Utilization of walnut shells as filler in polymer composites
Abstract
In this study, the utilisability of Walnut Shell (WS) flour in polypropylene (PP) and high density polyethylene (HDPE) matrix composites are investigated due to its relative hardness and availability. The WS flour was compounded with PP and HDPE at 50% (weight) content with and without coupling agent in a single screw extruder. Then, granulated compositions were manufactured by press moulding process. Some mechanical properties (Tensile, impact, flexural strength), TGA and DSC were performed on the polymer composites samples. When WS flour were added 3% coupling agent bending properties of the HDPE and PP samples increased to 1340 MPa and 1514 MPa, respectively. However, WS2 samples which HDPE composites type was added 3% coupling agent in the form showed 26% lower impact factor than WS1. The addition of coupling agents improved the properties of polymer composites. MAPE coupling agents performed better in HDPE while MAPP coupling agents were superior in PP based composites. According to mechanical properties of the composites groups, the lowest strength was in the WS3 which content 50% PP without couple agent. All produced composites provided mechanical properties required by the ASTM D662 standard for plastic lumber decking boards. The analysis showed that MAPE didn’t affect to thermal degradation of 47% WS filled HDPE composites samples. Melting temperature was around WS1 and WS2 130 °C while WS3 and WS4 around 165 °C. The second melting peak temperature of WS2 composites with 3% coupling agent was around 170 °C. As a result Walnut shell which was considered agricultural waste can be utilized in polymer composite production.