Design of microwave plasma and enhanced mechanical properties of thermoplastic composites reinforced with microwave plasma-treated carbon fiber fabric

Microwave plasma equipment was designed and manufactured to improve the interfacial bonding and mechanical interlocking between carbon fiber fabric (CFF) and the polymer matrix. Tensile specimens for the composites reinforced with the as-received and microwave plasma-treated CFFs were prepared using high-speed fabrication with a polymerizable and low-viscosity cyclic butylene terephthalate (CBT) oligomer matrix. Compared with the polymerized CBT (pCBT) matrix, the tensile strengths of the as-received and plasma-treated CFF reinforced composites (CFFRCs) were enhanced by approximately 362.5% and 436.3%, respectively. A high carbon fiber content of 70 vol.% was achieved without introducing pores and/or defects into the CFFRC due to the low viscosity and high impregnation characteristics of the CBT resin. It was confirmed that the microwave plasma can increase the surface roughness of the tested CFF without varying the chemical composition and defect level of the CFF. In addition, the interfacial bonding and mechanical interlocking between the CFF and polymer matrix were improved.