Filled radiation curable compositions for coating optical fiber and the coatings produced therefrom

A radiation curable composition for coating an optical fiber comprising, relative to the total weight of the entire radiation curable composition:

• a reactive oligomer comprising at least one polymerizable group and a backbone;
• a reactive diluent monomer;
• a photoinitiator;
• a filler component;
• and
• optionally, one or more additives;
• wherein the radiation curable composition possesses a liquid glass transition temperature (Tg,rheo), a first viscosity at 25° Celsius (C) (η25), a second viscosity at 55° C. (η55), and a third viscosity at 85° C. (η85);
• wherein
• (1) the Tg,rheo of the radiation curable composition is less than −100° C., or less than −110° C., or less than −120° C., or from −170 to −100° C., wherein Tg,rheo is determined by fitting equation (8) to experimental viscosity versus temperature data for the radiation curable composition:
• η
• ⁡
• (
• T
• )
• /
• η
• 25
• =
• 1
• ⁢
• 0
• ⁢
• (
• -
• 562.5
• /
• (
• 62.5
• -
• T
• q
• ,
• r
• ⁢
• h
• ⁢
• e
• ⁢
• o
• )
• *
• (
• T
• -
• 25
• )
• 37.5
• +
• T
• -
• T
• q
• ,
• r
• ⁢
• h
• ⁢
• e
• ⁢
• o
• )
• ,
• where η(T) is the viscosity (in Pa·s) of the composition at temperature, T (in ° C.).