繊維の伸張と動的弾性率

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The measurements have been made of the sonic moduli (pulse propagation moduli) and the tensile moduli simultaneously on the filaments produced from various polymers to investigate the orientation characteristics of molecules in the drawing process. The tensile moduli have been measured dynamically by giving the sample sinusoidal strain, whose amplitude is about 0.4% and frequency is 0.12 cps, and by stress relaxation statically. These three moduli gives different information each on the behavior of polymer molecules during the elongation. The variance of pulse propagation time (ΔT) has also been measured when the sample is given dynamic strain (Δγ) or stress (ΔS) of the low frequency of 0.12 cps. The physical meanings of the coefficients ΔT/Δγ and ΔT/ΔS are discussed from the point of molecular orientation. The measuring apparatus consists of pulse propagation viscoelastic meter, strain meter, stress meter, bias current part drawing device and X-Y recorder. The dynamic tensile moduli have been measured by Lissajous method. Only the change of pulse propagation time has been amplified after the electric current corresponding to the propagation time of the sample, which was not dynamically strained, was cut off by the opposite bias current. The measurements have been made mainly on polypropylene filaments (1050 d) at room temperature (about 30℃). The results are as follows : (1) The dynamic tensile moduli (E') and pulse propagation moduli (E_s) do not change so much for polypropylene filaments of lower draw ratio, but increase much for that of higher draw ratio with the increase of static strain. E' increases monotonously with the increase of draw ratio. E_s, however, has a minimum at the draw ratio of about 1.5. The reason why the E_s curve passes the minimum seems to be found in the process of crystalline orientation which gives much influence upon the drawing process at the lower elongation. At the higher elongation, E' and E_s increase in accordance with the increase of amorphous orientation. (2) The propagation moduli on polypropylene filaments were measured during the stress relaxation. The stress relaxation moduli (E_r) decrease monotonously within the measured time. Because of increase of molecular orientation E_x increases to about 100 sec and reaches the constant value which corresponds to the strain. R. S. Stein et al. have reported that crystalline orientation is completed within 1 sec from the observation of dynamic birefriengences and dynamic X-ray diffraction. Taking accounts of these results, it is considered that the change of E_s within 100 sec has been occasioned by the relaxation of the orientation of the amorphous parts though the orientation is usually complete within 100 sec. The change of E_s which is derived from crystalline orientation seems to be too fast to observe.
社団法人日本材料学会の論文
1965-04-15

繊維の伸張と動的弾性率

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