Thermal, mechanical and morphological properties of plasticized polyurethane binders based on PEG and HTPB blends

Improving the properties of hydroxyl-terminated polybutadiene (HTPB) has always been one of the important topics for researchers in the propellant field. In this research work, a prepolymer from blend of HTPB and polyethylene glycol (PEG) is prepared with isophorone diisocyanate (IPDI). This prepolymer is mixed with glycerol for the synthesis of polyurethane (PU) elastomer. The compatibility of n-butyl nitroxyethylnitramine (n-BuNENA) as an energetic plasticizer with a non-energetic PU matrix was investigated. The properties of HTPB-PEG blend elastomer prepared with n-BuNENA plasticizer were compared with elastomers made by HTPB. The results of SEM analysis showed that incorporation of PEG improved the compatibility of plasticizer with PU matrices. DSC, FTIR spectroscopy and tensile analysis revealed that the phase separation degree and crystallinity in PEG-based PU were much higher than HTPB elastomer. It was determined by TGA results that the n-BuNENA plasticizer reduced the thermal stability of PU. Mechanical studies also indicated that the incorporation of PEG increases the modulus and tensile strength while the addition of plasticizer decreases the modulus and enhances the tensile strength and elongation.

Automated summary

In this research, a prepolymer from a blend of HTPB and PEG was prepared and used for synthesizing PU elastomer with glycerol. The compatibility of n-BuNENA as a plasticizer with non-energetic PU matrices was investigated. The results showed that the incorporation of PEG improved the compatibility of the plasticizer with PU, but reduced the thermal stability. Addition of PEG increased the modulus and tensile strength, while addition of plasticizer decreased the modulus but enhanced the tensile strength and elongation.