Experimental and FEM analysis of scratch behavior on polypropylene thin films: Effect of film orientation and ethylene monomer content

• The scratch resistance of polypropylene-based films was studied.
• It improves with higher film orientation and lower ethylene content.
• This is associated with stress concentration shift from interface to surface.
• Influential film constitutive parameters: Yield stress and strain hardening.
• Scratch resistance is higher in machine direction.

Polypropylene films are extensively used in many applications and susceptible to various tribological damages like scratch. To improve their resistance to these damages, their mechanical properties can be modified through different approaches. In this study, we investigate the effects of molecular orientation and architecture, modified through the incorporation of ethylene comonomer, on the scratch resistance of polypropylene-based films using a standardized scratch testing methodology and FEM simulation. Results show that film tensile properties increase with higher orientation and lower ethylene comonomer, improving the scratch resistance. This improvement is associated with stress concentration shift from the interface toward the surface, and caused mainly by higher yield stress and strain hardening. Approach for designing polymeric films with better scratch performance is discussed.

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