摘要:

AbstractThe topological entanglements between subchains of two interpenetrating polymer networks are described in the simplest approximation supposing that the primitive path of each subchain is influenced due to the shift of one network relatively to the other. The entanglement contribution to the free energy of the networks is shown to behave as 1/q2for the state with deviation from uniform densities with the wave vector of orderq. This contribution is shown to cause the microphase type of segregation.

ISSN:1022-1344    

DOI:10.1002/mats.1993.040020401

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractComputer simulations of the molecular motion of polymer chains in the presence of a strong nematic field were carried out by the method of Brownian dynamics. Two models were studied: the first model (linear liquid crystal) is a freely jointed chain with rigid bonds, the second model (comb‐like liquid crystal) is a chain with fixed bond angles and rigid side groups. The influence of ordering on chain conformations, orientational and translational mobility and spectra of relaxation times was investigate

ISSN:1022-1344    

DOI:10.1002/mats.1993.040020402

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractIn this paper we review some applications of the cooperative‐motion simulation algorithm to dense polymer melts. The basic idea behind the algorithm and its implementation on a computer are discussed. Furthermore we show how to include intra‐and intermolecular interactions in the simulation. Exemplary results are presented concerning on one hand the static properties of athermal and semiflexible lattice polymers and on the other hand the phase behaviour of polymer mixtures and diblock copolym

ISSN:1022-1344    

DOI:10.1002/mats.1993.040020403

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe perturbed enantiomorphic‐site (E) model was developed for the analysis of tacticity of Ziegler‐Natta polymers. Theoretical probability expressions for tacticity diads, triads, tetrads and pentads were derived, and a computer program incorporating perturbed enantiomorphic‐site and Bernoullian models was written to facilitate NMR analysis. Examples are shown of the use of the perturbed models to study the13C NMR tacticity of poly(propylene) made with homogeneous metallocene catalysts. The perturbed E model is shown to be a suitable theoretical framework for the analysis of many polymers made with these cata

ISSN:1022-1344    

DOI:10.1002/mats.1993.040020404

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractA new so‐called reactant‐solvent complex model is proposed to describe the effect of solvent on chain propagation in homopolymerization. It takes into account complex formation of both monomer and radical with solvent by equilibria. Evaluation methods presented permit to estimate the complex equilibrium constantKwhich is assumed to be nearly the same for both monomer and radical complexation and the relative reactivity ratior11, for complexed monomer. Measured reaction rates as function of monomer concentration are needed for calculati

ISSN:1022-1344    

DOI:10.1002/mats.1993.040020405

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe Tobita‐Hamielec kinetic model of the crosslink density distribution is further elaborated and extended to incorporate divinyl loop formation. Divinyl loop formation, primary and secondary cyclization, and their effects on the elastically effective crosslink density distribution are extensively examined as a function of cyclization parameters and double bond reactivities. Under conditions of equal double bond rectivity and negligible cyclization, primary chains born at different conversions have the same crosslink density. The variance of the crosslink density distribution is mainly due to unequal reactivities of double bonds and secondary cyclization. Divinyl loop formation and primary cyclization contribute neither to gelation nor to network elasticity and have an insignificant effect on the variance of the crosslink density distributio

ISSN:1022-1344    

DOI:10.1002/mats.1993.040020406

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY