THERMAL-IMPACT DAMAGE OF POLYAMIDE AND POLYESTER YARNS

Thermal impact, that is, the effect of short duration contact between hot objects and polyamide or polyester yarns, is analyzed in relation to the temperature of the hot object and the tension of the yarn. Ther mal impact is of practical importance in high speed and heavy duty sew ing and in the inflation of uncoated automotive airbags. Yarn damage b y thermal impact can be analyzed by visual inspection or by measuring the loss of properties. The melting point and the specific latent heat of the yarn are the main parameters of thermal impact. Polyamide 4,6 yarn performs better than polyamide 6,6, polyester, and polyamide 6 ya rns in thermal-impact testing, because it has a higher melting point a nd a higher specific latent heat.