Processing and Characterization of Hybrid Composite Materials Made of Recycled HDPE and Mechanically Recycled Glass Fiber Thermoset Composites

ABSTRACT: Household plastic waste and industrial polymer matrix composite material scrap present two scales of problems that can lead to pollution and other environmental issues. Recycling waste and scrap has become increasingly important and has drawn tremendous attention as a promising approach to solving the growing polymer pollution issue. This study aims to create energy-efficient and scalable procedures to manufacture hybrid composite materials using household thermoplastic waste and industrial thermoset matrix composite scrap for the first time to our best knowledge, and evaluate the structural performance of upcycled fiber-reinforced composites. Recycled scrap of pultruded glass fiber vinyl ester composite (rComposite) was mechanically split with an energy-efficient process and subsequently molded with recycled household high-density polyethylene (rHDPE) waste to produce thermoset composite reinforced thermoplastic matrix (rComposite/rHDPE) composites at different rComposite contents, i.e., 20, 27, and 35 wt%. Various characterization methods, including Fourier transform infrared spectroscopy, differential scanning calorimetry, optical microscopy, and scanning electron microscopy analyses, were performed to evaluate the constituent materials and the molded composite. Mechanical testing was also conducted to evaluate the mechanical properties of the composites with different rComposite contents. It was found that the tensile and flexural properties of the rComposite/rHDPE composite increased with increasing rComposite content. There was a 256% increase in tensile strength and an 885% increase in tensile modulus for the 35%-rComposite reinforced rHDPE composite over neat rHDPE, respectively. Overall, this study presents a potential approach of recycling household plastic waste and polymer matrix composite material scrap by developing a hybrid composite material with great mechanical properties.