SOME EXAMINATIONS ON DEUTERATION OF NYLON 4 WITH D2O AT HIGH TEMPERATURE
1980 Volume 36 Issue 5 Pages T189-T195
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1980 Volume 36 Issue 5 Pages T189-T195
The influence of hydrolysis of nylon 4 to the analysis of its water accessibility was examined by the viscosity measurement of hot water treated nylon 4 and the deuteration with hot D2O. The results were obtained as follows. The rate constant of hydrolysis of nylon 4 assumed as the first order reaction is 1.59×10-4 min-1 (4×10-6 min-1 for nylon 6). The activation energy of hydrolysis is 17 kcal/mol (24 kcal/mol for nylon 6) and the equilibrium degree of hydrolysis, α, is 35×10-3 (5.5×10-3 for nylon 6) at 150°C. These results show that nylon 4 is hydrolyzed more easily than nylon 6. The influence of hydrolysis on the partition coefficient of D between nylon 4 and D2O aq. solution is included in the equation, where CdD is the overall value of the partition coefficient, CNHD, CCOOHD and CNH2D are partition coefficients between -NHCO-, -COOH and -NH2 groups and D2O solution, respectively, and b is the number of -NHCO- linkage in the main chain. The values of CCOOHD and CNH2D were determined as 1.12 and 1.14, respectively, by use of succinic acid and β-alanine as model substances of terminal groups of hydrolyzed nylon 4.
It is shown that the hydrolysis gives 0.2_??_0.3% error in the observed accessibility for nylon 4 with b=113. It is also confirmed that the deuteration does not occur by a proton transfer mechanism in nylon 4 as well as in nylon 6.
