高强聚氨酯复合材料力学性能及拉压本构模型

Mechanical performance and tensile-compressive constitutive model of high-strength polyurethane composites

  • 摘要: 为探究不同组分对添加分子筛制备的高强聚氨酯复合材料(HSPUC)力学性能的影响机理,设计了16组不同异氰酸酯指数(R)、分子筛掺量及聚灰比的HSPUC,通过宏观试验测试了各配合比HSPUC的抗压、弯曲及拉伸强度,分析了各因素对强度及应力-应变曲线的影响规律,获得了HSPUC的最佳配合比,结合FT-IR和SEM揭示了各因素对HSPUC力学性能的内在影响机制。宏观试验表明:随R值的增大、分子筛掺量的增加及聚灰比的减小,HSPUC的抗压、弯曲及拉伸强度均呈先增大后减小的趋势发展,应力-应变曲线弹塑性特征逐渐减弱;当R为1.25,分子筛掺量为7.5%,聚灰比为1.0时,HSPUC的抗压、弯曲、拉伸强度分别为104.8 MPa、79.4 MPa、25.1 MPa,拉伸应变能密度为0.085 J·mm−3,展现出最优的强度和良好的韧性性能。微观试验表明:R值决定了HSPUC的软、硬链段比例;分子筛的加入优化了HSPUC的孔隙结构。基于实测应力-应变曲线和普通混凝土本构关系建立了HSPUC受拉、受压本构模型,为HSPUC的工程应用提供了模型基础。

     

    Abstract: To investigate the mechanism of the influence of different components on the mechanical performance of high-strength polyurethane composites (HSPUC) prepared with the addition of molecular sieve dosages, 16 groups of HSPUC with different isocyanate indices (R), molecular sieve dosages, and polymer to cement ratios were designed. The compressive, flexural, and tensile strengths of each mix ratio of HSPUC were tested through macroscopic experiments. The influence of various factors on the strength and stress-strain curves was analyzed, and the optimal mix ratio of HSPUC was obtained. The intrinsic influence mechanism of various factors on the mechanical performance of HSPUC was revealed by combining FT-IR and SEM. The macroscopic experiments showed that with the increase of the R value, the increase of molecular sieve content, and the decrease of the polymer to cement ratio, the compressive, flexural, and tensile strengths of HSPUC all showed a trend of first increasing and then decreasing, and the elasto-plastic characteristics of the stress-strain curves gradually weakened. When R was 1.25, the molecular sieve dosage was 7.5%, and the polymer to cement ratio was 1.0, the compressive, flexural, and tensile strengths of HSPUC were 104.8 MPa, 79.4 MPa, and 25.1 MPa, respectively, and the tensile strain energy density was 0.085 J·mm−3, showing the most superior strength and excellent toughness performance. Microscopic experiments indicated that the R value determined the proportion of soft and hard segments in HSPUC; the addition of molecular sieves optimized the pore structure of HSPUC. Based on the measured stress-strain curves and the constitutive relationship of ordinary concrete, a constitutive model for HSPUC under tension and compression was established, providing a foundational model for the engineering application of HSPUC.

     

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