Coated optical fibers

Primary coating composition when cured having an equilibrium modulus of about 1.5 MPa or less and a cavitation strength at which a tenth cavitation appears (σ10cav) of at least about 1.0 MPa as measured at a deformation rate of 0.20% min−1 and having a dynamic modulus at 23° C. (E′23), said cavitation strength being at least about 1.4 times said dynamic modulus at 23° C.

Method for curing a primary coating composition comprising the steps of preparing said primary coating composition, which when cured without preflash is having an equilibrium modulus of about 1.5 MPa or less and a cavitation strength at which a tenth cavitation appears (σ10cav) of at least about 0.9 MPa as measured at a deformation rate of 0.20% min−1, said cavitation strength being about 1.0 times or less of its dynamic modulus at 23° C. (E′23), and curing said composition with a first dose comprising at least one flash of UV-light of a total energy between about 5 and 50 mJ/cm2 and subsequently curing the pre-cured coating with such a second UV-dose that the pre-cured coating attains at least 85% of its maximum attainable equilibrium modulus.

Primary coating having an equilibrium modulus of about 1.5 MPa or less, wherein said coating, when measured in an uniaxial tensile test and represented in a relative Mooney plot, shows a curve which increases on lowering 1/λ and of which at least one part has a value higher than the value calculated by using the function f(λ) equal to

• 10 f ⁡ ( λ ) = a ⁢ L - 1 ⁡ ( λ b ) - λ - 3 2 ⁢ L - 1 ⁡ ( 1 λ ⁢ b ) λ - 1 λ 2
• for 1/λ of about 0.60 or less wherein a=0.94 and b=11.20.

Primary coating having an equilibrium modulus of about 1.5 MPa or less, wherein said coating, when measured in an uniaxial tensile test and represented in a relative Mooney plot, shows a curve which increases on lowering 1/λ and of which at least one part has a value higher than the value calculated by using the function f(λ) equal to

• 11 f ⁡ ( λ ) = a ⁢ L - 1 ⁡ ( λ b ) - λ - 3 2 ⁢ L - 1 ⁡ ( 1 λ ⁢ b ) λ - 1 λ 2
• for 1/λ of about 0.60 or less wherein a=1.17 and b=15.0 and wherein said coating has a strain energy release rate Go, as measured at a rate of about 1.10−5 s−1 or less, of higher than 55.0-24.0×Eequilibrium.

Primary coating having an equilibrium modulus of about 1.5 MPa or less and a volumetric thermal expansion coefficient αequilibrium of about 6.85×10−4 K−1 or less.