Influence of Drawing and Annealing on the Crystallization, Viscoelasticity, and Mechanical Properties for Middle-molecular-weight Polyethylene Fishing Monofilaments

The influence of drawing and annealing on the crystallization, viscoelasticity and mechanical properties for middle-molecular-weight polyethylene (MMWPE) fishing monofilaments was investigated. It was found that the drawing procedure had a positive effect on the crystallization of the MMWPE fishing monofilaments. Meanwhile, the glass transition temperature of the MMWPE monofilaments shifted to higher temperature, and the α-relaxation associated with crystalline phases became higher and broader with the increase in the drawing ratio. Moreover, the breaking strength of MMWPE fishing monofilaments can be effectively improved by increasing the drawing ratio. Meanwhile, the knot strength increased first and then decreased. However, the increase in annealing temperature improved the knot strength. With increasing annealing temperature, the orientation factor decreased and induced the γ-relaxation peak at high magnitude. This indicated that the amorphous structure could become disordered during annealing treatment. In addition, the annealing temperature can clearly influence the working temperature dependence of the stress-strain behavior. When the working temperature rose from 20 °C to 30 °C, the MMWPE monofilaments after annealing at 120 °C exhibited low modulus loss due to their high α- transition temperature. Thus, an important method for improving the mechanical properties by controlling the drawing and annealing conditions was established.