Photopolymerisation: Internal Stress Measurement

This lecture explores the process of photopolymerization, focusing on the internal stresses that arise during the solidification of resins. The instructor discusses the chemical and thermal aspects of stress formation, demonstrating a test using a bilam setup to measure internal stresses. The experimental setup involves applying a photopolymerizable resin on a flexible metal blade, monitoring its curvature changes to quantify internal stresses. The lecture emphasizes the importance of working under UV light for safety and accurate results. By analyzing the deflection of the blade and the resin layer, the instructor calculates the internal stresses using the Stoney equation, comparing experimental values with theoretical predictions to validate the results.