Effect of some process parameters on acrylic yarns and knitted fabrics made of those yarns

Abstract

High bulk acrylic yarns having relax and unrelax fibre blends with varying ratios are commonly used for knitted fabrics. Within acrylic yarn production, bulking process parameters and blending ratio of relax and unrelax acrylic fiber have considerable effect on the desired yarn volume as well as on optimum yarn properties. This study aimed to investigate the effect of ply twist (tpm), bulking temperature (°C) and bulking machine velocity (m/sec) on acrylic yarn properties as well as on supreme knitted fabric properties from those yarns where a constant blend ratio of relax/unrelax acrylic fibre blends were utilized. For this purpose, three different ply twist (185, 215 and 245 tpm) and bulking machine velocity of three levels (550, 650 and 750 m/sec) were selected. Bulking process was achieved at 110 and 130 °C. Tenacity, elongation, crimp contraction and shrinkage properties of untreated acrylic yarns and of acrylic yarns treated with bulking process were evaluated. Additionally, weft knitted fabrics from those yarns were produced at constant production parameters. Bursting strength, air permeability and pilling properties of acrylic knitted fabrics were compared. In order to obtain the optimum ply twist, bulking temperature and bulking machine velocity regarding to desired yarn and fabric properties, numerical optimization method was used at 5% significance level. According to the test results; it was concluded that ply twist, bulking temperature and bulking machine velocity had significant effect on yarn shrinkage. In addition, interaction of ply twist and bulking temperature was found to be an influential factor on bursting strength, bursting distention and air permeability properties. As a consequence, desirability ratio with the value of 57.2% could be provided for the fabrics with the acrylic yarns produced at 185 tpm ply twist with 614 m/sec bulking machine velocity at 130 °C bulking temperature.