Effect of sol-gel derived nano-silica and organic peroxide on the thermal and mechanical properties of low-density polyethylene/wood flour composites

The influence of nano-silica, synthesized and mixed with low-density polyethylene (LDPE) through a sol-gel process, on the thermal and mechanical properties of LDPE and LDPE/wood flour (WF) composites, prepared in the absence and presence of dicumyl peroxide, was investigated. Scanning electron microscopic (SEM) analyses show a uniform dispersion of silica nano-particles of size 10-50 nm in the matrix, and Fourier-transform infrared (FTIR) spectroscopic results indicated interaction between the nano-silica and the LDPE matrix, which seems to improve for samples prepared in the presence of dicumyl peroxide (DCP). WF and nano-silica, as well as the presence of DCP during sample preparation, substantially improve the thermal stability of the LDPE matrix. The tensile strength of the samples decreased with increasing wood flour content, while the tensile modulus substantially increased. The presence of nano-silica gave rise to lower values for both tensile strength and tensile modulus, while higher tensile strength (and an increase in tensile strength with WF content) is observed for samples prepared in the presence of DCP. The tensile modulus increases with increasing WF content, but is not substantially influenced by the presence of nano-silica or by sample preparation in the presence of DCP. The DMA results were in line with the tensile results.