High Performance Materials Obtained by Solid State Forming of Polymers

Orientation of polymers such as polyethylene (PE) by solid state extrusion near but below the melting temperature and poly(ethylene terephthalate), polyamides and poly(etheretherketone) at different temperatures by roll drawing has been performed. Draw ratio of 11 for PE and of at least 4 for the other polymers were readily achieved. For the solid state extruded material, it was observed that lubrication and geometry of the die is critical. For the roll drawn materials, tension between the rolls was very important in compensating in part for the relaxation of the material after the rolling. Slippage between the rolls was observed in all cases. From the properties point of view, an increase in the melting temperature and degree of crystallinity was observed for the oriented materials. Significant improvements in the tensile modulus and strength were observed and materials with modulus and tensile strength above 10 GPa and 500 MPa respectively were obtained. The mechanical properties can be correlated with molecular orientation. Finally, for the solid state extruded material, comparison of the experimental results in terms of the load as a function of displacement with the predictions of numerical simulations were performed and good agreement was observed.