Effect of short carbon fiber content and water absorption on tensile and impact properties of PA6/PP blend based composites

PA6 absorbs moisture, restricting its use in humid applications. The first objective of this study is to process composite parts to be used in high humid applications using PA6 blend based matrix (PA6/PP/PP-g-MA) and SCF (3-15 wt%) reinforcement. The second objective is to perform tensile and impact tests in both dry and wet conditions. The third objective is to carry out the in-depth analysis of fractography of blends and composites. For blend, more than 50% reduction in water absorption was observed in comparison to pure PA6, indicating the need to blend with PP. The tensile strength of the composite with 15 wt% SCF was 55% and 133% higher than matrix blend in dry and wet conditions respectively indicating the need to reinforce the blend with SCF. Injection molded composites with 15 wt% SCF revealed the tensile strength of 54 MPa, 46 MPa and modulus of 5 GPa, 4 GPa in dry, wet state respectively. At higher SCF content, both SCF and PP are well dispersed in PA6 matrix but fiber pull out led to fracture of dry samples. Post water absorption, tensile fractured samples showed significant fiber pull out, indicating reduction in interfacial adhesion due to water absorption.