Thermal insulation and mechanical characteristics of polyester filled with date seed wastes

In this study, the feasibility of utilizing date palm seeds (DS), the primary waste in date industry, as a filler in unsaturated polyester (UPR) matrix to develop thermal insulation material was investigated. Stable homogenous DS-UPR composites with up to 70 vol% natural filler were prepared at room temperature following a thermoset curing process. The developed composites were subjected to different physical, thermal, and mechanical tests. Moreover, the developed composites were characterized using different techniques (such as scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FTIR)). Density and water retention measurements were verified using different theoretical models. FTIR analysis suggests the existence of hydrogen bonding between DS fibers and UPR, which was more pronounced at high filler loadings. Replacing till 50 vol% of UPR with DS produced composites that possess promising thermal insulation and construction properties with relatively low thermal conductivity (0.126 – 0.138 W/(m∙K)), low thermal diffusivity (0.109 – 0.096 mm²/s), low water retention (0.47–3.44%), and high compressive (38.4–88.0 MPa) and tensile strengths (9.4 – 35.1 MPa). Moreover, addition of date seeds to unsaturated polyester matrix slightly increased its glass transition temperature and improved its thermal stability. The novel DS-UPR developed composite can be used as an alternative insulation material because of its superior properties compared with those of the traditional thermal insulators.