The effect of blend ratios of unrelaxed and relaxed acrylic fibres on physical properties of high-bulk worsted yarns

Abstract

High-bulk acrylic yarns which contract and increase in bulk during the heat relaxation process are produced by blending two types of fibres with different shrinking power in the spinning process. In this paper, high-bulk acrylic yarns (steamed and dyed) with different shrinkable fibre blending ratios were produced. Experimental results show that by increasing the shrinkable fibre blending ratio up to 40%, the specific volume and shrinkage of both dyed and high-bulk acrylic yarns are steadily increased while their tensile strengths are decreased. Further increasing the shrinkable fibre blending ratio causes the specific volume and tensile strength properties to decreased and increased respectively. However, the yarn shrinkage does not change significantly. It is also found that both dyed and high-bulk acrylic yarns have the highest elongation at 20% shrinkable fibre blending ratio. In general, the specific volume and tensile strength of high-bulk acrylic yarns are more than those of dyed acrylic yarns but their shrinkage and elongation values are similar.