Development and Performance Evaluation of HDPE Waste Plastic-Diatomite and Sawdust Based Composite Material for Thermal Insulation in Buildings

Abstract

Applying thermal insulation material in the wall is a major means of improving building energy conservation. However, traditional building insulation materials have defects in varying degrees, including, water absorption, low strength and not environment-friendly. To solve this problem, a novel thermal insulation bio-composite composed of spent brewery diatomite earth, sawdust and HDPE waste plastic-based composite materials were manufactured by the melt mixing method followed by compression molding. The effect of HDPE, DE and, SW weight proportion and mold compression load (CL) on composite properties were investigated to evaluate their physical (water absorption, density, morphological properties), thermal (thermal conductivity, thermal diffusivity, specific heat capacity and thermal stability) and mechanical (compressive and flexural strength) tests. A D-optimality design was employed to determine the optimum preparation condition of the thermal insulation bio-composites, to obtain the lowest thermal conductivity and water absorption value and the highest compressive strength. It was found that composites were best fit by a linear * quadratic regression model with high coefficient of determination (R2 ) value (0.9995, 0.9988, and 0.9998) for WA, CS, and TC respectively. The selected optimum condition was 72.13 wt.% HDPE, 25wt.% DE, 2.87 wt.% SW, and 10 MPa mold compression load (CL), leading to a desirability of 75.6 %. Under the optimum condition, the thermal conductivity, water absorption, and compressive strength of the bio-composites were 0.023 W/(m.k), 0.603 %, and 87.579 MPa, respectively. Those selected optimum parameter formulation was also gave the maximum flexural strength ~94.2 MPa. The thermal conductivity, thermal diffusivity and bulk density of the samples decreased as filler (DE/SW) contents were increased and mold compression load (CL) decreased. In addition, the thermal stability of the samples increase with DE weight proportion and mold compression load (CL). The compressive and flexural strength of the TIDSPCs were higher than those the commonly used insulating materials and comparable to those of construction materials (52.47 - 87.579 MPa) and (50.8 - 94.2 MPa), respectively. The characteristic of the TIDSPCs indicate that they are stable composites with promising insulation and construction capacity. The developed materials may be used in the handle of kitchen utensils and other materials that required thermal insulation.