Properties and Performance of Polymer Blends
This chapter presents an overview of properties and performance of polymer blends. It is structured into six sections dealing with aspects required for assessing the performance of a polymer blend. These are: 1. low speed mechanical properties, viz. tensi
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PROPERTIES AND PERFORMANCE OF POLYMER BLENDS
S. F. Xavier
Indian Petrochemicals Corporation Ltd., Vadodara, Gujarat, India
12.1
Abstract
This chapter presents an overview of properties and performance of polymer blends. It is structured into six sections dealing with aspects required for assessing the performance of a polymer blend. These are: 1. low speed mechanical properties, viz. tensile, compressive, and flexural strength, rigidity and hardness, fatigue failure, 2. high speed mechanical properties and fracture mechanics, viz. Izod and Charpy impact strengths, fracture toughness, toughening mechanisms (such as crazing, shear yielding and cavitation), 3. chemical and solvent effects, 4. thermal and thermodynamic properties, viz. thermal conductivity, heat capacity, heat deflection temperature, the thermodynamic interaction parameter, 5. flammability, 6. others, such as electrical and optical properties, viz. the methods of determining electrical conductivity, resistivity, break-down voltage, optical transparency, haze and refractive index of polymer blends, etc. Each section opens up with standard test methods such as ASTM, BS, DIN and ISO for each property evaluation and is summarized. Since presentation of all test methods for each property is beyond the scope of this chapter, one popular test method is described in detail while others are discussed with reference to it. The factors controlling each property are also examined. Each section concludes with an outline of the state of the art pertinent to the aspect in focus. Definitions of all terms from each section are grouped together in an Appendix. Toughening plays an important role in designing polymer blends. Due emphasis has been given to this aspect by presenting different methods of determining blends toughness, specially using ductile fracture mechanics, the mechanisms of toughening and also factors influencing toughness. Flammability aspect assumed a great deal of interest ever since the USA Federal Trade Commission’s (FTC) action in 1972. Commercial exploitation of a polymer blend is regulated, since then, by its flammability characteristics. A brief review on factors affecting flammability is presented and a list L.A. Utracki (Ed.), Polymer Blends Handbook, 861-950. © 2003 Kluwer Academic Publishers. Printed in the Netherlands.
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of fire retardant chemicals is provided in an Appendix. The chapter concludes with perspectives for the future developments. 12.2
Introduction
Modern technology thrusts challenging demands on the performance capabilities of materials, including polymers and their blends. A new approach to the science and technology of polymer blends has emerged recently, i.e., polymer blends by design, rather than by availability. These polymeric materials must perform under strenuous mechanical, chemical, thermal and electrical conditions imposed by the requirements of a specific application. Service in these applications usually involves several criteria to be fulfilled without a loss of economic advantage. Indeed, perform
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