PEG-沸石固-固相变材料的制备及性能

摘要：采用接枝共聚法合成了以聚乙二醇（PEG）为相变物质,沸石为骨架的PEG沸石固-固相变材料。通过红外光谱（FT—IR）、热失重分析（TGA）和差示扫描量热法（DSC）等测试手段对PEG-沸石固-固相变材料的结构、相变行为及热稳定性进行了研究。结果表明：通过改变PEG的分子量,可以得到不同相变焓和不同相变温度的PEG-沸石固-固相变材料,其相变焓可达105．41J／g,热稳定性良好,起始分解温度高于300℃。     

KBF4非等温固-固相变热性质的测定

利用DTA-TG和DSC热分析技术研究了无机塑晶材料KBF4固-固相变的热性能,测得转变温度为284.13℃,转变焓为105.73J/g.KBF4固-固相变的机理是随着温度的升高,晶体中离子键部分断裂,晶体逐渐由低对称的正交晶系向高对称立方晶系转变,并在这过程中,同时引入化学键的振动和转动无序,从而吸收大量的相变焓.     

纤维素丙酸酯-g-二乙二醇正十六烷基醚固-固相变材料的制备及性能

以二月桂酸二丁基锡(DBTDL)为催化剂,微晶纤维素为骨架材料,二乙二醇正十六烷基醚(E2C16)为相变材料,采用化学接枝法制备了系列纤维素丙酸酯-g-二乙二醇正十六烷基醚(CP-g-E2C16)固-固相变材料.利用傅里叶变换红外光谱(FTIR)、核磁共振氢谱(1H NMR)、差示扫描量热仪(DSC)、热重分析(TG)和X射线衍射(XRD)对CP-g-E2C16相变材料的结构和热性能进行了表征.结果表明,得到了E2C16的取代度和接枝含量分别为0.12~0.37和17.1%~33.4%的CP-g-E2C16固-固相变材料.CP-g-E2C16接枝共聚物的相变温度和相变焓分别为25~34℃和40~62 J/g,符合人的体感舒适温度范围.CP-g-E2C16固-固相变材料的耐热温度高于237℃,与E2C16相比提高21~40℃,有望应用于熔融纺丝法制备纤维素基储热调温纤维领域.     

固相反应法制备微/纳米复合相变储能材料及其测试表征

采用低热固相化学反应法制备了表面包覆SiO2的不同硬脂酸含量的复合相变储能微纳米材料.XRD分析表明所制备的相变材料均呈晶相结构,红外图谱显示复合材料包覆层SiO2与相变主体材料硬脂酸C18H36O2(SA)存在键合作用,扫描电镜图片说明所合成复合材料呈较均匀颗粒状,而差热分析则表明所制得复合相变材料的相变温度分别为66.4、64.9 ℃,相变焓分别为148.97、111.54 J/g,具有良好的蓄热能力,可用于太阳能利用等方面的储能蓄热.     

长链烷酸接枝羟丙基纤维素相变材料的制备及其性能

采用酯化的方法将具有相变特征的长链脂肪酸接枝到羟丙基纤维素主链上, 得到了一系列性能稳定, 温度范围适宜的高分子固-固相变材料, 并利用傅里叶红外光谱(FT-IR)、核磁共振(NMR)、差示扫描量热仪(DSC)、热失重分析仪(TGA)和X射线散射等技术手段对其化学结构及相变行为进行了研究。 结果表明, 该材料呈现出可逆的固-固相转变特性, 相变温度范围可通过改变脂肪酸的长度调节。 利用棕榈酸、硬脂酸和花生酸获得的相变材料焓值达到60 J/g, 所获得的材料在250 ℃以内不发生热分解。 通过将两种长链脂肪酸混合同时接枝到羟丙基纤维素主链上, 所得产物的吸/放热温度随着混合脂肪酸组分含量的变化而变化, 同时X射线散射的结果也证明羟丙基纤维素混合酯的分子间距是位于其两种单一酯之间的。这一结果为制备一定温度范围内任意相变温度的高分子固-固相变材料提供了简便的方法。     

聚乙二醇单甲醚(MPEG)/聚乙烯醇(PVA)高分子固-固相变材料的合成与性能

高分子固-固相转变材料是近年来新兴的课题,其主要优点是体积变化小,发生相转变时不出现液态,可以减少对容器的要求,甚至不需要容器即可把相变材料作为结构材料,可简化工艺和降低成本,我们相继合成了系列聚乙二醇／聚乙烯醇高分子固-固相变材料,由于形成交联网络结构,难溶于一般有机溶剂。     

接枝共聚法制备聚乙二醇(PEG)/聚乙烯醇(PVA)高分子固-固相变材料性能研究

用接枝共聚法将具有相变特征的聚乙二醇(PEG)接枝到具有较高熔点的聚乙烯醇(PVA)主链上,得到了系列性能稳定的PEG/PVA高分子固-固相转变材料,用DSC,WAXD和POM对其相变行为及形态结构进行了研究.结果表明,该材料呈现出可逆的固-固相转变特性;其结晶峰值温度和相变焓比纯PEG低,接枝率对相变温度和归一化相变焓影响不大;接枝率只影响结晶与熔融行为,不影响结晶结构.     

聚乙二醇型聚氨酯软硬段对其相变储热性能的影响

以不同分子量的聚乙二醇(PEG)为软段,MDI-BDO为硬段,采用两步法溶液聚合合成一种具有固-固相变储热性能的聚氨酯材料.通过DSC,WAXD等测试手段对体系的软硬段结晶性,微相分离,相变可逆性及循环热稳定性进行研究,结果表明,聚氨酯中硬段的存在对软段结晶有着很大的影响,当软段分子量达到2000或以上时,软段才具有较大的结晶度和熔融相变焓,且硬段含量必须高于一定值才能形成较为完善的物理交联网络以保证材料在发生相变时维持固体状态.同时符合这两个条件的试样能具有较好的固-固相变储热性能.就软段PEG含量及分子量对材料储热性能的影响进行了研究,通过调节软段含量与分子量得到一系列具有不同相变焓和相变温度的聚氨酯固-固相变储热材料.经测试还发现,该材料具备很好的相变可逆性和循环热稳定性,是一类很有开发前景的相变储热材料.     

纤维素苯甲酸酯接枝二乙二醇十六烷基醚的制备及性能

分别以1-烯丙基-3-甲基咪唑氯盐([Amim]Cl)和1-乙基-3-甲基咪唑醋酸盐([Emim]Ac)/N,N-二甲基乙酰胺(DMAc)为溶剂体系,以微晶纤维素(聚合度为220)和苯甲酰氯(BC)为原料制备纤维素苯甲酸酯(CB).探索了溶剂体系、反应温度和投料比对产物取代度、溶解性和熔融性能的影响.结果表明,以[Amim]Cl为溶剂时,随着反应温度的升高(60~80℃)或体系中苯甲酰氯与葡萄糖单元环(AGU)投料量的增加(3∶1~9∶1),产物的溶解性和熔融性能均提高,取代度也随之升高(0.13~2.98);以[Emim]Ac/DMAc为溶剂时,产物中苯甲酰基的接枝度较低,且共聚物中引入乙酰基不适合制备纤维素-g-苯甲酰氯.初步探讨了在[Amim]Cl中合成纤维素苯甲酸酯接枝二乙二醇十六烷基醚(CB-g-E_2C_(16))固-固相变材料的性能,研究结果表明,CB-g-E_2C_(16)相变材料的相变温度为12.7~29.1℃,相变焓为12~24 J/g,在294℃仍能保持热稳定性,为该类纤维素基固-固相变材料的可熔融加工奠定了理论基础.     

相变储热材料C10CoCl/C18CoCl二元体系相图

合成了具有层状钙钛矿结构的固-固相变材料四氯合钴酸癸铵(n-C10H21NH3)2CoCl4和四氯合钴酸十八铵(n-C188H37NH3)2CoCl4,并制得一系列C10CoCl/C18CoCl二元体系.利用差示扫描量热(DSC)技术测定其相变温度,并在此基础上绘制了C10CoCl/C18CoCl二元体系相图.在实验相图中确定了新的稳定化合物(n-C10H21NH3)(n-C18H37NH3)CoCl4的存在和2个不变的共晶点,共晶点温度分别为70和73℃.     

Preparation and characterization of pentaerythritol/butane tetracarboxylic acid/polyethylene glycol crosslinking copolymers as solid-solid phase change materials

Pentaerythritol/butane tetracarboxylic acid/polyethylene glycol (PBPEG) crosslinking copolymers as a novel solid-solid phase change material (SSPCM) were successfully synthesized through the reaction mechanism and conditions of hydroxyl-carboxyl condensation reaction. The composition and chemical structure, crystalline properties, phase change behaviors, thermal reliability and chemical stability of PBPEG crosslinking copolymers were investigated by Fourier transform infrared spectroscopy (FT-IR), wide-angle X-ray diffraction (WAXD), polarization optical microscopy (POM), differential scanning calorimetry (DSC), and thermogravimetry (TGA), respectively. The results show that PBPEG crosslinking copolymers have typical solid-solid phase transition temperatures in the range of 10.31～53.27°C and high latent heat enthalpy in the range of 89.6～102.8 J/g, the synthesized SSPCMs have good thermal reliability and chemical stability after 300 thermal cycles, and PBPEG crosslinking copolymers have good thermal stability before 364°C. In summary, the synthesized PBPEG crosslinking copolymers could be potentially used for thermal energy storage.     

Synthesis and properties of bulk-biodegradable phase change materials based on polyethylene glycol for thermal energy storage

The bulk-biodegradable solid–solid phase change materials (SSPCMs) based on phase change polyethylene glycol (PEG) were synthesized by solvent-free polyaddition. On the basis of the fact that the water absorption is up to 800 mass% and that the poly(ethylene oxide) molecular chains can be degraded by microorganisms, the bulk-biodegradable mechanism of SSPCMs was put forward and studied. The X-ray diffraction patterns and the polarizing optical microscopy images show the SSPCMs possess the defective crystal and small grain compared with PEG. The differential scanning calorimetry data demonstrate the melting temperature and enthalpy of the synthesized SSPCMs are, respectively, 41 °C and 128 J g^?1. The bulk-biodegradable SSPCMs have the preeminent thermal reliability and the high thermal stability due to the onset thermal degradation temperature above 302 °C, which will give a good insight into bulk-biodegradable PCM system.     

A Novel Solid-Solid Phase Change Material Based on Poly(styrene-co-acrylonitrile) Grafting With Palmitic Acid Copolymers

(SAN-g-PA) as new solid-solid phase change materials (SSPCMs) were synthesized starting from poly(styrene-co- acrylonitrile) (SAN) and palmitic acid (PA). The chemical structure of the synthesized SAN-g-PA were characterized with Fourier transform infrared (FTIR), and Nuclear Magnetic Resonance (¹H-NMR), their thermal energy storage properties and thermal stability were investigated with differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. Moreover, the crystalline morphology and crystal structures were also measured with polarized optical microscopy (POM) and X-Ray Diffraction (XRD). The result shows that the PA molecule was grafted onto the SAN, SAN-g-PA were obtained successfully. The crystalline morphology and crystal structures of the synthesized SAN-g-PA are different from palmitic acid and SAN. As novel SSPCMs, SAN-g-PA possess suitable phase transition temperature, the higher enthalpy value, and good heat stability.     

Evaluation of PCM/diatomite composites using exfoliated graphite nanoplatelets (xGnP) to improve thermal properties

This paper deals with the thermal performances of shape-stabilized phase change materials (SSPCM) for energy saving in various fields. This study enhanced thermal properties of SSPCM using exfoliated graphite nanoplatelets (xGnP). SSPCM, which contains the xGnP, was prepared by mixing and melting techniques for high dispersibility, thermal conductivity, and latent heat storage. In the experiment, we used hexadecane, octadecane, and paraffin as phase change materials (PCMs), and they have 254.7, 247.6, and 144.6 J g^?1 of latent heat capacity, and melting points of 20.84, 30.4, and 57.09 °C, respectively. The characteristics of SSPCMs were determined using SEM, DSC, FTIR, TG, TCi, and Energy simulation. SEM morphology showed homogenous dispersion of PCM and xGnP in the porous diatomite. DSC analysis results showed the latent heat capacity of SSPCM and SSPCM/xGnP composites, and TG analysis results showed the thermal reliability of the samples. Also, we checked the thermal conductivity of the SSPCM that contains xGnP, by TCi analysis.     

改性氧化石墨烯稳定Pickering乳液法制备高导热相变整体材料

采用表面引发原子转移自由基聚合法(SI-ATRP)改性氧化石墨烯(GO), 并用其稳定Pickering高内相乳液, 一步成型制得高导热氧化石墨烯/石蜡复合整体相变材料. 通过SI-ATRP方法, 在氧化石墨烯表面引入分子刷, 提高GO的分散性, 实现了低GO含量下优异的导热强化效果. 当GO添加量仅为相变复合材料整体的0.4%(质量分数)时, 其热导率(3.968 W?m^-1?K^-1)比纯石蜡的热导率(0.608 W?m^-1?K^-1)有较大提升. 通过测试发现, 在1000次循环后相变材料的泄漏率仅为1.1%~1.3%, 表现出良好的形状稳定性和热可靠性. 制备的新型形状稳定相变材料在温控、 储能应用中具有潜在的用途.     

Synthesis and thermal properties of poly(styrene-co-acrylonitrile)-graft-polyethylene glycol copolymers as novel solid–solid phase change materials for thermal energy storage

A novel poly(styrene-co-acrylonitrile)-graft-polyethylene glycol(SAN-g-PEG) copolymer was synthesized as new solid–solid phase change materials(SSPCMs) by grafting PEG to the main chain of poly(styrene-co-acrylonitrile). The chemical structure of the SAN-g-PEG was confirmed by the Fourier transform infrared(FT-IR) and proton nuclear magnetic resonance(1H NMR) spectroscopy techniques. The thermal energy storage properties and the storage durability of the SAN-g-PEG were investigated by differential scanning calorimetry(DSC). The SAN-g-PEG was endowed with the solid–solid phase transition temperatures within the range of 23–36 8C and the latent heat enthalpy ranged from 66.8 k J/kg to 68.3 k J/kg. Thermal cycling tests revealed that the SAN-g-PEG kept great heat storage durability after 1000 thermal cycles. The thermal stability was evaluated by a thermal gravity analysis(TGA), and the initial decomposition temperature(Td) of SAN-g-PEG is 350 8C, which proves that the SAN-g-PEG possessed good thermal stability.     

Synthesis and Characterization of Storage Energy Materials Prepared from Nano-crystalline Cellulose/Polyethylene Glycol

The development and the application of phase change materials (PCMs) as a new kind of materials have attracted both scientific and industrial interest1-4. According to the patterns of phase conversion, commonly PCMs are divided into solid-liquid phase cha…     

聚乙二醇/二醋酸纤维素相变材料的组成与储能性能间的关系

以刚性的二醋酸纤维素 (CDA)链为骨架 ,接枝上聚乙二醇 (PEG)柔性链段 ,可得到一种具有固固相变性能的网状储能材料 .利用该材料的PEG支链从结晶态到无定形态间的相转变 ,可以实现储能和释能的目的 .具体研究了PEG的百分含量及PEG的分子量对材料储能性能的影响 .研究结果表明 ,通过改变PEG的百分含量与PEG的分子量 ,可以得到不同相变焓和不同相变温度的材料     

二乙二醇十八烷基醚单甲基丙烯酸酯及其聚合物的制备和表征简

以二乙二醇十八烷基醚和甲基丙烯酰氯为原料,采用醇钠-酰氯法合成了二乙二醇十八烷基醚单甲基丙烯酸酯(DEGOEMA),并利用自由基聚合得到聚(二乙二醇十八烷基醚单甲基丙烯酸酯)(PDEGOEMA). 采用凝胶渗透色谱(GPC)分析测试了PDEGOEMA的分子量和分子量分布. 通过傅里叶变换红外光谱(FTIR)、核磁共振氢谱(1H NMR)、差示扫描量热(DSC)、热重(TG)和X射线衍射(XRD)对DEGOEMA和PDEGOEMA的结构、相变行为、热稳定性和晶体结构进行了研究. 结果表明,这种新型单体及其聚合物是一种具有稳定的结构、良好的结晶性能、高相变焓及良好热稳定性的相变材料. PDEGOEMA的起始吸热温度为41 ℃,起始放热温度为36 ℃,热焓为73 J/g,在314 ℃以下热稳定性良好,可用于加工或使用温度较高的环境.     

二乙二醇十八烷基醚单甲基丙烯酸酯及其聚合物的制备和表征

以二乙二醇十八烷基醚和甲基丙烯酰氯为原料, 采用醇钠-酰氯法合成了二乙二醇十八烷基醚单甲基丙烯酸酯(DEGOEMA), 并利用自由基聚合得到聚(二乙二醇十八烷基醚单甲基丙烯酸酯)(PDEGOEMA). 采用凝胶渗透色谱(GPC)分析测试了PDEGOEMA的分子量和分子量分布. 通过傅里叶变换红外光谱(FTIR)、 核磁共振氢谱(¹H NMR)、 差示扫描量热(DSC)、 热重(TG)和X射线衍射(XRD)对DEGOEMA和PDEGOEMA的结构、 相变行为、 热稳定性和晶体结构进行了研究. 结果表明, 这种新型单体及其聚合物是一种具有稳定的结构、 良好的结晶性能、 高相变焓及良好热稳定性的相变材料. PDEGOEMA的起始吸热温度为41 ℃, 起始放热温度为36 ℃, 热焓为73 J/g, 在314 ℃以下热稳定性良好, 可用于加工或使用温度较高的环境.