Quality inspection of laid fabric epoxy resins prepreg by near infrared spectroscopy

Near infrared (NIR) spectroscopy has been applied for non-contact quality inspection of the laid fabric prepreg. The cure process of the epoxy resin and the prepreg sample has been studied using near infrared spectroscopy. Abundant information of prepreg related to the resin content and the volatile content was observed in the spectra. Multivariate calibration method based on partial least square (PLS) regression could be used to obtain the relevant analytical information and determine the quality indexes. Sixteen samples were collected randomly, and were analyzed by the reference and NIR methods. The results of the paired t-test revealed that there was no significant difference between the two methods.

The NIR spectroscopy method can be used to predict the resin content and the volatile content simultaneously. Besides, the prepreg could be analyzed once within 30 s without sample destruction. The change of the processing parameters could be used to control the resin content and the volatile content. The study indicates that the NIR analysis is sufficiently rapid and effective for quality inspection in the laid fabric prepreg.