Assessment and Non-Destructive Evaluation of the Influence of Residual Solvent on a Two-Part Epoxy-Based Adhesive Using Ultrasonics

Polymers are increasingly being used in higher demanding applications due to their ability tailor the properties of structures while allowing for a weight and cost reduction. Solvents play an important role manufacture polymeric since they allow reduction polymer’s viscosity or assist with dispersion fillers into polymer matrix. However, incorrect removal solvent affects both physical chemical materials. The presence residual can also negatively affect curing kinetics final quality polymers. Destructive testing is mainly performed characterize these this type involves using lab-type equipment that cannot be taken in-field perform situ requires specific sample preparation. Here, method presented non-destructively evaluate process viscoelastic materials ultrasonics. In study, changes longitudinal sound speed were detected during aerospace epoxy adhesive as result variations chemistry. To simulate solvent, samples containing different percentages isopropyl alcohol manufactured tested Thermogravimetric analysis was show decomposition IPA within structure. Adding 2, 4, 6 wt.% decreased adhesive’s lap shear strength by 40, 58, 71%, respectively. Ultrasonics how influenced adhesive. Young’s modulus Poisson’s ratio determined speeds Using ultrasonics has potential non-invasively polymers manufacturing settings, ensuring reliability use applications.