Method for enhancing the pullout strength of polymer-coated optical fiber

摘要

Applicants have discovered that low pullout strength of optical fiber is attributable to volatile, unreacted monomers and impurities which result from the incomplete polymerization of liquid coating materials. They have further discovered that removing these unreacted liquids as by heating in air, heating in vacuum or by application of a solvent mixture improves fiber coating adhesion. By heating cured polymer-coated fiber in air at temperatures of 100 DEG C or more, the fiber pullout strength is enhanced by 25% or more. This postcure heating can advantageously be done off-line by placing loosely wound fiber in a heated oven. Alternatively, the postcure heating can be done on-line by reel-to-reel passage of the fiber through a heated furnace. Preferred temperatures are in the range 100 DEG C - 300 DEG C. Even greater enhancement of pullout strength can be effected by heating in vacuum or by solvent extraction.