Desenvolvimento e caracterização de compósitos PBAT-amido/ casca de arroz.

Abstract

made with a commercial blend of PBAT-starch as the matrix and rice husk (RH) as filler were obtained and characterized. The mechanical properties and biodegradation of composites with different RH contents, obtained by two different processing methods, were determined. Both matrix and filler were characterized with respect to their rheological, thermal and morphological characteristics and the data was used to determine the parameters employed for processing composites with 10, 20 and 30% w/w rice husk in an internal mixer and in a twin-screw corotating extruder. The rheological, thermal and mechanical properties as well as the morphological and biodegradation characteristics of PBAT-starch/RH composites were determined. SEM analysis indicates that filler particles were satisfactory wetted by the matrix and that matrix/filler adhesion is good, which reflected on the systems’ mechanical properties. Results indicate that elastic modulus was affected by the processing method adopted, being higher for the composites processed by twin-screw extrusion. Impact strength significantly decreased and tensile strength moderately increased with filler content, regardless of the processing method employed. DSC analysis indicates that RH addition on extruded composites leads to higher crystallization temperatures, which can be attributed to a nucleating effect of the better dispersed filler obtained by the extrusion process. Biodegradation determined by weight loss of samples buried in soil, indicates that microorganisms preferentially degrade the matrix. However, when biodegradation was determined using the Sturm method, both matrix and filler were degraded and CO2 evolution increased with rice husk content.