Abstract
Natural fibres have been used in a wide range of polymer composite reinforcements to produce new composites with good properties that can be used in many applications. In this study, the fracture toughness, acoustic, and thermal properties of date palm fibre (DPF)/polyester composite and DPF/sheep wool hybrid reinforced polyester were investigated. Physical properties, such as water absorption and thickness swelling, have also been reported. Finally, scanning electron microscopy (SEM) images of the composites and hybrids were obtained. The composites and hybrids were produced by compression moulding and cut into standard shapes before being tested. DPF and DPF/sheep wool contents (wt%) were 0%, 10%, 20% and 30%. The test results indicate that the fracture toughness improved from 3.45 MPa center dot m(1/2) (with 0% additive content) to 11.55 MPa center dot m(1/2) (with 20% DPF content) and 13.95 MPa center dot m(1/2) (with 20% hybrid content). The energy release rate increased from 3.99 kJ/M-2 (with 0% additive content) to 39.82 kJ/M-2 (with 20% DPF content) and 53 kJ/M-2 (with 20% hybrid content) due to the good adhesion between the matrix and fibres. DPF improved the acoustic insulation properties of the polyester/DPF composite with mass fractions of 10%, 20%, and 30%. At a frequency of 2000 Hz, the acoustic attenuation in decibels (dB) increased from 16.2 dB with pure polyester to 17.2, 18.2, and 19.5 dB with 10%, 20%, and 30% DPF content, respectively. The increase in sheep wool and DPF hybrids in the polyester matrix increased the acoustic attenuation to 18.4, 20.6, and 24 dB, respectively, because DPF and sheep wool have good acoustic insulation properties. Thermal conductivity was 0.161 W/m center dot C with 0% additive content, decreasing to 0.133, 0.107, and 0.082 W/m center dot C with 10%, 20%, and 30% DPF content, respectively, and 0.112, 0.073, and 0.051 W/m center dot C for 10%, 20%, and 30% DPF/sheep wool hybrid content, respectively, owing to good thermal insulation properties of DPF and sheep wool. Water absorption gradually increased with DPF and DPF/sheep wool hybrid because DPF and sheep wool have good absorption properties. Thickness swelling increased with increasing DPF and DPF/sheep wool hybrid contents but not to the same extent. SEM images indicated good distribution and bonding of DPF with the polyester matrix up to 20% and good results for DPF/sheep wool with the polyester hybrid at 10% and 20% hybrid content.