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  • 11
    Electronic Resource
    Electronic Resource
    Coconut husk lignin. III. Reactivity of alkaline extracts with formaldehyde (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 47 (1993), S. 37-44 
    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 this article we report results of the evaluation of the reactivity of polyphenolic extracts of coconut husk with formaldehyde in both acidic and alkaline media. The objective of this evaluation was to determine if the extracts could be used in the preparation of phenol-formaldehyde-type resins. Extracts were obtained using aqueous solutions of NaOH (with and without anthraquinone) and NH4OH. Because of their low Stiasny's Number values, these extracts are not suitable for phenol-formaldehyde resin preparation in acidic conditions unless they are mixed with phenol or phenolic derivatives. Nevertheless, extracts obtained with NaOH, especially at 100 and 120°C, showed sufficient reactivity with form-aldehyde in basic conditions and may therefore be considered suitable for resin preparation in an alkaline medium. The resins were characterized using infrared spectroscopy (IR), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). A transition temperature prior to decomposition was not detected; their thermal stability was similar to phenol-formaldehyde-type resins. © 1993 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070470106
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  • 12
    Electronic Resource
    Electronic Resource
    Photoacoustic monitoring of adhesive curing (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 35 (1988), S. 103-114 
    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 crosslinking reaction of an epoxy-based resin has been monitored by observing the time evolution of the thermal diffusivity of the mixture, using photoacoustic spectroscopy. The results are interpreted in terms of the expected thermal properties of liquids, polymers and solids, and a comparison with the reported viscosity behavior in similar systems is also made. The potential of the technique for following the curing process is discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1988.070350109
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  • 13
    Electronic Resource
    Electronic Resource
    Coconut husk lignin. II. Characterization by infrared and nuclear magnetic resonance spectroscopy (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 645-653 
    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: Results of the characterization of coconut husk lignin by infrared (IR) and proton nuclear magnetic resonance (H-NMR) spectroscopy are presented. Lignin was extracted with both alkaline and organosolv liquors. The IR spectra of dioxane lignin were very similar to those reported for hardwood lignins. Furthermore, these results combined with those obtained from the H-NMR studies suggest that coconut husk lignin can be classified into the Lm-type lignins. These lignins are characteristic of the monocotyledon class, of which the coconut palm is a member. The H-NMR studies showed that anthraquinone significantly inhibited the occurrence of lignin condensation during the alkaline extraction with sodium hydroxide solutions. This inhibition was more intense in the lignin extracted at 150°C than in that extracted at 100°C.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070450411
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  • 14
    Electronic Resource
    Electronic Resource
    Mechanical properties of acrylate networks formed by visible laser-induced polymerization. I. Dependence on photopolymerization parameters (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 51 (1994), S. 931-937 
    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 mechanical properties of network molecular systems, prepared through visible (Ar+) laser-induced polymerization of multifunctional acrylates, were studied as a function of some of the photopolymerization parameters. The properties investigated were the Young's modulus of elasticity and the stress-at-break, both derived from the stress versus strain test of dogbone-shaped photopolymerized samples. The parameters studied included the dye and co-initiator concentrations, and the laser power. We also compared the mechanical properties of samples made using different types of fluorone dyes and using two different amines as co-initiator. Better polymers are formed by the dyes with low fluorescence quantum yield. The three photopolymerization parameters modify the mechanical properties in a very similar way: they initially tend to increase both the Young's modulus and the stress-at-break but have a deleterious effect on the material strength if used in excess. N-phenylglycine, NPG, was shown to form stronger polymers (higher Young's modulus) than if N,N-dimethyl-2,6-diisopropylaniline, DIDMA, was used as co-initiator. We discuss the possible molecular mechanisms for such observations. © 1994 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070510515
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  • 15
    Electronic Resource
    Electronic Resource
    Poly(lactic acid) degradation in soil or under controlled conditions (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 62 (1996), S. 2295-2302 
    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 fate of a racemic lactic acid polymer (PLA50) was investigated by allowing parallelepiped plates of PLA50 to age in liquid medium containing a mixed culture of Fusarium moniliforme and Pseudomonas putida at 30°C. Microbial activity was monitored by measuring pH, lactic acid formation by high-performance liquid chromatography, and esterase activity in supernatant. Degradation of the plates was monitored by weighing, size exclusion chromatography, and visual examination. Under the selected conditions, pH increased up to 8, whereas it remained constant in the microorganism-free control. No significant lactic acid formation or esterase activity was detected in the supernatant during the experimental period (32 weeks). For the first 17 weeks, the water absorption rate of the plates was the same in both the microbial and the control media. Subsequently, plates absorbed more water in microbial than in control media. Typical surface/center differential degradation of plates was observed until 17 weeks, but it reduced progressively. At 32 weeks, specimens appeared completely disintegrated in the microbial medium. PLA50 plates were also buried in the soil for 8 weeks. After recovery, plates were allowed to degrade 8 weeks under controlled conditions. Scanning electron microscopy of these plates showed the development of some filamentous fungi at the surface and into the bulk of plates. Five fungal strains were isolated which appeared to be able to assimilate PLA50 oligomers in mixed cultures. It was assumed that PLA50 plates had been first degraded by chemical hydrolysis, followed by the bioassimilation of degradation by-products in both experiments. © 1996 John Wiley & Sons. Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Dielectric constant, optical transmission, and thermal diffusivity monitoring of iodine-impregnated polystyrene films (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 39 (1990), S. 1361-1373 
    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: A simple method for the iodine doping of atactic polystyrene films is described. The marked changes in the physical properties of the polystyrene films, such as dielectric constant, optical absorption coefficient, and thermal diffusivity, are presented as a function of the doping time. The results show strong evidences of the onset of an order-disorder transition as a function of the doping time.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070390612
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  • 17
    Electronic Resource
    Electronic Resource
    Coconut husk lignin. I. Extraction and characterization (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 633-644 
    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: Recently lignin has been the object of a renewed interest because of the need to use raw materials from renewable resources. One such resource is coconut husk, a material usually discarded during the copra extraction process. Due to its high lignin content, coconut husk has been recognized as having a variety of applications. Therefore, it is important to know the approximate structure of coconut husk lignin and those variations introduced by different isolation methods. This work reports a general characterization of coconut husk lignin. Results are given of the contents of hydroxyl and noncondensed guaiacyl units, the extractability of the lignin in alkaline and “organosolv” media along with thermal properties of the extracted lignins. The extraction system of NaOH-anthraquinone at 150°C was most conveniently based on the relatively low amount of condensed lignin generated.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070450410
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  • 18
    Electronic Resource
    Electronic Resource
    Blends of cellulosic esters with poly(caprolactone): Characterization by DSC, DMA, and WAXS (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 54 (1994), S. 1141-1159 
    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: Binary blends of poly(caprolactone) (PCL) with cellulosic esters [cellulose diacetate (CDA), cellulose acetate-butyrate (CAB), and cellulose triacetate (CTA)] were studied by using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and wide-angle X-ray scattering (WAXS) techniques, and qualitative comparison was made with the results obtained by polarizing optical microscopy. The PCL-CAB system was proved to be partially miscible, whereas PCL-CDA and PCL-CTA appeared to be immiscible. A double-melting behavior was showed for PCL-CAB and PCL-CTA blends. As these peaks did not shift by varying the heating rate of DSC runs, this behavior can be due to melting of two populations of crystals of PCL, which may be different in size. On the other hand, blends of PCL containing a low amount of CAB or CDA seem to develop more crystallinity for the PCL than this polymer alone. The solvent seems to have a certain influence on the thermal and morphological behaviors of the as-cast blends of these three systems, affecting the extent of crystallinity of PCL, as well as its Tm and ΔHf. This finding is discussed in the light of WAXS and polarizing optical microscopy results. © 1994 John Wiley & Sons, Inc.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070540818
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  • 19
    Electronic Resource
    Electronic Resource
    Compatibility studies on blends of poly(ethylene ortho-phthalate) and poly(vinyl acetate) (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 32 (1986), S. 6095-6106 
    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: Blends of poly(ethylene ortho-phthalate) (PEOP), and poly(vinyl acetate) (PVAc), appear to be compatible at all compositions, from visual examination at room temperature and differential scanning calorimetry tests. Both low- (PEOP-1) and high-molecular weight (PEOP-2) alloys with PVAc show a single composition-dependent glass transition temperature (Tg). Some blends show Tg values that are below the Tg for either of the pure polymers. Couchman's equation, with a slight modification, can be used to model Tg behavior. All PEOP-2 blends with PVAc, phase separate at high temperatures, whereas PEOP-1-PVAc blends remain miscible under the same conditions. The composition dependence of the blends refractive index shows a deviation from simple additivity rules, and a similar trend is observed in density measurements. When comparing Flory's characteristic parameters for the polymers, compatibility is predicted for PVAc-PEOP blends. In contrast, blends of PEOP and poly(methyl methacrylate) (PMMA), which has a similar chemical structure to that of PVAc are predicted to be incompatible, in agreement with experimental evidence. It is suggested that compatibility is produced because of possible specific interactions between the aromatic group of PEOP and the ester carbonyl on PVAc, which is not sterically hindered as is the corresponding moiety on PMMA.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1986.070320735
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  • 20
    Electronic Resource
    Electronic Resource
    Square wave adsorptive stripping voltammetry of nickel(II) in flowing systems at a wall-jet mercury film electrode plated in situ (1997)
    Weinheim : Wiley-Blackwell
    Electroanalysis 9 (1997), S. 145-149 
    Details
    ISSN: 1040-0397
    Keywords: Nickel ; Adsorptive stripping voltammetry ; Square wave voltammetry ; Flow analysis ; Wall-jet mercury film electrode ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A rapid and highly sensitive adsorptive stripping voltammetry method for the measurement of traces of nickel(II) in flowing systems is described. The method involves a mass-transport controlled preconcentration step, during which the NiII-dimethylglyoxime complex is adsorbed onto an in situ plated mercury film wall-jet electrode, followed by a reductive square wave stripping scan. The optimization of the experimental conditions and square wave parameters was carried out in order to achieve high sensitivity, reproducibility and fast response. The detection limit, restricted by the amount of nickel in the blank solution, was found to be 1.3 × 10-10 M, with a relative standard deviation of ±12.2% (n = 15), for a 1-min accumulation time. Linear calibration plots were obtained up to 8 × 10-10 M. This method can be applied to continuous on-line monitoring of trace levels of nickel in flowing systems, enabling easy automation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140090211
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