Efeito de aditivos de processo nas propriedades de composições de polipropileno reciclado.

Abstract

The rising production of industrial plastics and of plastics packing waste has rendered plastics recycling increasingly important. Recycling of these systems, however, is difficult as polymer blending usually leads to incompatible products and polymer properties depend on molecular weight and molecular weight distribution, the presence of impurities, moulding methods and processing conditions as well as degradation caused by use. The performance of recycled plastics can ber enhanced by criterious material selection and separation methods, the proper choice of specific aditives and processing conditions. In this work the effect of different mixing conditions on the performance of four different plastics formulations based on recycled PP/CaCC>3 was ascertained. These formulations differed among them selves by the addition of PE wax, apoxidated soyabean oil and a mixture of both of these additives. Different mixing conditions were obtained by the use of serews with three different profiles during extrusion. Our results show that PE wax addition did not significantly alter the mechanical properties of the base formulation while addition of a epoxidated soyabean oil or of a misture both, did lower tensile strenght at break, elastic modulus and hardness and increased impact strenght, elongation at break and flexural strenght of the formulations under study. Varying screw profiles did not lead to significant variations on mechanical properties, however, processing energy was much lower with screw •£ 1 (standard screw). A better balance of mechanical property energy spent on processing was obtained of the formulation containing both: PE wax and epoxidated soyabean oil, extruded with the standard screw.