镁基多功能纳米复合粒子的结构设计、合成及性能研究

As one environmentally friendly flame-retardant, magnesium hydroxide with the function of flame retardancy, smoke suppression and stuff, is already widely applied in polymeric materials. However, magnesium hydroxide is of strong polarity and with poor affinity for hydrophobic polymers, resulting in poor application performance. Moreover, due to the low flame retardant efficiency of magnesium hydroxide, high addition levels are typically needed, which can deteriorate mechanical properties of the composite materials. On the basis of enhanced feature of magnesium borate, the synergistic flame retardancy of organic phosphate and magnesium hydroxide and good compatibility between organic phosphate and polymeric matrix, in this project, OP-MH@MBO nano-composite particles with the function of enhance performance, flame retardancy and smoke suppression will be designed and synthesized by in-situ growth and inorganic-organic hybrid surface modify techniques. Firstly, we will study the key control factors and growth mechanism of in-situ growth of magnesium hydroxide on the surfaces of magnesium borate, and eventually effectively control crystallization process and morphology of MH@MBO. Secondly, we will investigate the internal connections among composition, structure and morphology of nano-composite particles and the flame retardancy and smoke suppression of polymer composites, and reveal the mechanism of flame retardation and smoke inhibition. At last, we will investigate the effect of organic phosphate structure on mechanical property of polymer composites, and demonstrate the structure-activity relationship of organic phosphate and polymer composites. Research results can provide both theoretical fundamentals and technological guidelines for high-value utilization of salt lake resources and development of novel magnesium-based functional materials.

氢氧化镁作为一种环保型的阻燃剂，兼具阻燃、抑烟和填充等功能，在聚合物阻燃领域有着广泛的应用。但是氢氧化镁与聚合物界面相容性差和较大的添加量导致复合材料力学性能下降严重等问题。本项目基于硼酸镁纳米棒（MBO）具有增强的特性、有机磷酸酯（OP）与氢氧化镁（MH）高效协同阻燃以及有机磷酸酯与聚合物良好的相容性，采用原位生长技术和有机无机杂化改性的方法，设计合成具有增强、阻燃和抑烟等功能的OP-MH@MBO有机-无机纳米复合粒子。研究氢氧化镁在硼酸镁纳米棒表面原位生长的关键控制因素和机理，实现对其结晶过程和结构的有效控制；研究纳米复合粒子组成、结构和形貌等与复合材料阻燃和抑烟性能的内在联系，揭示其阻燃和抑烟机理；研究有机磷酸酯结构对复合材料力学性能的影响规律，阐明有机磷酸酯结构与复合材料力学性能的构效关系。项目研究结果可为盐湖资源高值化利用和镁基功能材料的研究提供理论依据和技术基础。

镁铝氢氧化物作为一种环保型的阻燃剂，兼具阻燃、抑烟和填充等功能，在聚合物阻燃领域有着广泛的应用。但是镁铝氢氧化物与聚合物界面相容性差和较大的添加量导致复合材料力学性能下降严重等问题。本项目基于硼酸镁晶须（MBW）具有增强的特性、有机磷酸酯等与镁铝氢氧化物高效协同阻燃以及与聚合物良好的相容性，设计合成具有增强、阻燃和抑烟等功能的有机-无机复合粒子。开展了MH在MBW表面的原位生长以及氢氧化铝（ATH）和镁铝层状氢氧化物（LDH）包覆MBW的无机改性研究。MH、ATH和LDH均成功地包覆在MBW表面，形成核壳结构的无机复合粒子。表面包覆镁铝氢氧化物后，-OH吸收峰明显，解决了MBW表面活性基团少，化学改性困难的问题；选用DDP、KH550、DPPES、DOPO等为有机改性剂，开展了无机复合粒子的表面性质调控研究。通过P-OH、Si-OH等基团与MBW表面包覆的镁铝氢氧化物的-OH反应，形成了稳定的化学键。有机改性后复合粒子在EP基体中分散性变好，与EP基体的分界线不明显，解决了无机复合粒子在EP中易团聚和与EP基体相容性较差的问题；将制备的有机无机复合粒子添加到环氧树脂（EP）中，开展了有机-无机复合粒子/EP复合材料的制备及性能研究。有机-无机复合粒子的加入，使EP复合材料的开始分解温度和最大分解温度降低、残炭量增加、玻璃化转变温度增大、复合材料的阻燃性能和抑烟性能显著提升。其阻燃、抑烟机理归因于MBW和镁铝氧化物的物理阻隔作用、分解产物水蒸气等的稀释作用和有机磷酸酯分解产物磷的含氧酸催化成炭作用。三者之间的协同作用下形成了致密、稳定的炭层，阻隔了气相和凝聚相间的热量和质量传输。此外，复合材料的拉伸等力学性能与纯EP相比，都有不同程度的提升，解决了添加阻燃剂后，复合材料力学性能下降的问题。项目研究结果可为盐湖资源高值化利用和镁基功能材料的设计提供理论依据和技术基础。