Latent Heat Enhancement of Paraffin Wax in Poly(divinylbenzene-co-methyl methacrylate) Microcapsule

Abstract

The preparation of divinylbenzene (DVB)-methyl methacrylate (MMA) copolymer microcapsule encapsulated Rubitherm27 (RT27) P(DVB-co-MMA)/RT27 used as heat storage material by the microsuspension polymerization was studied to improve the latent heats of the encapsulated RT27 with sufficient polymer shell strength. Percent loading of RT27 and DVB:MMA ratio were optimized. The optimal condition was 30% loading of RT27 and 30:70 (% w/w) of DVB:MMA ratio. The nonspherical microcapsules with a dent having core-shell morphology were obtained. The thermal properties of the encapsulated RT27 in the P(DVB-co-MMA)/RT27 capsules were measured by thermogravimetric analyzer and differential scanning calorimeter. The heats of melting (DH m ; 153 J/g-RT27) and crystallization (DH c ; 164 J/g-RT27) of the encapsulated RT27 in the prepared copolymer capsules were higher than those in PDVB and closed to those of bulk RT27 (162 and 168 J/g-RT27 for DH m and DH c , respectively).

Encapsulation of paraffin wax by rigid cross-linked poly (styrene divinylbenzene-acrylic acid) and its thermal characterization

“…The ratio of DVB and styrene was optimized at the weight ratio of 30:70 to improve the latent heats of the encapsulated paraffin wax with sufficient polymer shell strength. The group reported that the thermal properties of RT27encapsulated with copolymer using DVB and styrene was ΔHm = 153 kJ/kg and ΔHc = 164 kJ/kg, which is much higher than those encapsulated using only DVB (ΔHm = 127 kJ/kg and ΔHc = 133 kJ/kg) and closed to bulk RT27 (ΔHm = 162 kJ/Kg and ΔHc = 168 kJ/kg) [5]. Taegu Do et al reported that the fabrication of hydrophilic poly (2-hydroxyethyl methacrylate) (pHEMA) encapsulated paraffin-wax sphere as the PCM capsule with high encapsulation ratio and thermal storage capability.…”

“…A phase change material changes its state from solid to liquid state due to gaining of thermal energy and changes from liquid to solid due to release of energy via latent heat storage concept. Phase change materials are categorized into (i) organic-paraffin (C n H 2n+2 ) and non-paraffin, (ii) inorganic-salt hydrates (M n H 2 O) and (iii) eutectic,-a combination of organic and inorganic compounds [5,6]. Paraffin waxes are the most common PCM for thermal management having a high heat of fusion per unit weight (i.e.…”

“…energy density), the selection of PCM depends upon its application in varied thermal ranges, dependable thermal cycling, non-corrosive and chemically inert nature [7]. Even though paraffin wax has its advantages, designing systems with paraffin require greater attention towards (i) void management i.e., due to the volume change from solid to liquid [2,3,5], (ii) sub-cooling, and (iii) instability of paraffin wax [1,2],which can reduce its functionality as a latent heat storage fluid [8]. The encapsulated PCM materials are largely utilized in space heating and cooling systems, integrated with building materials like concrete or paints [9,10].…”

“…The advanced methods like interfacial polymerization, suspension, and emulsion polymerization techniques have to be carried out for micro-encapsulation and nano-encapsulation of PCMs with polymeric materials. The size of the particle formed can be varied from nano-size to micro-size [5,13]. In general, polymerization of vinyl monomers such as styrene (St), divinyl-benzene (DVB), acrylic acid (AA), hydroxyethyl methacrylate (HEMA), methyl methacrylate (MMA), polyvinyl chloride (PVC), etc.…”

“…In general, polymerization of vinyl monomers such as styrene (St), divinyl-benzene (DVB), acrylic acid (AA), hydroxyethyl methacrylate (HEMA), methyl methacrylate (MMA), polyvinyl chloride (PVC), etc. [5,9,[14][15][16][17]. can be carried out via free-radical or ionic polymerization through thermal or photochemical route.…”