Gajdošová Veronika, Špírková Milena, Aguilar Costumbre Yareni, Krejčíková Sabina, Strachota Beata, Šlouf Miroslav, Strachota Adam
Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovskeho nam. 2, CZ-162 00 Praha, Czech Republic.
Materials (Basel). 2023 Feb 21;16(5):1767. doi: 10.3390/ma16051767.
Morphology, macro-, and micromechanical properties of novel poly(urethane-urea)/silica nanocomposites were analyzed by electron microscopy, dynamic mechanical thermal analysis, and microindentation. The studied nanocomposites were based on a poly(urethane-urea) (PUU) matrix filled by nanosilica, and were prepared from waterborne dispersions of PUU (latex) and SiO. The loading of nano-SiO was varied between 0 (neat matrix) and 40 wt% in the dry nanocomposite. The prepared materials were all formally in the rubbery state at room temperature, but they displayed complex elastoviscoplastic behavior, spanning from stiffer elastomeric type to semi-glassy. Because of the employed rigid and highly uniform spherical nanofiller, the materials are of great interest for model microindentation studies. Additionally, because of the polycarbonate-type elastic chains of the PUU matrix, hydrogen bonding in the studied nanocomposites was expected to be rich and diverse, ranging from very strong to weak. In micro- and macromechanical tests, all the elasticity-related properties correlated very strongly. The relations among the properties that related to energy dissipation were complex, and were highly affected by the existence of hydrogen bonding of broadly varied strength, by the distribution patterns of the fine nanofiller, as well as by the eventual locally endured larger deformations during the tests, and the tendency of the materials to cold flow.
通过电子显微镜、动态热机械分析和微压痕技术，对新型聚（聚氨酯 - 脲）/二氧化硅纳米复合材料的形态、宏观和微观力学性能进行了分析。所研究的纳米复合材料以聚（聚氨酯 - 脲）（PUU）为基体，填充纳米二氧化硅，由PUU（乳胶）和SiO的水性分散体制备而成。在干燥的纳米复合材料中，纳米SiO的负载量在0（纯基体）至40 wt%之间变化。所制备的材料在室温下均处于橡胶态，但它们表现出复杂的弹黏塑性行为，范围从较硬的弹性体类型到半玻璃态。由于使用了刚性且高度均匀的球形纳米填料，这些材料对于模型微压痕研究具有重要意义。此外，由于PUU基体的聚碳酸酯型弹性链，预计所研究的纳米复合材料中的氢键丰富多样，从非常强到弱不等。在微观和宏观力学测试中，所有与弹性相关的性能都具有很强的相关性。与能量耗散相关的性能之间的关系很复杂，并且受到强度广泛变化的氢键的存在、精细纳米填料的分布模式、测试过程中最终局部承受的较大变形以及材料的冷流倾向的高度影响。
