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  • Polymer and Materials Science  (23)
  • Analytical Chemistry and Spectroscopy  (5)
  • Wiley-Blackwell  (28)
  • 1990-1994  (28)
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  • Wiley-Blackwell  (28)
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  • 11
    Electronic Resource
    Electronic Resource
    An optical study of phase transitions of poly (ethylene terephthalate-co-p-hydroxybenzoic acid) liquid crystal (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 28 (1990), S. 1677-1684 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The copolyester containing 40 mol % ethylene terephthalate (PET) and 60 mol % p-hydroxybenzoate (HB) units has been reported by several investigators to be biphasic in the solid and the liquid states. The reported thermal transitions in the two phases, however, are in part contradictory, perhaps partly due to different polymerization conditions. The present work is a study of the transitions in each of the two phases of this copolyester by polarized light microscopy and by light transmission measurements. By light transmission measurements, the two phases were found to have two different glass transition temperatures for the onset of segmental motion, consistent with two assignable temperatures (T.). Cold crystallization and melting in each of the two different phases was also detected. The results help clarify the nature of transitions and agree with the results of dynamic mechanical analysis on the same thermotropic liquid crystalline copolyester.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1990.090281003
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  • 12
    Electronic Resource
    Electronic Resource
    A raman LAM study of lamellar thickness of virgin polyethylene powder (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 29 (1991), S. 1189-1192 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The lamellar thickness of polyethylene virgin reactor powder has been successfully measured using the Raman longitudinal acoustic mode (LAM). Relatively high lamellar thicknesses have been found. These values change with polymerization temperature in an unusual way, with lamellar thickness being larger for lower polymerization temperature, i.e., at higher undercooling for crystallization. Agreement within an experimental error of 10% has been obtained between values from LAM and those calculated by the Thompson - Gibbs equation from the melting point measured by differential scanning calorimetry.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1991.090291003
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  • 13
    Electronic Resource
    Electronic Resource
    A calorimetric investigation on high molecular weight polyethylene reactor powders (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 29 (1991), S. 1179-1188 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Reactor powders of high- and ultrahigh-molecular weight polyethylene have been investigated. Two different Ziegler-Natta synthesis processes were used: polymerization in a slurry and in the gas phase. Synthesis temperature range was 30-85°C. Monoclinic crystals were identified in samples synthesized at 30°C. Investigations of thermal parameters were carried out by differential scanning calorimetry. A range of heating rates (0.4-10.0°C/min) was used to obtain information on sample reorganization on heating. The corresponding melt-crystallized samples were scanned and their thermal parameters were compared with those obtained from the original nascent powders. Percent crystallinity and average lamellar thickness, computed by the Thompson-Gibbs equation, were found to be controlled by conditions of synthesis. For reactor powders, the fraction of crystallinity is found to be insensitive to synthesis temperature. Crystallinity is controlled mainly by the synthesis process type: slurry or gas phase. Lamellar thickness was found to decrease as synthesis temperature was increased. This trend is the opposite of what is obtained on melt crystallization and can be interpreted on the basis of Lauritzen and Hoffman's theory of crystal growth. Nascent reactor powders give experimental support for the dependence of lamellar thickness on crystallization temperature that follows the pattern described in the theory at high undercooling. The influence of molecular weight on crystallinity and lamellar thickness of both nascent powders and melt-crystallized samples was also studied. Catalyst and synthesis conditions were found to control crystallinity and crystallite dimensions of the reactor powders. Thus, polyethylenes suitable for a specific purpose can be obtained directly on synthesis.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1991.090291002
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  • 14
    Electronic Resource
    Electronic Resource
    Equibiaxial deformation of poly(4-methyl-1-pentene) by a forging process (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 535-540 
    Details
    ISSN: 0887-6266
    Keywords: poly (4-methyl-1-pentene) ; isotactic polypropylene ; biaxial deformation ; stress-strain behavior ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(4-methyl-1-pentene) (PMP) has been uniaxially compressed by a forging (equibiaxial) process. The rheology of the process has been examined for this semicrystalline polyolefin, melting point about 235°C. The yield energy, area under the compressive stress-strain curve up to the yield point, as a function of temperature was found to consist of two linear components of different slope. These two linear relations arise from the glassy and crystalline phases of PMP. The intercept temperature (Ti) at zero yield energy for the glassy phase has been evaluated. The attainable maximum compression ratio without sample rupture (CRmax) increased steadily on increasing forging temperature above Ti, and below Tm. In this range, the crystalline relaxation temperature (Tc), evaluated from an Arrhenius plot of yield stress was 160°C. Above Tc, a CRmax of 240 was reached. This value is five times higher than that attained for isotactic polypropylene (i-PP). However, the draw efficiency evaluated by elastic recovery in the plane direction of PMP (0.76) is lower than for i-PP (0.97). Differential scanning calorimetry analyses showed that the melting peak became a complex doublet on increasing compression ratio ( 〉 100). The drawing and stress-strain behavior of PMP are compared with i-PP. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1994.090320314
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  • 15
    Electronic Resource
    Electronic Resource
    Combined processing of polypropylene film by coextrusion and zone-annealing (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 43 (1991), S. 429-435 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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 order to improve the mechanical properties of polypropylene film, a new processing combining extrusion and zone-annealing has been applied. It was found that there are suitable conditions for each step in the combined processing. When the coextrusion draw ratio was low, the total draw ratio and modulus could be increased by the zone-annealing subsequently done. The highest modulus was obtained when the film was coextruded at extrusion draw ratio 4 and then zone-annealed at 120°C under 7 kg/mm2. The value was 12 GPa in Young's modulus or 17 GPa in dynamic modulus. The peak temperature of αc dynamic dispersion for the combinedly processed film was 109°C, which is higher by 10°C than that for the as-coextruded film. Four drawing methods were compared in dynamic viscoelasticity. These methods are the coextrusion, zone-drawing/zone-annealing, two-step coextrusion, and the combined processing by coextrusion and zone-annealing. The highest dynamic modulus for each method was arranged in the above order. The combined processing indicated the most effective improvement in mechanical properties, because it is believed that lamellae in the original film were broken by cooperating interaction of shear stress, compression, and tension on coextrusion and then the superstructure with a high crystallinity and a high molecular orientation was formed on zone-annealing.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070430303
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  • 16
    Electronic Resource
    Electronic Resource
    Rolling and roll-drawing of ultrahigh molecular weight polyethylene reactor powders (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 43 (1991), S. 1559-1564 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Ultrahigh molecular weight polyethylene (UHMWPE) reactor powders have been found to be processable in the solid state by the techniques of rolling and roll-drawing. Plates of compacted UHMWPE reactor powder were prepared below their melting points. These plates were then rolled at 124°C. The maximum uniaxial draw ratio (DR) obtained by multiple rolling was about 10. In additional experiments, rolled plates of a DR of 6 were further drawn by tensile stretching at a temperature of 135°C. The specimens prepared by rolling and by the two-stage draw were characterized by tensile measurements, differential scanning calorimetry (DSC), and X-ray diffraction. Results show that, on rolling alone, the tensile modulus and tensile strength achieved were 3 GPa and 42 MPa, respectively, at a DR of 9.6. The rolled plates were effectively drawn further to a total DR of 86. Such highly drawn films exhibited tensile moduli and tensile strength up to 81 and 1.3 GPa, respectively. A high crystallinity and high crystal orientation were also obtained by the two-stage draw.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070430819
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  • 17
    Electronic Resource
    Electronic Resource
    Properties of oriented polyethylene bars of large cross section (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 52 (1994), S. 1211-1215 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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 technique has been used to prepare uniaxially oriented polyethylene bars with rectangular end cross sections of 6 × 50 mm2. They were extruded at 110°C from billets of high density polyethylene. The tensile modulus and strength for the extrudate with a draw ratio (DR) of 14 were 17.9 and 0.32 GPa, respectively. The mechanicals were also measured in the transverse direction by means of the proportional elastic limit (PEL) bending test. The PEL results do not change after DR 14 due to the fibrillate structure formation. Crystallinity and shrinkage tests were made on samples taken over the bar cross section. They show that uniform properties were achieved across the width of the bar with proper die design. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070520905
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  • 18
    Electronic Resource
    Electronic Resource
    Pressure effects in the capillary flow of amorphous polymers (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 1355-1356 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070410543
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  • 19
    Electronic Resource
    Electronic Resource
    Polyester adhesion to chromium-coated steel for poly(ethylene terepthalate) and an isophthalate copolymer (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 1679-1683 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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 performance of PET [poly(ethylene terephthalate)] and a copolymer of PET has been tested as an adhesive for chromium-coated steel. Crystallinity in the polyesters is found to limit adhesion, probably by restricting chain mobility. Lamination temperatures above the melting point of each polyester give the best adhesion. Degradation of the polyesters at yet higher temperature resulted in both reduced polymer cohesion and adhesion.Optimum bonding to steel was obtained at lamination temperatures between 230 and 275°C for the copolyester and between 280 and 300°C for PET. The standard laminate compression time was 15 min at 50 kg/cm2. Adhesion was evaluated by the ASTM T-peel test. Assessments were made by both the peel energy and the peak load for peel.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070440923
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  • 20
    Electronic Resource
    Electronic Resource
    Thermal analyses of graft copolymers of poly (methyl methacrylate) main chain with poly (propylene oxide-b-ethylene oxide) graft chain (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 49 (1993), S. 1211-1222 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Poly(methyl methacrylate-g-(propylene oxide-b-ethylene oxide)) and poly (methyl methacrylate-g-(ethylene oxide-b-propylene oxide)), comprising chemically dissimilar sequences, exhibit intramolecular phase separation. These compositions have applications in coatings and as surface-tension modifiers. This paper presents the thermal behavior of these graft copolymers: separate samples of the homopolymer and of the grafts were also analyzed to provide comparisons. The phase behavior has been analyzed by differential scanning calorimetry and by dynamic-mechanical thermal measurements. Two glass transitions (Tg) are observed, caused by the partial incompatibility within the copolymers. The activation energy of the Tg relaxation process of the main chain is decreased by the graft chain. The influence of poly(propylene oxide-b-ethylene oxide) grafts on the thermal degradation of the poly(methyl methacrylate) (PMMA) main chain was studied by using thermogravimetric analysis. Prolysis of the graft copolymers occurs in three stages and begins on the graft chain and at a lower temperature than the pyrolysis of pure PMMA. Both the phase behavior and the thermal stability are found to depend sensitively on the composition of the copolymer. © 1993 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070490710
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