X-ray phase contrast microtomography for the analysis of the fibrous microstructure of SMC composites

X-ray microtomographs of samples cut from non-deformed and compression moulded Sheet Moulding Compounds (SMC) plates have been analysed using the phase contrast mode. Results emphasise a significant decrease of the porosity after moulding, this phenomenon being enhanced with increasing the initial SMC temperature. They also show that pronounced migration of the polymer-matrix occurs through the thickness of the plates during compression moulding. The substructures of compression moulded plates through their thickness exhibit a core zone sandwiched between upper and lower skins. Inside the skins, the fibre content and the porosity are weaker than in core zones, and fibre-bundles are highly broken up. On the contrary, fibre-bundles remain preserved in core zones. Therein, the significant flattening and widening of bundles, their weak bending as well as their orientation have been quantified.

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