The microstructure and mechanical properties of eggshell powder and glass fiber reinforced recycled polyethylene/high-density polyethylene as non-structural building composites

The output of polyethylene (PE) is enormous and widely used, but the waste polyethylene products pollute the environment. In this study, a new composite material with excellent mechanical properties, good thermal stability and crystallization properties was prepared by using recycled polyethylene/high-density polyethylene (R-PE/HDPE) as matrix, PE-g-MAH was used as a compatibilizer, glass fiber (GFKH) and eggshell powder (ESPKH) treated with silane coupling agent KH550 were used as reinforcement phases. The results showed that the composite containing 30 wt% GFKH and 0.5 wt% ESPKH (GFKH/ESPKH0.5) exhibited significant enhancements in multiple properties compared to R-PE/HDPE. Specifically, its crystallinity, storage modulus, tensile strength, bending strength, and impact strength were measured as 62.9 %, 918.8 MPa, 49.91 MPa, 42.73 MPa, and 10.68 KJ/m 2 , respectively. These values represent substantial improvements of 33.3 %, 107.9 %, 125.3 %, 115.3 %, and 79.8 % over those of R-PE/HDPE (47.2 %, 441.9 MPa, 22.15 MPa, 19.85 MPa, and 5.94 KJ/m 2 , respectively). Thermal analysis revealed that the incorporation of GFKH and ESPKH significantly enhanced the thermal stability of R-PE/HDPE. Specifically, the GFKH/ESPKH0.5 composite demonstrated a Vicat softening temperature (VST) of 122.6 ℃ and a temperature at 5 % weight loss (T 5 % ) of 415.6 ℃, corresponding to increases of 6.9 ℃ and 41.0 ℃, respectively, compared to those of pristine R-PE/HDPE (115.7 ℃ and 374.6 ℃). Through the analysis of variance (ANOVA) parameters P-value and F critical value, it can be seen that ESPKH had a significant effect on the mechanical properties of the composite. This experiment primarily investigates the relationship between composite material properties and microstructure, and it provides a novel approach for modifying recycled thermoplastic resin and designing high-performance composite materials. A comparison of the test results with those of traditional building materials reveals that GFKH/ESPKH0.5 composite exhibits strong potential in the manufacture of sustainable construction components, parts, and products.