Mechanical and structural properties for recycled thermoplastics from waste fishing ropes

To develop the utilization of recycled plastics made from fishing ropes waste, which have been drifted ashore on the seaside, mechanical and structural properties of the waste were analyzed. Fourier transform infrared spectrometry and differential scanning calorimetry measurements revealed that the fishing ropes waste used in this study was composed of polyethylene (PE) fiber or a mixture of PE and polypropylene (PP) fibers. The mechanical properties of the recycled PE plastic substantially changed after different heat treatment condition, i.e., quenching at 0 °C or heating at 70 and 110 °C. The results showed that this recycled material became stiffer and more brittle as the crystallinity increased. In contrast, the mechanical properties of the recycled PE/PP plastic were not dependent on the heat treatment; the mechanical properties of this material remained relatively low regardless of the selected heat treatment. This observed lack of improvement occurred because PE and PP are non-compatible, so the structure inside the material was phase-separated. By adding ground rice hull (RH) as a modifier to the PE/PP resin, the elastic modulus of the composites increased substantially, whereas the degree of elongation decreased. The improvement in mechanical properties was remarkable for the composites containing an average RH particle diameter of 17 μm.