Influence of Commercial Additives and y-Irradiation on Structural and Mechanical Properties of rHDPE/rGFRP

In response to environmental regulations, particularly within the European Union, there is an urgent need to implement new, sustainable materials derived from recycling processes. This study investigates the potential for modifying and predicting the mechanical properties of composites made from recycled high-density polyethylene (rHDPE) and recycled glass fiber-reinforced polymer (rGFRP). Specifically, it examines tensile strength parameters and structure changes in rHDPE/rGFRP treated with three different chemical additives, including a silica-based agent (S) and maleic-anhydride polyethylene (MAH) compatibilizers; and a thermal stabilizer dedicated for the recycled polyolefins. The findings reveal that these additives do not significantly change the mechanical properties of the composite. All additives increase elastic modulus (compared to rHDPE/rGFRP for max. 3% - S), tensile strength (max. for 14%, MAH), and offset yield strength (max. 16%, MAH). Moreover, the strength of the composite can be enhanced through γ-irradiation, which was found to affect the stress-strain characteristics of the rHDPE/rGFRP blend. Notable differences were observed in the strength and elongation behavior of the composite (for rHDPE increased to 0.58 for 40 kGy and decreased for 100 kGy dose to 0.35, which is very close to the non-irradiated sample), suggesting that irradiation could be a viable method for modifying the properties of recycled composites for specific applications.