The Synthesis And Properties Of Azido Cellulose Derivaties

A few novel cellulose-based energetic binders were synthesized in this paper.Readily soluble hydroxyethyl cellulose(HEC) was sujected to tosylation and chlorination, respectively, to prepare corresponding intermediates under homogeneous conditions, followed by azidation to produce azido-cellulose derivatives.Nitrocellulose(NC) was directly azidized using sodium azide under conventional heating condition. The parameters such as mole ratio, temperature and reaction time,were optimized, and the influencing trends of different conditions were analyzed.Instead, microwave was adopted, exploring the effect of radiation time on yields and substituting degrees.Structrual characterizations and peroperty measuments were carried out for a series of azidocellulose nitrates(ACN). Several methods such as elemental analysis, fourier transform infrared spectroscopy(FT-IR), gel permeation chromatography(GPC),X-ray diffraction(XRD)were applied to study the chemical structures, explosive properties. Meanwhile, thermal behaviors and thermal decomposition mechanism were researched by thermogravimetric analysis(TG), differential scanning calorimetry(DSC) and RS/FT-IR.The results are shown as follows. The tosylation and subsequent azidation of HEC produced insoluble resultants due to unavoidable crosslinking; while the chloridation and following azidation of HEC resulted in residual holagen, which is infavorable of further application. A nitrocellulose with nitrogen content of 8.84 % was reacted with sodium azide in DMSO solution under conventional heating condition. The substitution degree(DS) of azido groups could be 0.13~ 0.70 under the following conditions: 1:1~6:1 molar ratio of NaN3 to nitrate groups on NC, 55~95 ? of reaction temperature, 12 ~ 60 h of reaction time. Under microwave radiation, DS could reach 0.56 in only 10 min at 75 ? in case that NaN3/nitrate groups molar ratio is 5:1; The obtained ACN showed good solubility in acetone, and its maximum explosion heat could reach 5771 J/g derived through theoretical energy calculation.XRD analysis revealed that both crystalline and amorphous states existed in ACN,and crystallinity became lower compared with NC. In addition, serious decompostion occured during azidation of NC, proveed by GPC. TG analysis indicated that ACN is not a single decomposition process, but the gradual process of pyrolysis. DSC analysis indicated that ACN had greater energy potencial than NC.