Enhancement of properties of walnut shell/attapulgite/polyvinyl chloride composites with ultrasonic and hydrothermal treatment

Abstract

The effects of ultrasonic and hydrothermal treatment on the physical, mechanical, wear resistance, water absorption and thermal stability of the walnut shell (WS)/attapulgite (ATP)/polyvinyl chloride (PVC) composite and its enhancement mechanism were investigated. WS was treated by ultrasound and hydrothermal treatment and mixed with PVC and ATP, and the WS/ATP/PVC composites were prepared by melt extrusion. The properties of composites were characterized, and the results showed that after ultrasonic and hydrothermal treatment, the main chemical structure of composites was not changed significantly. Compared with untreated composites, the wear resistance after ultrasonic treatment for 10 min is the best. After ultrasonic treatment for 15 min, the bending strength, tensile strength and impact strength of the composite are increased by 8.9%, 10.3% and 46.2%, respectively. Hydrothermal treatment at appropriate temperatures also improved some properties of the composites. The composites after hydrothermal treatment at 110°C had the best thermal stability and highest hardness, and the bending strength and tensile strength values were increased by 5.9% and 5.2%, respectively. The impact strength of the composite increased with the increase of hydrothermal treatment temperature. The results showed that ultrasonic and hydrothermal treatments have the potential to improve the performance of wood–plastic composites as environmentally friendly pretreatment methods.