Multi Layered Natural Rubber Coated Woven P-aramid and UHMWPE Fabric Composites for Soft Body Armor Application Rupayan Roy, Animesh Laha, Nikita Awasthi, Abhijit Majumdar , Bhupendra Singh Butola Department of Textile Technology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India In this work, the authors have investigated the impact per- formance of natural rubber (NR) coated high strength, high modulus fabrics. P-aramid (Kevlar 129) and ultra high molecular weight polyethylene (UHMWPE) fabric were coated with different concentrations of NR solutions (20%, 30%). Samples were produced with different add on percentage. The NR solutions with 20% and 30% solid content provided 4 and 6% add-on on p-aramid fabric and 6 and 9% add-on on UHMWPE fabric. Multilayered fabric structures coated with NR were also studied. Compres- sion molding technique was used to prepare the layered fabric structures. The effect of coating with different add- on percentages of NR on fabrics was studied. The pull out force increased by 480% and 360% on NR-coated p-ara- mid and UHMWPE fabrics, respectively. Although the impact energy absorption of single layer NR-coated fab- rics was lower than that of neat fabrics, there was sub- stantial improvement in the impact energy absorption of the two layered p-aramid and UHMWPE rubber coated fabrics as compared to untreated two layered ones. The increase was 44% and 81%, respectively, for Kevlar and UHMWPE fabrics. Further, the effect of NR latex treatment on tensile strength of fabrics has also been studied. POLYM. COMPOS., 00:000–000, 2017. V C 2017 Society of Plastics Engineers INTRODUCTION Soft body armors are used by para-military forces, secu- rity, and police personnel, etc. to get protection against low level threats like pistols and hand gun attack [1]. Various high performance fibers like Kevlar, Spectra, Dyneema, PBO, and M5, etc. are used to make soft body armors. These fibers are characterized by low density, high modu- lus, and low elongation, which make them suitable for bal- listic applications [2, 3]. Generally, multiple layers (20– 30) of these high performance fabrics are stitched together to prepare soft body armor. However, this makes the body armor heavy and bulkier, also it is associated with layer to layer non-uniform stress transfer during an event of impact [4, 5]. Researchers are constantly trying to improve the efficacy of soft body armors. The simplest way to improve is adding more number of layers. However this will increase the weight and bulkiness [5]. Recently, many researchers are using shear thickening fluid (STF) for improving the efficacy of soft body armors materials [1, 6–10]. Again stitching of multiple layers is must to make a single panel, so uniform stress transfer could not be achieved. Of late Ahmad et al. [11–13] reported several articles on coating of high strength fabrics with NR latex and studied its mechanical properties (tensile and tear strength). However, the add-on percentage was high (40– 64%) which resulted in improved tear and tensile force in case of rubber-coated fabrics. The NR latex film on the fab- ric surface restricts yarn freedom of movement under load- ing. It also assists the yarns to bunch together and resist the propagation of tear or break by sharing the load with a greater number of yarns before the fabric fails completely. Additionally, it can be said that coating with NR latex increases the energy absorption and the elasticity character- istics of the coated fabrics and prevents them from severe damage during loading. Further they got high extension-to- break value for coated fabric compared to the high strength uncoated woven fabric. Therefore, the use of NR latex as a coating element combined with a high strength woven fab- ric such as p-aramid improves the tensile and tearing strength of composite, finally high impact resistance could be obtained. Researchers are trying to understand different modes of energy absorption mechanisms during impact. Different researchers concluded different modes of energy absorp- tion. Recently, Majumdar et al. [10] reported that yarn pull- out, yarn extension, and yarn rupture are three major modes of energy absorption during an event of impact. On the other hand, Nilkantan et al. [14] concluded that the basic modes of energy absorptions are yarn pull-out and yarn sliding. Whereas Hwang et al. [15] concluded that yarn pull-out, rupture of primary yarns, failure of secondary yarns, and fibrillation etc. are the major modes of energy absorption. Thus, it can be concluded from all the above studies that yarn pull-out is a common mode of energy absorption. Further yarn pull-out force is purely dependent Correspondence to: B.S. Butola; e-mail: bsbutola@textile.iitd.ac.in DOI 10.1002/pc.24391 Published online in Wiley Online Library (wileyonlinelibrary.com). V C 2017 Society of Plastics Engineers POLYMER COMPOSITES—2017