Preparation and properties of azide-modified nitrocellulose and its click reaction curing elastomer

To improve the toughness of the semirigid chain of nitrocellulose (NC), and to avoid the phenomenon of small molecule gas generated by isocyanate polycondensation reaction in the curing of propellant, glycidyl azide polymer (GAP)-hexa-methylene diisocyanate (HDI)-NC (GAP-HDI-NC) graft polymer and its click reaction elastomer were successfully fabricated by azide-alkyne cycloaddition click reaction in this contribution. In addition, the formulations of GAP-HDI-NC graft polymer and its elastomer were optimized on the basis of improving the mechanical properties, thermal stability and safety. With the increasing of GAP content, the peak value of alpha transition at high temperature increases, that is, mechanical loss increases and tensile strength decreases. When the mass ratio of GAP to NC is 45:55, the tensile strength (sigma(m)) and breaking elongation (epsilon(b)) of GAP-HDI-NC graft polymer are 44.1 MPa and 58.7% respectively, and the Tg(1) of GAP-HDI-NC click reaction curing elastomer reaches the minimum value of 105.7 degrees C, which is much lower than that of pristine NC. When R-2 value is 1.0, the sigma(m) of GAP-HDI-NC click reaction curing elastomer reaches the maximum value of 47.6 MPa, while when R-2 value is 0.9, its epsilon(b) reaches the maximum value of 55.8%. In addition, the click reaction of azide group is beneficial to improve the thermal stability and safety performance of GAP-HDI-NC click reaction curing elastomer, which has good potential as solid propellant binder. [GRAPHICS] .