THE RESEARCH OF THE PARA-ARAMID THREADS DURABILITY LOSS IN THE WEFT KNITWEAR PRODUCTION PROCESS

Abstract

Research of the weft knit parameters influence on the loss of strength of para-aramide threads after knitting. Methodology. We used the mathematical modeling and regression analysis methods. An experimental method of research was used for determination of the breaking characteristics of para-aramide threads on KT-7010AZ tensile testing machine in accordance with the State Standard ISO 2062:2004. As a result of the full three-factor experiment implementation, mathematical regression models were obtained that adequately describe the knit parameters influence on the strength retention of para-aramid
thread. As the controlled factors of the knitting process knockover depth, the takedown traction of the fabric and the linear density of the thread were chosen. The breaking load value per thread after knitting is influenced by all three factors. However, the linear density of the para-aramid thread has a decisive influence. Increasing the knockover depth increases the breaking load. At the same time, an increase of the takedown traction reduces the
breaking  load  per  thread.  Only two  factors  have  an  impact  on  the  loss  of  strength  index: linear  density  and knockover depth. Their increase leads to an increase of the loss of strength index. To reduce the loss of strength of  para-aramid  threads  after  knitting  at  constant  linear  density,  the  knockover  depth  should  be  increased. It provides a reduction per unit length of the para-aramid thread inflection points, curved into loops in the knitting process, and helps to preserve its strength.  Originality. Consists in identifying the character of influence of the thread linear density, the kockover depth and takedown traction of the fabric on the loss of strength of a para-aramid thread after knitting. Practical  value.  The  establishment  of  optimal  parameters  of  knitting,  providing  the  maximum preservation of the strength characteristics of aramid threads after their processing into textile material for the manufacture of protective products for technical purposes.