Heat transfer simulation of the cure of thermoplastic particle interleaf carbon fibre epoxy prepregs

Abstract

Thermochemical properties are needed to develop process models and define suitable cure cycles to convert thermosetting polymers into rigid glassy materials. Uncertainty surrounding the suitability of thermal analysis techniques and semi-empirical models developed for conventional composite materials has been raised for the new class of particle interleaf materials. This paper describes kinetics, conductivity, heat capacity, and glass transition temperature measurements of HexPly ® M21 particle interleaf material. Thermal models describing conventional, non-particle epoxy systems were fit to the data and validated through a thick-section cure. Results from curing experiments agree with heat transfer simulation predictions, indicating that established thermal analysis techniques and models can describe polymerisation and evolving material properties during processing of a material representing the class of interleaf toughened systems. A sensitivity study showed time savings up to about 20%, and associated energy-efficiency-productivity benefits, can be achieved by using cure simulation for particle interleaf materials.

Lab-based in-situ micro-CT observation of gaps in prepreg laminates during consolidation and cure

“…Therefore, a cure cycle was defined for the in-situ experiments with a target ramp rate of 0.5 ○ C/min to a temperature of 150 ○ C, where the sample was held at constant temperature for 2h before naturally cooling to ambient temperature. This cure cycle advances the degree-of-cure to roughly 60%, estimated by the thermal model developed by Mesogitis et al [26], which used the same batch of prepreg as in this study.…”

Studies of curing cycle of carbon fiber/epoxy resins (8552� and M21�) prepregs based on thermal and rheological analyses

“…Figure 2a shows the dynamic DSC curve with the presence of an endothermic peak in the region of 190-200 °C more accentuated at the rates of 2 and 5 °C min -1 . This behavior can be directly related to the formulation of prepreg M21, because, according to the literature, it has polyamide and poly(ether sulfone) thermoplastics in its composition (Mesogitis et al, 2018;Paris et al, 2012). According to Paris et al (2012), prepreg M21 is a thermoset resin loaded with thermoplastic particles, which limit the propagation of cracks.…”

Effects of heat transfer coefficient variations on composite curing

“…The curing process of the thermoset laminate was modelled using FE in COMSOL Multiphysics to solve coupled heat transfer and cure kinetics equations. The cure kinetics model was derived by Mesogitis et al 25 by fitting differential scanning colorimeter data to an adapted version of the Kamal and Sourour model 26 and was validated against experimental data.…”

“…Heat Transfer Sub-ModelThe heat equation in the composite domain writeswhere ρc is the effective density, Cpc is the effective specific heat capacity, kc is the effective through thickness thermal conductivity and L is the volumetric latent heat, defined as the product of the total heat of reaction, the density and volume fraction of the resin, taking values 415000Jkg −1 ,1280kgm −3 and 0.4 respectively. 25 In the laminate domain, effective density was the density of the fibres and resin joined through rule of mixtures assuming a fibre volume fraction of 0.6. The effective specific heat capacity and conductivity were functions of degree of cure and temperature.…”