EFFECT OF CREEP ON THE YOUNG MODULUS OF ARAMID FIBERS

The effect of creep and recovery on the Young's modulus of different a ramid fibres was investigated by an acoustic method. Creep leads to th e growth of the Young's modulus of up to 215 GPa. Some of the differen ce between moduli values obtained by the acoustic and mechanical metho ds can be traced to fibre viscoelastic deformation. The dependence of the reciprocal Young's modulus on the creep strain is described by a s traight line, the slope of which is practically independent of stress and temperature. Creep and recovery may be described as a thermoactiva ted transition between two energy states that have different elasticit ies of the polymer chain. These states are supposed to be the straight ened molecule and a molecular kink.