Effects of chemical structure on low-temperature modulus for UV-curable polybutadiene acrylates as an optical fiber coating material

The relationship between chemical structure and low-temperature modulus of ultraviolet(UV)-radiation-cured optical-fiber coating materials has been investigated. The coating materials are low-viscosity liquid compounds consisting of a 1,4-polybutadiene diacrylate oli-gomer, a monomer, and a photoinitiator. Dynamic mechanical test results show that low-temperature modulus and glass transition temperature (T_g) are affected by the monomer structure and monomer concentration in the coating material in cases where the same oligomer is used. With increasing alkyl group chain length of the alkylacrylate monomer, the T_g value is shifted to lower temperatures. Low-temperature modulus increases with increasing monomer concentration in the coating material. Low-temperature excess optical losses of coated fibers have been found to be closely related to low-temperature modulus of the coating.