Influence of small amount of glass fibers on mechanical properties of discontinuous recycled carbon fiber-reinforced thermoplastics

The effect of residual contamination, such as glass fibers (GFs), on the application of discontinuous recycled carbon fibers (rCFs) is still unclear. In this study, GFs are used to substitute rCF at volume fractions (Vfs) of 0%, 1%, 2%, and 5% in carbon fiber paper-reinforced thermoplastics fabricated through a papermaking process. After an investigation with the three-point bending tests, the flexural modulus will not decrease when the GF content increased. Unlike the flexural modulus, the flexural strength decreased with an increase in the GF volume. In order to illustrate the effect of small amount of GF on flexural modulus, a modified rule of mixture (ROM) is used to derive a coefficient, Factor c₁, depicting the effect caused by discontinuous and randomly distributed reinforcement fibers. Furthermore, modified Halpin–Tsai model with Factor c₁ illustrated that the experiment results of flexural modulus is not decreased as fast as predicted results. Therefore, small amount of GF will not affect the application of rCF.