Blast-Resistant Properties and Mechanism of Anti-Explosion Polyurea Coating
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摘要: 通过广角X射线衍射仪、差示扫描量热法实验、扫描电子显微镜以及聚脲喷涂钢筋混凝土板的接触爆炸实验,研究了Qtech T26抗爆型聚脲(T26聚脲)的力学强度、分子结构及热性能,分析了有无涂层钢筋混凝土板的宏观形貌及涂层的微观形貌,考察了T26聚脲喷涂钢筋混凝土板的抗爆能力和防护机理。结果表明:T26聚脲的拉伸强度达到25.4 MPa,断裂伸长率为451.9%;其分子链中软段与硬段之间排列有序,微晶区结晶度为24.11%;软段玻璃化转变温度为−44.9 ℃,硬段玻璃化转变温度为36.5 ℃,呈现出一定的微相分离形态。爆炸实验后,无涂层钢筋混凝土板的迎爆面出现较大凹坑,背爆面被震塌,混凝土破碎;而对于有涂层的钢筋混凝土板,其迎爆面出现较小凹坑,迎爆面涂层除了因瞬间高温而导致的聚脲软化外,爆炸反射波的稀疏拉伸作用使聚脲材料发生破坏,聚脲涂层被撕裂,而背爆面则由于聚脲涂层削弱了稀疏拉伸波的作用,从而保护混凝土材料不被破碎,避免爆炸碎片飞溅。Abstract: The mechanical strength, molecular structure and thermal properties of Qtech T26 anti-explosion polyurea (T26 polyurea) were studied by wide-angle X-ray diffraction (WXRD), differential scanning calorimetry (DSC), scanning electron microscope (SEM) and contact explosion experiment of polyurea coated reinforced concrete plate. The blast-resistant properties and protection mechanism of T26 polyurea coated reinforced concrete plate were investigated based on analyses of the macro morphology of reinforced concrete plate with or without coating and the micro morphology of coating. The results show that the tensile strength of T26 polyurea is 25.4 MPa and the elongation at break is 451.9%; the soft and hard segments of the molecular chain are arranged orderly, and the crystallinity of the microcrystalline region is 24.11%; the glass transition temperature of soft segment and hard segment was −44.9 ℃ and 36.5 ℃, respectively. After the explosion experiments, the uncoated reinforced concrete plate had a large pit on the contact blast face. The backburst surface appeared explosion earthquake collapse and fracture. The reinforced concrete plate with coating had a smaller pit on the contact blast face besides the softening of polyurea caused by the instantaneous high temperature. Moreover, the sparse tensile wave of the explosion reflection caused the damage of polyurea material, leading to the tearing of the coating material. As for the backburst surface coating, the polyurea coating weakened the effect of the explosion impact tensile wave, thus protecting the concrete material from breaking and preventing the explosion debris from splashing.
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表 1 T26聚脲与其他聚脲材料的物理性能对比
Table 1. Physical properties comparison of T26 polyurea with other polyureas
Material Density/
(g·cm−3)Elastic modulus/
MPaTensile strength/
MPaPeel strength/
(N·mm−1)Breaking elongation/
%T26 0.977 84.05 25.4 75.5 451.9 T1[13] 1.020 19.2 391.7 T2[17] 1.02−1.07 18.0 350.0 Note: (1) T1 is energy absorbing polyurea for strengthening masonry wall explosion test;
(2) T2 is common polyurea for explosion test of reinforced autoclaved aerated concrete plate.表 2 T26聚脲的WXRD分峰处理结果
Table 2. WXRD peak separation results of T26 polyurea
Specimen Peak position/(°) Peak area Crystallinity/% Amorphous region Microcrystalline domain Amorphous region Microcrystalline domain T26 20.52 38.16 24042.85 7638.57 24.11 表 3 宏观形貌分析方法
Table 3. Analysis method of macroscopic morphology
Exp. condition Coating Coating thickness/mm Failure plane Macroscopic morphology comparison 1 None 0 Contact blast face Failure mode and diameter Back burst face Failure mode and diameter 2 T26 10 Contact blast face Failure mode and diameter Back burst face Failure mode and diameter 表 4 有无涂层板的破坏结果对比
Table 4. Comparison of failure results of coated plates with uncoated plates
Plate Damage diameter Failure depth or bulge height Uncoating/cm Coating/cm Error/% Uncoating/cm Coating/cm Error/% Blast side 41.0 24.5 40.24 60.0 0 100 Rear side 11.2 9.4 16.07 5.0 0 100 Debris situation More and wide
dispersion rangeLess and more
concentrated
in pitsLarger, larger
splash rangeNo debris -
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