On the conformational behavior and solid‐state extrudability of crystalline polymers

Extrusion experiments on thirteen polymers in our laboratory and extrusion and forging studies on nine polymers in other laboratories reveal that solid‐state extrusion and malleability occur in semi‐crystalline polymers that have a crystalline relaxation, α c at the temperature T α c , and do not occur in semicrystalline polymers devoid of α c . The solid‐state extrusion takes place in the temperature range of T α c ≤ T < T m with T m being the melting point. In this temperature, range, the polymeric crystals show a measure of disorder, observed by several techniques and by small heats and entropies of fusion. A survey of the literature indicates that, in general, polymers which have a α c and are solid‐state extrudable have shallow and broad bottoms to the energy‐wells describing their most stable crystalline conformations, and polymers showing no α c have steep‐walled energy‐wells for the same conformations.