摘要:

Polymer blending is an alternative approach to obtaining new materials with unique or desirable properties based on those commercially available polymers rather than to design and synthesize total novel polymers [1]. Since thermotrolpic liquid crystalline polymers (TLCPs), which have dis-played good thermal and mechanical properties and dimensional stability, especially excellent melting processability, were developed about 20 years ago, this new class of high performance polymers has receiived significant attention. Not only have many TLCPs with various chemical structures been synthesized, but some related research fields have also rapidly devel-oped [2, 31. Blending TLCPs with conventional thermoplastic polymers is one of these branches [4]. Polymer blends involving TLCPs as one of the components are termed “in situ composites” [5]. The purpose of preparing such an “in situ composite” is mainly to improve the processability of the thermoplastic matrix with the aid of a small amount of TLCP, due to its relatively low melt viscosity, and also to reinforce the matrix or to enhance its dimensional stability simultaneously. This summary is an attempt to provide a brief picture of recent developments in this field. The general blending of polymer pairs; the mixing, blending, and processing methods or some specially developed techniques; the blend morphology and rheology features and characterizations; and the thermal and mechanical properties, especially for some important factors that directly affect the efficiency of the reinforcement derived from the TLCP, will be discussed in detail.

ISSN:1532-1797    

DOI:10.1080/15321799508014587

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In the experimental colloid science literature, considerable information on the subject of polymer-surfactant interactions has accumulated over many years. However, few physicochemical studies were done on the inter-action between oppositely charged polyelectrolytes and surfactants in the early work. This may be due t o the strong interaction which starts a t a very low surfactant concentration and which is often accompanied by precipita-tion, making it difficult t o measure the low surfactant concentration in the region of interest.

ISSN:1532-1797    

DOI:10.1080/15321799508014588

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In the polymerization of vinyl chloride, as in other radical polymeriza-tion processes, the chain transfer reaction plays a large part. The state of knowledge on the chain transfer of polyvinyl chloride (PVC) radicals to vinyl chloride and to PVC was recently considered in detail in the papers of Xie, Hamielec, Wood, and Woods [1-3]. In the present paper, chain trans-fer to various additives in the polymerization mixture is reviewed. These include chain transfer agents (CTA) used as regulators of the molecular weight of PVC. The review relates, on the whole, to chain transfer which proceeds without causing significant change in the polymerization rate; chain transfer leading to inhibition of polymerization is not discussed.

ISSN:1532-1797    

DOI:10.1080/15321799508014589

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

It is well known that the highest elastic moduli reported for linear poly-mers are generally much smaller than their theoretical values. This has been shown particularly by Nakamae and coworkers [1]. For a range of poly-mers they have summarized their crystal moduli determined by x-ray dif-fraction as measured in the stiffest direction, parallel to the polymer chain axis. These values on crystals approximate the ultimate polymer moduli; they therefore may be compared with the much lower presently reported values for the conventional structure of these polymers (Fig. 1). This figure shows that most polymers, including those with rigid backbone chains, have tensile moduli far below those of their crystalline lattice in the chain direction. The exceptions are specially drawn ultrahigh molecular weight polyethylene (UHMW PE), which in PE parlance is generally considered to mean molecular weight above one million, and for isotactic polypropyl-ene that also has been drawn to tensile moduli that approach the value from theory.

ISSN:1532-1797    

DOI:10.1080/15321799508014590

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The discovery of a new catalyst for the low temperature and low pressure polymerization of ethylene by Ziegler at the Mulheim Institute in Germany in the mid-1950s opened the door to a whole new world in the synthesis of polyolefins [1]. Shortly thereafter, Natta and his group at the Milan Insti-tute in Italy announced that propylene and higher a-olefins could also be polymerized by the use of coordination catalysts, for example Tic], -Al(eth), F [2, 3]. The discovery of stereospecific polymerization allowed steric control on the growth of polymer chains for the first time. A major consequence of this polymerization is a significant effect of stereoregularity on physical, in particular, and mechanical properties. Another major con-tribution by Natta and his group was the development of methods for characterizing polymer configurations and conformations.

ISSN:1532-1797    

DOI:10.1080/15321799508014591

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Chitosan [(1-4) 2-amino 2-deoxy-β-D-glucan] is a polyaminosacchar-ide, normally obtained by alkaline deacetylation of chitin which is a very abundant naturally occurring polymeric material. It occurs as a principle constituent of the protective cuticles of crustacea and insects and also in the cell walls of some fungi and microorganisms.

ISSN:1532-1797    

DOI:10.1080/15321799508014592

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:1532-1797    

DOI:10.1080/15321799508014586

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor