POS7-1239
Mechanistic Quantification of Property Enhancement in Heat-Resistant CFRTPs by Carbon Fiber Sizing Agents
Topic
S7. Innovations in Polymeric Composites: From Design and Processing to Industrial Applications
When and Where
Sep 30, 2026
08:30 - 09:30
Room 301 (Grand Ballroom)
Session Chairs
Heesuk KIM
Jinhye BAE
Presenter(s)
Satoru Hamajima (Graduate School of Engineering, Gifu University)
Co-Author(s)
Abstract
Carbon fiber reinforced thermoplastics (CFRTPs) using super engineering polymers such as PEEK, PPS, and PEI as matrix resins are expected to be widely applied in aerospace fields due to their combination of high mechanical performance at elevated temperatures and lightweight characteristics. Sizing agents for carbon fibers, which function as fiber bundling and interfacial adhesive materials, are also required to exhibit high heat resistance.
In this study, a sizing agent specifically designed for super engineering polymer matrices and mainly composed of heat-resistant polymers was developed. Commercial carbon fibers were desized and subsequently treated with the developed sizing agent, as well as with a commercial sizing agent for comparison. Flexural tests were conducted on unidirectional CFRTPs with PEEK, PPS, and PEI matrices to evaluate the influence of sizing agents on mechanical properties. Furthermore, the mechanisms were quantitatively analyzed by comparing experimental results with theoretical calculations.
It was demonstrated that CFRTPs with improved mechanical properties were obtained for all matrix systems when the heat-resistant sizing agent was applied. At a fiber volume fraction of approximately 30%, the flexural modulus was improved by up to about 12%. In addition, a theoretical model exhibiting good agreement with experimental results was constructed by combining the rule of mixtures, Timoshenko beam theory, and classical laminate theory. Based on the comparison between experimental and theoretical values, the mechanisms by which sizing agents enhance CFRTP properties were quantitatively separated into a void reduction effect and a fiber dispersion effect. The magnitude of these effects was found to depend on processing temperature, melt rheological properties of the matrix, and the chemical affinity between the matrix and the sizing agent. These findings provide practical design guidelines for high-performance CFRTP systems.
In this study, a sizing agent specifically designed for super engineering polymer matrices and mainly composed of heat-resistant polymers was developed. Commercial carbon fibers were desized and subsequently treated with the developed sizing agent, as well as with a commercial sizing agent for comparison. Flexural tests were conducted on unidirectional CFRTPs with PEEK, PPS, and PEI matrices to evaluate the influence of sizing agents on mechanical properties. Furthermore, the mechanisms were quantitatively analyzed by comparing experimental results with theoretical calculations.
It was demonstrated that CFRTPs with improved mechanical properties were obtained for all matrix systems when the heat-resistant sizing agent was applied. At a fiber volume fraction of approximately 30%, the flexural modulus was improved by up to about 12%. In addition, a theoretical model exhibiting good agreement with experimental results was constructed by combining the rule of mixtures, Timoshenko beam theory, and classical laminate theory. Based on the comparison between experimental and theoretical values, the mechanisms by which sizing agents enhance CFRTP properties were quantitatively separated into a void reduction effect and a fiber dispersion effect. The magnitude of these effects was found to depend on processing temperature, melt rheological properties of the matrix, and the chemical affinity between the matrix and the sizing agent. These findings provide practical design guidelines for high-performance CFRTP systems.
