Maleic anhydride compatibilized peach waste as filler in polypropylene and high density polyethylene biocomposites

It is estimated that roughly 103, 515 tons of peach waste is produced annually in the US. The majority of the waste is disposed of in landfills, which contributes to climate change as they release 93 million metric tons of CO2 equivalent. Peach waste principally consists of remaining stone and seed after flesh removal. The agro-waste includes both cellulose and lignin, which can be utilized as a filler in plastic packaging to reduce carbon footprints and material cost. The objectives of this research are (1) to develop peach flour (PF)-filled biocomposites with a polyolefin matrix using maleic anhydride-g-high density polyethylene (MAH-g-HDPE) coupling agent resin and (2) to investigate the composites’ physicomechanical, thermal, and water absorbance changes. First, preliminary experiments examined a range of PF concentrations (5-50%) and MAH concentrations (0-17%) were tested to narrow the variability of PF and MAH loading mixture in an HDPE matrix. Preliminary experiments suggested that a 2:1 ratio of PF:CR provides maximum tensile properties. Response surface methodology (RSM) was utilized to analyze and optimize the tensile strength of the PW composite. The RSM parameters were MAH loading (5-20%), PF loading (2.5-10%), and polyolefin matrix (HDPE or polypropylene). The properties of PF-HDPE biocomposites were analyzed using several instrumental analyses. Mechanical strength (including tensile strength, elongation, and Young’s modulus) and thermal properties (thermal degradation, melting point, and crystallinity), and water resistance with the addition of PF and MAH were investigated. Biocomposite mechanical properties generally resulted in a nonsignificant decrease compared to the controls. Water absorption significantly increased with PF loading (P<0.01, =0.05). PF-PP biocomposites demonstrated a shift in thermal stability with an average 9.6% increase in Td compared to its control, whereas PF-HDPE biocomposites displayed no change in Td compared to its control. PF-PP and PF-HDPE biocomposites experienced a 36.7% and 16.0% decrease, respectively, in crystallinity with PF addition. The results provided evidence that peach byproduct can be diverted from landfills and utilized a filler in a polyolefin matrix. Polyolefin biocomposites with 2.5% PF would possess comparable tensile strength to a commercially available control. PF-polyolefin biocomposites can be used for packaging, automotive, and non-weightbearing construction parts.