Int. J. Adv. Sci. Eng. Vol.5 No.3 1056-1063 (2019) 1056 E-ISSN: 2349 5359; P-ISSN: 2454-9967 Usha Sayed and Aman Samarth International Journal of Advanced Science and Engineering www.mahendrapublications.com Auxetic Polymers in Textiles - Review Usha Sayed , Aman Samarth Department of Fibres and Textile Processing Technology, Institute of Chemical Technology, Nathalal Parekh Marg, Matunga, Mumbai-400019, India 1. INTRODUCTION Auxetic Materials vary from different kind of Conventional materials as they are depending upon Negative Poisson Ratio (NPR). They have a rubber like Property means as they expand when stretched and get contract when compressed [1]. This kind of behavior gives auxetic materials an various enhanced effect like shear stiffness, increased plane strain fracture toughness, increased indentation resistance and improved energy absorption properties [2,3]. An improved indentation resistance makes them suitable for use in protective equipments; an featured ability to formed doubly curved surfaces particularly to construct dome-shaped surfaces while its acoustic properties make them suitable for making sound proofing equipments [4]. Auxetic behavior achieved from any material level that is from molecular to macroscopic as the Poisson’s ratio is a physical parameter that is independent of any material scale.[5,6] With a Successful production of auxetic materials leads to the manufacturing of different materials such as polymers, metals, ceramics, composites and a variety of products with negative poisson ratio which were been proposed, investigated and fabricated, including polymeric and metallic foams[7-13] , honey combs [14- 19]. Use of Auxetic materials varies from industry to industry as they have a lot of potential application from biomedical to automotive and defense industries. Also they have an application in fiber reinforcement as a composite material in Crash helmet, Sports Equipment, Filtration and shock absorbing materials [20]. Generally there are two roots for manufacturing auxetic textiles. The first one includes the use of auxetic fibers to produce an auxetic textile structure, whereas the other utilizes conventional fibers to produce an auxetic textile structure. 2. MECHANISM 2.1 Auxetic Polymers The first synthetic auxetic microporous polymer was anisotropic form of expanded polytetrafluoroethylene (PTFE). Caddock and Evans [21] and Evans and Caddock [22] found that a large negative strain-dependent Poisson’s ratio, with values as large as -12, was a consequence of the polymer’s complex microstructure and not an intrinsic property of the PTFE itself. Nodules interconnected by fibrils of approximately 1 μm diameter react to applied force by hinging the fibrils and co- operatively producing an auxetic effect. Once the fibril hinging is complete, the additional stage of fibril stretching was proposed as an explanation of the experimental data on tensile loading at higher strains for auxetic PTFE. [23,24] Different attempts were made to reproduce that microstructure and to achieve auxetic behavior in other polymers. Alderson and Evans [26] presented a similar microstructure of a microporous form of ultra high molecular weight polyethylene (UHMWPE) produced by a novel thermoforming processing route. These polymers demonstrate Poisson’s ratios as low as –1.2, depending on the degree of anisotropy in the material. A similar three- stage thermal processing route was used to engineer polypropylene [27] and nylon [24] also consisting of nodules interconnected by fibrils. The polymers were processed by compacting finely divided powder with a rough surface, sintering, and extruding the powder through a conical die. Examination of powder morphology on the auxetic behavior revealed that particle shape, size, and surface roughness are critical variables for successful processing. The negative Poisson’s ratio values for this polypropylene were up to –0.22 at 1.6% strain.[27] Alderson et al.[28]reported the fabrication of a highly fibrillar auxetic form of UHMWPE, utilizing a powder processing route comprising only two stages: sintering and extrusion. The density, flexural modulus and flexural strength of the UHMWPE were substantially reduced due to the omission of the compaction stage that usually occurs prior to sintering and extrusion. However, attenuation absorption for this two-stage material excelled that seen for either the structural (i.e. with a modulus of at least 0.1 GPa and produced in a three stage process) auxetic material or the conventionally processed UHMWPE. Therefore it is likely to be an ideal material for ABSTRACT: In the past few years, there is an advanced development in manufacturing process in Technical Textiles and this review deals with technology of materials with Poisson’s Ratio. Common Materials have poisson’s ratio ranging from 0.0 to 0.5 but Auxetic material possess Negative Poisson’s Ratio (NPR). In recent years, the use of Auxetic Materials has attracted more and more attention in Textile Industry. As they expand laterally when stretched longitudinally and contract laterally when compressed. This review covers with general information about Auxetic Material, Auxetic Polymers and manufacturing it from Conventional Fibres, Application and Uses. KEYWORDS: Auxetic Materials, Negative Poisson’s Ratio, Non-woven, Fibers, Auxetic Effect https://doi.org/10.29294/IJASE.5.3.2019.1056-1063 © 2019 Mahendrapublications.com, All rights reserved *Corresponding Author: ushatxt@gmail.com Received: 11.12.2018 Accepted: 22.02.2019 Published on: 27.02.2019