Structural Changes in Polymethyl Methacrylate during Laser Machining

The focus of the article is an issue of laser machining of polymethyl methacrylate materials. Specifically, it deals with evaluation of structural changes in polymers as due to the effect of concentrated energy there appears vaporization of the material in the place of cut as well as heat transfer into the material around the place of cut and thus to the heating. As a result of the raised temperature, different structural changes may occur in the material; some high-molecular substances begin to break down into low-molecular substances, and depoly-merization or degradation of the material may occur. All these changes may result in a change of the final properties of the product. For experimental machining and subsequent study using the "Fourier Transform Infrared" vibration spectroscopy, PMMA was chosen as it is one of the most feasible polymeric materials in this technology. (paper)