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软段结构对聚氨酯弹性体性能的影响

张聪聪1 郑梦凯1 李伯耿1

(1.化学工程联合国家重点实验室浙江大学化学工程与生物工程学院, 浙江杭州 310027)

【摘要】分别以聚四氢呋喃二醇(PTMG)、聚己内酯二醇(PCL)、高顺式端羟基聚丁二烯(HTPB)和自由基聚合制得的端羟基聚丁二烯(FHTPB)为软段,采用溶液聚合两步法制得了四种聚氨酯弹性体(PUE)。通过拉伸试验、动态力学性能分析(DMA)、差示扫描量热(DSC)和热重分析等手段,考察了软段结构对它们室温及低温下力学性能、热性能等的影响。结果表明,四种PUE低温(-30℃)下的拉伸强度和断裂伸长率均大于室温下的对应值。这不仅与低温下软段诱导结晶所产生的自增强效应有关,也与软、硬两段的微相分离程度增大有关。相较于其他三种PUE,HTPB-PUE软段不仅玻璃化温度(Tg)最低,而且极性也最弱,因而微相分离程度高,具有优异的柔性,-30℃下其断裂伸长率仍达660%以上。PCL-PUE和PTMG-PUE因软段易结晶,且软段与硬段的微相分离程度低,则刚性强。低温循环拉伸试验表明,-30℃下HTPB-PUE和FHTPB-PUE有较强的弹性恢复能力,而PCL-PUE和PTMG-PUE则相对较差。DSC和DMA结果显示HTPB-PUE的Tg远低于其他三种PUE,其Tg(DSC)低至-103℃。此外,四种PUE的初始分解温度十分相近,均在270℃左右。

【关键词】 聚氨酯;弹性体;软段;结构;性能;

【DOI】

Effect of soft segment structure on properties of polyurethane elastomers

ZHANG Congcong1 ZHENG Mengkai1 LI Bogeng1

(1.State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, Zhejiang, China 310027)

【Abstract】Using four different soft segments, i.e., polytetrahydrofuran diol (PTMG), polycaprolactone diol (PCL), hydroxyl-terminated polybutadiene with high cis-1,4 content (HTPB), and commercial hydroxyl-terminated polybutadiene produced by free radical polymerization (FHTPB), four kinds of polyurethane elastomers (PUEs) were prepared by two-step solution polymerization. The effects of soft segment structure on mechanical properties and thermal properties at room temperature and low temperature were investigated by tensile test, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It is found that the tensile strength and elongation at break of the four PUEs at low temperature (−30 °C) are superior to those at room temperature. This is not only related to the autofrettage effect induced by crystallization of soft segment at low temperature, but also associated with the increase in the degree of micro-phase separation between the soft and hard segments. Compared with the other three kinds of PUE, the HTPB-PUE has the soft segment with the lowest polarity and glass transition temperature (Tg), so the micro-phase separation is in the highest degree, and the elastomer has the most excellent flexibility. Even at −30 °C, the elongation at break of the HTPB-PUE is up to 660%. PCL-PUE and PTMG-PUE are rigid because their soft segments are easy to crystallize and their degree of micro-phase separation between soft and hard segments is low. The cyclic tensile testing indicates that HTPB-PUE and FHTPB-PUE still have excellent elasticity at −30 °C. The results from DSC and DMA show that the Tg of HTPB-PUE is much lower than those of the other three PUEs, and the value from DSC is about −103 °C. The initial thermal decomposition temperatures of the four PUEs are very similar, and are all around 270 °C.

【Keywords】 polyurethane; elastomer; soft segment; structure; properties;

【DOI】

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This Article

ISSN:0438-1157

CN: 11-1946/TQ

Vol 70, No. 10, Pages 4043-4051

October 2019

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Article Outline

Abstract

  • Introduction
  • 1 Materials and methods
  • 2 Results and discussion
  • 3 Conclusions
  • References