Synthesis of Polybutadiene- Caprolactone Triblock Copolymer (PCL-HTPB-PCL) and Investigation of its Curing Conditions in the Presence of Energetic Plasticizers

Polycaprolactone is a polyester binder that has a polar structure and is compatible with polar plasticizer. Also, due to ester structure, oxygen balance of this polymer is more suitable than HTPB, therefore, by combining these two binders as a copolymer, the disadvantages of HTPB are eliminated and its advantages are preserved. In this research work, triblock copolymer of PCL-HTPB-PCL is made by ring opening polymerization of caprolactone by HTPB (1000 g.mol -1 ) molecular weight as a initiator and 69% yield. This copolymer was characterized by (FT-IR) and 1H-NMR spectroscopy. The investigation of the curing conditions showed that the copolymer with IPDI and N100 isocyanate in a ratio of 80: 20 were properly cured. Finally, the compatibility of cured copolymer with high energy plasticizers was investigated using swelling test and it was found that PCL-HTPB-PCL copolymer is more compatible with Bu-NENA and TEGDN plasticizers than BTTN and TMETN.