摘要:

AbstractSome special aspects of the radiation induced ionic polymerisation and grafting of vinyl monomers will be described. In particular the effects of solvents on the cationic polymerisation of the vinyl ethers will be discussed in detail. The unequivocal free ion nature of the polymerisation makes such information of considerable general interest. Estimates of the propagation rate constants with free cation polymerisation in solvents of different dietectric constants and solvation powers will be presented. Finally, some observations on the radiation induced graft polymerisation of ethyl vinyl ether to poly (vinyl chloride) and to polypropylene will be presented.

ISSN:0007-1641    

DOI:10.1002/pi.4980130302

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractThe design and construction of a stopped flow rotational viscometer is described. This novel technique enables rapid polymerisation reactions in thin films to be studied in a controlled environment over a range of temperatures. The apparatus enables two components of a polymerisation system (typically monomer/solvent and initiator/solvent) to be separately and rapidly delivered to the sample cavity of a cone and plate viscometer. The flow of the components can be simultaneously arrested and the viscosity of the resultant monomer/initiator/solvent mixture monitored as a function of time. The system was designed for the study of cyclo olefin‐based polymerisation and cross‐linking reactions in the development of metal coating systems capable of high cross‐linking rates. An initial evaluation was however carried out using the well characterised free radical polymerisation of styrene and the cationic polymerisation of styrene catalysed by boron trifluoride etherate in to

ISSN:0007-1641    

DOI:10.1002/pi.4980130303

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractMechanical test data are reported on lap joints and tensile test specimens which have been subjected to a defined post cure cycle. The mechanical properties exhibited an apparently systematic variation with temperature. Inspection of the resins indicated that chemical modification does not appear to occur to a significant extent below 433K. The change in the strength of the joints tensile test samples are discussed in terms of the relative importance of physical and chemical changes on the mechanical properties. It is evident that in the presence of oxygen considerable chemical modification can occur and this is observed both in terms of a change in colour of the resin and the appearance of voids.

ISSN:0007-1641    

DOI:10.1002/pi.4980130304

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractUses of silica in the immobilisation of enzymes and functionalized reagents for resolution of racemic mixtures and synthesis of peptides, oligonucleotide and other compounds are discussed. Silica is superior over organic polymers in its high chemical stability, and being virtually nonswellable. This inhibits the influence of the solvent on physical and chemical behaviour of attached moeties and permits automisation of batch processes.

ISSN:0007-1641    

DOI:10.1002/pi.4980130305

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

ISSN:0007-1641    

DOI:10.1002/pi.4980130306

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractThe interaction of phenylphosphonic dichloride and sodium or lithium phosphate gives glassy polymers which are hybrids of lithium and sodium metaphosphate glasses and polyphenylphosphonates. Tg's increases as the proportion of the alkali metal incorporated in the polymer increases. Reaction is most conveniently carried out by heating in chloroform under reflux. Polymers were prepared with up to 1 in 5 of the phosphorus atoms associated with Li+and up to 1 in 6 associated with Na+. Glasses could also be formed by reaction in the absence of solvent but difficulty was experienced in the complete removal of hydrogen chloride.

ISSN:0007-1641    

DOI:10.1002/pi.4980130307

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractPolyphenylphosphonates have been prepared by (i) the elimination of hydrogen chloride from mixtures of PhPOCl2and PhPO(OH)2, (ii) the elimination of methyl chloride from PhPOCl2and PhPO(OMe)2, and (iii) the elimation of methanol from PhPO(OMe)2and PhPO(OH)2. Products have been characterised by elemental analyses, gel permeation chromatography, molecular weight measurement and infrared spectroscopy. In each case mixtures of rings and chains were obtained. Polyphosphonates were also obtained by the elimination of hydrogen chloride from mixtures of MePOCl2and MePO(OH)2and from mixtures of PhOCl2and MePO(OH)2.

ISSN:0007-1641    

DOI:10.1002/pi.4980130308

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractMixtures of polyphosphonasiloxane oligomers have been prepared by the interaction of Ph2SiCl2with PhPO(OH)2and of Me2SiCl2with MePO(OH)2. Substitution of LiH2PO4for PhPO(OH)2and MePO(OH)2leads to the formation of polyphosphonasiloxanes containing ‐ O−Li+groups. TheTg's of these products increase as greater amounts of lithium phosphate are incorporated. Use of NaH2PO4does not produce polymers containing ‐ O−Na+, instead reaction of the ‐O−Na+groups with Si‐Cl leads to the elimination of NaCl and the formation of cross‐

ISSN:0007-1641    

DOI:10.1002/pi.4980130309

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractA ‘shot growth’ technique has been developed which enables a monodisperse polymer latex to be overcoated with a range of coating thicknesses by a different polymer. This has enabled a range of polymer latices to be produced which have mechanical and diffusional characteristics which are very different from either the seed latex or the coating poly

ISSN:0007-1641    

DOI:10.1002/pi.4980130310

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY

摘要:

AbstractThe concentration and molecular weight distribution (GPC) of polystyrene (PS) in the two phases of the PS‐SO2(δ)‐system were determined. Typical concentrations of PS in the upper phase were around 30%, while the lower phase contained at most 1% PS. An exception was a PS‐grade with a low molecular weight (MW 3.5 · 103), which dissolved homogeneously. The molecular weight of PS in the lower phase was substantially below an the one found in the concentrated phase. Mechanical agitation was necessary to attain an equilibrium state; during the equilibration the upper phase became more diluted. At the same time the molecular weight of the lower phase PS‐fraction increased, while the MW value in the upper phase remained practically unchanged and equal to that of the virgin sample. The fractionation with regard to the molecular weight between the two phases was also reflected in theTg‐values of the fractions. The value of X(Flory‐Huggins parameter) determined from vapour pressure data above the concentrated ph

ISSN:0007-1641    

DOI:10.1002/pi.4980130311

出版商:John Wiley&Sons, Ltd    

年代:1981

数据来源: WILEY