Characterization of PAN based carbon tow for structural composites

Abstract

Fibers are load carrying component in a fiber reinforced polymer composite materials. Tensile properties of composite are affected by the properties of the fiber. Polyacrylonitrile (PAN) based carbon fibers are widely used as a reinforcement in composite materials because of its high tensile strength and tensile modulus. Stringent characterisation of PAN based carbon tow is paramount for the fabrication of high performance advanced composite products. This paper presents characterization of PAN based carbon tow for structural composites. The physical and chemical parameters of carbon tow namely tex, density, diameter of single fiber, sizing content and carbon content were characterized for carbon fiber. Tensile properties of PAN based carbon tow can be determined by mono filament test and liquid resin impregnated tow tensile test. In the present study, tensile strength and modulus of PAN based fiber was evaluated by mono filament test. It was observed that tensile failure load was varying from filament to filament for same lot of fiber in mono filament test. High scattering in tensile strength values of filaments was observed due to statically distributed surface flaws on the filaments. Coefficient of variance for tensile strength of filament by mono filament tensile test was varied from 12-25 % from one lot to other lot of carbon tow. Liquid resin impregnated tow tensile test was conducted with specified resin system with low temperature cure cycle, to get more consistent and more accurate values of fiber tensile strength, modulus and % strain. Carbon tow was characterized by laminate level mechanical properties namely NOL ring hoop tensile strength and ILSS with high temperature curing epoxy resin system, which is used for fabrication of actual structural composite product.