Experimental study of the torsional effect for yarn break load test of polymeric multifilaments

Polymeric multifilaments have gained a significant interest in recent decades. In the studies of mechanical characteristics, although there are different types tests, such as rupture, abrasion, creep, impact and fatigue, it can be said that main characterisation is tensile rupture strength (Yarn Break Load, YBL), which also serves parameter for other tests. The objective this work to evaluate results breaking under torsional conditions polymeric determine optimal twists failures. test were carried out with following materials: polyamide, polyester, high modulus polyethylene (HMPE), conditions: 0, 20, 40, 60, 120, 240, 480 turns per metre. As result, these torsion groups, curves obtained three materials present an point maximum value, was experimentally proven. twist optimises HMPE 38 metre, 56 metre 95 polyamide. groups exceed deleterious effect on material, where multifilament ceases homogeneous starts create excessive "spring effect". found differ from recommendation standard regulates YBL test, thus, relationship built between linear density provides evidence increase causes increase, while places condition 30 densities greater than 2200 dtex, 60 less dtex. addition values, conclusion paramount, procedure makes general does not optimise strength.