【摘要】：相變材料可根據(jù)環(huán)境溫度的不同實(shí)現(xiàn)熱能的儲存和釋放,能有效地克服熱能供給時(shí)的時(shí)空限制。碳材料因具有導(dǎo)熱率高、密度低、穩(wěn)定性高、與相變材料兼容性好等諸多優(yōu)點(diǎn),以其作為骨架材料制備的復(fù)合相變材料有望有效地解決單一相變材料在實(shí)際應(yīng)用過程中導(dǎo)熱率低、過冷度大、相變過程易泄露等缺點(diǎn),進(jìn)而增強(qiáng)相變材料的實(shí)用價(jià)值。本文以氧化石墨烯(GO)為骨架材料,以十六醇和赤藻糖醇為相變介質(zhì)制備了兩種定形復(fù)合相變材料,并采用紅外光譜儀(FT-IR)、X射線衍射儀(XRD)、X射線光電子能譜儀(XPS)、掃描電子顯微鏡(SEM)、透射電子顯微鏡(TEM)、示差量熱掃描儀(DSC)、熱失重分析儀(TG)、導(dǎo)熱系數(shù)儀等分析測試手段對其結(jié)構(gòu)和性能進(jìn)行了表征和測試,研究了化學(xué)接枝法對泄露性的影響以及增稠劑對過冷度的改善。為了增強(qiáng)十六醇的形狀穩(wěn)定性、循環(huán)使用可靠性,提高其導(dǎo)熱性能,以石墨粉為原料,在對石墨氧化、酰氯化處理的基礎(chǔ)上,接枝十六醇制備了氧化石墨烯接枝十六醇復(fù)合相變材料(GO-g-HD),并對其結(jié)構(gòu)和性能進(jìn)行了表征和測試。結(jié)果表明,GO-g-HD以物理吸附和共價(jià)鍵接枝方式負(fù)載得十六醇含量高達(dá)62.7 wt.%,其中接枝的十六醇含量為36.5 wt.%,接枝密度為1.51 mmol/g。GO-g-HD的熔融溫度和潛熱分別為49.7℃和152.3 J/g,凝固溫度和潛熱分別為45.4℃和129.9 J/g。GO-g-HD的導(dǎo)熱率為0.519W/m·K,相對純十六醇導(dǎo)熱率提高了41.8%。熱循環(huán)實(shí)驗(yàn)表明,由于十六醇與骨架材料氧化石墨烯之間超強(qiáng)的共價(jià)鍵相互作用,制備的復(fù)合材料表現(xiàn)出卓越的化學(xué)穩(wěn)定性、熱穩(wěn)定性、極好的耐熱性,并且相變溫度不變,相變潛熱僅僅降低了0.5%,使其在未來具有很高的應(yīng)用前景。以赤藻糖醇(ET)為相變儲熱材料,以氧化石墨烯為骨架材料,采用溶膠-凝膠法制備了赤藻糖醇/氧化石墨烯定形復(fù)合相變材料(ET/GO),研究了GO和增稠劑羧甲基纖維素(CMC)對ET的過冷度和放熱能力的影響。結(jié)果發(fā)現(xiàn),三維網(wǎng)狀結(jié)構(gòu)的氧化石墨烯薄膜均勻地包裹著赤藻糖醇,防止了相變過程時(shí)的泄露現(xiàn)象。赤藻糖醇的熔融潛熱和凝固潛熱分別為349.9 J/g和224.2 J/g,過冷度為90.3℃,放熱能力為64.1%。分別添加質(zhì)量分?jǐn)?shù)為3.0%、1.5%、1.0%的氧化石墨烯,結(jié)果發(fā)現(xiàn),氧化石墨烯含量為3.0%的復(fù)合相變材料(ET/GO30)具有更好的儲熱性能,其熔融和凝固潛熱分別為346.6 J/g和236.2 J/g,放熱能力為68.1%,同時(shí),氧化石墨烯起到了成核劑的作用,其過冷度為73.4℃。為了進(jìn)一步解決復(fù)合材料的過冷度問題,分別添加質(zhì)量分?jǐn)?shù)為0.2%、0.5%、0.7%的增稠劑CMC,結(jié)果發(fā)現(xiàn),CMC含量為0.7%的復(fù)合相變材料(ET/GO30-7C)過冷度最小,僅為17.9℃,熔融和凝固潛熱分別為316.8 J/g和295.1 J/g,放熱能力高達(dá)93.2%。此外,ET/GO30-7C的導(dǎo)熱率為0.563 W/m·K,導(dǎo)熱率卻提高了80.4%,具有良好的結(jié)構(gòu)穩(wěn)定性、儲熱穩(wěn)定性和熱穩(wěn)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，

本文編號：2508204