DBM和BDO为扩链剂的聚氨酯粘合剂性能

以聚己二酸乙二醇丙二醇酯(PEPA)、环氧乙烷/四氢呋喃无规共聚醚(PET)为软段,异佛尔酮二异氰酸酯(IPDI)、二羟甲基丙二酸二乙酯(DBM)和1,4-丁二醇(BDO)为硬段,采用熔融二步法合成了具有键合功能的可用作推进剂粘合剂的聚氨酯弹性体。通过傅立叶变换红外(FTIR)、凝胶渗透色谱(GPC)、差示扫描量热分析(DSC)以及力学性能测试对合成的弹性体进行了研究。结果表明,随着扩链剂中BDO摩尔分数的增加,聚氨酯弹性体的微相分离程度增加,软段玻璃化转变温度逐渐降低,当BDO含量超过50%时,软段的玻璃化转变温度可低于-70℃;BDO含量增加,热塑性聚氨酯弹性体(TPUE)的拉伸强度逐渐增加,而断裂延伸率则有逐渐降低的趋势。采用混合扩链剂制备的TPUE对硝胺改性双基推进剂(NMDB)力学性能的改善要优于单独以BDO或DBM为扩链剂制备的聚氨酯粘合剂。

Properties of Thermoplastic Polyurethane Elastomers Extended with BDO and DBM

A series of thermoplastic polyurethane elastomers(TPUEs) with bonding function which can be used as propellant binders were synthesized from polyethylene/polypropylene adipate diol(PEPA),tetrahydrofuran/ethylene oxide copolyether(PET),isophorone diisocyanate(IPDI),1,4-butanediol(BDO) and diethyl bis(hydroxymethyl) malonate(DBM) as primary substances by melt pre-polymerization method.Then Fourier transform infrared spectroscopic(FTIR),gel permeation in chromatography(GPC),differential scanning calorimetry(DSC) and tensile test techniques were employed to characterize the structures and properties of TPUEs.Results show that the microphase segregation of TPUEs become more obvious with the BDO content in chain extenders increasing.When the molar content of BDO exceeds 50% in chain extender,the glass transition temperature of soft segment become lower than-70 ℃.It is also observed that tensile strength of the TPUE increased with the BDO content increasing,while the elongation to break decreased.TPUEs extended with mixed diols have better effect than that extended with BDO or DBM to improve the mechnical properties of modified double-based propellant.