ISSN:0007-1641    

DOI:10.1002/pi.4980110402

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe polyorganosiloxanes prepared by the trimethylsilylation of mineral silicates contain Q [SiO4/2] units and M [CH3)3SiO1/2] units. Investigations into the behaviour of these materials in the temperature range 100‐1000°C and for times varying from 2‐64 hours have shown that a variety of reactions take place with a general increase in number average molecular weight (Mn). Organophilic polyorganosiloxanes withMn>6000 can be obtained by heat treatment under vacuum or a stream of nitrogen. The thermal stability of the polymer derived from pseudowollastonite in closed systems in the presence of acid/base catalysts is also reported. This work is part of a general programme to prepare higher molecular weight Q/M polymers with more potential uses as industrial materials than the initially prepared trimethylsilylated derivat

ISSN:0007-1641    

DOI:10.1002/pi.4980110403

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe interaction of dimethyidichlorosilane with polyorganosiloxanes prepared by the trimethylsilylation of mineral silicates is catalysed by ferric chloride hexahydrate and results in the formation of higher molecular weight polyorganosiloxanes and also trimethylchlorosilane. The nature of the products and particularly the molecular weight depends on the relative amounts of reactants. It is also shown that during the course of the reaction a substantial proportion of the ferric chloride is reduced to ferrous.

ISSN:0007-1641    

DOI:10.1002/pi.4980110404

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe trimethylsilylation of pseudowollastonite gives a polyorganosiloxane (Mn, 890). The aim of this work was to increase the molecular weight of this initial or pre‐polymer and to bond into the molecule further functional groups. The methyl groups of the trimethylsilyl moiety have been converted to a series of organic derivatives: ‐>Si(CH3)2CH2X; × = C1, Br, I, Ac, OH: which are capable of further reaction to give higher molecular weight homologues. As expected the ‐>Si(CH3)2CH2OH group reacts readily with chlorosilancs whilst the original pre‐polymer hydroxyl groups give disappointing yields in these and other reactions owing to their sterically hindered env

ISSN:0007-1641    

DOI:10.1002/pi.4980110405

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractDDT (I) was polycondensed with 2,2‐bis(4‐hydroxy phenyl)‐ propane (bisphenol‐A) to form polyether. The following monomers were synthesised from DDT: 2,2‐bis(4‐chloro‐phenyl)1, 1‐dichloroethylene(II), 2,2‐bis(3‐nitro‐4‐chlorophenyl)ethane (III) and 2,2‐bis(3‐nitro‐4‐chloro‐phenylethylene (IV) and polycondensed with bisphenol‐A. They were also copolymerised withbis(4‐chlorophenyl)sulphone and bisphenol‐A in several molar ratios. The polymers and copolymers were characterised by various techniques. The results obtained show that the DDT has a low reactivity, but nitration and dehydrochlorin‐ation increas

ISSN:0007-1641    

DOI:10.1002/pi.4980110406

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractA new method, using the propagation expectation defined by Case, is presented to compute directly and simply the general expressions of average molecular weights for condensation polymerisation of polyfunctional monomers. In particular, the weight average molecular weight in systems composed of monomers endowed with both A and B coreactive functional groups is derived.

ISSN:0007-1641    

DOI:10.1002/pi.4980110407

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980110408

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractA copolymer series was synthesized for migration imaging applications from isobutyl methacrylate and isobutyl styrene such that each homopolymer and all copolymers had glass transition temperature (Tg) near 55°C. TheTgof poly (p‐isobutylstyrene) was predicted from literature values of similar polymers to be near 55°C. Poly (p‐isobutylstyrene) was synthesised by acetylation of isobutyl benzene, reduction ofp‐isobutylacetoph‐enone to the carbinol, dehydration top‐isobutylstyrene and free radical polymerisation to the polymer. TheTgof the homopolymer was 55°C, in excellent agreement with the predicted value. Copolymers of isobutyl methacrylate andp‐isobutyl styrene were synthesised and theirTg's measured across the series by DSC (57°C ± 5°C). refractive index temperature coefficient (42°C ± 5°C). The copolymer series was also characterised by melt vi

ISSN:0007-1641    

DOI:10.1002/pi.4980110409

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe trimethylsilylation of biotite and phlogopite gives good yields of polyorganosiloxanes. Al3+ions have an important influence on the fragmentation of the mineral structure into silicate anions prior to trimethylsilylation.The authors have shown by using wet analytical techniques as well as X‐ray diffraction and electron probe microanalysis that biotite and phlogopite retain aluminium in preference to magnesium during the course of extensive trimethylsilylation reactions. The labile nature of the>Al‐O‐Si<‐ bonds, and the size of the AI3+ion which allows exchange between the octahedral and tetrahedral mineral sites, contribute to the good yields of polyorganosiloxanes which can be produced by this method. The mechanism for the reaction is presented. Yields may be increased by decreasing the particle size of the mineral and also by removing polyorganosiloxanes from the mineral

ISSN:0007-1641    

DOI:10.1002/pi.4980110410

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980110412

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY