高导热膨胀石墨/棕榈酸定形复合相变材料的制备及储热性能研究

采用棕榈酸(palmitic acid, PA)作为相变材料,膨胀石墨(expanded graphite, EG)作为添加基质,通过“熔融共混-凝固定形”工艺制备了PA/EG定形复合相变材料以提高相变材料的综合性能。预测并制备了21种不同配比的定形复合相变材料,对其形貌结构和孔隙率进行了微观表征与理论分析,并在此基础上对样品进行了传热性能分析、热物性测试、热稳定性研究和储热性能分析。SEM形貌分析显示所使用工艺可使棕榈酸能较好地被吸附于膨胀石墨的孔隙结构并使之均匀分布;DSC测试结果表明定形复合相变材料[70%(质量) PA]的焓值为193.01 J/g,纯PA的焓值为275.35 J/g,对应于熔点分别为61.08℃和59.53℃。EG的添加,可有效提高相变材料的热导率。当样品密度为900 kg/m³,EG含量为30%(质量)时,定形复合相变材料的热导率为14.09 W/(m·K),相比于纯PA[0.162 W/(m·K)]提高约87倍;对制备的样品进行50次循环稳定性实验,EG含量为24%(质量)和30%(质量)的样品形态均未出现明显变化,表现出良好的充放热循环稳定性。     

用于储能的复合定形相变材料的制备与性能研究

以泡沫聚合法制得的超多孔水凝胶(SPH)为基材,季铵盐类离子液体(ILPCM)为相变材料,氧化石墨烯(GO)为添加剂,制备了一种新型的复合定形相变材料(GO-ILPCM/SPH),且对其性能进行了表征。研究结果表明:SPH是一种潜在的复合定形相变材料的基材,可负载较多的ILPCM,质量分数最高可达约85%。GO-ILPCM/SPH是一种优良的储能相变材料,具有适合冷藏产品的相变温度4℃及较高的相变潜热(约150J/g)。制备的复合定形相变材料具有较快的储热和放热速率,适当地添加GO一类导热性高的物质,可提高其相变储热和放热速率,进而在应用中提高热能利用效率。     

Preparation and thermal energy storage properties of poly(n‐butyl methacrylate)/fatty acids composites as form‐stable phase change materials

This work is focused on the preparation, characterization, and determination of thermal energy storage properties of poly(n‐butyl methacrylate) (PnBMA)/fatty acid composites as form‐stable phase change material (PCM). In the composite materials, the fatty acids act as latent heat storage material whereas PnBMA serves as supporting material, which prevents the leakage of the melted fatty acids. The maximum encapsulation ratio for all fatty acids was found to be 40 wt%. The composites that do not allow PCM leakage in melted state were identified as form‐stable PCMs. The compatibility of fatty acids with PnBMA is investigated by optical microscopy (OM) and Fourier Transform Infrared (FT‐IR) spectroscopy. Thermal properties and thermal reliability of the form‐stable composite PCMs were determined using differential scanning calorimetry (DSC). DSC analysis revealed that the form‐stable composite PCMs had melting temperatures between 29.62°C and 53.73°C and latent heat values between 67.23 J/g and 87.34 J/g. Thermal stability of the composite PCMs was studied by thermal gravimetric (TG) analysis and the results indicated that the form‐stable PCMs had good thermal stability. In addition, thermal cycling test showed that the composite PCMs had good thermal reliability with respect to the changes in their thermal properties after accelerated 5,000 thermal cycling. On the basis of all results, it was also concluded that the prepared form‐stable composite PCMs had important potential for many thermal energy storage applications such as solar space heating of buildings by using wallboard, plasterboard or floors integrated with PCM. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

蛭石/氯化钙复合吸附剂的吸附特性和储热性能

为了储存120℃以下的热能,提出了以水为介质的热化学吸附储热方法。配制了一种以膨胀蛭石为多孔基质、氯化钙为反应盐的新型复合吸附剂,并对其进行了微观形貌表征、吸附性能测试、同步热分析测试和储热密度的理论计算。扫描电子显微镜（SEM）观测显示膨胀蛭石特有的片层状的大孔结构产生了相对巨大的孔体积;利用恒温恒湿箱实验排除有溶液泄漏问题的含盐量;通过恒温恒湿箱对30℃、3种相对湿度下的动态吸附过程进行测试,分析了含盐量和相对湿度对吸附特性的影响,证实了该复合吸附剂具有3个不同的吸水阶段,包括物理吸附、化学吸附和溶液的气-液吸收过程;利用同步热分析测试（STA）和数值计算进一步对上述3个吸附过程的吸水量、吸附热和反应温度进行分析。最终优选出含盐量47.9%（质量分数）的复合吸附剂,其吸水量高达1.24 g·g^-1,质量和体积储热密度分别高达1.25 kW·h·kg^-1和213.56 kW·h·m^-3。     

聚乙二醇/膨胀石墨相变储能复合材料

利用膨胀石墨孔隙结构的吸附性能,制备了聚乙二醇/膨胀石墨相变储能复合材料,用差示扫描热量法研究了材料的热性能.结果表明复合材料的相变温度不随聚乙二醇含量的改变而变化,材料的相变潜热随着聚乙二醇含量的增加而增加.复合材料的导热性能随着聚乙二醇含量的增加而减小.膨胀石墨的多孔结构对聚乙二醇有很好的吸附性能,聚乙二醇在固-液相变时,未见有液态聚乙二醇的渗出.     

癸酸-石蜡/膨胀石墨定形相变材料的制备及性能

通过物理吸附法将癸酸-石蜡（CA-PC）二元低共熔混合物与膨胀石墨（EG）复合形成癸酸-石蜡/膨胀石墨定形相变材料,实验结果显示,CA与PC、CA-PC与EG的最佳质量配比分别为8.1∶1.9和7∶1。利用扫描电子显微镜（SEM）和傅里叶红外光谱仪（FTIR）分析了定形相变材料的微观形貌和结构特点,发现CA-PC/EG的FTIR曲线上同时存在二元低共熔混合物和膨胀石墨的特征吸收峰,表明二元低共熔混合物与膨胀石墨之间没有发生化学反应,二者依靠表面张力和毛细力作用在一起,并且CA-PC二元低共熔混合物依靠物理作用被有效包封于EG的孔隙中,经过1000次加速冷热循环后,基本没有液态二元复合相变材料泄漏。通过差示扫描量热仪（DSC）得到CA-PC/EG的熔化温度和凝固温度分别为27.04℃和22.26℃,熔化潜热和凝固潜热分别为144.4J/g和133.7J/g,且EG的高导热性促进了CA-PC的蓄放热速率。同时,根据热重分析（TG）与蓄放热实验结果发现其拥有优良的热可靠性和耐热性能。因此,该CA-PC/EG定形相变材料是一种良好的低温储能材料。     

Thermal characterization of erythritol/expanded graphite composites for high thermal storage capacity

Expanded graphites (EGs) with various interlayer distances were combined with molten erythritol and then erythritol/EG composites as phase change materials (PCMs) and the composites were prepared by a simple blending and impregnating method. The effects of the additives of various interlayer distances of EGs on thermal behaviors were investigated by a thermal equilibrium technique. The latent heat and thermal cycling stability were evaluated by DSC traces. The results revealed that both the thermal conductivity and latent heat increased with increasing EG interlayer distance. In particular, erythritol/EG composites having the largest EG interlayer distance showed thermal conductivity of 3.56 W/m K and a latent heat value of 90 mass% of pure erythritol. The thermal cycling tests were performed 5 times and the latent heat of the erythritol/EG composites were constant from the third cycle onwards, demonstrating excellent thermal cycling stability.     

相变材料复合八水氢氧化钡的制备及热性能

纯八水氢氧化钡相变蓄热材料在使用过程中存在凝固过冷、相分离及体积变化等问题,因此需要对其进行相应的改性研究。本文根据相变蓄热材料成核机理,以八水氢氧化钡为相变蓄热材料基材,一水氢氧化钡及去离子水作为复合添加剂,制备了混合比例为95.1% Ba（OH）₂·8H₂O+2% Ba（OH）2·H₂O+2.9% H₂O的复合相变蓄热材料。对该复合相变蓄热材料进行了热性能测试,结果表明：复合相变蓄热材料的平均热导率为1.2W/（m·K）、相变潜热值为263.7kJ/kg;在复合相变蓄热材料融化过程中进行升温-压力实验,测试数据显示容器内部的相对压力不超过0.09MPa;利用恒温金属浴仪器对该复合相变蓄热材料进行300次融化/凝固循环实验,测试数据显示复合相变蓄热材料过冷度增加量0.7℃、相变潜热值降低0.796%。改性后的复合相变蓄热材料相变温度适宜、热性能稳定,可推广应用于中低温相变储热系统。     

石蜡/高密度聚乙烯/木粉/石墨复合相变储能材料的制备及性能

以石蜡为相变材料,高密度聚乙烯(HDPE)为支撑材料,木粉(WF)为载体材料,石墨为填料,采用加热共熔法制备石蜡/HDPE/WF/石墨复合相变储能材料。利用扫描电子显微镜(SEM)、热重分析仪(TGA)、差示扫描量热仪(DSC)、步冷试验和渗漏实验等对复合相变材料进行性能测试。结果表明,石蜡质量分数为50%,WF质量分数为10%,石墨质量分数为4%时,该复合相变材料结构稳定,密封性能优异,热稳定性好,相变温度为60.1℃,相变潜热为93.71 J/g,渗漏率低,应用前景广阔。     

膨胀石墨基相变储能材料的研究

利用膨胀石墨孔隙结构的吸附性能,制备了石蜡/膨胀石墨、聚乙二醇/膨胀石墨、十四醇/膨胀石墨相变储能复合材料,用差示扫描热量法研究了材料的热性能.结果表明,复合材料的相变潜热随着石蜡、聚乙二醇、十四醇含量的增加而增加.复合材料的导热性能随着石蜡、聚乙二醇、十四醇含量的增加而小.膨胀石墨的多孔结构对石蜡、聚乙二醇、十四醇有很好的吸附性能,石蜡、聚乙二醇、十四醇在固一液相变时,未见有液态石蜡、聚乙二醇、十四醇的渗出.     

太阳盐/钢渣定型复合相变储热材料的制备与性能研究

全球范围内的能源短缺和环境污染问题迫使人们积极开发可再生新能源.储热技术是解决新能源不稳定性问题的关键技术.相变材料是重要的储热介质之一.熔盐相变材料因其储热密度高,可操作温度范围广的优势,成为储热材料领域研究的热点.为解决熔盐液相易泄漏、低导热和高成本的问题,选择钢渣为基体材料,制备了太阳盐/钢渣定型复合相变储热材料...     

纳米材料/十四酸混合相变蓄热材料的制备与特性

选用纳米金属Cu和碳素材料石墨烯纳米片（GnPs）为改性剂分别添加至十四酸（MA）中,制备出Cu质量分数为1%、2%、3%和4%的Cu/MA混合相变蓄热材料及GnPs质量分数为1%、2%和3%的GnPs/MA混合相变蓄热材料,并对混合相变材料性能进行表征。结果表明：Cu/MA固态和液态热导率随Cu质量分数增加呈线性提高,1%（质量）GnPs/MA固态热导率较纯MA显著提高101.51%,随GnPs质量分数增加,热导率增幅减缓;FT-IR谱图表明Cu与MA及GnPs与MA间的混合均为物理作用;DSC结果显示添加Cu或GnPs可降低MA的过冷度和相变潜热,且随质量分数增加,相变潜热逐渐降低;4%（质量）Cu/MA和3%（质量）GnPs/MA放热时间相比于纯MA分别减少了23.4%和38.7%;4%（质量）Cu/MA和3%（质量）GnPs/MA在经历300次快速热循环试验后,晶体结构和相变温度基本保持不变,相变潜热分别降至168 J·g^-1和181 J·g^-1左右,仍满足蓄放热要求,两种材料均具有良好的热循环稳定性。     

甘露醇水溶液低温储能相变材料的制备及热物性

研制了一种应用于-1~-3℃、具有高相变潜热值的有机无机复合相变材料。通过10次重复实验筛选出复合相变材料主基液（3%甘露醇水溶液,质量分数,余同）,在基液中添加成核剂硫酸钾（K₂SO₄）、乙酸钠（CH₃COONa）和六偏磷酸钠[（NaPO₃）₆]及增稠剂聚丙烯酸钠（PAAS）研究其对相变材料过冷度、相变平台和放冷速率的影响,并进行热循环实验。实验结果表明,3%甘露醇水溶液平均过冷度最小,相变潜热为319.5J/g;0.5% K₂SO₄、1% CH₃COONa和1%（NaPO₃）₆可以完全消除甘露醇水溶液的过冷度,（NaPO₃）₆对相变潜热影响最小,仅降低4.3%;PAAS质量分数从0增加至0.4%,材料相变平台延长了60%,从0.4%增加至1%,相变平台缩短了25%;通过50次和100次的循环实验,发现该复合相变材料热稳定性良好。     

Preparation and properties of novel natural rubber/organo‐vermiculite nanocomposites

Polymer‐layered silicate nanocomposites have an attracting increasing attention over recent years because of their unique mechanical, thermal, and other properties. In this article, a new kind of natural rubber (NR)/organo‐vermiculite (OVMT) nanocomposites were investigated. The vermiculite (VMT) was intercalated by cetyltrimethylammonium bromide with ball mill method. The intercalation led to an increase of the d₍₀₀₁₎ of VMT from 1.46 nm to 4.51 nm. NR/OVMT nanocomposites were prepared via a melt process in a HAAKE mixer and were analyzed by X‐ray diffraction and scanning electron microscope observations. The mechanical properties of the vulcanized nanocomposites were tested. It was found that the tensile strength and the elongation at the breaking point of the NR/OVMT nanocomposites loading 15 phr of the OVMT reached 28.4 MPa and 623.2%, respectively. The 300% modulus, tear strength, and hardness (Shore A) of the nanocomposites increased with the increase of the OVMT loading. The thermal properties of the nanocomposites were investigated by dynamic mechanical analysis, and the results showed that the storage modulus and the glass transition temperature of the nanocomposites were increased. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Preparation of form-stable silica/polyethylene glycol composites using flash-drying for large-scale melt-spun fibers with thermal management property

The combination of phase change materials (PCMs) with fibers can afford smart fibers with thermal management properties. However, the issues of easy leakage and poor thermal stability of PCMs often limit their use in high-temperature spinning. Herein, we report a form-stable PCM of spherical SiO₂/PEG composite that was prepared through flash-drying using inorganic dendritic silica (D-SiO₂) as the core skeleton to support organic polyethylene glycol (PEG). The SiO₂/PEG composite not only presents high crystallization enthalpy (101.35 J/g), but also maintains a superior phase change stability. Meanwhile, it exhibits a significant temperature hysteresis effect during heating and cooling, and the endothermic and exothermic time are 381.95 and 293.57 s, respectively. Because the degradation temperature of 300°C for SiO₂/PEG is higher than the melt processing temperature of 240–270°C for the preparation of polyamide 6 (PA6) fibers, PA6/SiO₂/PEG fibers were prepared using melt spinning. The prepared PA6/SiO₂/PEG fibers exhibit high latent heat (17.14 J/g), outstanding thermal cycling stability and satisfactory temperature adjustment properties, and the temperature-adjustment time of 458.97 s and temperature difference of 10.68°C under the thermal environment. Moreover, the tensile strength of PCFs-20% reached 1.97 cN/dtex after drawing, which make PCFs meet the requirements of uses in textile industries.     

Preparation and characterization of nano-encapsulated n-tetradecane as phase change material for thermal energy storage

Nanocapsules used as phase change material (PCM) were prepared by using in situ polymerization methods. N-Tetradecane was used as the core material. Urea and formaldehyde were used for the shell polymerization. Sodium dodecyl sulfate was used as the emulsifier and resorcin was used as the system modifier. The morphology of the nanocapsules was observed by a scanning electronic microscope (SEM). The thermal properties were investigated by a differential scanning calorimeter (DSC) and a thermogravimetry analysis (TGA). The SEM analysis indicated that the nanocapsules had general size of about 100 nm and the core material was well encapsulated. DSC analysis indicated that the mass content of n-tetradecane was up to 60%, which resulted in a high latent heat of fusion of 134.16 kJ/kg. TGA showed the thermal stability of the nanocapsules could be improved by the additives (NaCl) used in the polymerization. The nanocapsules could be applied for thermal energy storage and heat transfer enhancement.     

膨胀石墨基复合材料的制备及其导热性能的研究

以中间相沥青和聚酰胺酸为黏结剂和增密剂,用两种不同方法与预压膨胀石墨进行复合。再经过模压炭化,得到高密度、高取向和高导热的炭/石墨复合材料。同时研究了不同沥青含量和不同聚酰胺酸溶液浓度下复合材料的致密性和导热性能。结果表明,随着沥青用量增加,复合材料的密度增加,并在沥青含量占30%时密度达到最大值。热导率在沥青用量为15%时达到最大,为530.64 W/m·K,比铜的热导率高33%。液相浸渍法下,浸渍溶液浓度为12%时,浸渍效果最好,复合材料的热导率和密度达到最大值。相比而言,中间相沥青比聚酰胺酸对膨胀石墨的密度和热导率提升效果更好,这主要是由于在热压条件下,沥青的软化和流动性造成的,流动的沥青能够更好地填充膨胀石墨的孔隙。     

石墨烯导热高分子复合材料的制备、性能与机理

石墨烯是一种具有超大的比表面积、良好的热和化学稳定性、超高的热导率以及易于化学修饰的蜂窝状单层碳材料,已作为填料广泛应用于导热高分子复合材料领域。近年来石墨烯导热高分子材料的研究重点是改善石墨烯在聚合物基体中的界面相容性和分散性能。阐述了近年来石墨烯导热高分子复合材料的制备方法及其热性能,并重点对石墨烯导热高分子复合材料的导热机理进行综述,同时结合研究现状对石墨烯导热高分子复合材料的研究方向进行展望。     

Novel phase change materials based on fatty acid eutectics and triallyl isocyanurate composites for thermal energy storage

In this study, a series of dimension‐stabilized fatty acid eutectics and triallyl isocyanurate (TAIC) composite phase change materials were prepared via in situ reaction by blending the fatty acids and TAIC, in which the fatty acids were introduced as a phase change material (PCM), and TAIC performed as a supporting material by self‐crosslinking. Fourier transform infrared spectroscopy, X‐ray diffraction, differential scanning calorimetry, scanning electron microscopy (SEM), and thermogravimetric analysis were applied to investigate the chemical structure, crystalline properties, phase transition behavior, microstructure, and thermal stability of the composites. The results indicated that the composite possessed excellent thermal reliability and heat storage durability even after 300 heating–cooling cycles. Moreover, the composites had applicable phase transition temperatures in the range of 26–40 °C and satisfying latent heat storage capacities of higher than 110 J/g. The SEM images showed that the particle size of the nanoparticles of the composites was about 200 nm after treatment. The dimensional measurement of the composites proved a high service temperature of 100 °C, indicating that the composites were promising for thermal energy storage materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44866.