Abstract
Most wood-plastic composites (WPCs) are fabricated using thermoplastics and sawdust (or other natural fibers). In this study, we used polypropylene (PP) and recycled rice straw (RS) as raw materials to prepare 22 types of WPCs for indoor use. We also incorporated chemical agents to enhance resistance to UV light, coupling capability, and flame retardancy. We then assessed how the PP/RS ratio and the addition of chemical agents affected the density of the resulting WPCs and the water-absorption rate (WAR), length-swelling rate (LSR), and microstructure. We also performed a thermogravimetric analysis, evaluated the weathering performance and flame retardancy, and measured the release of organic volatile matter (formaldehyde) to determine whether the proposed WPCs meet established standards for indoor usage. Samples prepared without a coupling agent exhibited increased WAR and LSR values with an increase in the content of recycled RS powder (24- h soaking test). Samples prepared with a coupling agent presented increased WAR values with an increase in soaking time when the content of recycled RS powder exceeded 50 phr (indicates the percentage of additives in rubber (or resin)) (28-day soaking test). The best composites evaluated in this study were self-extinguishing (limited oxygen index (LOI) = 27) and flameproof (based on V-0 criteria), exhibited low formaldehyde release (0.07 mg/L), and presented no differences in appearance before and after weathering tests.