可快速固化、阻燃聚氨酯复合屏蔽材料的制备及性能

Preparation and Performance of Fast-curing,Flame-retardant Shielding Composites Based on Polyurethane

针对核设施退役过程中可能存在对设施内部放射性预估不当而导致在解体去污过程中辐射量超标的紧急情况,采用实验室一步成型法制备了一种可快速固化的阻燃聚氨酯复合屏蔽材料,研究了屏蔽填料(氧化钨)及阻燃填料(硼酸锌)的总含量对材料固化时间、微观结构、密度、压缩强度、阻燃性能及屏蔽性能的影响。结果表明,双组分聚氨酯混合体系的乳白时间受填料含量变化的影响较小,而表干时间随填料含量增大先减小后增大,但仍保持较快的固化速度;填料主要分布在泡孔孔壁中,随着填料含量的增加,材料的泡孔逐渐细化;材料的密度随填料含量增加逐渐变大而压缩强度逐渐减小;极限氧指数随着硼酸锌含量增加逐渐提高;不同γ射线能量下射线的透射率随填料含量增加逐渐减小,但是随着射线能量增强材料屏蔽性能逐渐减弱,在相同能量下,增加材料的厚度可以有效改善其屏蔽性能。当氧化钨和硼酸锌质量分数分别为40%和20%时,该新型复合屏蔽材料具有较短的固化时间和较好的阻燃及力学性能,在中低能射线辐照下具有较好的屏蔽性能,其在应对核电站退役过程中保障工作人员辐照安全方面具有较大的应用前景。

During the decommissioning of nuclear facilities,if the radioactivity of the waste was evaluated improperly,theradiation dose the workers received would exceed the standard when the facilities were under the process of cutting and dismantling,so a new type fast-curing,flame-retardant shielding composites based on polyurethane were prepared with the shielding filler of WO3and flame-retardant of Zinc borate （ZB） through one-step,laboratory-scale method. The effects of the content of the two fillers oncuring time,microstructure,density,compressive strength,flame-retardant property,and γ-ray-shielding performance of the compositeswere studied. The results show that the cream time of two-component polyurethane blending system is stable and the tackfreetime decreases first and then increases with the increase of fillers content,but faster curing speed is still kept. The fillers mainlyexist in the cell wall,as the fillers content increases,the cell size is decreased,the density increases and the compressive strengthdecreases. The limiting oxygen index （LOI） increases as the ZB content increases. The γ-ray transmittance at different energies decreasesas the WO3 filler content increases. However,the shielding performances of the composites become bad with the γ-ray energyincreasing. But under the same energy,increasing the thickness of the composites can improve the shielding performances. Whenthe mass fraction of WO3 and ZB is 40% and 20% respectively,the new type shielding composite has short curing time,good flameretardantand mechanical properties,and has better γ-ray shielding performance under irradiation of medium-low γ-ray energy,ithas a large potential application in protecting the workers from irradiation during the decommissioning of nuclear facilities.