Abstract
In the liquid composite molding process, a binder is used to fix the preform. In this study, the influence of a non-reactive epoxy binder was investigated. To allow the measurement of permeability, the preform specimen was produced under three preforming conditions: neat fabric preform, binder-treated fabric preform without heat treatment, and binder-treated fabric preform with heat treatment. The in-plane directional permeability, K1 (having maximum flow velocity), and K2 (having minimum flow velocity) of the binder-treated fabric preform decreased approximately 80% compared to the neat fabric preform. The permeability in the out-of-plane direction decreased approximately 80% in the binder-treated fabric preform without heat treatment and about 98% in the binder-treated fabric preform with heat treatment. This decrease occurred because the treated binder on the fiber hindered resin impregnation. The effect of the binder on the friction coefficient of carbon fabric was also investigated. The friction coefficient was high when the binder was on the friction surface and increased 40–200% at 110 °C, compared to 25 °C.
Highlights
As the demand for composite materials with high strength and light weight increases, composite manufacturing processes are being investigated to reduce production costs
The fiber preform process using a binder is recommended, because fiber layers should be bonded to each other to fix the desired shape
K1, and the permeability of the fiber tests were conducted on two cases with fiber volume fractions of 55% and 60%
Summary
As the demand for composite materials with high strength and light weight increases, composite manufacturing processes are being investigated to reduce production costs Among these processes, liquid composite molding (LCM), including resin transfer molding (RTM) or structural reaction injection molding (S-RIM), is advantageous for manufacturing complex-shaped products. The changes in the coefficient of friction between fabrics and between fabric and the metallic mold were observed via friction tests These tests demonstrated another important effect of binder on the friction coefficient, using a parameter for predicting fiber wrinkles in the LCM process. By analyzing both kinds of process parameters, it was possible to determine the characteristic changes in reinforcements in LCM as a function of the binder usage during the preforming process
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