Thermal and physico-mechanical stability of recycled high density polyethylene reinforced with oil palm fibres

Abstract

The impressive physical and mechanical properties achievable with organic fillers make them a good choice for polymer composite reinforcement. In this study, oil palm fibres (OPF), often hardly thought of as having any reasonable economic value in developing economy was used as reinforcing fillers in recycled high density polyethylene (rHDPE). Thermal behaviour, physical and mechanical stability of rHDPE filled with OPF have been studied. Fourier Transform Infrared Spectroscopy (FTIR) results present band spectra characteristic of OH stretching vibration in the cellulose of the fibre material. The absorption bands of the spectra are attributed to the presence of stretching vibration of CO group mostly found in the form of hemicelluloses and lignin structure in the fibre. Upon examination of the test specimens produced through compression moulding technique, it was found that the addition of OPF (filler) into rHDPE (matrix) increased the composites’ water absorption rate linearly for the first 16 days of exposure to the water environment. Stability was achieved for all the materials after this period. Thermal studies of the various compositions (OPF/rHDPE: 5/95, 10/90, 15/85, 20/80 and 25/75) using derivative thermogravimetric analysis (DTGA) showed two main degradation peaks at 490 °C and 380 °C. The mechanical study revealed that the composite with 20 wt% filler contents was the most eco-friendly and had the best mechanical properties while that with 25 wt% was the most thermally stable. This material was thermally stable up to approximately 330 °C. Microstructure examination of the different components of the composites further explains the reason for good physical and mechanical strength of the sample with 20 wt% filler. It can, therefore, be inferred from the results of the various analyses conducted that OPF is a good reinforcing phase for rHDPE and a potential material for construction and automotive industries