https://orcid.org/0000-0002-9803-9725
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ABSTRACT
The commercial shape-stabilized phase change material (PCM) products are obtained from synthetic raw materials. These materials are produced from carbon-intensive petroleum-refining processes. The carbon footprint can be minimized by using biobased products. Beeswax is a naturally available PCM with high phase transition enthalpy comparable to synthetic PCMs. In the previous literature studies, beeswax was shape-stabilized with synthetic materials. In the present study, beeswax was shape-stabilized with biopolymer ethyl cellulose by emulsion solvent evaporation method. The study aims to determine optimum microencapsulation process parameter levels for synthesizing microcapsules with high thermal energy storage (TES) capacity. The optimized process parameters for formulating microcapsules were 60:40 core/shell ratio, 2% PVA concentration, ethyl acetate solvent, and 40°C evaporation temperature. The microcapsules prepared with optimized process parameters were characterized using differential scanning calorimeter (DSC), T-history analysis, Fourier transform infrared (FTIR) spectroscope, and scanning electron microscope (SEM). FTIR and SEM analysis confirmed ethyl cellulose shell formation over the beeswax core. The optimized MPCM formulation possesses 115.8 J/g melting enthalpy with peak phase transition temperature of 58.2°C and thermal conductivity of 0.219 W/mK. The porous structure of the shell reduced melting enthalpy of optimized MPCM formulation to 84.6 J/g after 50 thermal cycles. The synthesized microcapsules comprise sustainable materials and have high TES capacity. The fabricated microcapsules can be used as TES additive in composite and coating formulations in food packaging.
Abbreviations and symbols
| BW | = | Beeswax |
| DCM | = | Dichloromethane |
| DI | = | Deionized |
| DSC | = | Differential scanning calorimeter |
| EA | = | Ethyl acetate |
| EC | = | Ethyl cellulose |
| EE | = | Encapsulation efficiency |
| ER | = | Encapsulation ratio |
| FTIR | = | Fourier transform infrared spectroscope |
| MPCM | = | Microencapsulated phase change material |
| PCM | = | Phase change material |
| PU | = | Polyurethane |
| PVA | = | Polyvinyl alcohol |
| SEM | = | Scanning electron microscope |
| TES | = | Thermal energy storage |
| cp | = | Specific heat of the sample, |
| k | = | Thermal conductivity of the sample |
| MPCM1 | = | Microcapsules with BW/EC ratio 40:60 |
| MPCM2 | = | Microcapsules with BW/EC ratio 50:50 |
| MPCM3 | = | Microcapsules with BW/EC ratio 60:40 |
| MPCM4 | = | Microcapsules with BW/EC ratio 70:30 |
| MPCM5 | = | Microcapsules with BW/EC ratio 80:20 |
| ∆Hc | = | Crystallization enthalpy |
| ΔHc,M | = | Crystallization enthalpy of MPCM |
| ΔHc,P | = | Crystallization enthalpy of PCM |
| ∆Hm | = | Heat of fusion of the sample |
| ΔHm,M | = | Melting enthalpy of MPCM |
| ΔHm,P | = | Melting enthalpy of PCM |
| R | = | Radius of the test tube |
| Tcp | = | Peak crystallization temperature |
| tf. | = | Time of solidification of the molten sample |
| Tm | = | Melting temperature |
| Tmp | = | Peak melting temperature |
| Toc | = | Onset crystallization temperature |
| Tom | = | Onset melting temperature |
| T∞ | = | Temperatures of atmosphere |
| ρp | = | Density of the sample |
Acknowledgements
The authors acknowledge research facilities provided by Institute of Chemical Technology, Mumbai.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Author contributions
T.A. performed writing – original draft preparation; P.M. performed review and editing. All authors have read and agreed to the published version of the manuscript.
Data availability statement
The data presented in this study are available on request from the corresponding author.
Additional information
Funding
Notes on contributors
Tejashree Amberkar
Tejashree Amberkar is currently working as a PhD research fellow under the supervision of Prof. Prakash Mahanwar at the Institute of Chemical Technology, Mumbai, India. Her research focuses on investigating the thermal energy storage performance of phase change material in packaging applications. She has published twelve papers in international peer reviewed journals and presented research work at various international and national conferences. The prototype developed on the idea of her Doctoral research has received awards at International and National level.
Prakash Mahanwar
Prakash Mahanwar is Director of Institute of Distance & Open Learning at Mumbai University, India. He is also senior professor at Institute of Chemical Technology, Mumbai, India. He is owner of six national patents. He is bestowed with h-index of 33 and i-10 index of 83. He has published 200+ papers in following disciplines of Polymer Science: Biodegradable and Biocompatible Polymers, Polymer Blends and Composites, Control Release Formulations, Polymer Nanocomposites, Non-Conventional Energy Utilization for Polymer Synthesis, Micro and Nano Emulsions, Micro and Nano Encapsulation, Solar Energy Management Coatings, Green Decorative and High-Performance Coatings, Plastics Waste Management and Recycling.