Improved mechanical, thermal, and flame-retardant properties of hybrid composites with different recycled plastics

This research aims to improve the flame-retardant properties of wood-plastic composites with different recycled plastics. Acrylonitrile butadiene styrene (ABS) and polyvinyl chloride (PVC), flame-retardant materials, and recycled polypropylene (PP) were used as matrix in this research. Recycled ethylene propylene diene monomer (EPDM) with flame-retardant properties was also added to mix with rubberwood flour (RWF) to improve mechanical properties. The rubberwood flour, coupling agent (MAPP), and lubricant are fixed at 44.5%, 4%, and 1%, respectively, whereas recycled plastics and EPDM rubber contents are in the range of 30.5-50.5% and 0-20%, respectively. The composite materials were manufactured into panels using a twin-screw extruder and hot press machine. The experimental results were statistically analyzed by analysis of variance (two-way ANOVA) at a 95% confidence level. The highest values of the mechanical parameters of wood-plastic composites reinforced with recycled polypropylene (RWF44.5PP50.5) were 15.89 MPa, 42.26 MPa, 41.79 MPa, and 0.0202 J for tensile strength, flexural strength, compression strength, and impact strength, respectively. An increasing EPDM rubber content of wood-plastic composites provided better thermal properties. The thermogravimetric analysis and differential scanning calorimetry of hybrid composites with recycled ABS (RWF44.5ABS30.5EPDM20) obtained the highest value with thermal stability in the range of 255-284 degrees C. For the flammability properties, the hybrid composites with high EPDM rubber content were less flammable. Recycled PVC with content of RWF44.5PVC50.5 outperformed hybrid composites reinforced made from ABS and PP in terms of UL-94 and the limiting oxygen index with values of 25.73%.