Abstract
Two types of poly-para-phenylene-copolymers (PR-120 as an extrusion and PR-250 as an injection moulding grade) are commercially available. In this paper, their mechanical properties were evaluated as a function of their molecular characteristics. The higher viscosity PR-120 possesses a higher strength, modulus and hardness, which is in agreement with its lower molecular flexibility compared to PR-250. On the other hand, the latter version shows a better fracture toughness. All tests were carried out at room temperature.