Morphology of a deformed rubber toughened poly(methyl methacrylate) film under tensile strain

The morphology of rubber toughened poly(methyl methacrylate) (PMMA) films was studied during deformation using environmental scanning electron microscopy (ESEM) combined with real time small angle X-ray scattering (SAXS). These two methods provide two different approaches to an in situ study of the morphology of the deforming polymer film. The ESEM study shows that the polymer film exhibits multiple craze-like streaks under tensile strain. Every streak runs through several apparently cavitated rubber particles. Further study by SAXS reveals that these streaks are not crazes. Instead they appear to be lines of cavitated rubber particles which form a particular type of dilatation band known as a ''croid''. The ESEM study also shows that with increasing strain the rubber particles gradually increase in size, and that both the number and size of the croids increase. Finally the croids evolve into cracks just before the breakdown of the sample.