Structure And Characterization Of Metallocene-Catalyzed Cycloolefin Copolymer And Its Fibers

Cycloolefin copolymer (COC) has low moisture absorption, low dielectric constant, high heat resistance, low birefringence, high transparency, low density and other characteristics. It has been used in optical, electric, packaging, biological/medical, printing and so on many domains.In this article, the microstructure of TOPAS(?)COC was analyzed by FTIR and 13C-NMR. It could be concluded that TOPAS(?)COC was copolymerized from norbornene and ethylene using metallocene catalyst, was mainly composed of alternating and diad sequences of norbornene. The large volume alicyclic structures resulted in its amorphous structure with high transparent. The molecular weight and its distribution were measured by GPC. It was found that the Mn values of TOPAS(?)COC was about 245000, while with narrow MWD(Mw/Mn=1.2). The thermal property of TOPAS(?)COC was studied by the means of DMA and TG. It was showed that the glass transition temperature and the initial weight loss temperature were about 138℃and 446.9℃respectively, which means high thermal resistance.Based on the study on rheological properties of COC and PP/COC blend systems, it was found that their melt belonged to a typical shear thinning fluid, the low melt flow activation energy of COC indicated the less sensitivity of viscosity to temperature. With PP content increased, the apparent melt viscosity decreased, the melt flow activation energy increased, the sensitivity of viscosity to temperature enhanced, non-Newtonian index decreased. From the rheological test it can concluded that COC can be melt-processing at typical melting spinning temperature.COC and PP/COC fibers were spun by melting blending extrusion spinning machine which was designed by special method. The mechanical properties and the orientation of the fiber were studied. The results showed that jet stretch ratio and orientation degree increased with the increasing of winding speed, so the strength of the fiber was improved. By way of electrostatic properties test, it is found that the surface resistivity of COC and PP/COC fibers were large(over 1013Ω·m); with PP content increased, the surface resistivity and the the half value time of charge decreased. The dielectric properties test results showed that both COC and PP/COC fibers had low dielectric constant(about 2.3) and low dielectric loss(about10-5); with PP content increased, the dielectric constant and the dielectric loss had a small increase.