PROPERTIES AND PERFORMANCE OF POLYMER BLENDS

The use of polymer alloys for automobile fenders. Here the general requirements (viz. weight reduction, part consolidation, cost, design flexibility, increased impact, crashworthiness), translate into requirements for: stiffness, strength, impact resistance, low coefficient of linear thermal expansion, weight reduction, chemical, corrosion and heat resistance, finish, oven paintability and cost.




Low speed Mechanical Properties
Low speed Mechanical Properties which include: Tensile Strength, Tensile Modulus, Elongation compressive, and flexural strength, rigidity and hardness, fatigue failure.The tensile stress-strain test is most widely used. Owing to the viscoelastic nature of polymers, the test is only a rough guide to how a polymer will behave in a fished product.
The low-speed stress-strain dependence for PS and HIPS is shown in (Figure 1). These data well illustrate the change induced by incorporation of elastomeric particles into PS matrix. As shown, upon toughening, PS brittle behavior changes into ductile with flow.

Figure 1 Tensile stress-strain curves for PS and HIPS
The low-speed mechanical properties of polymer blends have been frequently used to discriminate between different formulations and methods of preparation Examples of the results can be found in the references listed in Table 1.





Table 1
Measurements of tensile stress-strain behavior of polymer blends is essential. The rubber-modified polymer absorbs considerably more energy, thus higher extension to break can be achieved. By contrast, an addition of rigid resin to ductile polymer enhances the modulus and the heat deflection temperature. These effects are best determined measuring the stress-strain dependence.
Compressive Strength
Stress-strai