Analysis of the Mechanical Properties of Recycled PET Plastic Composites for Lightweight Structural Applications

This study analyses the mechanical properties of composites fabricated from recycled polyethylene terephthalate (PET) plastic reinforced with short glass fibres, targeting lightweight structural applications in the Nigerian manufacturing sector. Nigeria generates millions of tonnes of PET plastic waste annually, creating both an environmental challenge and a raw material opportunity for composite fabrication. Recycled PET flakes are obtained from a plastic recycling facility in Ibadan, Oyo State, South West Nigeria, compounded with glass fibres at 10, 20, and 30 weight percent using a twin-screw extruder, and injection-moulded into standard test specimens. Mechanical properties evaluated include tensile strength, tensile modulus, flexural strength, impact strength, and hardness following ASTM standards. Differential scanning calorimetry and thermogravimetric analysis are performed to assess the thermal properties and thermal stability of the composites. Morphological analysis of fracture surfaces is conducted by SEM. Results show that tensile and flexural properties increase progressively with glass fibre content, with 30 weight percent glass-filled rPET achieving tensile strength of 68 MPa and flexural modulus of 4.2 GPa. Impact strength decreases with increasing glass fibre loading due to reduced ductility. DSC analysis confirms no significant degradation of the PET matrix during reprocessing. The study recommends rPET-glass composites as viable materials for automotive interior components and lightweight structural panels. Keywords: recycled PET, glass fibre composite, mechanical properties, lightweight, polymer composite.