ISSN:0005-9021    

DOI:10.1002/bbpc.19850891102

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY

ISSN:0005-9021    

DOI:10.1002/bbpc.19850891103

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY

摘要:

AbstractThe term polymer blends describes mixtures of polymers that differ from each other in their chemical and physical properties. As in the case of metal alloys, no simple combining of the properties of the individual components occurs, but new properties result. For example, a polymer blend that contains phases of different modules, as compared with conventional polymer organic solids, reacts to mechanical stress with completely different dynamics ‐ Characteristic of polymer blends, apart from the chemical structure of the components, are, in particular, the phase structure and the conformation of the chain molecules in the phases. The thermodynamic interaction of individual chain segments and the molecule conformation can be determined by neutron scattering. ‐ The phase structure ‐ the formation of supermolecular structures – is based on separation phenomena in the solution or melt. Hence thermodynamic investigations are intended to shed light on the laws relating to the mixing and separating of high molecular weight polymers. The phase structure of polymer blends is intended to be derived from experimental characteristic data of the individual components. – The existence of upper miscibility gaps – corresponding to lower critical solution temperatures – is common for amorphous high polymer blends. This behavior can be appropriately described by an equation of Patterson and Flory. If the changes in entropy and enthalpy are known for the contact of individual segments, the separation temperature for given molar weights can be calculated in advance from characteristic data of the individual components, e. g. thermal expansion coefficients. – Polymer blends encompass a broad spectrum of chemical and morphological structures and properties. The formation of interfaces as an adhesion‐promoting layer is essential in multiphase polymer blends for techn

ISSN:0005-9021    

DOI:10.1002/bbpc.19850891104

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY

ISSN:0005-9021    

DOI:10.1002/bbpc.19850891105

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY

摘要:

AbstractThe theory of phase separation and microdomain formation in block copolymer‐homopolymer blends is reviewed. The calculations involve the solution of modified mean field diffusion equations for the polymer distribution functions, which are used to construct a general free energy expression, taking into account the connectedness of the blocks of the copolymer, and including changes in the conformational entropy in interphase regions, stretching of the polymer chains, enthalpic interaction terms between different chemical species, and configurational entropy terms. The effect of solid surfaces on grafted polymers is also included in the theory. As examples we discuss pure block copolymers, the use of block copolymers as surfactants in mixtures of incompatible homopolymers, and the structure of block copolymer micelles in a homopolymer matrix. A few interesting features of the equilibrium phase diagrams of blends are pointed out, and we give a preview of current theoretical work on crystalline‐amorphous block copolym

ISSN:0005-9021    

DOI:10.1002/bbpc.19850891106

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY

摘要:

AbstractTrends in the research of rubber elasticity in the last decade are shortly reviewed. Scientists are presently concerned mainly with the questions, to which extent are cycles relevant for the elastic modulus, and whether a certain affineness is still a necessary requisite for a polymeric network? After a discussion of the state of theories recent experimental results are presented. These show: (i) Cycles are formed already in the pre‐gel state, and in realistic networks many of these are not elastically effective. (ii) Small angle neutron scattering from long labled chains incorporated in the network show clearly that affineness on stretching the network is not obtained even for long chains of about 3000 monomer units in length. (iii) Deuterium NMR from stretched rubbers in the dry as well as in the swollen state disclose segmental orientation which is more pronounced for segments near a junction point. Again this behavior is not predicted by current theorie

ISSN:0005-9021    

DOI:10.1002/bbpc.19850891107

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY

摘要:

AbstractA retrospective recalculation of the parameters of four known swelling equations has been performed so as to give the best correspondence to the swelling data points reported in the literature for homogeneous model polystyrene networks in benzene. A one parameter modification of the relation which fits the reported data best is used to describe the structural network heterogeneity according to a two phase model. This modified relation has been applied to study the increasing structural heterogeneity with increasing monomer conversion during the radical network formation of styrenedivinylbenzene networks with different initial divinyl composition as parameter.

ISSN:0005-9021    

DOI:10.1002/bbpc.19850891108

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY

摘要:

AbstractWe have studied the tensio‐active properties of acrylate diesters at the oil‐water interface. Measurements of the interfacial tension indicate that the molecules are subsequently adsorbed at the interface. The amphiphatic compounds in the monolayer can be polymerized and cross‐linked by UV irradiation. The gelation process of the two‐dimensional system has been studied by measuring the shear mechanical properties. We observed a clear transition from a viscous solution to a cross‐linked gel state. The two‐dimensional films behave like rubber elastic systems. The elasticity depends strongly on the concentration of the cross‐linking agent. The polymerisation of mixed films of monoacrylates and diacrylates can be used to built up two‐dimensional structures with defined rheolog

ISSN:0005-9021    

DOI:10.1002/bbpc.19850891109

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY

摘要:

AbstractThe influence of solid surfaces on the polymerization of diacetylenes has been studied using 3,5‐octadiyn‐1,8‐diol as a model compound. The first molecular layers on polar surfaces are adsorbed by hydrogen bonds. Their relative orientation hinders the polymerization of these molecules. Subsequent layers can be polymerized by UV radiation. After the unreacted monomer has been extracted a highly stable polymer film remains on the su

ISSN:0005-9021    

DOI:10.1002/bbpc.19850891110

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY

摘要:

AbstractFor styrene‐isoprene blockcopolymers of lamellar morphology obtained by casting from solution the influence of various modifications of thermodynamic interactions on lamellar dimensions and longperiods is studied by electron microscopy. The thermodynamic interactions are modified by the generation of a broad interphase caused by the insertion of a poly(isoprene‐co‐styrene)copolymer block of random structure between the pure blocks and by use of a preferential solvent of the diene component in blockcopolymers containing 20 wt‐% isoprene leading to a highly ordered asymmetrical lamellar morphology. Both modifications lead to a compression of the lamellar domains and longperiods relative to the dimensions of symmetrical unmodified systems. The influence of the interblock content is described by the same functional dependence for both symmetrical and asymmetrical

ISSN:0005-9021    

DOI:10.1002/bbpc.19850891111

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY