Fibers

The mechanical reliability of fused silica glass fibers is significantly influenced by the properties of their polymer coatings. The primary coating, which is in contact with the fiber surface, is expected to control the chemis ry there, but the secondary coating does have a considerable effect on the strength and aging behavior of the fiber. This observation is confirmed by data obtained for ten fused silica fibers, having the same primary coatings but ten different secondary coatings. These fibers were aged at 85oC in both de-ionized water and 85 % relative humidity for up to 6 weeks and the residual strength as a function of aging time was measured. Dynamic fatigue measurements were carried out on as-received and aged fibers using two-point bending. The results show that the secondary coating has a notable effect on the aging behavior and the coating strip force, but does not greatly influence the dynamic fatigue parameter