Indian Journal of Fibre & Textile Research Vol. 32, March 2007, pp. 80-87 Static and kinetic frictional characteristics of staple fibres and woven fabrics A Das a & S M Ishtiaque Department of Textile Technology, Indian Institute of Technology, New Delhi 110 016, India Received 7 February 2006; accepted 21 March 2006 An instrumental has been developed for measuring static and kinetic frictional characteristics of staple fibres and fabrics. The influence of fibre length and fineness on static and kinetic frictional characteristics of polyester and viscose staple fibres has also been studied. A comparative study has been carried out to ascertain the difference in frictional forces measured by an attachment fitted with Instron tensile tester. The developed instrument is also used to study the frictional characteristics of acrylic staple fibres at different levels of finish application. A wide variation in frictional characteristics is observed among different varieties of cotton, even within same variety from different place of origin. It is also observed that warp density and fabric thickness have good correlation with static and kinetic frictional properties of both warp-on-warp and weft-on-weft motions. Keywords: Cotton, Frictional index, Kinetic friction, Polyester, Staple fibre, Static friction, Viscose, Woven fabric IPC Code: Int. Cl. 8 D03D, G01N33/36 1 Introduction Textile scientists and technologists have recog- nized the contribution of inter-fibre or fibre to other material frictions in controlling fibre flow during spinning process, affecting physical properties of yarn and fabric with deformation behaviour of fibre assembly. The knowledge of the frictional values of individual fibres is very important to predict whether the processing will be satisfactory or not, when other physical properties are satisfactory. The processability of a staple fibre is affected, in general, by two factors, namely (i) geometrical structure of each fibre and (ii) surface properties. The detailed studies have already been reported 1-5 on the frictional properties of fibres. The frictional properties of fabrics have been accepted for a long time in the subjective evaluation of smoothness or roughness and perhaps taken for granted. One of the factors which influences the subjective judgment of fabric is undoubtedly the static and/or kinetic coefficient of friction between the cloth surface and the fingers. It has been widely reported that the classical friction laws by Amontons fail to describe the frictional behaviour of materials that deform visco- elastically, such as textiles. Firstly, the coefficient of friction of both fabric-to-fabric 6-8 and fabric to other material 9-11 is not independent of the normal force but decreases with the increase in normal force up to some constant value. Secondly, the friction is dependent on the geometric area of contact between the two bodies. In spite of its great importance in textiles, the measurement of friction has been given least importance for practical purpose. A large number of studies has been reported on frictional behaviour of textiles and most of the researchers have used either some attachments fitted with common tensile testers like Instron 7, 12 where chances of errors are there due to friction between connecting thread and pulley, or they have used some complex systems to carry out specific friction-related studiey. 8 The present work was therefore undertaken with the objectives (i) to design and develop an instrument for measuring static and kinetic frictional behaviour of staple fibres as well as fabrics. The instrument should be an independent one and not to be attached with any other instrument; and (ii) to characterize the friction-related parameters of different types of staple fibres and woven fabrics with the help of the above instrument. The effects of place of origin of cotton variety; length and fineness of polyester and viscose staple fibres; and different levels of surface finish for acrylic staple fibres, on frictional characteristics have also been studied. ________________ a To whom all the correspondence should be addressed. E-mail: apurba_das@hotmail.com / apurba@textile.iitd.ernet.in