NEPE推进剂固化交联的流变学研究

Rheological Study on the Crosslinking of NEPE Propellant

采用动态流变学方法研究了硝酸酯增塑聚醚(NEPE)推进剂的固化历程.结果表明,推进剂固化初期(黏流态)的储能模量(G′)和损耗模量(G″)随时间增加缓慢增大,G′<G″;固化中期推进剂药浆形成凝胶,G′和G″显著提高,且G′逐渐接近并超过G″;固化末期(黏弹态)的G′和G″随时间增大而趋于稳定,G′(～106Pa)明显大于G″(～105Pa).温度升高推进剂的凝胶时间(tgel)缩短,但推进剂在凝胶点和固化结束时的储能模量G′gel(622～781 Pa)和G′∞(831.1×103～868.3×103Pa)的变化不大.推进剂在固化初期(反应控制阶段)符合一级反应动力学关系,推进剂的固化过程符合Hsich动力学模型,由反应速率常数(kc)、凝胶时间(tgel)和特征松弛时间(τ)得到推进剂的表观反应活化能ΔEc,ΔEg和ΔEτ分别为129.6,122.1和120.6 kJ/mol.

The curing process of the NEPE （nitrate ester plasticized polyether） propellant was studied by means of the dynamic rheology method. The results indicated that the viscoelastic properties of the propellant slurry changes obviously in different curing stages, in the initial curing stage （viscous fluid state）, where G＇ （storage modulus） and G＂（ loss modulus） increases slowly, G＇ is less than G＂; in the medium of the curing process, the propellant slurry is gelated, G＇ and G＂ increase significantly in the mean time, G＇ is equivalent to G＂ and higher than that; in the finial curing stage（viscoelastic state）, where G＇ and G＂ increase to the maxi- mum and level off, G＇ （ - 106 Pa） is obviously higher than G＂（ - 10^5 Pa）. It was experimentally show that tgel （gel time） of the propellant decreases as the curing temperature increases, while G＇gel （storage modulus at gel point） and G＇∞ （storage modulus at the end of curing） change slightly, which are in the range of 622 Pa to 781 Pa and 831.1 × 10^3 Pa to 868.3 × 10^3 Pa, respectively. It was found that the crosslinking kinetic of the propellant in the initial curing stage is reaction controlled, and follows the first-order model. The curing of the propellant is in agreement with the Hsich kinetic model, ko （reaction rate constant）, tgel and τ （characteristic relaxation time in the Hsich model） are used to calculate the apparent activation energy（△Ec, △Eg and △Eτ） of the curing of the propellant, which are 129.6, 122. 1 and 120.6 kJ/mol, respectively.