Polytriazole Binders Based on Chemical Modification Strategies: Microphase Separation Optimization and Performance Enhancement

Abstract

A traditional butahydroxy solid propellant is widely used because of its good energy and safety properties, but its isocyanate curing system is easily affected by water and has low combustion efficiency during curing. In this paper, by means of the chemical modification method, toluene 2,4-diisocyanate was first used to seal the hydroxy-terminated polybutadiene (HTPB), and then the alkynyl group was introduced to successfully prepare a new alkyny-terminated polybutadiene adhesive (AT-HTPB), which is not subjected to moisture during the curing process and has better comprehensive properties. The process of reaction heat release was monitored online by a fully automatic chemical reactor, which proved that the synthesis path was safe and efficient. The structure of AT-HTPB was characterized by Fourier infrared spectroscopy (FT-IR), hydrogen nuclear magnetic resonance spectroscopy (¹H NMR), and gel chromatography (GPC). The results showed that the prepared AT-HTPB had a high purity and good consistency. Differential scanning calorimetry (DSC), dynamic thermomechanical analysis (DMA), and thermogravimetric mass spectrometry (TGA-MS) showed that AT-HTPB had better thermal stability and retained the advantages of lower glass transition temperature (T_g) than HTPB. It is observed that AT-HTPB has more obvious microphase separation through an atomic force microscope (AFM), and the mechanical properties of AT-HTPB elastomers are more superior than those of AT-HTPB elastomers. Then, AT-HTPB was applied to the solid propellant and the combustion performance was compared with that of the BUtadiol propellant. The results showed that the AT-HTPB propellant had a more concentrated flame and better bonding effect. This study proves that AT-HTPB as a new adhesive has broad application prospects in solid propellants.