Study of the resistance to repeated bending of high-modulus polymer fi lm materials

The resistance of high-modulus polymer films to repeated bending has been studied. The coefficient of strength retention during tensile testing of fi lms after repeated bending with a constant number of load application cycles, including when changing the bending angle and the load applied during bending, was chosen as a criterion for resistance to deformation loads. It is shown that the bending angle and the applied load have a significant effect on the change in the deformation and strength properties of fi lms. Biaxially oriented PET (BOPET) fi lms were found to be the most resistant to repeated bending. Amorphous APET and PET-GAG fi lms demonstrated low bending resistance and were brittle in the selected conditions. A comparison of the resistance to repeated bending of general-purpose films and original drum membranes showed a slight decrease in strength properties. Non-oriented PA6 films showed a signifi cant drop in deformation-strength properties, and a combined material of biaxially oriented PA6 film with nylon fabric showed a slight decrease in properties after bending.