Influence of Knot Structure on Technical Yarns Strength

Abstract

The article is intended to handle the problem of various technical yarn knots and their strength. These formations are necessary to tie threads or other products (strings, ropes) into a knot, but casual formations of knots in these products are unacceptable: it is known that knots decrease the strength of yarns. On the other hand, a lot of knots of various constructions are known. The research into high-strength yarn knots is actually done due to the high importance of strength properties of knots. In this article, a wide variety of knots that can be used in tying yarns or other textile products, as well as their characteristics, tying schemes and purposes has been presented. The high-strength yarns, e.g. paraaramid (”Kevlar”, ”SVM”), blended para- and metaaramid (”Nomex Delta TA”), high-strength polyester, as well as polyamidimid (”Kermel”) has been researched. The most commonly used knots where chosen for the research: the “Weaver‘s”, the “Two Strand Overhand‘s”, the “Granny‘s”, the “Fisherman‘s”, and the “Shoemaker‘s” (“Alpine Butterfly‘s”) knots. A comparison of strength in knots is given. It was determined that the “Weaver‘s” knot, which is very often used in textiles, is not the strongest knot: the strength in the knot is only 14-40 % of the yarn strength, while the strength in the “Fisherman‘s” and the “Alpine Butterfly‘s” knots is higher, i.e. 37-71 % and 40-70 % respectively. For these reasons, the above-mentioned knots can be recommended for tying high-strength yarns or other textile products.