Effects of Adhesive Type and Surface Preparation on the Mechanical Strength of Thermoplastic and CFRP Structures

Composite materials are widely used in industries for their lightweight, durability, and flexibility. Carbon fiber-reinforced composites are particularly demanded and used in aerospace, automotive, and space industries due to their high strength and low weight. They are also critical in manufacturing high-pressure hydrogen storage tanks, where the interfacial strength between thermoplastic and thermoset materials is crucial. This study investigates the effects of adhesive type and surface preparation on the mechanical strength of carbon fiber-reinforced composites bonded with HDPE. Tensile tests were performed according to ASTM D5868, and SEM analyses were conducted to evaluate damage mechanisms. The results show that DP190 adhesive achieves optimal performance with 120-grit sanding, DP460 performs best with 180-grit sanding, and epoxy is ideal for high-strength applications. These findings contribute to enhancing the safety of Type-IV hydrogen tanks and developing more reliable bonding methods for industrial applications.