Temporal residual spontaneous cure in L‐shaped composites structures: The influence of angular stacking sequence, autoclave cooling rate cycle, and thickness

Abstract This work shows the degree of cure achieved after traditional autoclave curing is not completed. Pre‐impregnated, prepreg, based on resin F8552 system was used in the manufacture of various L‐shaped specimens. This system contains carbon tapes as reinforcement structures. Differential scanning calorimetry (DSC) was used in order to obtain quantitative data which support the investigation about the influence of the several factors on L‐shaped composites degree of cure. Approximately 1 year interval was considered in DSC analyses for each sample configuration. The influence of degree of cure has been studied by using symmetric, balanced, and unbalanced laminates with three different thicknesses. The influence of three autoclave cooling rate cycles was also studied. A total 81 samples were used to perform the study. It is observed that the degree of spontaneous residual curing was more significant in thinner samples. The slower cooling rates produce higher degree of cure over time. Last, the degree of residual cure is more pronounced in unbalanced laminates.