对氧化石墨烯(GO)分别采用热还原(1200℃)和还原剂还原(水合肼)方法制备了两种还原氧化石墨烯(RGO)粉体。进而采用真空浸渍法,分别制备质量含量5% RGO,35%金属有机框架材料[MOF,MIL-101(Cr)-NH2]和60%石蜡(PW)的复合相变材料(CPCM)。采用扫描电镜(SEM)、X射线衍射(XRD)、红外光谱(FT-IR)和拉曼光谱对两种RGO的结构进行了考察,并用Hot Disk比较两种RGO对MOF基复合相变材料热导率的增强作用。结果表明:两种方法均有利于GO中含氧官能团的去除以及sp2杂化碳晶格有序度的变化,GO得到了有效还原。然而,负载两种RGO的金属有机框架材料基复合相变材料表现出了不同的导热性能。在常温下,MIL-101(Cr)-NH2和纯石蜡的热导率分别约为0.21W/(m·K)和0.25W/(m·K)。加载5%还原剂法得到的RGO/MOF基复合相变材料的热导率值达到1.43W/(m·K),远远高于加载5%热还原法得到的RGO/MOF基复合相变材料的值[0.33W/(m·K)]。因此,与低温热还原法相比,还原剂法对GO还原效果较好,在热管理用复合相变材料的导热增强方面更具有优势。
Two kinds of reduced graphene oxide (RGO) powders were prepared from graphene oxide (GO) by thermal reduction (1200℃) and reducing agent reduction (hydrazine hydrate) methods,respectively.Then,composite phase change materials (CPCM) with 5wt% RGO,35wt% MOF,MIL-101(Cr)-NH2 and 60wt% paraffin (PW) were obtained by vacuum impregnation method.The structures of the two RGOs were investigated by SEM,XRD,FT-IR and Raman,and Hot Disk was used to compare the enhancement effect of the two RGOs on the thermal conductivity of MOF-based CPCM.The results showed that both methods were conducive to the removal of oxygen-containing functional groups in GO and the change of lattice order of sp2 hybrid carbon,and GO was effectively reduced.However,the metal-organic frameworks based CPCMs loaded with two kinds of RGO exhibited different thermal conductivities.At room temperature,the thermal conductivity of MIL-101(Cr)-NH2 and pure paraffin was about 0.21W/(m·K) and 0.25W/(m·K),respectively.The thermal conductivity of RGO/MOF-based CPCM obtained by loading 5wt% reducing agent method reached 1.43W/(m·K),which was much higher than that of RGO/MOF-based CPCM obtained by loading 5wt% thermal reduction method [0.33W/(m·K)].To sum up,compared with the low-temperature thermal reduction method,the reductant method was more effective for GO reduction,and had more advantageous for the thermal conductivity enhancement effect of CPCM in thermal management.
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基金资助
国家自然科学基金面上申请项目(51966004和21962006);江西省自然科学基金项目(20192BAB216030和20212BAB204029);江西省教育厅(GJJ180498)
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