摘要:

AbstractPolymer bound reagents have become established components of the repertoire of synthetic organic chemists. Recent advances in this field are reviewed with particular attention focused upon the nature of the polymer support. The application of condensation polymers as supports are highlighted. Techniques for chlormethylating polymers containing oxyphenylene repeat units with 1,4‐bis [chloromethoxy] butane are presented and the properties of the new supports polymers are described. Aspects of site‐site interaction of crosslinked polymer matrices are discussed. The review includes a summary of applications for polymer‐bound transition metal catalysts, phase transfer catalysts and organic reagents. Finally, the future of polymeric reagents is exa

ISSN:0025-116X    

DOI:10.1002/macp.1979.020021979101

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractHighlights of recent research on the degradation and stabilization of polyolefins and poly(vinyl chloride) are outlined. The major defects in the molecular structure of poly(vinyl Chloride) are described and some controversial aspects of polyolefien photochemistry are discussed.

ISSN:0025-116X    

DOI:10.1002/macp.1979.020021979102

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractTheoretical treatments of network formation and the applicability of the tree‐like models to the calculation of structural parameters in the post‐gel state and to more complex systems of practical importance are discussed. The unseparability of structural interpretation of network properties from network formation is stres

ISSN:0025-116X    

DOI:10.1002/macp.1979.020021979103

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractA qualitative description is given to account for general picture of changes in properties of two types of polymer compositions–filled with fillers of high free surface energy and with polymeric fillers, or polymer‐polymer mixtures. It was shown that the properties of the surface layers are different in comparison to polymer in bulk as a result of interactions at the interface and changes in conditions of mass transfer during the process of structure formation. Depending on the conditions of surface layers formation, their structure and polymer‐filler ratio, various types of compositions arise. For polymer‐polymer mixtures there are various states of their structure depending on the thermodynamic compatibility of components in melt and cooling conditions and phase separation. An important role of small amount of the addition polymer in the properties of binary composition is shown as well as the role of low molecular weight homologues and admixtures in the processes of the structure fo

ISSN:0025-116X    

DOI:10.1002/macp.1979.020021979104

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractApplications of both polarized and depolarized dynamic light scattering to the study of polymers are described. Polarized light scattering is used to study translational diffusion, diffusion virial coefficients, rotational motion of long rod‐shaped polymers, long‐wavelength intramolecular motions, dynamics of pseudogels and gels and density fluctuations in bulk polymers. Depolarized scattering is used to study rotational diffusion of rigid macromolecules, local and long‐wavelength intramolecular motions, dynamics in semi‐dilute solutions, rotational motions of small molecules in glassy polymers and optical anisotrophy fluctuations of bulk p

ISSN:0025-116X    

DOI:10.1002/macp.1979.020021979105

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractThe characteristic fetures of isobaric volume and enthalpy recovery of glasses are briefly recalled and analysed in terms of a multiparameter model involving a distribution of retardation times, τi. The latter are assumed to depend both on temperature and on the instantaneous state (structure) of the glass, whereas the shape of the retardation spectrum is invariant and merely shifts, as τi, along the logarithmic time scale. Qualitative comparison of the theoretical predictions with various types of experiment reveals an excellent agreement. Some effects of structural recovery on the mechanical, or electrical properties of polymer glasses are also recalled and discussed in terms of the theoretical modelThe text which follows is merely an extended abstract of the work published elsewhere (see Refs 5&10)

ISSN:0025-116X    

DOI:10.1002/macp.1979.020021979106

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractNew synthetic techniques are now available for the preparation of “model” polymer networks of known and carefully controlled molecular structure. The preparation of such networks and their utilization in elucidating molecular aspects of rubberlike elasticity are illustrated using highly elastomeric, unfilled networks of polydimethylsiloxane. In one such preparative technique, hydroxyl‐terminated chains are end‐linked using either a tetrafunctional or trifunctional silicate, in either the undiluted state or in solution. Because of the selectivity and completeness of the reaction, the molecular weight and molecular weight distribution of the network chains are to good approximation those of the chains prior to their end‐linking into the network structure. The experimentally determined stress‐strain isotherms and degrees of equilibrium swelling of the resulting networks are then used to evaluate the molecular theories of rubberlike elasticity, particularly with regard to the dependence of the elastic modulus and ultimate properties on the degree of cross linking and the cross‐link functionality. Another preparative technique employs random and block copolymers containing reactive vinyl groups in known amount and known distribution along the chains. Selectively cross‐linking through these sites then yields model networks ranging from random to highly non‐random in chain length distribution. These networks are particularly useful for characterizing the effects of very short chains on the average degree of cross‐linking or average network chain length as obtained from stress‐strain and swelling equ

ISSN:0025-116X    

DOI:10.1002/macp.1979.020021979107

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY

ISSN:0025-116X    

DOI:10.1002/macp.1979.020021979108

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractThe statistical thermodynamics of the melt and the crystal are discussed by a unified approach which distinguishes between the two phases only in terms of a structure function minimizing the configurational free energy. The ensuing equations of state at atmospheric and elevated pressures are compared with typical experimental data for polymer and oligomer melts, and crystalline as well as semicrystalline systems, with satisfactory results. As to the glassy state, expansivity data clearly reflect nmot only the glass transition, but also sub‐glass relaxation processes. In the spirit of the preceding discussion of the equilibrium melt, quasi‐thermodynamic conditions are considered. Here the non‐equilibrium character is reflected in the dependence of the extensive thermodynamic functions on thermal history in addition to the ambient variables of state. This state is discussed in terms of modifications of the liquid state

ISSN:0025-116X    

DOI:10.1002/macp.1979.020021979109

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractRecent advances and status of x‐ray structure analysis of crystalline polymers are described using examples of α‐modification of poly(ethylene oxybenzoate), poly(ethylene oxide), isotactic poly(methyl methacrylate), and cellulose I. Next the relationship between crystal structures and crystallite moduli (one‐ and three‐dimensional) is discussed. Finally vibrational free energies of two crystal modifications of polyethylene are derived and d

ISSN:0025-116X    

DOI:10.1002/macp.1979.020021979110

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY