Correlation of mechanical and optical properties of polypropylene plastic waste for application in composite panels

Abstract

Sustainable plastic waste management systems are needed to reduce environmental pollution impacts as they are non-biodegradable and emit greenhouse gases when burned. This study investigates the feasibility of using recycled polypropylene (PP) from commonly used plastics to process composite panels. The samples were obtained from household plastics with a Resin Identification Code (RIC) of 5. In addition, other common polymer samples were obtained from plastic coffee cups (W) and red basin tubs (R) and moulded using an injection moulding machine. The mechanical strengths of the resultant composites were plotted and compared with the theoretical value of the pure polymer. The ultimate tensile strength of the white cups and the red basin tubs was found to be 36 MPa and 14.55 MPa, while their yield points were 14.45 MPa and 4.55 MPa, respectively. Infrared spectra of the absorption of the samples were obtained using Fourier transform infrared (FTIR) spectroscopy. The band gaps were analysed from Tauc’s plot and were found to be of white cups and the red bath tubs at 3.392 eV and 3.646 eV, respectively. These properties were found to be suitable for recycled plastics to be applied to process value-added panels with no significant adverse influence on material properties.