PNNL

Abstract

As the demand for more advanced engineering composites continues to rise across a variety of industries, high performance carbon fiber reinforced plastics (CFRP) have become the center of conversation. The properties of CFRPs like flexibility in design, corrosion and chemical resistance and their high strength to weight rations have made them a desirable material. While the use cases for CFRPs continues to rise, research into the functionalities of the materials is required. The joining of CFRPs to metallic materials by adhesive bonding has led investigation into various surface modification methods set on improving the performance of these joints. Current research into these methods illustrates improved adhesive properties due to plasma treatment of the CFRP surface prior to joining. The plasma treatment process can clean and create an activated surface prior to adhesive bonding to ensure strong and enduring joints. While the study of surface modifications like plasma treatments has grown, there is left a gap in understanding how pre-bonding environmental humidity affects the plasma treated surface of the CFRPs. The purpose of this study was meant to give insight into this area and aid in the understanding of how time duration in varying levels of humidity affect the plasma treated surface of the CFRP prior to adhesive joining. It was discovered that as the longer the plasma treated CFRPs were left in higher humidity environments, there was a decrease in the adhesively bonded joints lap shear strengths. This was seen because there was an increased hydroxylation on the surface of the CFRPs, promoting a change in the functional groups responsible for the overall adhesiveness of the plasma treated area.