Crystalline-amorphous phase transition of hyperbranched polyurethane phase change materials for energy storage

Hyperbranched polyurethane solid–solid phase change material (HB-PUPCM) has been prepared via a two-step process. The phase transition behaviors and morphologies of these HB-PUPCM films were investigated using differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and polarizing optical microscopy (POM). PEG soft segment in the polyurethane was found to be crystalline at room temperature. However, when the temperature was raised to PEG’s melting point, polyurethane did not melt into the liquid state as in the case of pure PEG but changed to an amorphous solid state. In HB-PUPCM, PEG’s molecules probably are tied to the hard segment chain so strongly by the chemical bonds that they cannot change to a liquid state but change to the amorphous state in the transition processing.     

Preparation and characterization of a series of diol di-stearates as phase change heat storage materials

A series of solid-liquid phase change materials, diol di-stearates, were prepared via esterification of stearyl chloride with the respective diol (1,2-ethanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol and 1,10-decanediol) using pyridine as acid absorbent, and were then characterized by FT-IR, WAXD, POM, DSC and TGA measurements. All of the resulting diol di-stearates were apt to crystallize due to structural symmetry and flexibility of long alkyl groups. The DSC results indicated that the melting point of the prepared diol di-stearates varied from 38.5 °C to 56.4 °C, and phase change enthalpy lies in the range 134 kJ/kg-189 kJ/kg.     

新型超支化聚羟甲基醚液晶的合成

合成了联苯氰类介晶基元。改变软段的长度对超支化聚羟甲基醚进行改性。POM，DSC的研究表明。当n=1时，改性超支化聚羟甲基醚不表现出液晶性；n=5,10时，改性超支化聚羟甲基醚表现出液晶性，且为向列型液晶。     

聚氨酯定型相变储能材料的结构与热物性分析

采用聚氨酯硬质泡沫作为封装材料,十八烷为相变材料,以自制纳米氧化硅作为稳定剂与成核剂,采用原位封装的方式实现封装。通过微观形貌和结构分析发现,所制备的聚氨酯定型相变材料具有微纳米级均匀的微观结构,相变材料均匀地分布在聚氨酯中。傅里叶变换红外光谱检测结果显示,聚氨酯与相变材料间属于物理混合,相变材料的相变特性不受聚氨酯的影响,且有助于进一步提高定型相变材料的结构稳定性。这一研究结果将为建筑节能材料结构的研究提供理论指导。     

环氧树脂/超支化聚酯/纳米SiO2复合材料的制备及性能

采用超支化聚酯与聚硅酸溶胶共混改性环氧树脂,制备了环氧树脂/超支化聚酯/纳米SiO2三元共混体系纳米复合材料。研究了超支化聚酯/聚硅酸溶胶增韧改性环氧树脂固化体系的力学性能及热性能,通过X射线衍射(WAXD)、差示扫描量热(DSC)、热重分析(TGA)及扫描电镜(SEM)等测试手段对材料的微观相态结构与性能进行了表征。结果表明,超支化聚酯/聚硅酸的加入使纳米复合材料的力学性能和热性能得到明显提高。当纳米SiO2的含量为1%(质量分数,下同)时冲击强度比纯环氧树脂提高了10.48kJ/m2,材料的起始热分解温度也提高了27℃。     

一种液晶聚氨酯的合成及应用

以对苯二酚、对羟基苯甲酸、甲苯二异氰酸酯（2,4-TDI）和二缩三乙二醇等为原料,采用溶液聚合的方法,共缩聚合成具有液晶性的主链型聚氨酯（PLCP）,并采用傅里叶红外光谱（FT-IR）、偏光显微镜（POM）及广角X射线衍射（WAXD）等对其结构进行了表征,研究证实该化合物为向列型液晶。研究了PLCP增韧改性环氧树脂固化...     

含亚胺基热致性液晶聚氨酯的合成与表征

以对苯二酚二对苯甲酸酯(HQB)、N,N′-二(ω-羟乙基)苯均四甲酰二亚胺(BHDI)、甲苯二异氰酸酯(TDI)为单体,利用溶液缩聚方法,合成了含有亚胺基的三种液晶聚氨酯(HBLCP)。采用红外光谱(FT-IR)、差示扫描量热(DSC)、偏光显微镜(POM)、X射线衍射(WAXD)和热重分析(TGA)等手段对液晶聚氨酯进行表征。结果表明,该类液晶聚氨酯的熔点(Tm)和各向同性温度(Ti)随着HQB含量的增加而提高;POM观察表明,在液晶态温度区间170℃～190℃范围内显示液晶行为,并呈现向列相织构;其广角X射线衍射图在2θ角为15°～32°范围内有一组强度不等的衍射峰,所合成的液晶聚氨酯具有较高的热稳定性。     

一种MGPM/Opal固-固相变储能材料的相变及结晶行为

采用含有相变单元的单体缩聚法合成了侧链含有聚乙二醇单甲醚（MPEG）的新型固-固相变储能复合材料（相变共聚物缩写名称为（MGPM）/蛋白石（opal））,通过广角X射线衍射（WAXD）、差热扫描量热仪（DSC）和热台偏光显微镜（POM）、热重（TG）等测试手段对其结晶结构、结晶行为、结晶形态和热稳定性进行了研究,结果表...     

新型酯类环氧液晶的合成及应用

采用相转移催化剂合成液晶环氧预聚物(PHQEP),用红外光谱、核磁共振谱、广角X射线衍射及偏光显微镜(POM)对PHQEP的分子结构和液晶性进行表征。研究了PHQEP增韧改性环氧树脂固化体系的力学性能,通过DSC、TGA及SEM等测试手段对材料的结构与性能进行了表征。结果表明,PHQEP是典型的向列型液晶,加入PHQEP的环氧固化体系,韧性和热稳定性都有很大的提高。     

Synthesis of shape-stabilized paraffin/silicon dioxide composites as phase change material for thermal energy storage

The shape-stabilized paraffin/silicon dioxide (SiO₂) composite phase change materials (PCM) were prepared by using sol–gel methods. Paraffin was used as the PCM, and silicon dioxide was acted as the supporting material. Fourier transformation infrared spectroscope (FT-IR) and scanning electronic microscope were used to determine the FT-IR spectra and microstructure of shape-stabilized paraffin/silicon dioxide composite PCM, respectively. The thermal properties and thermal stability were investigated by a differential scanning calorimeter and a thermogravimetric analysis, respectively. The SEM analysis showed that the paraffin was well dispersed into the porous network of silicon dioxide. DSC analysis indicated that the mass content of paraffin in silicon dioxide was up to 92.1%, and paraffin/silicon dioxide composites had solidifying temperature of 57.07 °C, solidifying latent heat of 59.66 kJ/kg, melting temperature of 58.10 °C, and melting latent heat of 139.59 kJ/kg.     

Polyacetal and thermoplastic polyurethane elastomer toughened polyacetal: crystallinity and fracture mechanics

The effect of thermoplastic polyurethane (TPU) elastomer on the melting point and the percentage crystallinity of polyacetal (POM) is studied by differential scanning calorimetry (DSC). Wide angle X-ray diffraction (WAXD) scans of POM, TPU and their blends have been taken and the results indicate that the crystalline structure of POM remains unaffected even after the addition of amorphous TPU. The influence of defects like holes and notches on the ultimate tensile strength has been examined. The resistance to crack initiation (J _c), the resistance to steady state crack propagation (R _p) and the resistance to crack growth at maximum load (R _max) are estimated. The POM/TPU blends display higher crack resistance values than pure POM. The hysteresis energy of blends is determined and is found to increase with TPU content.     

A capric–palmitic–stearic acid ternary eutectic mixture/expanded graphite composite phase change material for thermal energy storage

This paper demonstrated a capric acid–palmitic acid–stearic acid ternary eutectic mixture/expanded graphite (CA–PA–SA/EG) composite phase change material (PCM) for low-temperature heat storage. The CA–PA–SA ternary eutectic mixture with a mass ratio of CA:PA:SA = 79.3:14.7:6.0 was prepared firstly, and its mass ratio in the CA–PA–SA/EG composite can reach as high as 90%. The melting and freezing temperatures of CA–PA–SA/EG composite were 21.33 °C and 19.01 °C, and the corresponding latent heat were 131.7 kJ kg⁻¹ and 127.2 kJ kg⁻¹. The CA–PA–SA/EG composite powders can be formed into round blocks by dry pressing easily, with much higher thermal conductivity than CA–PA–SA. Thermal performance test showed that the increasing thermal conductivity of CA–PA–SA could obviously decrease the melting/cooling time. Thermal property characterizations after 500 heating/cooling cycles test indicated that CA–PA–SA/EG composite PCM had excellent thermal reliability. Based on all these results, CA–PA–SA/EG composite PCM is a promising material for low-temperature thermal energy storage applications.     

The waterborne polyurethane dispersions based on polycarbonate diol: Effect of ionic content

Three water-based polyurethane dispersions (PUD) were synthesized by modified dispersing procedure using polycarbonate diol (PCD), isophorone diisocyanate (IPDI), dimethylolpropionic acid (DMPA), triethylamine (TEA) and ethylenediamine (EDA). The ionic group content in the polyurethane-ionomer structure was varied by changing the amount of the internal emulsifier, DMPA (4.5, 7.5 and 10 wt.% to the prepolymer weight). The expected structures of obtained materials were confirmed by FTIR spectroscopy. The effect of the DMPA content on the thermal properties of polyurethane films was measured by TGA, DTA, DSC and DMTA methods. Increased DMPA amounts result in the higher hard segment contents and in the increase of the weight loss corresponding to the degradation of the hard segments. The reduction of hard segment content led to the elevated temperature of decomposition and to the decrease of the glass transition temperature and thermoplasticity. The atomic force microscopy (AFM), results indicated that phase separation between hard and soft segment of PUD with higher DMPA content is more significant than of PUD with lower DMPA content. The physico-mechanical properties, such as hardness, adhesion test and gloss of the dried films were also determined considering the effect of DMPA content on coating properties.     

Paraffin/carbon aerogel phase change materials with high enthalpy and thermal conductivity

Two kinds of carbon aerogels, graphene aerogels (GA) and carbon nanotubes-graphene aerogels (CGA), were prepared by modified hydrothermal method. The form-stable phase change materials (PCMs) were fabricated by adsorbing paraffin into carbon aerogels. Morphology, structure, form stability and thermal property were characterized by scanning electron microscope (SEM), in situ X-ray diffraction (in situ XRD) and differential scanning calorimeter (DSC). The results showed that GA presented wrinkled surface textures with curling edges, and carbon nanotubes (CNTs) were interspersed or attached to GA sheets. The phase transition temperature and the phase change enthalpy of the GA/paraffin PCM composite were 48.7 °C and 223.2 J/g, respectively. Thermal and mechanical properties of PCM composites achieved a qualitative leap with the adding of carbon aerogels. The PCM composites had a thermal conductivity of about 2.182 W/m K at the carbon aerogels loading fraction of 2 wt%. The form-stable PCM composites with high thermal conductivity and high enthalpy could be promising for thermal energy storage applications in construction field.     

稀土β成核剂含量对PPR性能与结晶行为的影响

选用新型稀土β成核剂(WBGⅡ)对无规共聚聚丙烯(PPR)进行改性。借助广角X射线衍射(WAXD)、差示扫描量热仪(DSC)及偏光显微镜(POM)研究了稀土β成核剂诱导无规共聚聚丙烯的结晶行为及晶体形态;并研究了WBGⅡ对PPR力学性能和热变形温度(HDT)的影响。结果表明,加入少量WBGⅡ后,PPR的晶型和结晶形态均发生变化;非等温结晶过程的结晶温度(Tc)从95.8℃提高到102.1℃;PPR的冲击强度提高24%,拉伸和弯曲性能却略有下降;热变形温度提高20℃。     

预聚法制备聚氨酯/分子筛复合材料及表征

采用预聚法制备了聚氨酯(PU)/沸石分子筛(zeo lite 13X)复合材料,并利用XRD、DSC和TG等手段表征了复合材料的晶态、硬链段的结晶及熔融温度、材料的耐热性能。结果表明,随着沸石分子筛在体系中加入量的增大,PU/13X复合材料的硬链段结晶度减小,而硬链段和软链段之间的混乱度增大,硬链段的结晶形态发生改变,晶面间距增大。力学性能测试表明,分子筛添加量小于7%时,拉伸强度和撕裂强度明显提高。     

向列型热致液晶聚酰胺的结构表征

采用傅立叶红外光谱仪（IR）、广角X射线衍射仪（WAXD）、热台偏光显微镜（POM）及扫描电子显微镜（SEM）对所合成热致液晶聚酰胺进行了结构表征。IR谱图显示了该聚合物为半刚性结构,与所设计的分子结构相一致;WAXD曲线显示处于液晶态的聚合物在2θ=20°左右有一弥散的峰,表明该液晶聚合物为向列型液晶结构;POM观察...     

HPB－b－PMMA增容PVC／PE共混物相分离与相态结构研究

以激光散射（ＬＳ）跟踪升温过程光散射强度变化的方法，研究了氢化聚丁二烯－聚甲基丙烯酸甲酯嵌段共聚物（ＨＰＢ－ｂ－ＰＭＭＡ）增容聚氯乙烯（ＰＶＣ）／聚乙烯（ＰＥ）共混物溶液浇铸膜相分离行为的特点，还以广角Ｘ光衍射（ＷＡＸＤ）测定了该膜的结晶状况，扫描电镜（ＳＥＭ）和相差显微镜（ＰＣＭ）观察、记录了表面相态结构。提出增容剂在此既有增容作用又有“协调链段活动”作用的看法。     

超支化水性聚氨酯的合成与表征

以异佛尔酮二异氰酸酯(IPDI)、二乙醇胺(DEOA)及二羟甲基丙酸(DMPA)为原料,合成超支化聚氨酯核HBPU-0;以IPDI、聚四氢呋喃(PTMEG)及DMPA等原料合成线性聚氨酯,然后,将线性聚氨酯接枝到HBPU-0上,制备了一种具有超支化结构的水性聚氨酯,产物具有良好的水分散性和耐水性,其中HBPU-6的24h吸水率为6%,48h吸水率为11%,72h吸水率为18%。通过红外光谱对产物结构进行了表征。采用电子万用试验机和热失重分析仪对产物的性能进行测试,结果表明,所制备的水性超支化聚氨酯具有良好的力学性能和热稳定性,HBPU-6的拉伸强度为16.8MPa,热分解温度达到238℃。     

超支化聚氨酯的合成与性能

以异佛尔酮二异氰酸酯(IPDI)和聚乙二醇2000(PEG2000)为单体,通过逐步聚合反应合成了-NCO封端的聚氨酯顸聚体(PPU);再通过接枝使PPU与端羟基超支化聚合物(HPAE)共聚得到一种新型超支化聚氨酯(HBPU).利用红外光谱仪(FT-IR)、核磁共振(1H-NMR)、热重分析仪(TGA)、X射线衍射(X...