The exothermic decomposition of nitrocellulose in a solution of mixed acid was studied in order to determine the conditions for safe production of
nitrocellulose by means of the nitration of cellulose with mixtures of nitric acid and sulphuric acid. Isothermal decomposition tests were carried out
and a temperature slightly higher than the nitration temperature in manufacturing was adopted as an experimental condition. The results obtained are as follows.
Nitrocellulose in mixed acid underwent exothermic degradation after a long induction period, which was affected by the reaction temperature.
This degradation showed the maximum rate in the middle of the reaction, which indicated the reaction to be autocatalytic. The activation energies obtained by
Arrhenius plots of rate constants from the autocatalytic rate equation were 31.4 - 59.1 kJ/mol . Moreover, plots of the logarithm of the induction period t vs.
the inverse of reaction temperature also showed good linearity according to the Arrhenius-type equation, and the obtained activation enrgies were 37.3 - 60.4 kJ/mol .
The induction period after which the exothermic reaction commenced decreased with the increasing NC/mixed acids ratio. An increase in the content
of nitric acid in the mixed acid then had a decreasing effect on the induction period. Moreover, this degradation was affected by atmospheric gases, and nitrogen
dioxide accelerated the reaction.
硝酸と硫酸からなる混酸中でのニトロセルロースの発熱分解を，自製の熱分析装置を用いて，実際の硝化温度よりも若干高い温度で検討した。得られた結果は以下の通りである。
混酸中のニトロセルロースは誘導期間の後に発熱分解を起こし，この誘導期間や発熱分解反応の速度は反応温度によって変化した。等温反応では発熱分解反応は反応の中間に最大速度を示す，自触媒型に特有の反応率一時間曲線を示した。この反応の活性化エネルギーは31.4-59.1 kJ/mol であった。誘導期から求めた活性化エネルギーは37.3-60.4 kJ/mol であった。
発熱反応が開始する誘導期は，混酸量の影響を受けてニトロセルロース量が増加するにつれ，また，混酸中の硝酸量が増加するにつれて減少した。さらに，分解に及ぼす雰囲気ガスの影響も認められ，二酸化窒素は反応を加速した。