Measuring fracture toughness of high-impact poly(methyl methacrylate) with the short rod method.

A comparison between the plane strain fracture resistance (Klc) of high-impact PMMA and conventional resins was made. Because microcracks and surface irregularities can be introduced when PMMA is cut, a specially designed sample-forming device that processed specimens with a minimal amount of machining was used. Specimens were made in the final shape of short rods as proposed by Barker and Barker and Baratta. The results showed that the fracture resistance (Klc) values of processed short rod specimens of high-impact Lucitone 199 resin were more than twice those of the control.