Search

Knowing the processes that take place in the macromolecular and morphological structure following repeated mechanical stresses, during the technological processing of chemical fibres and yarns is mostly important for the specialists in the field. This aspect is also motivated by the fact that, due to the viscoelasticity of the thextile fibres, during stresses, especial the tensile ones, with small forces but repeated at short times, fatigue appears represented by structural changes, difficult to be noticed, and in the most severe cases of stress destruction occurs. During the fatigue process in the fibre there are several non homogeneous deformations especially in the microcavities and areas where the structure has imperfections. Thus, modified isolated structures will be obtained, representing the primary destruction of the fabric by forming micro-fissures that progress rapidly by propagation, affecting the fibre in several areas, and in the end it results in the tearing of the fibres. The action of the mechanical forces upon the fibre triggers several chemical reactions that result in the breaking of the chemical bonds and the birth of free macroradicals, the concentration of which will depend on the intensity of stresses. These aspects of the fatigue process will influence correspondingly the fibre's physicochemical and chemical properties. This paper reports the experimental results regarding the effect of some cyclical stresses with constant force on the main properties of the textured filament yarn made of Polyethylene terephthalate (PET) and Polybutylene terephthalate (PBT) with a fibrillar matrix structure, of 110/32 dtex.