Studies on microfibrillar based composites

Abstract

ABSTRACT newlineMicrofibrillar composites (MFCs) are a new class of fiber reinforced newlinecomposites prepared from two thermoplastic polymers. In such newlinecomposites, a low melting and isotropic thermoplastic matrix is reinforced newlinewith in-situ formed microfibrils of another thermoplastic having a higher newlinemelting point. Making MFCs also provides a technology to make best use newlineof commingled plastic mixtures in which both low melting temperature newlinegeneral plastics and high melting temperature engineering plastics coexist newlineand cannot be easily separated. In this work, the properties of MFCs newlineprepared from polypropylene (PP)/ polyethylene terephthalate (PET) newlineand low density polyethylene (LDPE)/ polyethylene terephthalate (PET) newlineblends were analyzed. In the case of polypropylene/ polyethylene newlineterephthalate MFCs the effect of draw ratio on the morphology, static and newlinedynamic mechanical, thermal, rheological properties were studied. The newlinedraw ratio employed during the preparation of MFCs was optimized newlinebased on the results obtained. The mechanical properties of the MFCs newlinewere found to be superior to the normal blends. The MFCs prepared at the newlineoptimum draw ratio exhibited 41% and 50% increase in the tensile and newlineflexural moduli compared with the conventional blends. The microfibrils newlineof PET exhibited heterogeneous nucleating effect on the crystallization of newlinePP. In the case of LDPE/PET system, the effect of blend ratio and the newlineeffect of compatibilizer content on the properties of microfibrillar newlinecomposites were studied. Based on the morphological, static and dynamic newlinemechanical properties 75/25 w/w% was found to be the optimum blend newlineratio. The compatibilizer introduced during MFC preparation influenced newlinethe diameter of the PET microfibrils. The transport of a solvent (xylene) newlinethrough the MFCs was found to be retarded in comparison with LDPE newlineand LDPE/PET normal blend due to the tortuous path offered by the newlinerandom arrangement of PET microfibrils in the isotropic LDPE matrix.