Assessment of E‐glass/epoxy prepreg aging via analytical, physical and mechanical techniques

Abstract

E‐glass/epoxy prepregs are undisputedly a great advancement in processing and fabrication technology. They offer immense advantages over conventional composite manufacturing processes in terms of waste reduction and efficient manufacturing times. These prepregs are used in several industries including but not limited to automobile, construction, defense and aerospace. Their versatility and wide applicability however is shadowed by intricate storage and handling requirements. Prepregs usually need to be stored at below freezing temperatures and hence lose their chemical integrity during transportation if not handled properly leading to a lot of wastage and scrap generation. Therefore, it is essential to develop a rigorous regime in order to determine the shelf‐life and usability of these prepregs. Hereby, we report an extensive experimental design for assessing shelf‐life of commercially available prepregs using techniques like DSC and IR and corelating the findings with mechanical data. The degree of pre‐cure increased to 30% as a result of exposure to moisture over prolonged time and a substantial decrease in mechanical strength was observed. The shelf‐life was found to be about 7 weeks and a strong agreement between analytical and mechanical data was observed.Highlights Analysis of prepreg aging under ambient and accelerated storage conditions. Measurement of prepreg auto‐cure advancement using IR, Raman and DSC techniques. Comprehensive assessment of effect of moisture and temperature on prepreg integrity and tackiness. Co‐relation of spectroscopic and calorimetric data with mechanical properties of laminates prepared from aged prepregs Estimation of prepreg shelf‐life on exposure to room temperature simulating conditions.