【作者】 杨红艳；

【导师】 欧阳晓平； 张彪；

【作者基本信息】 湘潭大学 ， 材料工程， 2024， 硕士

【摘要】 聚氨酯弹性体（PUE）通常被视为重要的缓冲和吸收能源的防护组成部分,在多种防护领域中得到了广泛的使用,例如在运动防护、可佩戴的电子设备以及汽车的撞击防护等领域。然而,PUE在高速冲击载荷等极端环境下容易出现开裂和穿孔损坏问题,使其防护性能失效。这些缺点限制了聚氨酯在防护领域的应用。为了提高聚氨酯的高速抗冲击性能,需要进一步开发具有优异韧性和轻质优异结构的聚氨酯材料。本文受到生物抗冲击结构中软硬结合的可牺牲微区启发,利用不同键型修饰纳米SiO₂制备纳米增强填料,通过SiO₂的硬质模量和牺牲键的断裂耗能在聚氨酯网络中形成可牺牲微区。着重探究了聚氨酯复合材料的静态抗压缩性能、动态抗冲击性。通过粘弹性和热稳定性测试对其抗冲击原理进行微观表面分析。此外,还探究了填料含量对聚氨酯整体性能的影响。本文主要工作总结如下:（1）基于蝗虫后肢中软硬结合抗冲击结构（几丁质壳和弹性蛋白）,通过季铵化反应合成含动态二硫键的IPS（季铵化反应合成的淡黄色液体）,并通过季铵化反应将其修饰在硬质SiO₂上形成软硬结合的纳米增强填料（IPS@SiO₂）。实验结果表明:纳米填料表面含二硫键的有机基团能很好的改善SiO₂在聚氨酯基质中的团聚问题。此外,还探究了不同填料含量对聚氨酯性能的综合影响,试验结果表明制备出的IPS@SiO₂/PUE具有优异的压缩和回弹特性,并增加了聚氨酯抗冲击过程中能量耗散。其静态压缩模量比纯PUE高出106.08%,刚性部分、二硫键断裂以及填料与基体之间的联结所建立的多级耗能机制使复合聚氨酯的动态能量吸收率提高了98.06%。因此,通过填料掺杂改性制备的IPS@SiO₂/PUE具有优异的冲击能量吸收性能。（2）基于上述实验研究,进一步制备了牺牲位点更多防护性能更优的聚氨酯复合材料。选用材料价格更低廉,利用率更高的2’6-二氨基吡啶和Fe Cl₃制备含有牺牲配位键的FPS（合成的棕褐色液体）,用以修饰SiO₂制备FPS@SiO₂纳米填料。试验结果表明:改性后的FPS@SiO₂/PUE静态压缩模量比纯PUE高出128.39%,比二硫键改性的IPS@SiO₂/PUE静态压缩模量增加了22.31%,且损耗因子峰值和初始分解温度显著提高,对比PUE的E’提高了32.74%。刚性部分、配位键断裂以及填料与基体之间的联结所建立的含更多反应位点的多级耗能机制使复合聚氨酯的动态能量吸收率提高了213.1%,比IPS@SiO₂/PUE增强115.04%。FPS@SiO₂/PUE具有优异的冲击能量吸收性能。本工作通过不同牺牲键对硬质纳米粒子改性,在聚氨酯基质中形成软硬结合的可牺牲微区以形成聚氨酯基质中的多级耗能机制使得聚氨酯抗冲击性能进一步提升成为可能。更多还原

【Abstract】 Polyurethane elastomers（PUEs）are often regarded as a major cushioning and energy-absorbing component of protection and are widely used in a number of protection areas,such as in sports protection,wearable electronic devices and automotive impact protection.However,PUE is susceptible to cracking and perforation damage in extreme environments such as high-speed impact loads,rendering its protective properties ineffective.These drawbacks limit the application of polyurethane in the field of protection.In order to improve the high-speed impact resistance of polyurethane,further development of lightweight and high-quality structural materials with excellent toughness and strength is required.In this paper,inspired by the soft-hard combinations of sacrificable microregions in biological impact resistant structures,nano-reinforced fillers are prepared by modifying nano-SiO₂ with different bonding types,and sacrificable microregions are formed in polyurethane networks by the hard modulus of SiO₂ and energy dissipation through the fracture of sacrificial bonds.The static compression resistance,dynamic impact resistance,viscoelasticity and thermal stability of the polyurethane composites were also investigated with emphasis on the micro-surface analysis of the impact resistance principle and the effect of filler content on the overall properties of polyurethane.The main work of this paper is summarised as follows:（1）Based on the soft-and hard-bonded impact-resistant structures（chitin shells and elastin）in locust hind limbs,IPS containing dynamic disulfide bonds were synthesised by quaternization reaction and modified on hard SiO₂ to form soft-and hard-bonded nano-reinforced fillers（IPS@SiO₂）via quaternization reaction.The experimental results showed that the organic groups containing disulfide bonds on the surface of the nanofillers could well improve the agglomeration problem of SiO₂ in polyurethane matrix.In addition,the comprehensive effects of different filler contents on the performance of polyurethane were also explored,and the experimental results showed that the prepared IPS@SiO₂/PUE possessed excellent compression and resilience characteristics and increased the energy dissipation and formed the multi-directional force deflection during the impact resistance of polyurethane,and its static compression modulus was 106.08%higher than that of the pure PUE,and the rigid portion,the breakage of disulphide bonds,and the filler-matrix The multilevel energy dissipation mechanism established by the rigid part,disulfide bond breaking and the linkage between the filler and the matrix increased the dynamic energy absorption of the composite polyurethane by 98.06%.Therefore,the IPS@SiO₂/PUE prepared by filler doping modification has excellent impact energy absorption performance.（2）Based on the above experimental studies,in order to further prepare polyurethane composites with more sacrificial sites and better protective properties.2’6-diaminopyridine and Fe Cl₃,which are cheaper and have higher utilisation rate,were chosen to prepare FPS containing sacrificial ligand bonds,which were used to modify SiO₂ to prepare FPS@SiO₂ nanofillers.The experimental results showed that the modified FPS@SiO₂/PUE static compressive modulus was 128.39%higher than that of pure PUE,and 22.31%higher than that of disulfide bond-modified IPS@SiO₂/PUE static compressive modulus,and the peak loss factor and the initial decomposition temperature were significantly increased,and the E’of the modified FPS@SiO₂ nanofillers was increased by 32.74%comparing with that of PUE.The multistage energy dissipation mechanism containing more reactive sites established by the rigid portion,ligand bond breakage,and linkage between filler and matrix resulted in a 213.1%increase in the dynamic energy absorption of the composite polyurethane,which was enhanced by 115.04%compared to IPS@SiO₂/PUE.The FPS@SiO₂/PUE had excellent impact energy absorption properties.The present work provides a simpler preparation process and lower cost modification for polyurethane impact protection modification,i.e.,the formation of soft-rigid combinable sacrificial micro-regions in the polyurethane matrix through the modification of hard nanoparticles with different sacrificial bonds to form a multistage energy dissipation mechanism in the polyurethane matrix makes it possible to further enhance the polyurethane impact resistance.更多还原