DIFFUSION OF DYE IN SPANDEX AND ITS RELATION TO STRESS RELAXATION

Abstract

In order to study the dyeing property of Spandex, diffusion of p-nitroaniline (PNA) and p-aminoazobenzene (PAAB) and stress relazation of the samples (F-70 and T-280) were studied both at T=40-90°C in the dry state and following results were obtained.
(1) Diffusion coefficient D vs. 1/T is expressed by two lines intersecting at T_d=64-66°C, Apparent activation energy of diffusion (ΔE_d) is estimated to be about 18-20kcal/mol and 40kcal/mol for T>T_d and T<T_d, respectively. ΔE_d is slightly larger for PAAB than for PNA.
(2) Reduced relaxation modulus vs. log t superposable to yield a master curve. Logarithm of shift factor a_T vs. l/T is also linear and having a break at T_r, which is in good accordance with T_d. Activation energy of relaxation (ΔE_r) is close to the value of corresponding ΔE_d.
(3) Log D vs. log a_T is linear and breaks at the corresponding temperature with T_d or T_r. The slope of the line fluctuates slightly in the vicinity of unity as required by the theory.
(4) Both D vs. T and a_T vs. T obey to the WLF formula, where the observed parameters c_??_ and c_??_ are close to the theoretical values for T>T_d(T_r) but larger for T<T_d(T_r).
(5) The above mentioned behaviors of F-70 are very similar to those of T-280, although the former is of ester type while the latter is of ether type.
It is concluded that the soft segment behaves as similarly as amorphous polymers above T_g especially at temperature higher than T_d or T_r.