New developments in SEM for in situ tensile tests on polymers

Investigations of the microscopic deformation and damage mechanisms give access to very useful information to understand the macroscopic mechanical behaviour of materials. However for non conductive materials, specimens need to be coated with a conductive layer and in some cases the specimen surface has to be chemically prepared to reveal a contrast between the different phases. In situ mechanical testing in a SEM of these materials has been limited to small strain deformation since at larger strain, cracks in the conductive coating induce charging effect and thus hinders the observation of the samples. Moreover in any case and whatever the detection mode - i.e. backscattered electrons (BSE) or secondary electrons (SE) - SEM restricts so far to observations of the sample surface.