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Preparation, characterization, and prominent thermal stability of phase‐change microcapsules with phenolic resin shell and n ‐hexadecane core
Author(s) -
Jiang Yanbin,
Wang Dujin,
Zhao Tong
Publication year - 2007
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.25962
Subject(s) - materials science , thermogravimetric analysis , thermal stability , chemical engineering , fourier transform infrared spectroscopy , polymer , scanning electron microscope , melting point , microstructure , emulsion , differential scanning calorimetry , polymer chemistry , composite material , physics , engineering , thermodynamics
Abstract Microcapsules with phenolic resin (PFR) shell and n ‐hexadecane (HD) core were prepared by controlled precipitation of the polymer from droplets of oil‐in‐water emulsion, followed by a heat‐curing process. The droplets of the oil phase are composed of a polymer (PFR), a good solvent (ethyl acetate), and a poor solvent (HD) for the polymer. Removal of the good solvent from the droplets leads to the formation of microcapsules with the poor solvent encapsulated by the polymer. The microstructure, morphology, and phase‐change property as well as thermal stability of the microcapsules were systematically characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimety (DSC), and thermogravimetric analysis (TGA). The phase‐change microcapsules exhibit smooth and perfect structure, and the shell thickness is a constant fraction of the capsule radius. The initial weight loss temperature of the microcapsules was determined to be 330°C in N 2 and 255°C in air, respectively, while that of the bulk HD is only about 120°C both in air and N 2 atmospheres. The weight loss mechanism of the microcapsules in different atmosphere is not the same, changing from the pyrolysis temperature of the core material in N 2 to the evaporation of core material caused by the fracture of shell material in air. The melting point of HD in microcapsules is slightly lower than that of bulk HD, and a supercooling was observed upon crystallization. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007