Formation of free radicals during machining and fracture of polymers

Abstract

Abstract Electron paramagnetic resonance measurements of the number of free radicals formed during cutting and grinding of polymers are described. It was found in the semicrystalline polymers studied that below the glassy transition temperature that the number of free radicals formed is about 2 × 10 13 /cm 2 of surface formed. It is proposed that this number results from the crack progressing selectively through the glassy regions about more ordered regions in the polymers.