PCL-HTPB-PCL基聚氨酯弹性体的性能

Properties of PCL-HTPB-PCL-based polyurethane elastomers

聚氨酯弹性体(PUE)因其性能卓越,已在诸多领域得到广泛应用。然而,随PUE应用领域的不断拓宽,对PUE性能的要求也越来越高。在一些特殊领域,通用PUE已不能满足特殊的性能要求。为此,除调整PUE配方体系原料品种和配比外,调控链段结构也是一种有效途径。以端羟基聚丁二烯(HTPB)为大分子起始剂,由ε-己内酯(ε-CL)开环聚合,合成新型嵌段二元醇(PCL-HTPB-PCL,简称CHC)。由CHC与甲苯二异氰酸酯反应制得—NCO封端预聚体,—NCO封端预聚体经1,4-环己基二甲醇(CHDM)扩链后制得软链段中同时兼有聚己内酯二醇(PCL)与HTPB结构的PUE。力学性能测试及相关仪器分析表明,CHC分子量及含量对PUE力学性能的影响很大,对微观结构、断面形貌和热性能有一定影响。具体表现为:当CHC分子量一定时,随CHC含量的增加,PUE试样的硬度、比拉伸强度降低,断裂伸长率增加;当CHC含量、预聚体扩链系数相同时,CHC的分子量增加,PUE试样的硬度降低,但PUE试样的比拉伸强度和断裂伸长率增加、微相分离程度增大、PUE大分子链软段中PCL聚酯链段的玻璃化转变温度和硬段熔融温度升高。

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 adjusting 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 ofε-caprolactone(ε-CL)using hydroxy-terminated polybutadiene(HTPB)as macromolecular initiator.The—NCO terminated prepolymer 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.