STUDY ON DYNAMIC VISCOELASTIC PROPERTIES OF TIRE CORDS

Abstract

Dynamic viscoelastic properties in relatively low amplitude (0.30% elongation) and low frequency (1.21 c. p. s.) have been measured for several tire cord samples prepared under various spinning conditions and also various twisting conditions. The results are discussed in connection with the internal structures of the individual filaments and also with the cord structures. The following. observations are made:1) The frictional properties of the filaments are varied by changing the oiling treatment. However it was found that the frictional properties has very minor effects on the overall viscoelastic properties measured under these conditions.2) The cord structure was controlled by changing the number of twists and also the procedure of twisting. Apparently the properties of tire cords are governed exclusively by the cord structures.3) The internal structure of filaments, determined by the combinations of factors such as crystallinity, size of crystallite, degree of orientation, contribute strongly to the cord structure. Thus, even the same number of twists and the identical proceedure of twisting were applied, the cord structures were markedly different depending upon the properties of individual filaments used. As the results, it was found difficult to isolate the direct effects of internal structures of individual filaments on the final viscoelastic properties of cords, because of the strong interposition of the effects of cord structures on the properties in the low amplitude.