8 - Preparation, morphology, static and dynamic mechanical properties, and application of polyolefins and poly(ethylene terephthalate) based microfibrillar and nanofibrillar composites

Abstract

This chapter discusses the properties of micro and nanofibrillar composites prepared from blends of polyolefins and polyethylene terephthalate by a three-step protocol, namely melt extrusion, continuous drawing of extruded strands, followed by isotropization (annealing). These composites are unique in nature as the reinforcing fibrils are formed in situ during the melt blending process. The morphology development of the blends during each stage of preparation is analyzed by microscopic techniques. The static mechanical properties such as tensile strength, tensile modulus, elongation at break are examined. Dynamic mechanical properties analysis carried out gives information on the storage modulus, loss modulus, damping factor, and transition temperatures of in situ microfibrillar composites. The effect of draw ratio and blend ratio on the microstructure development is discussed in detail. The consequence of compatibilizer addition on the various properties of the in situ composites is reported. It is observed that an optimum draw ratio and blend ratio is imperative for maximizing the aspect ratio of the micro/nanofibrils which controls the strength and stiffness of the composite.