Indian Journal of Fibre & Textile Research Vol. 34, December 2009, pp. 338-344 Tensile characteristics of yarns in wet condition A Das a , S M Ishtiaque, S Singh & H C Meena Department of Textile Technology, Indian Institute of Technology, New Delhi 110 016, India Received 22 December 2008; accepted 25 February 2009 This paper reports the tensile characteristics of cotton, polyester, viscose and polyester/viscose (P/V) ring and rotor yarns of different linear densities and blend proportions in dry and wet conditions. An experimental set-up has been fabricated, which can be attached with the tensile tester to study the tensile characteristics of yarns under water. The tenacity of yarns is found to be higher in wet condition as compared to that in dry condition for all the yarns, except the viscose yarns where tenacity drops in wet condition. The increase in tenacity in case of cotton is much higher than that in case of polyester and P/V blended yarns. In case of polyester and cotton, the breaking elongation of yarns increases while in viscose and viscose-rich P/V blended yarns, the breaking elongation decreases in wet condition. In viscose and viscose-rich P/V blended ring-spun yarns, the increase in initial modulus is found to be very high, whereas in the case of polyester and cotton, there is moderate increase in initial modulus of yarns in wet condition. In case of cotton ring-spun yarns, there is very high level of increase in work of rupture in wet condition. Yarn fineness significantly affects the tensile characteristics. Keywords: Breaking elongation, Cotton, Initial modulus, Polyester, Ring yarn, Rotor yarn, Tenacity, Viscose, Work of rupture 1 Introduction There are many application areas where textile materials are used under water, e.g. swimming or any other under water activities. It will therefore be beneficial to know the tensile characteristics of yarns under water. Yarn properties, such as dimensions, tensile strength, elasticity recovery, elongation, modulus, rigidity, electrical resistance, and energy at break point, are affected by the amount of water absorbed. In the case of polyester, although the fibre is less hygroscopic, polyester yarns or fabrics absorb water by wicking action. Similarly, in case of yarns or fabrics made of hydrophilic fibres or blends, the absorption behaviour is entirely different. There are large numbers of publications available on the effect of various parameters on tensile characteristics of yarn. But, almost all the studies were carried out with normal dry yarn. Midgely and Pierce 1 first suggested the effect of rate of loading on the tensile properties of spun yarn. Balasubramanian and Salhotra 2 and Kaushik et al. 3 investigated the influence of rate of loading on the tensile behavior of rotor-spun yarns in dry conditions. Serwatka et al. 4 gave a new approach for modeling the stress-strain curve of linear textile products in dry conditions. They explained the stress-strain curve of yarn in three zones. Robert et al. 5 studied resiliency and modulus of viscose rayon as a function of swelling and temperature in wet condition. Bryant and Walter 6 measured the tensile properties of yarn, immersed in water, as a function of temperature. Paul et al. 7 presented preliminary result of the deep star polymer taut leg mooring project. Preston and Nimkar 8 studied the adhesion force between fibres in the yarn. They observed that the capillary water, present in the spaces between fibres, attracted to one another by the hydrostatic tension in water. The present work is undertaken to study the tensile characteristics of different types of yarns in wet condition. The tensile characteristics of yarns under water is expected to be affected by fibre type and blend proportion and also by the yarn structure. Hence, a detailed study has been reported on the effect of blend proportion and yarn count on tensile characteristics of ring and rotor yarns in dry and wet (under water) conditions. 2 Materials and Methods 2.1 Materials Polyester, viscose rayon, cotton and polyester/viscose (P/V) blend were used for the study. The specifications of cotton fibres were: ring-spun yarns–2.5% span length 30mm, fineness 4.2 micronaire; and rotor-spun yarns–2.5% span length 25 mm, fineness 4.5 micronaire. The lengths and deniers of polyester and viscose staple fibres were _____________ a To whom all the correspondence should be addressed. E-mail: apurba65@gmail.com