Viscosity Testing of HTPB Rubber Based Pre-binders

This paper presents the test results of viscosity changes, versus time and temperature, for the HTPB rubber based pre-binders used in the manufacture of heterogeneous solid rocket propellants (HSRP). A Brookfield HADV-II+PRO viscometer with a small sample adapter (SSA) and SC4-18 spindle, including a TC-550SD water bath, was used for the tests. The components of the prebinders tested were: HTPB-K domestic liquid synthetic rubber, R45M rubber, dioctyl adipate as the plasticizer, diisocyanate curing agents (DDI, IPDI) and various additives: triethanolamine (TEA), iron compounds, lecithin, glycerine and a solution of oxalic acid in glycerine, and difunctional aziridine amide. As a result of these tests, it was found that the additives have an influence on the viscosity versus time dependence. Moreover, the influence of temperature on the viscosity changes with time were compared for HTPB-K domestic rubber and R45M rubber based pre-binders. The experimental equations describing these changes were also determined.