Optimization of interface microstructure of high-strength-high-modulus polyimide fibers composites utilizing waterborne polyamide and hybrid sizing agent
Funding information: Fundamental Research Funds for the Central Universities, Grant/Award Number: XK1802-2; The Aeronautical Science Foundation of China, Grant/Award Number: 201718S9001; The National Key Research and Development Program of China, Grant/Award Number: 2017YFB0307600; Innovative Research Group Project of the National Natural Science Foundation of China, Grant/Award Number: Grant 51790501
Abstract
The weak interface adhesion between high-strength-high-modulus polyimide (PI) fibers and epoxy (EP) resin matrix has seriously hampered the application of PI/EP composites. Herein, a waterborne polyamide (WPA) sizing agent was used to modify PI fibers to enhance the interface adhesion strength between the PI fibers and EP resin matrix. The surface characteristics of PI fibers were investigated to determine chemical composition, morphology, roughness, wettability, interfacial shear strength (IFSS) and interlinear shear strength. The results indicated that the WPA sizing agent significantly enhanced the interface adhesion properties between the PI fibers and EP resin matrix with a 132% and 22.35% increment obtained for IFSS and interlaminar shear strength (ILSS) compared with unsized PI/EP composites. Then, the hybrid sizing agent generated by WPA and waterborne EP sizing agent exhibited the highest interface adhesion with 168.65% and 28.62% increment obtained for IFSS and ILSS compared with unsized PI/EP composites. Based on these results, a sizing mechanism with chemical interaction and mechanical interlocking was proposed, which provides an effective and feasible method to enhance the interface adhesion between the PI fibers and EP resin matrix.
CONFLICT OF INTEREST
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Open Research
DATA AVAILABILITY STATEMENT
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