Effects of the Polyhexamethylene Guanidine Grafting Degree on the Sustained Antibiofouling Efficiency and Mechanical Property of Polyethylene Aquaculture Nets

Polyethylene (PE) fishing nets are widely used in the fishing industry, yet biological fouling remains a significant challenge during fishing and aquaculture. Developing environmentally friendly and long-lasting antifouling fishing net materials is still a pressing issue. In this study, a safe and nontoxic cationic antibacterial agent, polyhexamethylene guanidine (PHMG), was chemically grafted onto PE molecular chains to achieve a permanent modification. The resulting PE-g-PHMG antibacterial plastic masterbatch was prepared using a twin-screw extruder and subsequently processed into PE-g-PHMG/PE monofilaments with varying grafting ratios via melt spinning with a single-screw extruder. These monofilaments were further processed by twisting, weaving, and shaping techniques to form fishing nets. FTIR spectroscopy confirmed the stable presence of PHMG in the monofilaments. The grafting rate of PHMG significantly influenced the thermal stability, crystallinity, relaxation behavior, mechanical properties, and antifouling performance of the monofilaments. As the PHMG grafting rate increased, the thermal stability, crystallinity, and mechanical properties decreased, leading to a reduction in the mechanical strength of both monofilaments and the final net structures. Compared with pristine PE nets, the biofouling coverage on PE-14 and PE-22 nets was reduced by 38.0 and 85.7%, respectively. Furthermore, the PHMG-grafted fishing nets demonstrated sustained antifouling efficacy in a 6-month field test, highlighting their potential for long-term marine applications.