Fabrication and characterization of microencapsulated n-octadecane with different crosslinked methylmethacrylate-based polymer shells

Abstract Microencapsulations of n-octadecane with different crosslinked methylmethacrylate-based polymer as shells were carried out by suspension-like polymerizations. 1,4-butylene glycol diacrylate (BDDA), divinylbenzene (DVB), trimethylolpropanetriacrylate (TMPTA) and pentaerythritol tetraacrylate (PETRA) were employed as crosslinking agents. The influences of the type and amount of crosslinking agent, the type of initiator and polymerization temperature on the properties of as-prepared microencapsulated phase change materials (MicroPCMs) have been studied. The MicroPCMs were characterized using Fourier transformed infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Thermal properties and thermal stability of MicroPCMs were investigated by differential scanning calorimetry (DSC) and thermalgravimetric analysis (TGA). Shell mechanical strength was measured by micro/nano-hardness tester. Thermal properties, thermal resistant temperatures as well as shell mechanical strength of MicroPCMs enhanced as the number of crosslinkable functional moieties of the crosslinking agents increased. The MicroPCMs containing 75.3 wt% n-octadecane obtained using PETRA as crosslinking agent has the highest latent heats of melting (156.4 J/g) and crystallization (182.8 J/g) and displays the highest thermal stability and shell mechanical strength. The MicroPCMs prepared with DVB shows a relatively higher shell mechanical strength and heat capacity compared with those prepared with BDDA. Both heat capacity and thermal stability of MicroPCMs prepared by combining 2,2 ′ -azobisisobutyronitrile (AIBN) and redox initiators at 45 °C were lower than that of MicroPCMs prepared with AIBN or benzoyl peroxide (BPO) at 85 °C. Hence, MicroPCMs with crosslinked methylmethacrylate-based polymer as shells, especially crosslinked polymer shells of higher crosslinking density, show a good potential as a solar-energy storage material.

[1]  John G. Tsavalas,et al.  Synthesis and Characterization of Paraffin Wax Microcapsules with Acrylic-Based Polymer Shells , 2010 .

[2]  A. Loxley,et al.  Preparation of Poly(methylmethacrylate) Microcapsules with Liquid Cores. , 1998, Journal of colloid and interface science.

[3]  A. Sari,et al.  Preparation, characterization, and thermal properties of microencapsulated phase change material for thermal energy storage , 2009 .

[4]  W. Li,et al.  Effects of ammonium chloride and heat treatment on residual formaldehyde contents of melamine-formaldehyde microcapsules , 2007 .

[5]  A. Sari,et al.  Preparation, thermal properties and thermal reliability of microencapsulated n-eicosane as novel phase change material for thermal energy storage , 2011 .

[6]  Xingxiang Zhang,et al.  Formaldehyde-free and thermal resistant microcapsules containing n-octadecane , 2009 .

[7]  S. C. Solanki,et al.  Heat transfer characteristics of thermal energy storage system using PCM capsules: A review , 2008 .

[8]  R. García-Valls,et al.  Interfacial polymerization of an epoxy resin and carboxylic acids for the synthesis of microcapsules , 2008 .

[9]  M. Hawlader,et al.  Microencapsulated PCM thermal-energy storage system , 2003 .

[10]  S. D. Pohekar,et al.  Performance enhancement in latent heat thermal storage system: A review , 2009 .

[11]  Wei Li,et al.  UV irradiation-initiated MMA polymerization to prepare microcapsules containing phase change paraffin , 2010 .

[12]  Xingxiang Zhang,et al.  Preparation and characterization of microencapsulated phase change material with low remnant formaldehyde content , 2007 .

[13]  R. Velraj,et al.  Phase change material-based building architecture for thermal management in residential and commercial establishments , 2008 .

[14]  J. Su,et al.  Fabrication and thermal properties of microPCMs: Used melamine‐formaldehyde resin as shell material , 2006 .

[15]  Wei Li,et al.  Morphology, structure and thermal stability of microencapsulated phase change material with copolymer shell , 2011 .

[16]  E. Onder,et al.  The manufacture of microencapsulated phase change materials suitable for the design of thermally enhanced fabrics , 2007 .

[17]  E. Onder,et al.  Encapsulation of phase change materials by complex coacervation to improve thermal performances of woven fabrics , 2008 .

[18]  J. Su,et al.  Preparation and characterization of polyurethane microcapsules containing n‐octadecane with styrene‐maleic anhydride as a surfactant by interfacial polycondensation , 2006 .

[19]  Amar M. Khudhair,et al.  A review on phase change energy storage: materials and applications , 2004 .

[20]  A. Sari,et al.  Microencapsulated n-octacosane as phase change material for thermal energy storage , 2009 .

[21]  A. Sari,et al.  Preparation, characterization and thermal properties of PMMA/n-heptadecane microcapsules as novel solid-liquid microPCM for thermal energy storage , 2010 .

[22]  J. Yeh,et al.  New crosslinked polymer from a rapid polymerization of acrylic acid with triaziridine‐containing compound , 2007 .

[23]  S. Bourbigot,et al.  Preparation of multinuclear microparticles using a polymerization in emulsion process , 2008 .

[24]  M. Jassal,et al.  Highly stable hexamethylolmelamine microcapsules containing n-octadecane prepared by in situ encapsulation , 2009 .

[25]  Hui Chen,et al.  Preparation of phase change materials microcapsules by using PMMA network‐silica hybrid shell via sol‐gel process , 2009 .

[26]  A. Sari,et al.  Fatty acid/poly(methyl methacrylate) (PMMA) blends as form-stable phase change materials for latent heat thermal energy storage , 2008 .