Research into the mechanical properties of Drawn filament sewing thread

This study presents research into drawing conditions' influences on the mechanical properties of Polyethylene Terephthalate (PET) filament sewing thread. The thread was drawn by varying the treatment temperature and contact time on the first heated cylinder (T1, n1) and on the second heated cylinder (T2, n2), as well as by using different draw ratios (λ). The critical treatment conditions were found using the drawing process (T14=130°C, n15=13 turns, λ5=1.25, T24=220°C, n23=9 turns) and the greatest improvement in the mechanical properties, respectively. Deterioration in the threads' mechanical properties was observed above the critical treatment conditions. The mechanical properties of the drawn threads were investigated under critical treatment conditions. It was found that the heat treatment conditions on the second cylinder, i.e. the treatment temperature and the contact time had the greatest influences on the improvement of the elastic modulus (D4=7.41 cN/tex, E3=7.40 cN/tex) and the breaking extension (D4=12.13%, E3=12.12%), when compared with the treatment temperature and the contact time on the first cylinder and the draw ratio between the heated cylinders. The maximal value of the breaking tenacity showed threads that were drawn at the critical draw ratio (C5=61.81 cN/tex) and the contact time of the thread with the second heated cylinder (E3=61.59 cN/tex). Simultaneously, the treatment conditions on the second cylinder affected the maximum reduction of the thread's linear density (D4=91.33 tex, E3=91.47 tex) and twist (D4=163 turns/m, E3=180 turns/m). The greatest improvement in the tension at the yield point achieved threads that were drawn at the critical draw ratio (C5=9.27 cN/tex) and the heat-treatment temperature on the second cylinder (D4=9.27 cN/tex). © 2012 Binary Information Press & Textile Bioengineering and Informatics Society.