摘要:

AbstractPolybutadienyllithium systems with M̄nin the range 1.5 × 103‐20 × 103are formed in hydrocarbon solvents by usingn‐butyllithium or 3‐dimethylamino‐propyllithium as initiator. These ‘living’ polymers, of low polydispersity and relatively high 1,4‐structure, react with 3‐chloropropyl(trimethoxy)silane at<− 20°C, in the presence of tetrahydrofuran, to give, primarily, polymers terminated by the 3‐chloropropyl(dimethoxy)silyl group, Si(OMe)2{(CH2)3Cl}, as characterised by GPC and by1H,13C and29Si NMR studies. Quaternisation by iodomethane of the telechelic polybutadiene with a dimethylamino end‐group produces a silylated cationomer containing the terminal functionality, I−+Me3N(CH2)3. In some silylation reactions of polybutadienyllithium systems, especially at higher temperatures, and in related reactions with Si(OMe)4, polymers coupled via the silyl groups are also formed. Hydrolysis of the terminal dimethoxysilyl functions occurs under acidic or basic conditions; end‐group coupling to silica gel also occurs and other rea

ISSN:0959-8103    

DOI:10.1002/pi.4990250102

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe effects of calcium carbonate modified with 4‐carboxy benzene sulphonyl azide on the mechanical properties of SBR mixes have been investigated. The studies include determination and comparison of tensile strength, elongation, tear strength, compression‐relaxation behaviour, and swelling measurements of modified and unmodified filler systems. The results show that the azide attached to the surface of the filler particles reacts with the rubber and improves the mechanical propert

ISSN:0959-8103    

DOI:10.1002/pi.4990250103

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractDimethyl sulfonium 2‐pyridyl carbonyl methylide (Ypy‐s) initiated radical polymerization of styrene in dimethyl sulfoxide at 85±0.1°C for 6 h under a nitrogen blanket using dilatometric techniques has been studied. The initiator and monomer exponent values were calculated to be 0.5 and 1.2, respectively. The system follows ideal radical kinetics with bimolecular termination. The higher monomer exponent value is ascribed to significant solvent effects on the initiation rate. The overall activation energy and average value ofk2p/ktare 52.0 kJ mol−1and 1.0 × 10−3litre mol−1s−1, respectively. The polymerization was retarded in the presence of hydroquinone or benzene; dimethylformamide, however, enhanced the rate of polymerization. Kinetic data and ESR studies indicate that the overall polymerization takes place via triplet carbene formation which acts as a source of

ISSN:0959-8103    

DOI:10.1002/pi.4990250104

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractSinglet oxygen lifetimes [τ(1O2)] in polymer matrices were calculated using the strong exponential correlation between the incremental rate constant (Kxy) of energy transfer from1O2to terminal oscillatorsX—Ycontained in solvent molecules and the energy (Exy) of the highest fundamental vibration of the oscillatorX—Y. The lifetimes in polymers correspond very well to experimental data in the literature. They depend only on the nature and quantity of molecular oscillators in the medium but not on the state of aggregation. The computed lifetimes in common polymers vary only from 10 to 50 μs. Therefore the lifetime of1O2in singlet oxygen reactions in polymers is of secondary importance in comparison to the diffusion coeffi

ISSN:0959-8103    

DOI:10.1002/pi.4990250105

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractNatural rubber was oxidised by hydrogen peroxide using 7 radiation. Various conditions such as variations in time of exposure to 7 radiation, H2O2concentration, grafting reaction time and monomer to polymer ratio were examined with respect to optimisation of grafting. The resulting graft ccpolymers were characterised by FTIR, DSC, contact angle measurement and electrokinetic potential measurements.

ISSN:0959-8103    

DOI:10.1002/pi.4990250106

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe ability to control charge nature, charge density and molecular weight enables the polymer chemist to design polyelectrolytes to provide a wide variety of functions, essential in many industrial processes. The flexibility of polymer design is summarised.

ISSN:0959-8103    

DOI:10.1002/pi.4990250107

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractStudies were made on the thermally stimulated discharge currents (TSDCs) in pure (undoped) and Fe‐doped polystyrene films as a function of polarizing field, polarizing temperature and dopant concentration. While undoped films exhibited a single peak, doped films showed two peaks one at low temperatures and another at high temperatures. The low temperature peak, which exhibits a shift towards lower temperatures with increasing dopant concentration, is attributed to the relaxation of the main chain, while the high temperature peak, which shows a tendency to shift towards higher temperatures with dopant concentration, is due to space charge polarization. The TSDCs were higher for low dopant concentrations than their undoped counterparts, while for high concentrations of the dopant, the TSDCs decreased. Formation of charge transfer complexes at low dopant concentrations and molecular aggregates at higher dopant concentrations are suggested as the possible reasons for this behaviou

ISSN:0959-8103    

DOI:10.1002/pi.4990250108

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractA calorimetric study of poly(mono‐n‐alkyl itaconates) containing 8, 10, 12 and 14 carbon atoms in the side chain was performed. No glass transition temperature (Tg) was observed in the temperature range 213‐263 K, but a melting process was observed for the dodecyl and tetradecyl derivatives, which was attributed to crystalline order in the long side c

ISSN:0959-8103    

DOI:10.1002/pi.4990250109

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThis report describes the synthesis and redox behaviour of polyaniline in aqueous solutions of benzene sulphonic acid and 4‐toluene sulphonic acid. The characterization of the polymer was carried out by electronic spectra, FTIR studies and1HNMR in DMSO

ISSN:0959-8103    

DOI:10.1002/pi.4990250110

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

ISSN:0959-8103    

DOI:10.1002/pi.4990250113

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY