INFLUENCE OF TALC MORPHOLOGICAL-CHARACTERISTICS ON THE TOUGHNESS OF A COMPOSITE BASED ON LOW-DENSITY POLYETHYLENE AND POLYPROPYLENE BLENDS

The toughness of polymer composites based on low-density polyethylene (LDPE)/polypropylene (PP) blends and filled with talcs of different particle size and particle size distribution was studied applying the two-variable Box-Hunter method of optimization. The effect of the polymer matrix composition and percent talc on the Charpy impact strength of the composites, at minus 30 degree C, was investigated. The results show a change in the polymer matrix behavior at PP contents of 60% and 75%, depending on talc particle size. At these percentages of PP, toughness exhibits a minimum that becomes lower as the filler content is increased. Optical microscopy shows a nucleating effect of the talc particles for the crystalline polymer. The larger the talc particle size, the higher the nucleation density. The minimum toughness arises at higher PP content in the matrix. At PP contents in the matrix below 35%, the filler has a minimal effect on composite toughness.