Preparation and properties of recycled polypropylene‐based wood–plastic composites reinforced with a bio‐based compatibilizer

Abstract Wood‐plastic composites are green composites made of plastic as the matrix and wood as the filler; however, the incompatibility between these two leads to the degradation of the composites. This paper reports the synthesis of a novel bio‐based compatibilizer, annotated as OA‐g‐H20, by grafting oleic acid (OA) on a hyperbranched polyester (Boltorn H20). The effect of modifying recycled polypropylene‐based wood–plastic composites with this compatibilizer was then assessed. The Fourier transform infrared spectroscopy, thermogravimetric analysis, and gel permeation chromatography techniques were employed to characterize the fabricated OA‐g‐H20, while its modification effect was assessed by differential scanning calorimetry, dynamic thermomechanical analysis, scanning electron microscopy, and mechanical property tests. The experimental results revealed that the optimal addition amount of OA‐g‐H20 was 2.0 wt.%. Highlights A new bio‐based compatibilizer, OA‐g‐H20, for wood–plastic composites is reported. OA‐g‐H20 was obtained by grafting oleic acid on a hyperbranched polyester (H20). OA‐g‐H20 provided good mechanical reinforcement for the wood–plastic composites. OA‐g‐H20 improved the crystallinity of the composites. The reinforcement mechanism of OA‐g‐H20 in wood–plastic composites is elucidated.