Crystallization mechanism and mechanical properties of CF/PPS thermoplastic composites manufactured by laser-assisted automated fiber placement

Abstract

In situ consolidation of the thermoplastic composites can be realized through laser-assisted automated fiber placement technology, and the properties of the composites are significantly affected by the crystallinity. Understanding the complicated crystallization process is very important for controlling the performance of the composites manufactured by automated fiber placement. In this work, the crystallization mechanism of carbon fiber/polyphenylene sulfide composites during the automated fiber placement process and its effect on the mechanical properties were investigated. Crystallization kinetics analysis indicated that the crystallization window of the carbon fiber/polyphenylene sulfide composites was 87–270°C. Furthermore, for carbon fiber/polyphenylene sulfide composites manufactured by automated fiber placement, the crystallinity was influenced by the parameters including laser temperature, placement speed and tool temperature, in which the tool temperature was the main factor. Increasing the tool temperature was an effective method to achieve high crystallinity. Meanwhile, when the tool temperature was in the range of the crystallization window, the composites could experience isothermal crystallization, which could further improve the crystallinity. With the increase of the tool temperature, the flexural strength and interlaminar shear strength were improved due to the enhanced self-adhesion of the matrix, while the Mode І fracture toughness was decreased because of the reduction of the matrix ductility. The combination of the kinetic method and experimental study was conducive to a better understanding of the crystallization mechanism and optimization of the processing conditions.

Physical, Thermal and Mechanical Properties of Carbon Fibre/Polyphenylene Sulfide (CF/PPS) Composite at Different Tool Temperatures Fabricated by Hot Press

“…When the tool temperature in the range of ithe crystallization window, the CF/PPS composite undergo the isothermal crystallization, which could increase crystallinity even further. The mechanical characteristics improved as the tool temperature increased due to improved matrix self-adhesion, whereas the fracture toughness declined due to lower matrix ductility [11,26]. kinetics, and weight loss of materials under controlled heating conditions.…”

“…This is because it influences the cooling rate of the formed components, resulting in different crystallization levels [8][9][10]. The investigation on CF/PPS composites manufactured using automated fibre placement by Zhao et al, [11] revealed that the tool temperature is the main factor influencing the crystallinity, and the properties of the CF/PPS composite are significantly affected by the crystallinity. Lona Batista et al, [8] also found that lower cooling rates during hot compression moulding processing resulted in higher DoC in the CF/PPS composites with the mechanical properties improved for the lower cooling rates.…”