Goodwin David G, Shen Shih-Jia, Lyu Yadong, Lankone Ronald, Barrios Ana C, Kabir Samir, Perreault François, Wohlleben Wendel, Nguyen Tinh, Sung Lipiin
National Institute of Standards and Technology, Materials and Structural Systems Division, Engineering Laboratory, Gaithersburg, MD, 20899, USA.
School of Sustainable Engineering and the Built Environment, Arizona State University, 660 S. College Ave, Tempe, AZ, 85281.
Polym Degrad Stab. 2020 Dec;182. doi: 10.1016/j.polymdegradstab.2020.109365.
The ultraviolet (UV)-induced degradation of graphene/polymer nanocomposites was investigated in this study. Specifically, the effect of few-layer graphene nanofillers on the degradation of a thermoplastic polyurethane (TPU) and the release potential of graphene from the degraded nanocomposite surfaces were assessed. Graphene/TPU (G/TPU) nanocomposites and neat TPU were UV-exposed under both dry and humid conditions in the NIST SPHERE, a precisely controlled, high intensity UV-weathering device. Neat TPU and G/TPU were characterized over the time course of UV exposure using color measurements and infrared spectroscopy, for appearance and chemical changes, respectively. Changes in thickness and surface morphology were obtained with scanning electron microscopy. A new fluorescence quenching measurement approach was developed to identify graphene sheets at the nanocomposite surface, which was supported by contact angle measurements. The potential for graphene release from the nanocomposite surface was evaluated using a tape-lift method followed by microscopy of any particles present on the tape. The findings suggest that graphene improves the service life of TPU with respect to UV exposure, but that graphene becomes exposed at the nanocomposite surface over time, which may potentially lead to its release when exposed to small mechanical forces or upon contact with other materials.
本研究对紫外线（UV）诱导的石墨烯/聚合物纳米复合材料降解进行了研究。具体而言，评估了少层石墨烯纳米填料对热塑性聚氨酯（TPU）降解的影响以及降解后的纳米复合材料表面石墨烯的释放潜力。在NIST SPHERE（一种精确控制的高强度紫外线老化装置）中，将石墨烯/TPU（G/TPU）纳米复合材料和纯TPU在干燥和潮湿条件下进行紫外线照射。在紫外线照射的时间过程中，分别使用颜色测量和红外光谱对纯TPU和G/TPU进行表征，以观察外观和化学变化。通过扫描电子显微镜获得厚度和表面形态的变化。开发了一种新的荧光猝灭测量方法来识别纳米复合材料表面的石墨烯片层，接触角测量对其提供了支持。使用胶带剥离法评估纳米复合材料表面石墨烯的释放潜力，随后对胶带上存在的任何颗粒进行显微镜观察。研究结果表明，就紫外线照射而言，石墨烯可提高TPU的使用寿命，但随着时间的推移，石墨烯会暴露在纳米复合材料表面，当受到小的机械力或与其他材料接触时，这可能会导致其释放。
