Temperature Distribution and Curing Behaviour of Carbon Fibre/ Epoxy Composite during Vacuum Assisted Resin Infusion Moulding Using Rapid Heating Methods

Abstract

This paper designs two kinds of rapid heating methods for vacuum assisted resin infusion moulding (VARIM) process aiming to reduce the cycle time of carbon fibre/rapid curing epoxy composite fabrication. One utilizes the silicone rubber heating sheet containing thin resistance wires, and the other takes advantage of carbon fibre conductivity to produce internal resistive heating. Conventional oven heating VARIM was performed as a reference. The heating rates and temperature distributions in carbon fibre preform heated by the three heating methods with and without epoxy resin injection were investigated and compared. The curing degree and glass transition temperature of laminates fabricated by different VARIM processes were determined. The heating rate of silicone rubber heating sheet was 26 °C/min, while the carbon fibre internal resistive heating reached 30 °C/ min, which was much higher than the heating rate of 2 °C/min in oven. Unlike the highly uniform temperature distribution in the oven heating process, there was a slight temperature gradient within 5 °C in the silicone rubber heating process and a relatively large gradient within 13 °C in internal resistive heating process for dry fibre preform. When epoxy resin was injected, the temperature gradients obviously increased along the resin flowing direction especially for the rapid heating methods. However, the temperature gradient seemed not to affect the curing degree and its uniformity of laminates for all studied VARIM processes. The cycle time of composite fabrication by the rapid heating VARIM processes was reduced by over 40% compared to oven heating VARIM.

Resistance heating forming process based on carbon fiber veil for continuous glass fiber reinforced polypropylene

“…The temperature profiles of composite flat under target temperatures of 200 and 220 C are very similar with the case under 240 C, except temperature platform. Traditional oven heating rate is around 2 C/min according to our work, 11 which is very low compared with that of resistance heating. And resistance heating process is more efficient in heat transfer than oven heating, because heat is transferred through direct contact heat conduction inside composite during resistance heating process, rather than through air convection during oven heating process.…”

“…We investigated curing behavior of carbon fiber reinforced epoxy resin matrix composite through carbon fiber resistance heating process and concluded that the cycle time was reduced by over 40% compared with oven heating process. 11 Recently nanomaterials, like carbon nanotube (CNT) and CNT films were reported to be used as heating elements during thermoset curing process. Mas et al 12 investigated the curing process of epoxy resins through Joule heating of dispersed CNTs in polymer matrix.…”

Novel composite curing methods for sustainable manufacture: A review

“…• Induction cure -the ability to heat at hundreds of degrees per minute [32] These technologies can have unique advantages over conductive heating methods, resulting in substantial research in this area [11,14,15,[31][32][33][34][35][36][37][38][39], (summarised in Table 1). Widespread adoption within industry is limited due to significant technical challenges that have not yet been solved, where turnkey solutions are required.…”

Effects of dynamic mold temperature control on melt pressure, cellular structure, and mechanical properties of microcellular injection-molded parts: An experimental study

“…In the field of traditional injection molding, the DMTC has experienced a long time of development, especially in recent years, it has obtained a great progress and found a wide application in the elimination of weld line, 37,38 improvement of optical performance, 39,40 enhancement of dimensional accuracy, 41,42 and reduction of surface floating fiber of molded fiber-reinforced plastic parts. 43 Therefore, a growing attention has been paid to DMTC technology in MIM research field. Recently, Xiao et al 44 developed a rapid thermal cycling molding technology with electric heating and water cooling to eliminate the surface defects of microcellular injection molded parts, the results showed that the microcellular polyoxymethylene cover plates with glossy appearance comparable to the solid counterpart can be molded when the mold temperature is raised above 150°C.…”