MORPHOLOGY OF A DEFORMED RUBBER-TOUGHENED POLY(METHYL METHACRYLATE) FILM UNDER TENSILE STRAIN

The morphology of rubber toughened poly(methyl methacrylate) (PMMA) fi lms was studied during deformation using environmental scanning electr on microscopy (ESEM) combined with real time small angle X-ray scatter ing (SAXS). These two methods provide two different approaches to an i n situ study of the morphology of the deforming polymer film. The ESEM study shows that the polymer film exhibits multiple craze-like streak s under tensile strain. Every streak runs through several apparently c avitated rubber particles. Further study by SAXS reveals that these st reaks are not crazes. Instead they appear to be lines of cavitated rub ber particles which form a particular type of dilatation band known as a ''croid''. The ESEM study also shows that with increasing strain th e rubber particles gradually increase in size, and that both the numbe r and size of the croids increase. Finally the croids evolve into crac ks just before the breakdown of the sample.