分别制备了以气相二氧化硅(SiO2)和羧甲基纤维素硝酸酯(CMCN)为胶凝剂的硝基甲烷(NM)凝胶推进剂,研究了两类凝胶的形成机理及胶凝剂类型对凝胶体系流变性的影响规律.采用线性的流变学方法研究了凝胶体系的屈服性、触变性、蠕变性与温敏性等动态粘弹性,分别利用Power-Law模型、Hersehel-Bulkley模型、Burger模型对凝胶的流动曲线、蠕变曲线进行了数据拟合.研究发现,NM/SiO2凝胶是SiO2粒子间通过氢键形成的小分子聚集体团聚而成堆积型网路结构凝胶,而NM/CMCN凝胶是由CMCN大分子链上两亲性基团与有机小分子基团间通过分子链间疏水键、氢键等非共价键相互作用形成的一种交联网络型凝胶.两类凝胶的非牛顿系数n≤0.60.与NM/CMCN凝胶相比,NM/SiO2凝胶具有较高的屈服应力、剪切稀化性和弹性柔量与弹性响应性,具有较差的触变恢复性和较小的内耗,且其凝胶强度在高温与低温下反而有一定的增强.%The nitromethane (NM) gels were prepared by using fumed silica(SiO2) and carboxymethyl cellulose nitrate (CMCN) as gelled propellant, respectively. The formation mechanism of two types of gels and the difference of rheological properties between NM/SiO2 and NM/CMCN gels caused by the gel type were investigated. The yield stress, thixotropy, creep and thermosensitivity of two types of gels were investigated by linear rheological methods. The flow data and creep data of gels were fitted by using Power-Law model, Herschel-Bulkley model and Burger model, respectively. The experimental results show that NM/SiO2 gel is a kind of accumulation gel agglomerated with small molecular aggregates formed by SiO2 particles with hydrogen bonds, while NM/CMCN propegel is a physical gel with a crosslinking network structure which is formed by non-covalent interaction of hydrophobic bonds and interchain hydrogen bonds between amphiphilic group along the macromolecular chain of CMCN and small organic molecules. The non-Newton coefficient n of two types of gels are all less than 0. 60. Compared with NM/CMCN gel, NM/SiO2 gel has higher yield stress, shear thinning, elastic compliance and elastic responsivity, and lower thixotropy recovery and internal friction- The gel strength of NM/SiO2 is become stronger at higher temperature and lower temperature.
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