Mechanical Properties and Aging Resistance of Recycled Polypropylene‐Based Composites: Filled With Unmodified/Modified Papaya Branch Fibers

ABSTRACT With the increasing attention of researchers worldwide to the technology of utilizing agricultural and forestry waste plant fibers, the development of environmentally friendly plant fiber reinforced resin based composite materials has become a research hotspot in recent years. In this study, novel composites were fabricated via melt‐blending and injection molding process, utilizing recycled polypropylene (rPP) as the matrix and South Shaanxi papaya branch fiber (SQBF) as the reinforcement. Prior to compounding, the chemical and morphological characteristics of SQBF were evaluated, followed by surface modification with tannic acid (TA) and nano‐silicon carbide (nano‐SiC). Furthermore, maleic anhydride‐grafted polypropylene (MAH‐g‐PP) was introduced to optimize interfacial adhesion between the hydrophilic fibers and the hydrophobic matrix. The study showed that compared with unmodified composite materials, the composite material with 2% MAH‐g‐PP added has the best comprehensive performance, significant improvement in mechanical properties, a maximum increase in tensile strength of 20.85%, and the best resistance to hydrothermal aging. After aging, the tensile strength and bending modulus only decreased by 2.33%. This study evaluated the effects of modification and aging treatment on the comprehensive properties of composite materials, confirming the feasibility of SQBF as a reinforcing fiber for rPP based composite materials, which can provide reference for the research and development of efficient and high‐value utilization technology for SQBF.