Mechanically adaptive thermoplastic polyurethane/cellulose nanocrystal composites: Process-driven structure-property relationships
Mechanically adaptive thermoplastic polyurethane/cellulose nanocrystal composites: Process-driven structure-property relationships
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DOI：
10.1002/app.46992
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发表时间：
2019-01-20
影响因子：
3
通讯作者：
Bortner, M. J.
中科院分区：
文献类型：
--
作者：
Fallon, J. J.;Kolb, B. Q.;Bortner, M. J.
为了实现纤维挤出添加剂制造机械自适应纳米复合材料，研究了熔融挤出对纤维素纳米晶(CNC)/热塑性聚氨酯(TPU)复合材料拉伸弹性模量和力学性能的影响。用10wt%的数控系统对TPU(Texin RxT70A)进行了多种形式的加工，包括溶剂流延薄膜和熔融挤出生产的长丝。用偏振拉曼光谱和小角X射线散射(SAXS)表征了碳纳米管的取向，发现其在挤出丝中是单轴取向的，在溶剂浇铸膜中是随机取向的。动态力学分析结果表明，加入10wt%的CNC10使溶剂浇铸和挤出成型的纳米复合材料的干态下的纯TPU储能模数从10提高到60~70 Mpa。在水饱和后，所有含有数控的样品都达到了大约26兆帕的相似的湿储存模数，而与数控取向和热历史无关。Fickian扩散标度因子(6.8到11.6)与随时间变化的经验标度因子(4.9到7.2)非常接近，证实了力学适应性的速率是由样品厚度中的水扩散驱动的。我们的结果表明，加工后保持了机械适应性，使其能够用作基于挤出的添加剂制造用于机械适应性零件的CNC/TPU复合材料的原料。(C)2018年威利期刊公司J.Appl。波兰姆。SCI。2019年，136%，46992。
To enable filament extrusion additive manufacturing of mechanically adaptive nanocomposites, the effect of melt extrusion on the tensile modulus and mechanical adaptiveness of cellulose nanocrystal (CNC)/thermoplastic polyurethane (TPU) composites was investigated. TPU (Texin RxT70A) was processed with 10 wt % CNC in multiple formats, including solvent-cast films and melt extrusion-produced filaments. CNC orientation is characterized by polarized Raman spectroscopy and small-angle X-ray scattering (SAXS) and found to be uniaxially oriented in extruded filaments, and randomly oriented in solvent-cast films. Dynamic mechanical analysis results show the addition of 10 wt % CNC increases the pure TPU storage modulus from 10 to 60-70 MPa in the dry state for solvent-cast and extruded nanocomposites. Following water saturation, all CNC-containing samples reach a similar wet storage modulus of approximately 26 MPa, regardless of CNC orientation and thermal history. Fickian diffusion scaling factors (6.8 to 11.6) scale closely to the time-dependent empirical scaling factors (4.9 to 7.2), confirming the rate of mechanical adaptivity is driven by water diffusion through sample thickness. Our results suggest that mechanical adaptivity is retained following processing, enabling use as a feedstock for extrusion-based additive manufacturing of CNC/TPU composites for mechanically adaptive parts. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 46992.