氧化石墨烯骨架复合相变储热材料的制备与表征

发布时间：2019-06-30 19:53

【摘要】：相变材料可根据环境温度的不同实现热能的储存和释放,能有效地克服热能供给时的时空限制。碳材料因具有导热率高、密度低、稳定性高、与相变材料兼容性好等诸多优点,以其作为骨架材料制备的复合相变材料有望有效地解决单一相变材料在实际应用过程中导热率低、过冷度大、相变过程易泄露等缺点,进而增强相变材料的实用价值。本文以氧化石墨烯(GO)为骨架材料,以十六醇和赤藻糖醇为相变介质制备了两种定形复合相变材料,并采用红外光谱仪(FT-IR)、X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、示差量热扫描仪(DSC)、热失重分析仪(TG)、导热系数仪等分析测试手段对其结构和性能进行了表征和测试,研究了化学接枝法对泄露性的影响以及增稠剂对过冷度的改善。为了增强十六醇的形状稳定性、循环使用可靠性,提高其导热性能,以石墨粉为原料,在对石墨氧化、酰氯化处理的基础上,接枝十六醇制备了氧化石墨烯接枝十六醇复合相变材料(GO-g-HD),并对其结构和性能进行了表征和测试。结果表明,GO-g-HD以物理吸附和共价键接枝方式负载得十六醇含量高达62.7 wt.%,其中接枝的十六醇含量为36.5 wt.%,接枝密度为1.51 mmol/g。GO-g-HD的熔融温度和潜热分别为49.7℃和152.3 J/g,凝固温度和潜热分别为45.4℃和129.9 J/g。GO-g-HD的导热率为0.519W/m·K,相对纯十六醇导热率提高了41.8%。热循环实验表明,由于十六醇与骨架材料氧化石墨烯之间超强的共价键相互作用,制备的复合材料表现出卓越的化学稳定性、热稳定性、极好的耐热性,并且相变温度不变,相变潜热仅仅降低了0.5%,使其在未来具有很高的应用前景。以赤藻糖醇(ET)为相变储热材料,以氧化石墨烯为骨架材料,采用溶胶-凝胶法制备了赤藻糖醇/氧化石墨烯定形复合相变材料(ET/GO),研究了GO和增稠剂羧甲基纤维素(CMC)对ET的过冷度和放热能力的影响。结果发现,三维网状结构的氧化石墨烯薄膜均匀地包裹着赤藻糖醇,防止了相变过程时的泄露现象。赤藻糖醇的熔融潜热和凝固潜热分别为349.9 J/g和224.2 J/g,过冷度为90.3℃,放热能力为64.1%。分别添加质量分数为3.0%、1.5%、1.0%的氧化石墨烯,结果发现,氧化石墨烯含量为3.0%的复合相变材料(ET/GO30)具有更好的储热性能,其熔融和凝固潜热分别为346.6 J/g和236.2 J/g,放热能力为68.1%,同时,氧化石墨烯起到了成核剂的作用,其过冷度为73.4℃。为了进一步解决复合材料的过冷度问题,分别添加质量分数为0.2%、0.5%、0.7%的增稠剂CMC,结果发现,CMC含量为0.7%的复合相变材料(ET/GO30-7C)过冷度最小,仅为17.9℃,熔融和凝固潜热分别为316.8 J/g和295.1 J/g,放热能力高达93.2%。此外,ET/GO30-7C的导热率为0.563 W/m·K,导热率却提高了80.4%,具有良好的结构稳定性、储热稳定性和热稳定性。
[Abstract]:Phase change materials can store and release heat energy according to the different ambient temperature, and can effectively overcome the space-time limitation of heat energy supply. Carbon material has many advantages, such as high thermal conductivity, low density, high stability, good compatibility with phase change material and so on. The composite phase change material prepared by carbon material as skeleton material is expected to effectively solve the shortcomings of single phase change material in practical application, such as low thermal conductivity, high undercooling, easy leakage in phase change process, and thus enhance the practical value of phase change material. In this paper, two kinds of shaped composite phase change materials were prepared by using graphene oxide (GO) as skeleton material and hexadecyl alcohol and algae alcohol as phase transition medium. infrared spectrometer (FT-IR) and X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS), scanning electron microscope (SEM), transmission electron microscope (TEM), differential scanning electron microscope (DSC), thermogravimetric scanner (TG), The structure and properties were characterized and tested by means of thermal conductivity meter. The effect of chemical grafting on leakage and the improvement of undercooling by thickener were studied. In order to enhance the shape stability, cyclic reliability and thermal conductivity of hexadecyl oxide, graphene oxide (GO-g-HD) was prepared by grafting hexadecyl oxide onto graphite powder on the basis of graphite oxidation and acyl chlorination. Its structure and properties were characterized and tested. The results showed that the content of hexadecyl alcohol was as high as 62.7 wt.%, by physical adsorption and covalent bond grafting, and the melting temperature and latent heat were 49.7 鈩，

本文编号：2508204