Microwave curing kinetics of carbon‐fiber‐reinforced epoxy composites by wet filament winding process

Abstract

A high-performance compound epoxy resin system suitable for wet filament winding was designed. The glass transition temperature reached 181.3 C, and the tensile strength, tensile modulus, and elongation of the resin casting body were 90.82 MPa, 3312.72 MPa, and 4.17%, respectively. In order to explore the mechanism of microwave curing, the microwave curing kinetics of the composites was studied. Based on differential scanning calorimetry, the curing degree and curing reaction rate of thermal and microwave curing composites were compared. The results showed that the curing degree and curing reaction rate of microwave curing composites were higher than that of thermal curing in the early and middle stages of curing reaction. The heat transfer mechanism model was proposed. The heat transfer of carbon fiber after absorbing wave is the reason for the above-mentioned phenomenon. In the later stage of curing reaction, the steric hindrance effect is greater than that of heat transfer mechanism on curing degree and curing rate, so there is little difference between the two curing methods. The kinetic parameters of thermal and microwave curing were calculated by the Malek method, and the activation energies were 70.40 kJ/mol and 61.18 kJ/mol, respectively. The correlation coefficient R 2 between the curing degree calculated by kinetic equation of microwave curing and measured by experiment was 0.951, indicating that the kinetic equation was in good agreement with the experimental results.

An adaptive activation energy method for predicting resin curing behavior and thermal overshoot in thick CFRP plates

“…Four common curing kinetic models were selected, with their forms and fitted parameters shown in Table 2. These four curing kinetic models consist of the kinetic model with the constant activation energy (CK-CAE), [20] Malek's most approximate curing kinetic model (CK-Malek), [22] the curing kinetic model considering both glass transition temperature and diffusion effects (CK-GD), [26] and the curing kinetic model considering only diffusion effects (CK-D). [25] The CK-D model was unable to describe the curing behavior of the GS-13 resin owing to the non-convergence of model parameters.…”

“…[14][15][16][17] Phenomenological fitting methods based on a form of curing kinetic equations [18,19] are widely used. Common forms of curing kinetic models include autocatalytic equations where the apparent activation energy in key parameters is considered as a constant, [20][21][22][23] formulas considering diffusion effects [24][25][26] and kinetic equations where the activation energy parameter is viewed to be variable, [27,28] etc. The kinetic equations with constant activation energy characterize the reactivity of thermoset resins to undergo cure reactions at different stages by the average value of the activation energy.…”

In‐plane and in‐depth frontal polymerization behaviors of continuous fiber‐reinforced epoxy composites

“…Thermosets and their corresponding fiber-reinforced composites have been increasingly employed in aerospace applications. [1][2][3] Usually, by the thermal curing method, high temperature, and high pressure are essential in curing fiber-reinforced thermoset composites for several hours or even longer, which is energy inefficient, costly, and environmentally unfriendly. [4][5][6] In contrast, the ultraviolet (UV) light curing method can effectively reduce air pollution and energy consumption but this method can be only used to cure a thin-layered thermoset due to the weak penetration capability of UV light.…”

Impact of Mendong fiber–epoxy composite interface properties on electric field frequency exposure

“…The properties of the cured resins are influenced by the specific conditions during the curing process. 15 Curing processes of epoxy can be conducted at an autoclave and oven that use a curing temperature of 120-160 C. 41,42 Microwaves are usually used for the curing process since the curing reaction rate was faster than thermal curing, 43 but it involves high energy and frequency. Utilizing the electric field is simple, and applying low frequency introduces no heat into the system but does not lead to a shortening process.…”