Olive hue visibleenear infrared camouflage properties of high speed melt spun poly(ethylene terephthalate) multifilament yarn M.A. Tavanaie a, * , N. Esmaeilian b , M.R.M. Mojtahedi b a Textile Engineering Department, Faculty of Engineering, University of Yazd, Yazd, Iran b Textile Engineering Department, Amirkabir University of Technology, Tehran, Iran article info Article history: Received 13 September 2014 Received in revised form 3 November 2014 Accepted 25 November 2014 Available online 4 December 2014 Keywords: Camouflage Poly(ethylene terephthalate) filament yarns Near infrared wavelength Melt spinning Pigments Olive hue abstract High speed melt spinning process was used to produce near infrared (NIR) camouflage poly(ethylene terephthalate) (PET) partially oriented yarns (POY) against natural olive hue by using C.I. Pigment Green 7 (0.1% weight fraction), C.I. Pigment Yellow 184 (0.05% weight fraction) and carbon black (CB) (0.01% weight fraction). The effect of drawing, texturizing and knitting processes on the reflectance properties of produced sample was evaluated, and it was concluded that knitted fabric by texturized yarns provides optimum simulation with natural olive hue. Also the effect of pigments and the process on the yarns' structure by using the thermal and mechanical tests of yarns was investigated. It was observed that the thermal and mechanical properties of all samples are in an acceptable range. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Near infrared (NIR) detection devices are among the most important tools that are used by armies throughout the world, and without using these detection devices, night military operations would be almost impossible [1]. So it is necessary to consider sur- face reflectance of all objects and bodies used in military operations at the range of 700e1200 nm [2,3]. There are many reports in the literature regarding the use of dyes and pigments by employing dying and printing methods to camouflage textile surfaces [4e8]. However, there are few research results about the camouflage produced fibers during the chemical spinning process though pro- duction of such yarns has various advantages such as higher uni- formity and fastness [9]. Frankel [10] manufactured modified polyamide 6 filament yarns (containing a CB additive) and fabrics. The fabrics made from these yarns may be advantageously dyed or printed to provide a camouflage fabric. Poly(ethylene terephthalate) (PET) fibers are among the most important fibers, which their camouflage properties were investigated [9]. In our previous work, production of camouflage PET filament yarn (containing pigments and dye for visibleeNIR camouflage) during low speed melt spinning method was reported. Since the structure of produced fi- ber by high speed spinning (industrial conventional) method is different from that of the fibers produced by low speed spinning method, and it can be effective on reflectance properties, in the present research, high speed melt spinning was used to manufac- ture camouflage partially oriented yarns (POY). Then the reflectance properties of POY, drawn, and texturized multifilament yarns and knitted fabrics by the produced camouflage multifilament yarn were studied. Three different pigments (C.I. Pigment Green 7, C.I. Pigment Yellow 184 and CB) were used to obtain NIR's camouflage property in the forest zones (olive hue). Also the thermal and me- chanical properties of the produced samples were characterized. 2. Experimental 2.1. Material Textile grade PET semi-dull granules were supplied by Tondg- oyan Petrochemical Co. (Iran) with the intrinsic viscosity of 0.66e0.68 g/mol (molecular weight ~18,000 g/mol [11]), melting temperature of 250 ± 2  C, and glass transition temperature (Tg) of about 80  C [12]. Green phthalocyanine pigment (C.I. Pigment Green 7) with the molecular weight of 1127.2 and yellow pigment (C.I. Pigment Yellow 184) with the molecular weight of 322.92 were * Corresponding author. Tel.: þ98 (35) 31232569; fax: þ98 (35) 31232560. E-mail address: ma.tavanaie@yazd.ac.ir (M.A. Tavanaie). Contents lists available at ScienceDirect Dyes and Pigments journal homepage: www.elsevier.com/locate/dyepig http://dx.doi.org/10.1016/j.dyepig.2014.11.019 0143-7208/© 2014 Elsevier Ltd. All rights reserved. Dyes and Pigments 114 (2015) 267e272