Light scattering studies on spherulite morphology and crystallization behavior of transparent crystalline cyclo olefin polymer

We investigated the spherulite morphology and crystallization behavior in a novel crystalline cyclo olefin polymer of syndiotactic hydrogenated poly (endo-dicyclopentadiene) (SH-DCP) by light scattering measurements using a short-wavelength laser at 450 nm. A four-leaf clover Hv (cross-polarized) light scattering pattern was observed in the highly transparent crystallized SH-DCP, indicating the formation of spherulite consisting of radially arranged crystals. During the isothermal melt crystallization, a circular Hv scattering pattern changed to yield the four-leaf clover pattern and the spherulite radius estimated from the scattering profiles decreased, suggesting that the structure in the spherulite changed from randomly arranged crystals to radially arranged crystals, and the number of smaller spherulites increased during the crystallization. At the late stage of crystallization, the Vv (parallel-polarized) light scattering intensity decreased and was close to the weak Hv one as the refractive index difference in each spherulite decreased due to the homogenization of the crystal arrangement, which may contribute to the transparency of the crystallized SH-DCP. Light scattering measurement using a short-wavelength laser is powerful for evaluating the spherulite morphology and crystallization behavior of transparent crystalline polymers composed of small spherulites. • Crystalline cyclo olefin polymer was highly transparent although it was crystallized. • Crystal morphology was evaluated by short-wavelength light scattering measurement. • Transparent crystals consisted of spherulite with radially arranged crystals. • The crystal arrangement within spherulite increased during isothermal crystallization. • Transparency is due to homogenization of the crystal arrangement in each spherulite.