Non-destructive and rapid analysis of resin and volatile contents in carbon fibre/epoxy resin prepreg cloth by near-infrared spectroscopy

Near-infrared (NIR) spectroscopy has been applied for qualitative analysis of carbon fibre/epoxy resin prepreg cloth. A partial least square (PLS) calibration model for the prediction of the resin content and volatile content was developed using 104 samples for calibration and 30 samples for prediction, respectively. The calibration model for the resin content was obtained by using no spectral data preprocessing (R2= 93.52, RMSEC= 0.60), and the volatile content was obtained by second derivation (R2= 94.57, RMSEC= 0.129). RMSEP of the prediction model for the resin content is 0.81% and for volatile content is 0.237%. Sixteen samples were collected randomly and analyzed by chemical and NIR methods. The results of the paired t-test revealed that there was no significant difference between the NIR method and the standard method. The NIR spectroscopy method can be used to predict the resin content and the volatile content simultaneously. Besides, the prepreg could be analyzed one time within 30 s without sample destruction. The study indicates that the NIR analysis is sufficiently accurate and effective for quality analysis in carbon fibre/epoxy resin prepreg cloth.