by the observation that in laminar flows, the interface between two fluid components tends to line up parallel to the streamlines, leading to decreased mixing efficiency. This decrease in effectiveness can be overcome by simultaneously applying mechanically induced shear forces and electrically induced destabilizing forces (which act on the interfaces) to mix the liquids. Results show a dramatic increase in mixing efficiency with the electrical-mechanical hybrid system. Descriptions of the analytical and experimental work done to characterize the concept and prove its efficacy are presented in detail. Scale-up factors are discussed in terms of dimensionless groups.
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    Polymer Engineering and Science 16 (1976), S. 687-689 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper takes a critical look at the applicability of the currently accepted Resin Flow Method of prepreg evaluation. The Resin Flow test is generally a high pressure, small dimension lamination experiment which is used to characterize materials processed tit high pressures and large dimensions. Several simple experiments are described which support previously reported theory and provide a basis-for more meaningful comparison of materials based on appropriate scaling via an analytical flow model.
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    Polymer Engineering and Science 16 (1976), S. 697-705 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Multilayer flat film coextrusion was studied, both experimentally and theoretically. For the experimental study, a sheet-forming die with a feedblock was designed, and plastic films of three and five layers were coextruded. The die was provided with three pressure transducers in the axial direction in order to determine the pressure gradient in the die, allowing the determination of the reduction in pressure drop when different combinations of two polymer melts were coextruded. Polymers used for coextrusion were: (1) low density polyethylene and ethylene-vinyl acetate; (2) low density-polyethylene and high density polyethylene; (3) low density polyethylene and polystyrene. For the theoretical study, the z-component of the equations of motion for steady fully-developed flow were solved using a power law non-Newtonian model, Comparisons were made between the experimental and the theoretically predicted volumetric flow rates. Predictions of the velocity distributions, shear rate profiles, and shear stress distributions were made as functions of the processing conditions and the rheological properties of the individual polymers concerned.
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    Polymer Engineering and Science 16 (1976), S. 690-696 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The dependence of the melt flow of polymers on temperature is of both theoretical and commercial importance. A useful representation of the temperature dependence of the shear-dependent viscosity, based on superposition of flow curves at various temperatures, has previously been presented by the author for several olefin polymers. This method is extended in the current work to styrene and styrene-acrylonitrile based polymers. The melt viscosity-temperature dependence of a broad range of styrenic polymers and copolymers, ranging from polystyrene to 82 percent AN styrene-acrylonitrile copolymer, with and without rubber inclusions, was investigated. Flow curves at the various temperatures were found to be superimposable, as had earlier been found to be the case for olefin polymers, and a unique quantitative relationship between the superposition shift factors and temperature was found applicable to the entire family of polymers. The resultant energy of activation for viscous flow is in excellent agreement with previously published results for polystyrene Newtonian viscosities, and the magnitude of the shift factors is consistent with a limited set reported for ABS polymers. Independent tests of the derived relationships provided excellent prediction of measured viscosities. Thus, it is considered that a general viscosity-temperature relationship has been defined for this family of polymers, independent of molecular structural detail.
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    Notes: Thermoplastic foam properties and processing stability depend strongly on the ability to obtain the proper rheological properties for the polymer melt at temperatures where the decomposition of a chemical blowing agent may be controlled. An experimental technique has been developed which allows stable processing conditions to be determined for the continuous extrusion of foamed thermoplastics with known foam properties. The technique involves a thermal analysis of the polymer-blowing agent formulation to determine the range of controllable extrusion temperatures. Rheological analysis was carried out using a slit die to establish a relationship between the thermal blowing characteristics of the polymer composition and rheological data which correlate with foam extrudability and the physical properties of the foam. This provides a means of predicting both processability and foam properties which aid in the scale-up to production. The rheological-foam property correlations were confirmed by continuous foam extrusion on a laboratory extruder.
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    Polymer Engineering and Science 16 (1976), S. 721-724 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Following the discovery that linear polyethylene can be drawn to very high draw ratios to produce oriented fibres and films with ultra-high initial moduli, a similar study has been undertaken for polypropylene. In particular, the modulus/draw ratio relationship has been obtained for a range of polymers of different molecular weight and molecular weight distribution. The effects of thermal history and draw temperature were studied, and it was shown that under optimum conditions material with an initial modulus at room temperature of 1.9 × 1010 Nm-2 (205 gdtex, 3 × 106 psi) can be obtained. This value is at least 50 percent greater than those previously recorded for drawn fibres and about one half of the theoretical modulus.
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    Polymer Engineering and Science 16 (1976), S. 799-802 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new rheometer has been developed to measure the extensional viscosity of molten thermoplastics at typical extrusion temperatures. It is at the same time versatile and easy to operate. One end of the test specimen is held in a fixed position by an oil-cooled chimp mounted on the end of a force transducer. The other end of the specimen is held by, a moving, oil-cooled chimp. The moving clamp is suspended from a carriage mounted on a ball nut which travels on a long lead screw. The lead screw is driven by an electric motor operating through a gear box, and its speed can be controlled to produce either a constant stress (creep) or a constant strain-rate (stress growth) experiment. Experimental results have verified that in the “constant strain rate” mode the strain rate does rise rapidly to a constant level. Measurements on several polyethylene resins indicated that the extensional viscosity rises with strain rate at low strain rates.
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    Polymer Engineering and Science 16 (1976), S. 823-826 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A recent and joint ACS/SPE symposium featured 40 papers on the fundamental mechanism of brittle fracture, low-speed crazing and fracture, high-speed impact mechanisms, fatigue failure, multi-phase polymer systems, and reinforcing fibers. A survey of these papers indicates the present state of our knowledge in this field, and the rapid progress it is making toward the development of high-performance plastic materials.
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    Polymer Engineering and Science 16 (1976), S. 827-830 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A rotating mandrel in a tubing die produces multiaxial orientation in the extruded melt. If the polymer melt is quenched rapidly, some multiaxial orientation is retained in the resultant tubing. Multiaxially oriented tubing exhibits reduced crack propagation and some enhancement of yield and fracture strengths. During the processing of multiaxially oriented tubing, relaxation occurs after the melt leaves the die and gives rise to wall thickening and reduction in the lumen of the tubing; the magnitude of these effects is a function of the rate of mandrel rotation.
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    Polymer Engineering and Science 16 (1976), S. 785-791 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Plates of bisphenol-A polycarbonate and poly(methyl methacrylate) have been quenched in ice water from temperatures slightly above their glass transition temperatures. Residual stresses are thus created, Measurement of these residual stresses has been accomplished by the “layer removal” method and the stress distributions through the thickness are presented. Compressive stresses, approximately 3000 psi, exist at the surface while tensile stresses-of at least 1000 psi exist in the interior. It is shown that these residual stresses can influence the notched Izod impact strengths for polycarbonates. The mechanism is thought to be suppression of craze initiation in advance of the notch due to the presence of residual compressive stresses for specimens notched prior to quenching. In the case of poly(methyl methacrylate), it is shown that compressive residual stresses at the surface can cause plastic yielding to occur in bending experiments resulting in permanent deformation and greater energy absorption.
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    Polymer Engineering and Science 16 (1976), S. 817-820 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In spite of the availability of- almost fifty commercial synthetic plastics, many new ones were announced at the recent First Chemical Congress of the North American. Continent at Mexico City. Among these are the high temperature resistant aramides and imides, poly(phenylene sulfide), poly(phenylene oxide), poly(aryl sulfone), H resin, modified phenolic resins and the phosphazenes. Other new polymers are block and graft copolymers, conductive polymers, barrier resins, poly 1,2-butadiene, polyolefins and polyurethanes. New coupling techniques and shortages of feed stocks have resulted in a renewed interest in filled plastics and recycled polymers.
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 16 (1976), S. 831-835 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polyphenylene sulfide is a new engineering plastic characterized by a unique combination of useful environmental, mechanical, and flame resistant properties. This paper presents a variety of new developments in molding methods and long term properties of polyphenylene sulfide. Optimum conditions for fabrication by injection molding, compression molding, and free sintering techniques are described along with a comprehensive tabulation of mechanical, factional, and electrical properties of various filled and unfilled compositions. The effect of injection molding conditions and post-treatments, such as annealing, on mechanical behavior is discussed. Long term stability of molded specimens of the polymer to a variety of chemical environments as well as oven aging studies are reported. The significance of these properties is illustrated by a discussion emphasizing new applications for various compositions based on polyphenylene sulfide.
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  • 75
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    Polymer Engineering and Science 16 (1976), S. 836-840 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Inhibitors to prevent vinyl polymerization were selected rapidly and effectively by differential scanning calorimetry. The autopolymerization temperature (APT) and the relative polymerization rate constants were used to define the type and amount of inhibitor necessary to prevent polymerization of acrylic esters and acrylamides. The APT was also used to determine the amount of inhibitor in a vinyl monomer. The rate of polymerization and storage stability of vinyl monomers were determined by these methods.
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  • 76
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    Polymer Engineering and Science 16 (1976), S. 1-10 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The history of PPO®, polymers of 2,6-dimethylphenol, and Noryl® resins is described from the initial discovery through commercialization. The scope of oxidative polymerization as applied principally to phenols and acetylenes is outlined as well as the chemical reactions which can be performed on the resulting polymers.
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  • 77
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    Polymer Engineering and Science 16 (1976), S. 11-14 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Gel permeation chromatography and liquid Chromatography are used for analyzing various epoxy resins. The chromatograms are compared with related information available from each. Because the separation is based on different principles, each method gives unique and different information about the same sample. For a complete analysis of epoxy resins, both techniques seem to be required.
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    Polymer Engineering and Science 16 (1976), S. 36-40 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effects of shock cooling and swelling with carbon tetrachloride on the dynamic mechanical spectrum of high density polyethylene have been studied with a torsional pendulum. The resulting spectra have a well-defined loss peak at -65°C which is associated with the glass transition of high density polyethylene. Similar experiments on polypropylene and low density polyethylene demonstrate the similar effects of these treatments on their glass transitions.
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  • 79
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    Polymer Engineering and Science 16 (1976), S. 41-45 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The length-temperature behavior of elongated elastomeric networks of cis-1,4 polybutadiene was observed following abrupt, nearly step-function changes in the temperature of the specimen environment. The thermal expansion behavior is reversible, and the transient length changes are in the direction anticipated from rubber elasticity theory, i.e., dL(t)/dT is negative. The observed long-time values of the thermal expansion coefficient are in good agreement with equilibrium length-temperature coefficients reported for other elastomers. Results indicate that both thermal diffusion and retarded creep deformation contribute to the transient phenomenon, with the latter mechanism dominating.
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  • 80
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    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A number of investigators have reported on the high degree of piezoelectricity manifested by oriented films of poly(vinylidene fluoride) (PVF2). To develop applications for this piezoelectric effect, our laboratory is involved in a systematic investigation of the factors responsible for this remarkable behavior of PVF2. In a unique high-speed process, commercial PVF2 film was uniaxially stretched to a series of draw ratios ranging up to 7/1. The resulting films were characterized by techniques involving infrared spectroscopy, density, birefringence, sonic modulus, X-ray diffraction, and dynamic mechanical response. The films were then poled at various electric field strengths, temperatures, and times. Correlations have been made between draw ratio, physical properties, poling conditions, and piezoelectric activity of the films. It was found that the piezoelectric activity increased to limiting values with draw ratio, poling voltage, poling temperature, and poling time. It was evident that for PVF2 film a significant amount of oriented phase I crystalline material is required for high degrees of piezoelectric activity. The Appendix gives the apparent rate dependence observed for the piezoelectric effect when signal is measured with a voltage sensor of relatively low input impedance.
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  • 81
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    Polymer Engineering and Science 16 (1976), S. 46-53 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This article describes the use of the Rheovibron Model DDV-III-B with a parallel plate modification of the sample holders to obtain oscillatory data in the shear mode for several high density polyethylene melts. A detailed analysis of the Rheovibron to obtain the dynamic shear: moduli of polymer melts using the new sample holders is given, as well as a procedure for determining the instrument compliance and inertia parameters which must be considered in analysis of the data. Using the principle of time-temperature superposition, the data are extended to an equivalent frequency range of 1500 rad/sec. These data are compared with those obtained using the Weis-senberg Rheogoniometer Model R-17 for the same polymers. It is concluded that reliable measurements for dynamic shear moduli for polymer melts using the Rheovibron Model DDV-III-B with the modified sample holders can be made for melts with indices of about 5 or less (i.e., zero shear viscosities of 6.0 × 104 poise or greater).
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    Polymer Engineering and Science 16 (1976) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 83
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    Polymer Engineering and Science 16 (1976), S. 54-58 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polyethylene and reactive, high molecular weight polydimethylsiloxanes have been blended under conditions of shear and elevated temperature in order to form uniform, thermoplastic blends. The materials can be extruded, coated on wire, injection molded, or compression molded. Despite the thermoplastic nature, a high gel fraction is present. A structure is proposed consisting of microgelled and grafted particles of silicone dispersed in polyethylene. When compared to pure polyethylene, the blends show lowered modulus over a temperature range of -150 to +65°C increased gas permeability, and lowered mixing energies. Electrical properties include corona resistance superior to polyethylene and a resistance to degradation under conditions simulating those experienced by buried cables superior to typical silicone rubber. Other electrical properties are intermediate between the values observed in the component polymers.
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    Polymer Engineering and Science 16 (1976), S. 59-64 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The migration of phthalate plasticizers from poly (vinyl chloride) into edible oils has been analyzed. The principal method used involved 14C-labeled dibutyl and dioctyl phthalates with detection by liquid scintillation spectrophotometry. In most cases, the migration of the main plasticizer was accompanied by the migration of the secondary plasticizer, when present, and by diffusion of the oil into the polymer. Comparison of the scintillation results with those obtained by weight loss measurements can give quantitative information on the amount of the liquid medium that diffuses during the migration process. The effect of the following factors on the migration process was examined; (a) the nature and acidity of the edible oil, (b) the composition and amount of phthalate plasticizer, (c) the amount of epoxy plasticizer, and (d) the temperature and time of contact.
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    Polymer Engineering and Science 16 (1976), S. 65-73 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Although polymeric materials have a relatively minor role in our solid waste disposal problems, they display a particular prominence as litter because of their environmental permanence, Photodegradation has been suggested as one possible solution, but considerable debate has centered on the need, costs, and limitations of such degradable systems. The chemical mechanisms involved in practical photodegradation are illustrated by a review of the oxidation schemes for normal and sensitized polystyrene. The different mechanisms associated with the use of additives, comonomers, and halogens are considered in some detail. A listing of patent literature relating specifically to photodegradable polystyrene is included in the review.
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    Polymer Engineering and Science 16 (1976), S. 125-125 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 87
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    Polymer Engineering and Science 16 (1976), S. 126-137 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The elongation and orientation of randomly coiled macromolecules in a strained melt or solution reduces their entropy and thus increases the crystallization or melting temperature of the ideal lattice. At any given temperature of experiment this enhances nucleation and crystal growth rate. As a rule, linear primary nuclei are formed. They contain more or less extended chains. The existence of row nuclei reduces the local gradient in the liquid to such an extent that further crystallization proceeds by epitaxial overgrowth of folded chain lamellae. Densely packed cylindrites are formed with the ribbon-like lamellae radiating from the central row nucleus. The irregular shish-kebab structure observed in stirred or sonicated solutions seems to be formed by subsequent exial deformation of cylindrites in the flow field. It displaces the lamellae irregularly and thus produces a great many microfibrillar elements parallel to the original row nuclei. The almost completely extended chains in the shish yield a high elastic modulus and tensile strength for exial loading. The shish-kebab morphology in fibers as spun does not affect to a great extent the mechanical properties obtainable by subsequent drawing. The lamellae are transformed into microfibrils in very much the same manner as in spherulitic samples. But the highly regular orientation of lamellae seems to result in a more uniform drawing and hence a stronger fiber. In an extremely high temperature and pressure gradient, the melt extrusion produces hard elastomers where the lamellae of the cylindrites seem to be locally stapled. Upon application of tensile load in the extrusion direction, the intervening sections bend like beams, thus forming thin holes extending in the direction perpendicular to the load. The holes enormously enhance the permeability for gases and liquids. The elastic bending of lamellae yields the high recoverable strain and low tensile modulus.
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    Polymer Engineering and Science 16 (1976), S. 222-226 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A macrostructure consisting of 1500 Å long network, elements has been studied in unoriented and oriented poly(ethylene terephthalate) film. The long dimension of the structure is oriented transverse to the stretch direction. A length to width ratio of approximately 10:1 is observed. The structure is observed by scanning electron microscopy after room temperature etching with n-propylamine under special conditions. Also studied are weight loss measurements for up to 80 hrs of etching and molecular weight degradation by gel permeation chromatography. The induction time before weight loss commences depends on sample elongation and thermal history. A coincidence of the following times are observed: (I) commencement of weight loss, (2) development of a well-defined macrostructure by SEM, and (3) completion of molecular weight degradation. Therefore, visual evidence of a macrostructure occurs when weight loss has commenced which requires degradation to products soluble in the etchant. The GPC curves vs rich time show that etched film oriented to a crystalline state possesses two molecular weight peaks. The peak for polymer in which no degradation occurred is replaced by a peak for polymer of nine to ten repeat units which is highly crystalline and, therefore, resistant to further attack.
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    Polymer Engineering and Science 16 (1976), S. 235-239 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Current industry trends toward increasing automation, as well as increased flexibility in material selection have focused a strong spot light on thermoset injection molding. The growth of thermoset injection molding is reviewed comparatively with the technical history and growth of thermoplastic injection. The progress we see to date and the promise for the future in material characteristics and properties, mold design features, equipment features, changing concepts and new thoughts are discussed.
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  • 90
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    Polymer Engineering and Science 16 (1976), S. 303-308 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The synthesis, processing characteristics, thermal propers, and adhesive and composite properties of polyphenvlqmnoxahnes are briefly reviewed. In addition, new high molecular weight soluble carbonate/phenylquinoxaline copolymers from the cyclopolycondensation of aromatic bis(o-diamines) with a bis(benzilyl) carbonate are reported.
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    Polymer Engineering and Science 16 (1976), S. 298-302 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Examples are given to show how molecular structures may be synthesized to prepare polymers useful for the formation of fibers intended for specific end uses, particularly for high performance applications. Current trends and developments taken from the literature are reviewed and some new work from the laboratories of Monsanto Company is presented concerning the use of aromatic polymers for heat and flame resistant fibers. Some new polymers and new routes of synthesis are described. Correlations are made between flame resistance as measured by oxygen index (O.I.) values and the structure of a large number of aromatic polymers.
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    Polymer Engineering and Science 16 (1976), S. 309-313 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: As part of an ongoing program to prepare and evaluate thermally-stable, processable materials, 18 aromatic, silicon containing polyamides (structures shown below) have been synthesized via interfacial polymerization of six silicon-containing diacid chlorides with 3,3′-diaminodiphenyl-nethane, 3,3′-diaminobenzophenone, and l-(3′-amino-benzy)-4-(3″aminobenzoyl)benzene. All polyamides were soluble in m-cresol and N,N-dimethylacetamide and had glass transition temperatures between 178 and 254°C, Thermogravimetric analyses conducted in static air on film specimens were-1 used to show 5 and 10 percent weight losses between 331-400°C and 354-440°C, respectively. 3,3′- and 4,4′-silane isomersR = R′ = Me; R = Me; R′ = Ph; R = R′ = Ph
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    Polymer Engineering and Science 16 (1976), S. 411-418 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The melt bon debility of ethyl en e copolymers to a high, pressure polyethylene has been investigated by a T-peel test consisting of polyethylene-copolymer-polyethylene. The three ethylene copolymers involved separately vinyl acetate, ethyl acrylate, and acrylic acid. The ethyl acrylate copolymers produce the highest peel strength over the test temperature range of -20 to 50°C, and also yield a high peel strength even at the bonding temperatures of 105-110°C, at which the welding of polyethylene to polyethylene does not occur. The observations of cross sections of the joints with an interference microscope show the presence of an interfacial boundary layer and a mixed layer (of the polyethylene and the copolymer). The relationship between the peel strength and these two layers is discussed. Further, the peel strength-temperature curves are compared with the tensile properties of the copolymers.
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    Polymer Engineering and Science 16 (1976), S. 537-543 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The influence of matrix properties on randomly oriented glass fiber epoxy composites has been studied. It is shown that an increased ductility (flexibility) of the matrix does not result in greater elongation to failure of the composite under tensile and flexural loads. The tensile (and flexural) strength and the modulus of elasticity are decreased as the ductility of the resin is increased. It is concluded that since the matrix material is subjected to a triaxial state of stress when the composite specimen is subjected to uniaxial loads, the effect of matrix modulus, Poisson's ratio, and yield strength are more important than the matrix ductility measured under uniaxial stress. The effect on mechanical properties of various surface treatments applied to the fibers is also investigated. Finally, scanning electron micrographs are presented showing matrix cracks, fiber debonding, and fiber pull-out.
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    Polymer Engineering and Science 16 (1976), S. 579-584 
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    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A method is presented for predicting rheological characteristics, such as shear dependent (non-Newtonian) viscosity and components of linear oscillatory (complex) response functions for polyethylene melts from molecular weight distribution data obtained from gel permeation chromatographic (GPC) analysis. The results are compared with measured values of the rheological functions obtained from a variety of instruments over an extensive range of shear rates-and frequencies. The agreement between predicted and measured rheological functions is quite good for high density resins. However, for a low density resin the agreement is not as good, although still reasonable over a considerable range of conditions. It is concluded that the quality of the GPC data is the key factor in the degree of success of the method.
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    Polymer Engineering and Science 16 (1976) 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Polymer Engineering and Science 16 (1976), S. 585-592 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Experimental studies of injection molding of polymer melts have classified two regimes of mold filling-simple filling and jetting. In this paper we have examined a wide range of polymer melts and mold designs in an attempt to devise a criterion for the transition between these regimes. This criterion is found to be related to the extrudate swell d, gate diameter D, and small cavity dimension at the gate h. For isothermal mold filling, if d/h exceeds 1.0, the-melt will contact the mold, stick to it, and induce a simple mold filling regime. The variation in behavior in vertical and horizontal mold filling is considered, as is the influence of barriers near the gate. For the non-isothermal mold case, the manner of filling is similar, and the criterion for jetting remains the same, The die swell behavior in the non-isothermal case is complex.
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    Polymer Engineering and Science 16 (1976), S. 652-654 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Quantitative Differential, Thermal Analysis has been used in the wire and cable industry for determining the degree of oxidative stability of polyolefins for quality control purposes in lieu of a direct antioxidant analysis, However, it has never been shown whether the presence of each additive in a stabilizer package could be detected by this method. The results presented here indicate that the presence of a primary antioxidant and a copper inhibitor in combination can be detected separately by comparing the oxidative induction times in copper and aluminum pans. The addition of a thioester synergist such as distearyl thiodipropionate, DSTDP, is evidenced by an increased induction time in aluminum pans. However, the presence of DSTDP makes it impossible by this method to determine whether an effective level of copper inhibitor is present since the sample shows a reduced stability on copper compared to aluminum. One of two factors can be invoked to explain these results: a) DSTDP interferes with the complexing ability of the copper inhibitor or b) the copper-inhibitor complex retards the synergistic effect of the DSTDP. In either case, this factor is not important at lower temperatures since oxygen uptake data at 130°C indicate that DSTDP is an effective synergist in the presence of copper.
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    Polymer Engineering and Science 16 (1976), S. 734-734 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Polymer Engineering and Science 16 (1976), S. 725-734 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Linear crystalline polymers can be processed to high degrees of orientation sufficient to produce dramatic increases in tensile strength and modulus. Three processes have been identified for inducing such orientation: cold drawing, hydrostatic extrusion, and solution spinning. All three processes utilize a high elongational velocity gradient in a critical temperature range to produce a high strength crystalline morphology. Although the molecular superstructure may differ in each case, the mechanical properties are similar, An increase in strength is achieved either through the creation of new tie molecules between crystal lamellae or through the creation of an extended chain crystal substructure. Temperature and molecular weight are the prime variables in determining which morphology will develop. The optimum processing temperature for many of the specific techniques is the crystalline dispersion temperature. At this temperature, the crystal structure is particularly adaptable to forming a new crystal morphology. Ul-tradrawn polymers are more Hookean in behavior than isotropic polymers and have properties similar to steel and glass. Polyoxymethylene has been processed most closely to its theoretical strength. Polyethylene, which is the most difficult to process, has achieved the highest modulus of any common polyolefin polymer, about 7 × 1010 Pa.
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