Abstract:

In order to test and evaluate the actual elasticity of the air covered elastic yarn, structure and tensile properties of air covered elastic yarns were analyzed, the test method of actual pre-draft ratio of spandex by non-pre-tensioning tensile test was proposed; The typical non-pre-tensioning tensile curve was analyzed, the calculation method of actual pre-draft multiple of spandex was given; the testing and analysis of the air covered elastic yarns with different specifications were carried out. The results show: The tensile elongation of spandex filament can be measured by non-pre-tensioning tensile test, combined with the specimen length of tensile test, the actual pre-draft ratio of spandex filament can be calculated; the measured pre-draft ratios are always less than the nominal pre-draft ratios, the difference between them depends on the pre-draft ratio and the linear density of spandex filament; the bigger the pre-draft ratio of spandex filament, the bigger the difference; the larger the linear density of spandex filament, the smaller the difference.

Key words: air covered elastic yarn, spandex filament, pre-draft ratio, non-pre-tensioning, tensile test