Search

Usually, polyethylene glycol (PEG)‐based biodegradable solid‐solid phase change materials (BSSPCMs) are synthesized with isocyanate and PEG, removing water is necessary due to the sensitivity to water of isocyanate groups. In this study, a water insensitive synthetic scheme based on carboxyl and aziridinyl was employed to prepare PEG‐based BSSPCMs via solvent‐free bulk polymerization: First, a carboxyl modified polyethylene glycol was synthesized through esterification reaction of citric acid and PEG with the molar ratio 2:1. Then, the BSSPCMs were prepared based on an self‐curing and organic solvent‐free process, using trimethylolpropane tris(1‐aziridine propionate) as the cross‐linking agent. The chemical structure, crystalline properties, phase change properties, thermal stability, and reliability were investigated by Fourier transform infrared spectroscopy, X‐ray diffraction, polarizing optical microscopy, differential scanning calorimetry, thermogravimetric analysis, and accelerated thermal cycling testing, respectively. Solid–solid phase change behavior was testified by the leakage test. The biodegradation experiment was conducted to prove the biodegradability of solid–solid PCMs. The results indicated that BSSPCMs had a similar crystalline structure to PEG, and the crystal size was smaller than PEG. The phase change temperature of BSSPCMs was in the range of 25–65°C, and the latent heat of phase change materials (PCMs) was about 103–108 J/g. Moreover, the extent of supercooling of BSSPCMs was reduced. Thermogravimetric analysis and accelerated thermal cycling test results confirmed the considerable thermal stability and reliability of BSSPCMs. The prepared PCMs also exhibited a good biodegradability in the natural environment. [ABSTRACT FROM AUTHOR]

Three kinds of thermoplastic poly(urethane‐urea) PCMs were synthesized by two‐step condensation polymerization for thermal energy storage. Polyethylene glycol (PEG) was employed as the phase‐change functional chain, and three kinds of diamine compounds were individually adopted as chain extender. The chemical structure, crystalline properties, phase‐change behaviors, thermal stabilities, and reliabilities were studied by Fourier transform infrared spectroscopy, X‐ray diffraction, polarizing optical microscopy, and thermogravimetric, respectively. The crystalline structure of synthesized thermoplastic PCMs is identical to pure PEG, but the spherulite size decreases to some extent due to the confined crystalline region. The synthesized thermoplastic PCMs have proper phase‐change temperature with high phase‐change enthalpy of about 88 J/g. The synthesized thermoplastic PCMs are stable at their processing and working temperature with the onset degradation temperature higher than 250°C, and tensile strength reaches 20.59 MPa. Thus, the synthesized thermoplastic PCMs can be processed into desirable shape for the special applications in energy storage. [ABSTRACT FROM AUTHOR]

ABSTRACT Antistatic polyurethane (APU) is prepared by in situ polymerization of polyester glycol (PEL), 4,4′-diphenylmethane diisocyanate (MDI), 1,4-butanediol (BDO), and antistatic agent (AA) formed by dissolving sodium salts in polyethylene glycol (PEG). Comprehensive properties of the APU are investigated by the FT-IR, mechanical characterization, surface resistivity measurement, relative humidity (RH) study, and TGA, respectively. It is found that the surface resistivity of the APU can be effectively reduced to 109.15 Ω, showing a good antistatic property. Moreover, the APU maintains a low surface resistivity (∼109.43 Ω) at the RH of 0.1%, revealing a non-RH-sensitive capacity of the APU. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39921. [ABSTRACT FROM AUTHOR]

PEG based thermosetting phase change materials (PCMs) have been frequently employed for thermal energy storage in building and other fields due to the low cost, no toxic, no corrosive, good thermal properties and no leakage in phase change process. In this article, thermosetting PCMs with polyethylene glycol (PEG) as phase change functional chain and polyaryl polymethylene isocyanate terminated polycarbonatediol (PCD) as curing agent were prepared through a facile and solvent-free bulk polyaddition. This preparation strategy can provide novel mean to design and synthesize PEG based thermosetting PCMs with different structure and performances according to the specific requirement. Moreover, the introduction of PCD will further improve the performance of PCMs. The chemical structure, crystalline properties, phase change properties, thermal reliability and stability of prepared PCMs were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), polarizing optical microscopy (POM), differential scanning calorimetry (DSC), accelerated thermal cycling testing and thermogravimetric analysis (TGA), respectively. FTIR spectra showed that the PEG based thermosetting PCMs were successfully synthesized. XRD and POM results indicated the similar spherulite structure of virgin PEG and prepared PCMs, and the crystallinity and crystal size of PCMs are affected by the introduction of curing agent. Meanwhile, DSC measurements showed that prepared PCMs have good phase change properties. Accelerated thermal cycling and TGA testing proved the excellent thermal reliability and thermal stability of prepared PCMs. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • High thermostable polymer-based shape-stabilized phase change materials (SSPCMs) were prepared. • The phosphaphenanthrene compound was successfully grafted on epoxy. • The chemical structure and microstructure of SSPCMs were studied by FTIR and SEM. • The melting and freezing latent of SSPCMs reached up to 112.0 J/g and 108.0 J/g, respectively. Abstract In this work, PEG based SSPCMs were successfully prepared using 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) modified epoxy resins as reliable supporting materials in the absence of solvent. The encapsulated PEG acted as phase change functional domains and DOPO was used to enhance the thermal stability of polymeric SSPCMs. The chemical composition and microstructure of prepared SSPCMs were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) were conducted to investigate the crystalline properties, phase change properties and thermal stability of SSPCMs. Heat storage and release performance test was conducted to certify the reversible heat storage and release performance of SSPCMs. Thermal cycling test was also performed to illustrate the thermal reliability of SSPCMs. From DSC results, the prepared SSPCMs melted at 67.7 °C and crystallized at 27.9 °C and the corresponding latent heat are 112.0 J/g and 108.0 J/g, respectively. TG results showed that SSPCMs have good thermal stability with the onset decomposition temperature far beyond their working temperature. [ABSTRACT FROM AUTHOR]

A carboxy modified long-chain diol (CMLCD) was synthesized for the first time through esterification of pyromellitic dianhydride (PMDA) and polytetramethylene glycol 1000 (PTMG1000). Waterborne polyurethane (WPU) was prepared based on an organic solvent-free and self-catalytic process, using synthesized CMLCD as a hydrophilic diol. The CMLCD has self-catalytic ability to the reaction of hydroxyl and isocyanate during the prepolymerization, which can greatly shorten the preparation period and avoid the utilization of highly toxic catalyst such as dibutyltin dilaurate. Importantly, the prepared WPU has narrow particle size distribution with the average particle size of 137 nm, which leads to good stability even centrifugated at 3000 rpm. Mechanical test results show that the WPU film possesses good mechanical performance with the tensile strength of 59.3 MPa and elongation at break of 819.2%. Additionally, the prepared WPU film has high water resistance. This study is attractive for future green WPU in industrial production and application. [ABSTRACT FROM AUTHOR]

In this study, two components based polyethylene glycol (PEG)/thermosetting solid-solid phase change material composites as novel form stable phase change material (FSPCM) were successfully prepared via free-radical polymerization. One of the components consists of PEG-based polyurethane acrylate prepolymer and extra pristine PEG. Another component is made up of 1,6-hexanediol diacrylate and benzoyl peroxide. The extra pristine PEG with low viscosity at melting state was used as diluents to decline the melting viscosity of PUA and served as phase change functional chains of the FSPCMs, endowing the FSPCM with high latent heats and flexible application ability for thermal energy storage. The chemical structure, crystalline performances, phase change properties and thermal reliability and stability of prepared FSPCMs were investigated by Fourier transform infrared spectroscopy, X-ray diffraction, polarizing optical microscopy, differential scanning calorimetry and thermogravimetry analysis, respectively. The leakage test results show that the maximum content of PEG in novel FSPCM without any leakage above the melting point of PEG is 85 wt%. The DSC analysis results show that the novel FSPCMs have high latent heats and the latent heats efficiency of novel FSPCMs is significantly higher than that of the traditional FSPCMs. The prepared FSPCMs exhibit good thermal reliability and stability from the thermal cycling test and TG analysis. [ABSTRACT FROM AUTHOR]

A semi-interpenetrating polymer network (semi-IPN) of polyethylene glycol (PEG)/poly(polyethylene glycol diacrylate) (PPGD) composites as novel form-stable PCMs was successfully prepared via in situ polymerization. The mass percentage of PEG reached 70 wt% without any leakage above the melting point of PEG. The prepared form-stable PCMs were investigated by scanning election microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), polarization optical microscopy (POM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TG), respectively. SEM and FTIR results show that the PEG is uniformly dispersed into the PPGD network and there are only physical interactions between PEG and PPGD. POM images and XRD patterns reveal that the crystalline structure of PEG is not affected by PPGD network and the crystal size of PEG in form-stable PCMs decreases due to the restriction of PPGD network. DSC analysis results present that the melting and freezing temperatures and the latent heats of form-stable PCM were measured as 58.62 and 37.45 °C and 117.41 and 115.17 J/g, respectively. Thermal cycling test and TG analysis confirm that the prepared form-stable PCMs exhibit good thermal reliability and stability. The prepared form-stable PCMs have great potential application in the area of solar energy storage. [ABSTRACT FROM AUTHOR]

The thermosetting solid–solid phase change materials (SSPCMs) composed of poly(ethylene glycol)-based two components, isocyanate-terminated prepolymer and tetrahydroxy prepolymer, were synthesized via solvent-free bulk polymerization, endowing the thermosetting PCMs with flexible application capability. The chemical structures, crystalline properties, phase change properties, thermal energy storage mechanism, thermal reliability and stability of the synthesized PCMs were respectively characterized by Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, polarizing optical microscopy, accelerated thermal cycling testing and thermogravimetric analysis. The intrinsic crystalline structure in SSPCMs is not influenced by the crosslinking reaction between two components. However, compared with the poly(ethylene glycol) (PEG), the lamellae and spherulite size in SSPCMs decrease to some entente and dramatically, respectively. The SSPCMs have proper phase change temperature of about 45 °C and high phase change enthalpy of about 100 J/g much less than the PEG, resulted from the small spherulite and lamellae size working together. The SSPCM-based thermal energy storage relies on the phase change from the crystalline state to the amorphous state and vice versa. The SSPCMs have good thermal reliability and stability with the degradation temperature higher than 300 °C. [ABSTRACT FROM AUTHOR]