On the stress relaxation of nylon 6

Abstract

The stress relaxation of low‐crystallinity nylon 6 is measured by torsional method at various temperatures in three (0, 40, and 75%) relative humidities. As the whole procedures are very accurate, the results contain little experimental error. The relaxation data at 0 and 75% relative humidity can be reduced to respective master curves by Ferry's reduction method. Considering the changes of structure by difference in humidity, it is found that these two master curves are reduced further to one single general master curve by the aid of some molecular theory of the crystalline polymers. By the use of first‐order approximation, the relaxation time spectrum of this crystalline polymer is obtained for a very wide time scale range, more than 1021 sec. The resultant spectrum is fairly high and flat, reflecting the characteristic features of crystalline polymers. It has, however, two weak but distinct maxima, corresponding to the so‐called “wedge” and “box” distributions in the relaxation time spectrum of the amorphous polymers. Based on the existence of this box distribution in the spectrum, it is suggested that there should exist some sort of clusters effective in the mechanical behavior of the crystalline polymers.

Humidity‐Responsive Starch‐Poly(methyl acrylate) Films

“…Superposition is based on the assumptions that relaxation mechanisms do not change with temperature, and that the time scales for all relaxation mechanisms change identically with temperature. An analogous MC–temperature superposition can be used with hygroscopic polymers such as polyamides,12 poly(vinyl acetate),10 and poly(vinyl alcohol) 13. Assuming that shrinkage in starch‐ g ‐PMA blown films is due to relaxation in the starch phase, and that plasticization by water and urea change only the time scales and not the mechanisms of relaxation, it follows that one can horizontally shift the data in Figure 2 with respect to a reference RH.…”

Stress relaxation of oriented nylon 6 fibers

“…C1 and C2 can be related to the free volume fraction at Tg Vg) and the expansion coefficient of free volume at Tg(cyf) by means of eqs. (5) and (6) C2 T -T , where B is a constant and taken as unity. By the use of eqs.…”

Study of creep behavior of ultra-high-molecular-weight polyethylene systems

“…The A and E a thus determined are given in Table II. The results in Table II indicate that the apparent activation energy E a of the shift factor for UHMWPE systems ranges from ∼50 to ∼100 kcal mol −1 and is dependent on both material systems and loading conditions. The E a values for UHMWPE systems are generally larger than those for relatively low-molecularweight polyethylene (E a = ∼10 kcal mol −1 ), 24 but they are comparable with polytetrafluoroethylene (E a = ∼40 kcal mol −1 ), 25 nylon 6 (E a = ∼100 kcal mol −1 ), 26 and other polymers. 27 The magnitude of E a is closely related to the extent of temperature dependence of the a T .…”