Properties of PCL-HTPB-PCL-based polyurethane elastomers
Polyurethane elastomer(PUE)has been widely used in many fields because of its excellent performance.However,with the constant extension of its application fields,the requirements for PUE performance have been becoming higher and higher.In some special fields,general PUE has been unable to meet the special performance requirements.Therefore,in addition to adjust-ing the variety and ratio of raw materials in the PUE formulation system,regulating the chain segment structure is also an effective way.New sandwich copolymer diols(PCL-HTPB-PCL,for short is CHC)were synthesized by ring-opening polymerization of ε-caprolactone(ε-CL)using hydroxy-terminated polybutadiene(HTPB)as macromolecular initiator.The—NCO terminated prepoly-mer was prepared by the reaction of CHC with toluene diisocyanate,and the prepolymer was extended by 1,4-cyclohexyldimethanol(CHDM)to obtain PUE with both polycaprolactone diol(PCL)and HTPB structures in its soft chain segment.The mechanical test and related instrument analysis show that the molecular weight and content of CHC have a great effect on the mechanical properties of PUE,have certain influence on microstructure,cross section morphology and thermal properties.Specifically,when the molecular weight of CHC was constant,with the increase of CHC content in the preparation of PUE,the hardness and specific tensile strength of PUE samples decrease,and its elongation at break increases.When the CHC content and the chain extension coefficient of the prepolymer are the same,the higher molecular weight of CHC can make the decrease of PUE's hardness,can make the increase of PUE's specific tensile strength,elongation at break and microphase separation degree,and the glass transition temperature of PCL polyester chain in soft segment of PUE macromolecular and the melting temperature of hard segment of PUE macromolecular increase.
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