Abstract:
Para-aramid fibres due to their low density, high specific strength, and specific modulus are suitable for production of a wide range of advanced engineering materials including ballistic fabrics and fibres reinforced composites. However, the smooth and chemically inert surface of aramid fibres severely limits its applications. The polymer chains of Kevlar are linked into locally planar structure by hydrogen bonds across the chains, with transversal strength considerably weaker than longitudinal one. In paper published more than 12 years ago [1] authors suggested that introducing outer enveloping layer of graphene, linked to polymer chains by strong chemical bonds may significantly strengthen Kevlar fibres with respect to transversal deformations.
The purpose of the research discussed in this article to develop method of ballistic Kevlar fabric functionalization with the nano-graphene coating on its fibres to improve the impact durability of the soft layers of the hybrid ballistic panel.
Kevlar woven fabrics ballistic protection ability is significantly lower compared to the Kevlar Uni Directional (UD) fabrics, while they have high flexibility and fragment protection better then UD fabrics [2]. Considering that two types of fabrics woven from high modulus Kevlar® KM2 and KM2+ fibres' yarns of linear density 600 and 440 dtex correspondingly were subjected to functionalization.
As a result of the research carried out by research group [3,4] the original method to apply a graphene-containing coating to the fibres of para-aramid fabric by ensuring adhesion of coating with the surface of para-aramid fibres developed. The method is applicable to modify also polyamide (nylon 6, nylon 66) fabrics to form a modifying graphene nano-level coating on their fibres.
The method includes several separate original solutions developed in the process of implementation: 1) Selection of liquid media components for graphene exfoliation from graphite flakes compatible with the para-aramid and graphene properties done and their relative percentages experimentally evaluated; 2) Developed technology for obtaining a stable graphene-containing emulsion from exfoliated graphite flakes; 3) Technology for applying graphene-containing coating to the surface of para-aramid fabric fibres developed; 4) Combining solutions 1-3 original technological sequence graphite flakes-graphene-containing emulsion-para-aramid ballistic fabric modification-aramid fabric with functional fibres surface modification created excluding graphene extraction and re-dispersion processes with high resource consumption, including energy-intensive ones.
There are no reports that such integrated studies have been carried out so far and the results obtained should be considered as a significant contribution to the development of know-how in the field of para-aramid fibres direct functionalization with the nano-graphene coating. Yarn pull-out and ballistic tests [5] show a significant increase in graphene modified fabrics resistance to the bullet impacts.
References:
1.Karen S. Martirosyan, M. Zyskin. Simulation of the Elastic Properties of Reinforced Kevlar-Graphene Composites. International Journal of Nanoscience, July 2012. DOI: 10.1142/S0219581X1250024X.
2.DuPont_Kevlar_Body_Armor_Brochure. dupont.com/life-protection.
3.I. Bake, L. Rampane, I. Balgale, S. Kukle, I. Adijans. Evaluation of the Graphene Dispersions for Kevlar Fabrics Functionalization Obtained by the Liquid-Exfoliation of Graphite. Environment. Technology. Resources. Proceedings of the 15th International Scientific and Practical Conference. Volume 1, 2024. 70-77 pp.
4.Kukle, S., Ba?e, I., Rampane, L. Graphene-Containing Para Aramid Fabric Coating Via Surfactant Assisted Exfoliation of Graphite. Materials Today: Proceedings, 2024, Vol. 97, pp.44-51. e-ISSN 2214-7853
5.Kukle S, Valisevskis A, Briedis U, Balgale I, Ba?e I. The Hybrid Soft BP Packages with Integrated into Their Composition Graphene-Modified Para-Aramid Fabric Layers in Combinations with the Different Ballistic Kevlar Textiles. Polymers, 2024, 20 pp.
Biography:
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