摘要:

AbstractBlends of a poly(ether sulfone) (PES) and a polycarbonate (PC) were prepared by melt‐mixing and were studied by tensile tests, differential scanning calorimetry, dynamic mechanical analysis, density measurements and transmission electron microscopy (TEM). The blends were found to be two‐phase systems and an interfacial layer was presumed to be formed between two phases, which was verified by TEM. A synergism of elongation at break and tensile modulus was shown in PES/PC blends. The effects of the crosshead speed on the mechanical properties were discussed for blends with different PES/PC weight rat

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052430101

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractFür die radikalischen Copolymerisationen von α‐Methylstyrol (MS) mit Methacrylnitril (MAN) sowie MS mit Acrylnitril (AN) wurden Untersuchungen zur Prüfung der in der Literatur postulierten kinetischen Modelle des „sequenzlängenunabhängigen”︁ bzw. „sequenzlängenabhängigen”︁ Terminalmodells mit Depolymerisationsschritten durchgeführt. Sie basieren auf Analysen der Sequenzverteilungen aus13C‐NMR‐Spektren. Resultate von13C‐NMR‐Untersuchungen an MS/MAN‐Polymeren variabler Zusammensetzung werden vorgestellt. Reaktionsparameter und Gleichgewichtskonstanten wurden direkt aus den Informationen der13C‐NMR‐Spektren für das Terminalmodell mit Depolymerisationsschritten in Abhängigkeit von der Reaktionstemperatur der Polymeren bestimmt. Hieraus konnten die Polymerisationsenthalpie ΔH = 26,5 ± 0,5 kJ mol−1, die Polymerisationsentropie ΔS = 95 ± 5 J mol−1K−1sowie die Ceilingtemperatur Tceiling= 65 ± 1°C für MS bestimmt werden. Es wurde nachgewiesen, daß im Rahmen der Terminalnäherung auch mit Berücksichtigung von Depolymerisationseinflüssen keine adäquate Beschreibung des Copolymerisationsverhaltens im Falle der untersuchten Systeme möglich ist. Vielmehr konnten als Ergebnis der Untersuchungen sowohl in Copolymeren von MS mit AN als auch mit MAN signifikante Penultimate‐Effekte nachgewiesen werden. Aufbauend auf diesen Ergebnissen wird die Anwendung eines auf einer Penultimate‐Näherung basierenden Modells, welches auch das Gleichgewicht in den Wachstumsreaktionen von MS berücksichtigt, zur theoreti

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052430102

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe Charpy impact fracture behaviour of unnotched specimens of phenolphthalein polyether ketone (PEK‐C) was studied over a temperature range from room temperature to 220°C by using an instrumented impact tester. The load‐time and energy‐time curves of PEK‐C at different temperatures were recorded. From these curves, some important parameters, such as the maximum impact load, the maximum stress, the total impact energy, the crack initiation energy, the crack propagation energy etc., were obtained and their temperature dependences of PEK‐C were investigated. The point of 100 percent maximum load on the load‐time trace was shown to be the yield point. Two parameters, the ductile ratio (D.R.) and the ductility index (D.I.) were applied to characterize the ductility of PEK‐C and their relationships to the relaxation processes

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052430103

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe copolymerization of styrene with three polymerizable UV stabilizers based on triazinylaminobenzotriazole was investigated. The relationship between the polymerization rate and the character of the UV stabilizer was established. The general conclusion was that the presence of the UV stabilizer retarded the polymerization of styrene, without significant effect on the molecular weight and the thermostability of the copolymers thus obtained.

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052430104

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe influence of temperature and type of initiator on the grafting efficiency of maleic anhydride onto isotactic poly(propylene) powder under solid‐state reaction conditions was investigated. The level of bonded maleic anhydride was found to be about 20% higher using aliphatic peroxide, such as lauroyl peroxide, in contrast to dibenzoyl peroxide, dicumyl peroxide, 2,5‐dimethyl‐2,5‐di‐tert‐butylperoxyhexane or tert‐butyl perbenzoate as initiator.The higher grafting efficiency of maleic anhydride onto polyethylene when compared with poly(propylene) is accounted for by a higher kinetic length of the addition‐transfer

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052430105

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractMagnesium oxide supported polytitazane cobalt (III) complex is demonstrated as an effective catalyst for the epoxidation of cis‐cyclooctene with molecular oxygen at atmospheric pressure in the presence of isobutyraldehyde as the sacrificial reductant. XPS data show that the high‐valent cobalt (III) is stabilized by the multidentate nitrogen ligand of polytitazane. The conversion of cis‐cyclooctene is as high as 95.2% with 100% selectivity to the cis‐cyclooctene oxide at 25°C within 5 h. The catalyst can be used at least nine times without loss of its

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052430106

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractPhenolic resins (resols) based on phenol and cardanol, a natural alkyl phenol from cashew nut shell liquid (Anacardium occidentale L.), were synthesized, and their thermal and chemical resistances as well as their mechanical properties were determined. The results show that the addition of certain amounts of cardanol (less than 15 wt.‐%) to phenol distinctly improves the chemical resistance and some mechanical properties such as tensile, flexural and Izod impact strengths of the resins. At the same time, the high thermal stability of pure phenol‐formaldehyde resins still remains in the temperature range of high releva

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052430107

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractDynamic mechanical properties are measured for a series of compression‐molded polypropene sheets having the same bulk crystallinity but different surface crystallinity. The temperature of the α‐dispersion was shifted to lower temperatures with lowering the surface crystallinities of the sheets. A shoulder peak, which is ascribed to the surface layer, appeared between the α‐ and β‐dispersion for the sheets. In addition, the application of the Takayanagi model to the experimental results suggests the difference in the continuity of the amorphous phase between the surface layer an

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052430108

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractTo improve the physical picture of the polymeric glassy state, the influence of morphological changes achieved by different thermal treatments of an amorphous glassy poly(alkylene terephthalate) film on the oxygen transport properties has been studied. Annealing treatments were performed on films in constraint imposed giving samples of different crystallinity contents and morphology.The dependence of the oxygen permeability and diffusion as the free volume from crystallinity content was investigated at sub‐Tgtemperatures within the range of 303–348 K.The investigations reveal that on crystallized samples, permeability and solubility coefficients decrease at higher crystallization temperature, while annealed samples showed an opposite trend despite higher crystallinities. Further, annealed films showed higher free volume content.The trend of results suggests that different parameters are likely to play a significant role in determining apparent permeability coefficients. The presence of microvoids in annealed samples may be suppo

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052430109

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractA series of conducting polyaniline/poly(butadiene‐co‐styrene‐co‐2‐vinylpyridine) (PBSP) latex composites was prepared by polymerization of aniline in the presence of PBSP latex. The mass loading of polyaniline in the composite latex can be controlled by varying the PBSP latex/aniline charging ratio and oxidant/aniline molar ratio. The composites were characterized by elemental analysis, transmission electron microscopy and thermogravimetric analysis. The effects of the concentration of the reactants on the conductivity at room temperature and the mechanical properties of the composite films formed from the latices wer

ISSN:0003-3146    

DOI:10.1002/apmc.1996.052430110

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY