摘要:

AbstractNiedermolekulares Poly(β‐hydroxybutyrat) (PHB) kann durch kontrollierte Hydrolyse des auf biotechnologischem Wege hergestellten Polymeren erhalten werden. Die Geschwindigkeitskonstanten des Kettenabbaus wurden in verschiedenen 85prozentigen Säuren bei 90 und 100°C bestimmt. Aus den so erhaltenen PHB‐Fraktionen im Molmassenbereich von 3000 – 500000 wurden Matrixtabletten hergestellt. Es wird gezeigt, daß der Retardeffekt stark von der Molmasse des verwendeten Polymere

ISSN:0003-3146    

DOI:10.1002/apmc.1988.051610101

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe radiation induced graft copolymerization of methylacrylate onto nylon‐6 fiber at room temperature and in nitrogen medium was investigated. The effects of monomer, dose rate, inhibitor etc. on the graft yield have been investigated. The effect of solvents on the rate of grafting was studied from which the chain‐transfer constant (Cs) of the solvent has been evaluated. Addition of certain inorganic salts was found to act as scavengers. The value of Gb, the number of branches per 100 eV of energy absorbed in the substrate polymer, was calculated. The density, moisture regain, alkali solubility, dyeability and thermal properties of the grafted nylon‐6 fiber have been eval

ISSN:0003-3146    

DOI:10.1002/apmc.1988.051610102

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe parameters of the supermolecular structure of styrene‐divinyl benzene copolymers with a degree of crosslinking equal to 5, 10, and 20% were examined. It was found that regions with different electron density occur in the copolymers.Mean sizes of heterogeneities,1, thicknesses of transition layers E, and specific areas S/V were determined. It was found that as the degree of crosslinking increases the inhomogeneity of the copolymer structure becomes greater and the separation of the phases is more visibl

ISSN:0003-3146    

DOI:10.1002/apmc.1988.051610103

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractAn attempt is made to improve the processing and operation properties of polyethyleneterephthalate (PETP) containing chemically bound pentaerythrol as modifier by increasing its viscosity through slight chemical crosslinking in the solid state.It is established that thermal treatment in vacuum for 8 h at 240°C of PETP containing 0.3 mol‐% pentaerythrol leads to an increase in its molecular weight from 20000 to 40000 mainly as a result of additional solid state polycondensation. Further more, annealing in vacuum for 6 h at 250°C of the polymer containing 0.4 mol‐% pentaerythrol leads to the formation of a loose three dimensional network resulting from chemical crosslinking in the solid state.It is shown that this crosslinking material has improved processing behaviour during injection moulding due to the increased viscosity of the

ISSN:0003-3146    

DOI:10.1002/apmc.1988.051610104

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractElectrokinetische Parameter wie die elektroosmotische Stromstärke (Qc) und das elektrokinetische Potential (ζ) von Fasern hängen stark von Masse und Struktur der untersuchten proben ab. Anhand von Polyamid‐, Polyester‐ und Polyacrylnitrilfasern wurde der Einfluß dieser Parameter untersucht. Dabei zeigte sich (a), daß es nicht möglich ist, mit Hilfe der elektroosmotischen Methode die echten Werte des Zeta‐Potentials festzustellen und (b), daß für einen relativen Vergleich des Zeta‐Potentials verschiedener Fasern diese Einflüsse nicht bestim

ISSN:0003-3146    

DOI:10.1002/apmc.1988.051610105

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractEs wurde die Bestimmung der elektrokinetischen Eigenschaften von Polyacrylnitrilfasern (PAN) mit Hilfe der elektroosmotischen Methode beschrieben und auf ihre Vor‐und Nachteile hingewiesen. Es zeigte sich, daß die Werte der elektrokinetischen Parameter wie elektroosmotische Stromstärke (Qc) und elektrokinetisches Potential (ζ) von der Masse und der Struktur der untersuchten Proben abhängen. Die Untersuchung dieser Abhängigkeit am Beispiel von Polyamid‐, Polyester‐ und Polyacrylnitrilfasern was das Ziel dieser Arbeit. Es zeigte sich, (a) daß es nicht möglich ist, anhand der elektroosmotischen Methode die echten ζ‐Werte zu bestimmen, und (b) daß es nicht notwendig ist, bei einem relativen Vergleich des Zeta‐Potentials verschiedener Fasern die Beziehung ζ

ISSN:0003-3146    

DOI:10.1002/apmc.1988.051610106

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractHydrochloric acid prehydrolysis of cotton cellulose resulted in a less accessible fine strucuture, higher crystallinity and lower reactivity in xanthogenation than sulphuric acid prehydrolysis. The reactivity was improved only when the duration of the hydrochloric acid treatment was reduced to 1 h. Hydrochloric acid prehydrolysis‐soda‐anthraquinone pulping raised the yield of α‐cellulose and improved greatly the affinities towards water and alkali, and resulted in much better reactivity in xanthogenation. The optimum quinone concentration was 0.2%. A comparison between the most reactive pulps obtained by sulphuric acid prehydrolysis‐soda‐anthraquinone pulping and hydrochloric acid prehydrolysis‐soda‐anthraquinone pulping indicated that hydrochloric acid allowed a great reduction in the duration of both prehydrolysis and pulping. Both acids resulted in the same α‐cellulose and the same degree of polymerization, but hydrochloric acid led to higher yield, higher crystallinity, more open and accessible fine structure, and much better reactivity in xanthogenation. However, in absence of anthraquinone, hydrochloric acid prehydrolysis resulted in a less accessible fine structure and lower reactivity

ISSN:0003-3146    

DOI:10.1002/apmc.1988.051610107

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractLow density monofilaments of polyethylene with varying draw ratios were subjected to high energy radiation using Co60gamma radiation source. It was found that the tensile strength is sharply improved with the increasing dose up to 20 Mrd beyond which a sharp decrease in tenacity and initial modulus was observed. The swelling behaviour also decreased with the increased in dose of irradiation. However, density showed an increasing trend. The shrinkage behaviour of all the filaments was found to increase with increasing dose and draw ratios. The results have been explained in terms of continuous increase in crosslink density with the increasing dose of irradiation along with loss of crystallinity, which appears to be more severe in the latter stages of exposure. The samples exhibited memory effect after redrawing at 100°C and cooling under tension followed by further heating at 110°C under relaxed condition. The shrinkage was still much higher but independent of draw rati

ISSN:0003-3146    

DOI:10.1002/apmc.1988.051610108

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractDiglycidyl ether of ethylene glycol was prepared and used as a reactive diluent in the curing of an epoxy resin, based on diglycidyl ether of bisphenol A. Effect of different fortifiers on the curing reaction of the resin‐diluent system has been investigated using differential scanning calorimetry. The dynamic scans were analyzed using four different relations to evaluate the kinetic parameters, the activation energy and the order of the reaction. The reactions are found to follow first order kinetics with an activation energy in the range of 36 – 84 kJ mo

ISSN:0003-3146    

DOI:10.1002/apmc.1988.051610109

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY

摘要:

AbstractThe structural properties of isotactic polypropylene films treated with tetrachloroethylene at high temperatures were characterized by proton spin‐lattice T1and spin‐spin T2relaxation times, loss in weight, crystallinity, molecular weight, and melting temperature, and heat of fusion. Two kinds of samples, a quenched and an annealed sample, were employed. There are a considerable loss in weight and large increases in crystallinity and in molecular weight when treated the sample at high temperatures especially in the quenched one. These morphological changes result in a shift of T1minimum to high temperatures and a decrease in T2a. The effects of the solvent on the annealed sample are qualitatively the same for the quenched one but are relatively m

ISSN:0003-3146    

DOI:10.1002/apmc.1988.051610110

出版商:Hüthig&Wepf Verlag    

年代:1988

数据来源: WILEY