The mechanical properties deterioration of rubberwood-latex sludge flour reinforced polypropylene composites after immersing in different water conditions

The hydrophilic nature of wood-plastic composites (WPCs) is a disadvantage that impacts its performance in applications for construction and building products. Therefore, developing the WPCs into composites that reduce water absorption needs further evaluation. The current work investigates the effects of different water types (distilled water, and water from the Gulf of Thailand and the Andaman Sea), latex sludge types, and immersion time on the physical and mechanical properties of rubberwood-latex sludge flour-reinforced polypropylene composites. The composite samples were produced by a twin-screw extruder (mixing) and a compression molding machine (forming). The results revealed that the composites exposed to different water conditions for a long period resulted in significant (α = 0.05) reduction in the modulus of rupture, modulus of elasticity, screw withdraw strength, and hardness with maximum percentage reduction values of 79.9, 117.5, 69.9, and 5.84, respectively. However, adding the latex sludge at 25 wt% resisted deterioration. The composites immersed in Andaman Sea water exhibited the least water absorption and deterioration for all the mechanical properties with a minimum hardness loss (3.74%). The composites immersed in distilled water showed the maximum deterioration for all mechanical properties, with 117.5% loss in modulus of elasticity. Overall, adding the latex sludge flour to the composites made them resistant to mechanical properties deterioration, which is favorable for WPCs used in environments involving contact with the seawater, especially the Andaman Sea.