A novel solid–solid phase change heat storage material with polyurethane block copolymer structure
Introduction
Latent heat storage is one of the most efficient ways of storing thermal energy due to its high storage density and small temperature variation in the storing and releasing heat processes. Phase change materials (PCMs) are the materials using latent heat to store energy. In recent years, as the energy crisis is becoming more and more serious, PCMs are attracting lots of attention. A great number of organic, inorganic, polymeric and eutectic PCMs have been studied [1], [2], [3], [4], [5], [6]. Among the various kinds of PCMs, polymeric solid–solid PCMs are fairly recently developed functional PCMs, which have been found to exhibit many desirable characteristics, e.g. no liquid or gas generation, small volume change, no receptacle needed to seal them, being processed into arbitrary shape, even being used as a system material directly [6], [7], [8], [9], [10]. Thus, it can simplify techniques and reduce cost greatly.
At present, there are two kinds of polymeric solid–solid PCMs. One kind is compound materials obtained by dispersing PCMs into higher melting point polymeric materials acting as supporting materials [11], [12]. As long as the temperature is below the melting point of the supporting materials, the compound materials can keep their solid shape even when PCM changes from solid to liquid. They are generally called form stable PCMs or shape stabilized PCMs. The other kind is synthesized by chemical methods [13], [14], Chemical grafting or blocking copolymerization are used to make good solid–liquid PCMs as the energy storage working materials component of solid–solid phase change materials. However, there are several defects in most of the polymeric solid–solid PCMs reported in previous work, e.g. the transition temperature is too high, the transition enthalpy is low and the thermal property is unstable. All these defects greatly limit their applications.
In this paper, a novel polymeric solid–solid PCM, segment polyurethane solid–solid phase change material (PUPCM), was synthesized by reacting calculated amounts of high molecule weight polyethylene glycol (PEG), a typical polymeric solid–liquid PCM, as the soft segment with 4,4′-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BDO) as hard segment. The properties of PUPCM were investigated with differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), scanning electronic microscopy (SEM) and polarization optical microscopy (POM).
Section snippets
Materials
Polyethylene glycol (PEG, Mn = 10,000, from Shantou Guanghua Chemical Reagent Co. Inc., China) was degassed and dried in a round flask under high vacuum (20 Pa) at 100–120 °C for 3–4 h. 4,4′-Diphenylmethane diisocyanate (MDI, from Wanhua Chemical Reagent Co. Inc., China) was used as received. Dimethylformamide (DMF, from Shantou Guanghua Chemical Reagent Co. Inc., China) and 1,4-butanediol (BDO, from Shanghai Medical Chemical Reagent Co. Inc. China) were dried by 5 Å molecular sieve for 24 h followed
Thermal properties
Fig. 1 shows the DSC curves of pure PEG and PUPCM, and the data of their melting temperature and enthalpy are summarized in Table 1. It indicates that there is a melting peak at about 66 °C in the heating scanning DSC curve of pure PEG and the latent heat of fusion is 189.6 J/g, while in the heating scanning DSC curve of PUPCM with 88.7% weight percentage of PEG shown in Fig. 1(c), it also shows a melting peak at 65 °C, and the enthalpy is 138.7 J/g. Both pure PEG and PUPCM undergo phase transition
Conclusions
From the above analysis, we can conclude that the PUPCM with the special solid–solid phase change behaviors of high thermal energy storage capability, suitable phase transition temperature, reversible latent heat transition and good thermal stability can be used as a new kind of solid–solid phase change material for thermal energy storage and temperature control. It has a great potential for thermal energy storage applications.
References (15)
Low temperature latent thermal energy storage system: heat storage materials
Sol Energy
(1983)- et al.
Low chain esters of stearic acid as phase change materials for thermal energy storage
Sol Energy Mater
(1995) - et al.
Thermal performance of myristic acid as a phase change material for energy storage application
Renew Energy
(2001) - et al.
Study on transition characteristics of PEG/CDA solid–solid phase change materials
Polymer
(2002) The viability of thermal energy storage
Energy Sour
(1999)- et al.
A review on phase change energy storage: materials and applications
Energy Conv Manage
(2004) - et al.
A study on latent heat storage exchangers with the high-temperature phase-change material
Int J Energy Res
(2001)
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2022, Journal of Energy StorageCitation Excerpt :Crystallographic hydrate-based inorganic PCM's aqueous solutions can be directly used in open-cell PUF for manufacturing PU-PCM [29]. J. Su et al. reported incorporating solid-solid PCM into the PU matrix by copolymerization [30]. To incorporate PCM into the PU matrix by the indirect method, the first PCM core should be encapsulated with a suitable shell; this EPCM has to disperse into the PU matrix by the process described in Section 2.1 & schematic flow diagram of EPCM based PU-PCM manufacturing shown in Fig. 4.