| 摘要 |
1. A pneumatic tyre comprising at least one carcass ply, said tyre being characterized by the fact that said carcass ply is formed, at least in part, of a regenerated cellulose fiber, said fiber being formed of at least one filament having a base of cellulose and/or of at least one cellulose derivative containing cellulose ester groups, at least a part of these ester groups being formate groups, said fiber having the following properties : (a) the degree of substitution DS of the cellulose by formate groups is zero or less than 2% and the degree of polymerization DP of the cellulose is greater than 150 and less than 1500 ; (b) the degree of polymerization DP of the cellulose, the tenacity T and the initial modulus M, of the fiber verify the following relationships, T and M, being expressed in cN/tex : for DP<200 : T>20 and Mi >1800 ; for 200=<DP<300 : T>30 and Mi >2000 ; for 300=<DP<400 : T>40 and Mi >2400 ; for 400=<DP<1500 : T>60 and Mi >2600 ; (c) each filament has a morphology such that it is formed, at least in part, by layers which are embedded in each other, these layers surrounding the axis of the filament, and such that in each layer the optical direction and the direction of crystallization vary pseudoperiodically along the axis of the filament. |
