Perspectives in Polymer Blend Technology

The subject of polymer blends has been one of the primary areas in polymer science and technology over the past several decades. Judging from publications, patents, major university programs, Ph.D. thesis topics, it continues to maintain significant importance. This will continue, as there are a number of unsolved problems and opportunities. As new areas of interest develop in polymer science, polymer blend technology often becomes an important segment (e.g., electrically conducting polymer blends). 

Although investigated in lesser detail earlier, the science and technology of polymer blends had its emergence in the 1970 s. Many of the basic principles existed prior to that time e.g., Flory-Huggins thermodynamic principles as well as contributions by Guggenheim and Prigogine). Commercial blends existed for decades before, however the concept of miscibility, phase behavior, and the basic nature of polymer blends was not well understood or appreciated. An initial review of polymer blends [Bohn, 1968] listed only 12 miscible polymer pairs, some of which were minor variations in copolymer structure. The review also noted that UCST (upper critical solution 

This concept is, in essence, the result of neighboring units of a copolymer having a lower affinity for these units than the units of another polymer or copolymer. Miscibility can occur if the interaction energy (interaction parameter) is more positive for the copolymer units than the interactions between these units and the admixed polymer. Cases can easily exist where all the 

Much of the published literature has been involved with the study of polymer miscibility. If there was a single development in polymer blend technology to choose, which promoted the interest in polymer blends (and miscibility), it would probably have to be the commercialization of miscible blends of poly(2,6 dimethyl-1,4 phenylene ether) and polystyrene (PPE/PS). This commercial, miscible blend provided the polymer science community an example of the potential of combining dissimilar polymer mixtures into unique compositions offering a price/performance balance not achievable with the unblended constituents. 

While miscible blends have attracted considerable interest due to the thermodynamic implications and commercial relevance, phase separated blends have had a prominent role in polymer blend technology. While mechanical compatibility is assured in miscible blends, phase separated blends can often achieve property advantages not capable with single phase blends. (Mechanical 

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In this introductory chapter the basic information on polymer blends (with a special emphasis on the commercial alloys) is presented in the sequence (i) a historical perspective on the polymer science and technology, (ii) polymeric structures and nomenclature, (iii) fundamental concepts in polymer blend science, and (iv) evolution of polymer blends technology. 

We are aware that the above topics do not cover all problems which are of huge interest in the field of rapidly developing science and technology of polymer blends. It seems however, that the papers included in this volume do indicate some new trends and perspectives for further research in the properties, problems and opportunities of this class of materials. 

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