Polymer Properties through Structure

In this chapter we aim to demonstrate the relationship of the structure of polymers with their thermal, solution, and rheological behavior. Besides providing a general review of such behavior, we will emphasize some of the recent developments in these areas. 

The thermal behavior of polymers is different from that of simple compounds in that, on heating, the transition of polymers from solids to liquids occurs not at 

1) The symbols used in this chapter are listed at the end of the text, under Notation . 

Handbook of Polymer Reaction En neering. Edited by T. Meyer, J. Keurentjes Copyright 2005 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 3-527-31014-2 

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Agarwal UD. Polymer properties through structure. In Meyer T, Keurentjes J, editors. Handbook of Polymer Reaction Engineering. Weinheim Wiley-VCH 2005. p 679-720. 

The growth rate of the use of particulate filled polymers is very fast in all fields of application [ 1 ]. Household articles and automotive parts are equally prepared from them. In the early stages, the sole reason for the introduction of fillers was to decrease the price of the polymer. However, as a result of filling all properties of the polymer change, a new polymer is in fact created. Some characteristics improve, while others deteriorate, and properties must be optimized to utilize all potentials of particulate filling. Optimization must include all aspects of the composites from component properties, through structure and especially interactions. 

Materials with totally new property combinations may be achieved by blending two or more polymers together. Through blending of thermotropic main-chain LCPs with engineering thermoplastics, the highly ordered fibrous structure and good properties of LCPs can be transferred to the more flexible matrix polymer. LCPs are blended with thermoplastics mainly in order to reinforce the matrix polymer or to improve its dimensional stability, but LCP addition may modify several... 

Minor (by amount) functionality is introduced into polymers as a consequence of the initiation, termination and chain transfer processes (Chapters 3, 5 and 6 respectively). These groups may either be at the chain ends (as a result of initiation, disproportionation, or chain transfer,) or they may be part of the backbone (as a consequence of termination by combination or the copolymerization of byproducts or impurities). In Section 8.2 wc consider three polymers (PS, PMMA and PVC) and discuss the types of defect structure that may be present, their origin and influence on polymer properties, and the prospects for controlling these properties through appropriate selection of polymerization conditions. 

Yet as the many sided debate went on, Wallace Carothers started a series of investigations in 1928 which would eventually establish the macromolecular concept. His objective from the beginning was to prepare polymers of known structure through the use of established reactions of organic chemistry (85). In the brilliant years before his untimely death in 1937, he studied the preparation and properties of polyesters, polyanhydrides, polyamides, and polychloroprene (28). 

As one tries to write down an analysis of the developments in the block polymers area, one realizes very soon that it is going to consist of a series of variations on a theme a theme which is the increasing ly stronger reality, in our everyday scientific life, of what can be now really called "the molecular engineering of polymers properties", i.e. the possibility to control, through precise (although sometimes small) modifications of molecular structures, the final bulk properties and macroscopic behaviour of polymeric materials. In other words, one deals there with a very acti ve version of the studies on structure-properties inter relationships, a question which by the way has always been a focal point among the many diversified interests of Professor Mark. 

O2 diffusion through the membrane seems to be limited by the percolation network of the diffusion path, which is not only defined by the amount of water in the membrane, but also by the different chemical structure of the membranes. It is difficult to make comparisons of gaseous diffusion behavior among polymers with different structures because polymer morphology can change drastically without appreciable changes in density, and the presence of water and the hydrogen bonds formed between polymer-water moieties also has major effects on system properties. However, some points can be made from these particular studies. 

Kato T, Kihara H, Ujiie S, Uryu T, Frechet JMJ. Structures and properties of supramolecular liquid-crystalline side-chain polymers built through intermolecular hydrogen bonds. Macromolecules 1996 29 8734-8739. 

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