摘要:

AbstractThe radiation stability of the random and block poly(propylene‐co‐ethylene) (CP, copolymer with 6% ethylene units) with and without nucleating agent (NA) was compared in relation to radiation sterilization of medical supplies. In both cases, it was found that the radiation stability of CP in the presence of NA was lower than that of CP without NA.Addition of NA to CP did not improve the transparency but the crystallization occurred at higher temperature. Thus, adding NA to CP has the advantage of shorter moulding time in the production of medical supplies.The radiation instability of the CP with NA was due to a different crystal structure, because the spherulite shape differs from that of CP without NA. Furthermore, by the chemiluminescence analysis, a higher oxidative degradation was observed in the sample with

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051740111

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractRubber modification of polybutyleneterephthalate was accomplished by the addition of suitable functionalized ethylene‐propylene copolymers (EPR) concurrently with the high temperature polycondensation of 1,4‐butanediol and dimethylterephthalate.The impact properties of blends obtained with plain EPR, with ester or hydroxyl groups modified EPR were analyzed by Charpy tests performed at different temperatures with a Ceast fracture pendulum. The morphological features of fracture surfaces have also been investigated. An attempt has been made to correlate the morphology of the surfaces with the fracture analysis resu

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051740112

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractEs wird versucht, für Verbunde aus mit Holzöl sowie Tricresylphosphat modifizierten Phenol‐Formaldehyd‐Polykondensaten und Cellulosepapier, die als Leiterplattenbasismaterial technisch in großem Umfang genutzt werden, mittels Torsionsschwingungs‐ und dielektrischer Messungen einen Zusammenhang zwischen dem strukturellen Aufbau und den Verbundeigenschaften herzustellen. Die innere Weichmacherwirkung von Holzöl wird diskutiert. Die Holzölmodifizierung bewirkt neben einer Flexibilisierung, daß durch Beseitigung sterischer Behinderungen ein größerer Umsatz der funktionellen Gruppen bei der Resitbildung erreicht und der Vernetzungsgrad im Vergleich zu einem unmodifizierten PF‐Hartpapier erhöht wird. Die Messungen zeigen, daß Tricresylphosphat als äußerer Weichmacher wirkt, der die zwischenmolekularen Wechselw

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051740113

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractBy using highly active peroxides, it is possible to reduce the polymerization temperature necessary for the synthesis of low density polyethylene. In order to examine a number of peroxides for their suitability as low temperature initiators, polymerization tests were carried out at 1900 bar, 70–140°C, with an average residence time of 30 s in a continuously operating laboratory facility equipped with a stirred autoclave. Apart from a number of perneodecanoates, two peroxy dicarbonates, a sulphonyl peroxide, and a difunctional peroxide were used.The initiator consumption was high at polymerization temperatures below 100°C. The results obtained with the different peroxides varied considerably. As the temperature increased, the initiator consumption decreased rapidly to reach almost the same level for all the individual peroxides at above 120°C. The difunctional compound that proved highly suitable for the low polymerization temperatures desired was 1,4‐di‐(2‐neodecanoyl peroxy isopropyl)benzene, the consumption at 100°C of which amounted to 13 g initiator/kg PE. Using a quantity of 40 g initiator/kg PE, a reactor temperature of 82°C could be employed. The peroxy dicarbonates and tertiary butyl perneodecanoate gave less satisfac

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051740114

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractStudy of melt flow properties and mechanical properties of sulfonated butyl rubber ionomers showed that in the case of lithium ionomers addition of zinc stearate lowered obviously the melt viscosity, represented by torque value of a Brabender rheometer, and enhanced tensile strength of the ionomer up to 25% of zinc stearate, while in the case of ethylamine neutralized ionomer addition of zinc stearate lowered the melt viscosity not so obviously as in the case of lithium ionomer and slightly affected the tensile strength. Amine neutralized ionomers exhibited very low permanent sets, while the lithium ionomer showed much higher permanent set, which increased with sulfonate group and amount of zinc stearate added. Increase of neutralization degree below equivalent ratio of 1 significantly raised the melt viscosity and tensile strength.For monovalent cation ionomer, melt viscosity and tensile strength diminished with decreasing ionic potentials, but for divalent cation ionomers with increasing ionic potentials and with decreasing covalent character tensile strength decreased and melt viscosity increased.For different amine neutralized ionomers tensile strength decreased in the following orders: ethylamine>triethylamine>diethylamine; isopropylamine>ethylamine>tertiary butylamine>methylamine; ethylamine>hexylamine>dodecylamine>octadecylamine.

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051740115

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractSaving product quality and quality consistency in polymer production needs a detailed knowledge of the polymerization process. A process model for the slurry polymerization of ethylene with high mileage Ziegler‐catalyst/cocatalyst systems has been developed. This model teaches which set of process parameters must be kept constant together with their acceptable deviations to keep product data within the required frame. The consequences for a technical production plant are also discusse

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051740116

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY

摘要:

AbstractThe influence of the filler particle size and dispersion degree on the Charpy notch toughness (U notch) and tensile impact strength (without notch) in the polypropylene‐microground calcium carbonate system was investigated. It was found that while the tensile impact strength was controlled by the content of particles and/or agglomerates coarser than about 10 µm (the strength decreased sharply with their increasing content), the Charpy notch toughness was not decreased even by large agglomerates (up to 100 µm), but dropped heavily with the increasing upper particle size of the filler measured before kneading into polymer. A model system polyethylene‐glass beads revealed even an increase of the notch toughness with the increasing upper diameter of the glass beads (the upper diameter being in the 50–400 µ

ISSN:0003-3146    

DOI:10.1002/apmc.1990.051740117

出版商:Hüthig&Wepf Verlag    

年代:1990

数据来源: WILEY