| Abstract: | We consider the effects of using urethane rubber/epoxide resin blends as matrices for unidirectional glass and carbon fiber and for balanced-weave glass fiber cloth composites. The mechanical properties of the unreinforced resin and various composites were measured for specimens with matrices containing up to 35 percent of urethane. The properties of the unreinforced resin show very marked changes between 30 and 35 percent of urethane due, it is believed, to the existence of discrete regions of urethane polymer throughout the matrix. The transverse properties of the unidirectional carbon fiber composites are significantly enhanced by the presence of 20 percent of urethane in the matrix without, apart from a decrease in the shear modulus, any marked change in other properties. This could prove useful in the applications of carbon fiber composites. Results for glass fiber materials are less dramatic, possibly because of poorer adhesion between the glass fiber and the urethane. If this is indeed the cause of the results, it should be possible to bring about an improvement for glass fiber composites by using fibers coated with a suitable coupling agent. |
