Fibers and Polymers 2012, Vol.13, No.6, 790-794 790 Effect of Polypropylene Fiber Cross Sectional Shapes on Some Structural/Mechanical Fiber Properties and Compressibility Behaviour of Plain Knitted Fabrics Sukran Kara*, Umit Halis Erdogan, and Nilufer Erdem Department of Textile Engineering, Dokuz Eylül University, Buca, Izmir, Turkey (Received July 8, 2011; Revised November 17, 2011; Accepted January 14, 2012) Abstract: Synthetic fibers are generally produced with circular cross sectional shapes. Other cross sectional shaped fibers such as trilobal, triangular, hollow and pentagonal fibers are also produced to improve some properties of fibers and fabrics such as lustre, handle, wicking rate, strength, stiffness and bulkiness. In this research we aimed to investigate compressional behaviours of fabrics knitted from polypropylene fibers having three different cross sectional shapes; namely circular, trilobal and triangular. Morphological, structural and mechanical properties of produced fibers were evaluated by using scanning electron microscopy, X-ray diffractometry, differential scanning calorimetry and tensile tester, respectively. In terms of structural and mechanical properties, no significant differences were found related to fiber cross sectional shapes. Then, plain knitted farbrics were produced and compressional properties of these fabrics were investigated. Fabrics knitted from trilobal fibers showed the highest compressibility properties and it is followed by fabrics which are produced from triangular and circular fibers. Keywords: Fiber cross section, Compression, Polypropylene fiber, Knitted fabric, Fiber structure Introduction Today, synthetic fibers are one of the most widely used raw materials in textile industry and their production rate is increasing day by day. Approximately 45.2 million tons of synthetic fiber were produced annually in 2010 [1]. Commercial synthetic fibers are generally produced with circular cross sections. In addition, fibers with different cross sectional shapes can be produced in order to modify some physical and aesthetic properties of textile products. With this modification, various properties of the fibers can be easily changed. Researchs on non-round cross sectional shaped fibers are generally focused on melt spun fibers, it is possible to change the cross sectional shape of the fiber only by changing the shape of the spinneret orifices. The initial studies on this area started in 1960s. Firstly, it was aimed to mimic the excellent gloss of the silk fibers by changing the fiber cross sections from circular to triangular shapes. Again at the same time, the cross sections of the fibers were changed into hollow shapes in order to use them in membranes. From that time up to these dates, fibers having cross sectional shapes like trilobal, triangular, flat, channelled, five or six lobed, hollow or pentagonal have been produced and various properties of them have been investigated [2-6]. Various attemps show that, changing the cross section of the fibers results in some differences of fiber properties such as lustre [7], strength [8,9], flexural rigidity, stiffness, bulkiness, handle, drape, pilling propensity, moisture and liquid transfer [10,11], resillience, frictional and surface properties [12], soiling [13], soil releasing, heat and acoustic insulation properties [14]. Thus, synthetic fibers can find new application areas both in conventional textile products and technical textiles. Today, fibers produced with non-round cross sectional shapes have been used in different textile products such as carpets, upholstery, cushions and matress paddings, silk-like fabrics, sportswears, medical textiles, thermal insulaton and sound absorption. Polypropylene fibers are one of the raw materials of these products where it is used in its knitted, woven or nonwoven forms. Its consumption increases due to its low density, low cost, high hydrophobicity, good strength and its resistance to most chemicals and microorganisms [15]. Compression property is one of the important physical properties of textile fabrics. It can affect various characteristics of fabrics such as fabric hand, drape, bulkiness, comfort and termal insulation property [16]. Compression properties of knitted fabrics produced from high bulk worsted acrylic fiber blend yarns were investigated under different compression loads [17]. Effects of fiber cross sectional shapes on the compressional properties of some nonwoven fabrics were also investigated and discussed [18]. In addition influence of the shape of the cross section on knitted fabric surface characteristics were studied [12]. Nevertheless, to the best knowledge of authors, effect of fiber cross sectional shapes on the compressional properties of knitted fabrics have not been studied yet. In the context of this research, at first polypropylene fibers having different cross sectional shapes were produced. Then the structural and mechanical properties of produced fibers were tested and evaluated. Finally, we focused on the effect of cross sectional shape to the compressional behaviour of knitted fabrics. *Corresponding author: sukran.kara@deu.edu.tr DOI 10.1007/s12221-012-0790-8