Ultra-high molecular weight polyethylene (UHMWPE) fiber, hereinafter referred to as UHMWPE fiber, meets the development requirements of modern fisheries thanks to its superior overall performance as a new synthetic fiber material, and has now been applied in the fisheries sector.
1.1 UHMWPE Characteristics
UHMWPE generally refers to unbranched linear polyethylene with a molecular weight above 150×104, whose molecular chains contain essentially no polar functional groups, with a crystallinity of 65%~85% and a density of 0.95~0.98 g/cm³. Because UHMWPE has excellent properties that other engineering plastics cannot match — high strength, wear resistance, corrosion resistance, low-temperature resistance and aging resistance — it plays a vital role in fisheries, military and marine engineering applications. A comparison of UHMWPE’s properties with those of other common engineering plastics is shown in Table 1. As Table 1 shows, compared with other common engineering plastics, UHMWPE’s density is effectively lower, while its elongation at break and impact strength are greatly improved.
1.2 Tensile Mechanical Properties of UHMWPE Rope and Net Materials for Fishing
A research team conducted a systematic study on the tensile mechanical properties of UHMWPE rope and net materials for fishing. The results showed that ropes made from UHMWPE fiber have a breaking strength 3.7 times that of PA ropes and 4.0 times that of PP ropes, along with good low elongation and excellent fatigue resistance, making them highly suitable for fisheries. Regarding synthetic fiber netting twine, the tensile mechanical properties of UHMWPE twine and high-density polyethylene (HDPE) twine were also compared. The results showed that, compared with HDPE twine, UHMWPE twine twisted from UHMWPE fiber has higher breaking strength, tensile modulus and knot strength loss rate and lower elongation at break, and that the knot strength and diameter indicators of the two twines show a significant linear relationship, while the tensile load and elongation indicators show a significant polynomial relationship.
1.3 Current Applications of UHMWPE Fiber in Fisheries
Because UHMWPE offers excellent performance and high cost-effectiveness, it has found many applications in fisheries, such as fishing nets, trawls, deep-water cages, high-end fishing lines, large aquaculture pens and raft ropes for algae cultivation. Thanks to the mechanical characteristics of UHMWPE fiber and the excellent performance of its products, materials such as ropes and nets made from UHMWPE fiber have been gradually applied in fisheries at home and abroad since 1957. In countries such as the United States, the Netherlands, China, Japan, Denmark, Norway, Spain and Iceland, UHMWPE fiber has been used in trawls, deep-water cages, aquaculture pens and other fishing gear and aquaculture facilities.