ISSN:0007-1641    

DOI:10.1002/pi.4980050102

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractBy slow cooling and annealing polyethylene a semiequilibrium crystallisation state is obtained. Under such crystallisation conditions changes in unit cell dimensions and crystallinities, as measured by X‐ray diffraction, may be related to the size and number of branch groups in polyethylene copolymers. Thus methyl and ethyl groups may be accommodated within the crystalline lattice whereas butyl groups are not. The method may be used to determine the type and extent of branching in unknown ethylene copolymer

ISSN:0007-1641    

DOI:10.1002/pi.4980050103

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractAddition of lithium chloride to solutions of a copolyamide prepared from di(p‐aminophenyl) ether, di(p‐aminophenyl) sulphone and isophthaloyl chloride enables the sequence distribution of the co‐units in the copolymer to be determined by nuclear magnetic resonance spectroscopy. Copolymers of controlled sequence distribution can be prepared by correct selection of polymerisation solvent, acid acceptor and the mixing sequence of the polymer forming reac

ISSN:0007-1641    

DOI:10.1002/pi.4980050104

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe reactions occurring in the system styrene + butyl bromide + lithium in tetrahydrofuran are studied as a model for olefine/dihalide reactions pioneered by Richards and co‐workers for the purpose of synthesising highly regular copolymers. Computer fittings of a kinetic scheme and of gel permeation chromatographs of the products leads to the conclusion that homopolymerisation of styrene tends to be a serious side reaction to the desired condensation between the styrene dianion and two moles of butyl bromide. As expected from previous work, this is found to be much less serious in the analogous system with alpha methyl styrene in place of styren

ISSN:0007-1641    

DOI:10.1002/pi.4980050105

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractA systematic study of the dielectric properties of Perbunan N mixed with silica in increasing quantities is carried out in the frequency range 500 Hz to 1010Hz at room temperature. The data are analysed using the Cole‐Cole method and the results are interprete

ISSN:0007-1641    

DOI:10.1002/pi.4980050106

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractAn attempt has been made to achieve thermoplastic behaviour in a chemically crosslinked elastomer by arranging that the crosslinks should undergo rapid exchange at high temperatures. Natural rubber was chemically modified to give pendent hydroxyl groups which were then used as crosslinking sites to form β‐keto‐ester or malonate crosslinks. The resultant vulcanisates showed high stress relaxation rates in the temperature range 120 to 160°C and some degree of remouldability at 180°C. The incursion of permanent crosslinking prevented quantitative correlation between stress relaxation rates and chemical exchange rates of the crosslinking s

ISSN:0007-1641    

DOI:10.1002/pi.4980050107

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractGel permeation chromatography has been used to study the acid‐catalysed condensation of resorcinol with formaldehyde in concentrated solution. Rate curves for the consumption of resorcinol and the formation of some of the oligomeric products, and changes in molecular weight distribution during the reaction have been compared for condensates prepared using various reaction condition

ISSN:0007-1641    

DOI:10.1002/pi.4980050108

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980050109

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980050110

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980050101

出版商:John Wiley&Sons, Ltd    

年代:1973

数据来源: WILEY