Cyclic Olefin Copolymers (COC)—Excellent Glass Formers with Low Dynamic Fragility

Abstract

AbstractApplications of cyclic olefin copolymers (COC) are manifold, and developing a complete understanding of the characteristics of the glass transition behavior of these materials is essential to their processing and use in a variety of those applications. Fast scanning calorimetry is employed to investigate the glass transition of three commercial TOPAS COCs of different norbornene content between 37 and 54 mol% at cooling rates varying from 0.01 to 100 000 K s−1. The glass transition temperatures as a function of cooling rate are determined as limiting fictive temperatures from reheating scans at 100 000 K s−1. The data, covering seven orders of magnitude in cooling rate, allows the determination of the dynamic fragilities. The dynamic fragilities of TOPAS 6013, 6015, and 8007 are in the range of 50–60 and increase with increasing norbornene content. Compared to literature data of other polymers, the dynamic fragilities are rather low, and the COCs are classified as relatively strong glass formers. In other words, relating this information to processability, they have a relatively large “working range” and are classified as “long” glasses. Such classification, borrowed from glass making (blowing) technologies, may also help to describe the processability of polymeric glass formers in general.