【摘要】：相變儲(chǔ)能材料的研究近年來引起了廣泛的關(guān)注,它可以應(yīng)用于太陽(yáng)能儲(chǔ)存、節(jié)能建筑材料和余熱的回收利用等諸多領(lǐng)域。有機(jī)相變材料具有理想的相變潛熱、無毒無腐蝕、化學(xué)性質(zhì)穩(wěn)定等優(yōu)點(diǎn),但具有導(dǎo)熱系數(shù)低、相變時(shí)易泄露等缺點(diǎn)。為了克服有機(jī)類相變材料的缺陷,必須提高相變材料的導(dǎo)熱性能。石墨烯具有諸多特殊的物理性能,如超高的導(dǎo)熱系數(shù),對(duì)于提高相變材料熱導(dǎo)率具有廣泛的前景。本論文通過三種不同的方法制備石墨烯,提高有機(jī)相變材料導(dǎo)熱性能,并采用多種測(cè)試方式對(duì)制備的復(fù)合相變材料的性能進(jìn)行深入研究。研究的主要內(nèi)容如下：(1)通過改進(jìn)Hummers法制備氧化石墨烯,再用水合肼還原制備了石墨烯納米片(GNs)。將GNs與相變材料(PCM)復(fù)合制備GNs/PCM復(fù)合相變材料。通過SEM、 TEM、FT-IR、XRD、DSC和熱常數(shù)分析儀等測(cè)試對(duì)石墨烯和復(fù)合前后的相變材料進(jìn)行測(cè)試。結(jié)果表明：隨著GNs添加量的增大,復(fù)合相變材料的熱導(dǎo)率逐漸增大,當(dāng)GNs含量為2 wt%時(shí),熱導(dǎo)率為1.8428 W/(m·K),是純PCM熱導(dǎo)率的10.1倍。200次冷熱循環(huán)后GNs/PCM復(fù)合相變材料的熱導(dǎo)率降低。GNs/PCM復(fù)合相變材料熱焓值△Hm和△Hc分別為208.2J/g和195.4 J/g,GNs的添加對(duì)相變材料的相變溫度和相變焓影響很小。FT-IR和XRD分析得出GNs和PCM沒有發(fā)生化學(xué)反應(yīng),并且晶體結(jié)構(gòu)沒有發(fā)生變化。(2)采用160℃水熱還原不同濃度的氧化石墨烯溶液制備石墨烯自組裝氣凝膠(SGA),分別采用自然吸附法和真空浸漬法制備SGA/PCM復(fù)合相變材料,并通過SEM、 FT-IR、XRD、DSC和熱常數(shù)分析儀等測(cè)試對(duì)復(fù)合前后的相變材料進(jìn)行測(cè)試。測(cè)試結(jié)果表明：當(dāng)GO濃度為2 mg/mL時(shí),自然吸附法和真空浸漬法制備的SGA2/PCM復(fù)合相變材料熱導(dǎo)率分別為1.7123 W/(m·K)和2.7324 W/(m-K),明顯高于純PCM的熱導(dǎo)率；熱焓值△Hm和△Hc分別為203.4 J/g和194.5J/g、209.1J/g和197.6J/g。真空浸漬法制備的SGA2/PCM復(fù)合相變材料比自然吸附法穩(wěn)定。SGA對(duì)PCM的晶體結(jié)構(gòu)基本沒有影響,沒有發(fā)生化學(xué)反應(yīng)導(dǎo)致新的物質(zhì)生成。(3)采用環(huán)境友好型還原劑維生素C還原氧化石墨烯的方法制備三維多孔石墨烯氣凝膠(VC-GA)。并通過SEM證實(shí)所制備的VC-GA結(jié)構(gòu)表面光滑而內(nèi)部三維多孔結(jié)構(gòu)。VC-GA可顯著提高相變材料PCM的熱導(dǎo)率,特別當(dāng)起始氧化石墨烯的濃度為3mg/mL時(shí),VC-GA3/PCM復(fù)合相變材料的熱導(dǎo)率為1.7324 W/(m·K),是純PCM熱導(dǎo)率的9.5倍,熱焓值△Hm和△Hc分別為213.5J/g和199.8 J/g。 VC-GA對(duì)PCM的熱穩(wěn)定性有明顯提高作用。VC-GA對(duì)PCM的晶體結(jié)構(gòu)基本沒有影響,沒有發(fā)生化學(xué)反應(yīng)導(dǎo)致新的物質(zhì)生成。
[Abstract]:The research of phase change energy storage materials has attracted extensive attention in recent years. It can be used in many fields such as solar energy storage energy saving building materials and waste heat recovery and so on. Organic phase change materials have the advantages of ideal latent heat of phase change, non-toxic and non-corrosive, stable chemical properties, but have the disadvantages of low thermal conductivity and easy leakage during phase transition. In order to overcome the defects of organic phase change materials, the thermal conductivity of phase change materials must be improved. Graphene has many special physical properties, such as ultra-high thermal conductivity, which has a broad prospect for improving the thermal conductivity of phase change materials. In this paper, graphene was prepared by three different methods to improve the thermal conductivity of organic phase change materials. The main contents are as follows: (1) graphene oxide was prepared by modified Hummers method and then (GNs). Was prepared by hydrazine hydrate reduction. GNs/PCM composite phase change materials were prepared by combining GNs with phase change material (PCM). Graphene and phase change materials before and after composite were tested by SEM, TEM,FT-IR,XRD,DSC and thermal constant analyzer. The results show that the thermal conductivity of the composite phase change material increases with the increase of GNs content. When the GNs content is 2 wt%, the thermal conductivity is 1.8428 W / (m K),. The thermal conductivity of GNs/PCM composite phase change material decreased after 200 cycles. The enthalpy values of Hm and Hc of GNs/PCM composite phase change material were 208.2J/g and 195.4 J / g, respectively. The addition of GNs has little effect on the phase transition temperature and enthalpy of phase change. FT-IR and XRD analysis show that there is no chemical reaction between GNs and PCM. The crystal structure did not change. (2) graphene self-assembled aerogel (SGA), was prepared by hydrothermal reduction of graphene oxide solution of different concentrations at 160 鈩，

本文編號(hào)：2326012