Guolin Song

Preparation, thermal property, and thermal stability of microencapsulated n -octadecane with poly(stearyl methacrylate) as shell

This study focused on preparation and thermal properties of poly(stearyl methacrylate) shell (PSMA) microcapsules containing n-octadecane as a phase change material (PCM). Pentaerythritol triacrylate (PETA) and divinylbenzene (DVB) were employed as crosslinking agents. The surface morphologies, particle sizes, and distributions of the microencapsulated phase change material (microPCM) were studied by scanning electron microscopy. The thermal properties, thermal reliabilities, and thermal stabilities of the microPCMs were investigated by differential scanning calorimetry and thermal gravimetric analysis. The microPCM with DVB exhibits higher phase change enthalpies of melting (87.9xa0Jxa0g−1) and crystallization (94.8xa0Jxa0g−1) and a greater thermal stability in comparison with the microPCM with PETA. The phase change temperatures and enthalpies of the microPCMs varied little after thermal cycles. Thermal images showed that the gypsum board with PSMA/n-octadecane microPCM possessed temperature-regulated property. Therefore, microencapsulated n-octadecane with PSMA as shell has good thermal energy storage and thermal regulation potential.

Preparation and characterization of self-emulsified waterborne nitrocellulose

Waterborne nitrocellulose (WNC) dispersion was successfully synthesized by self emulsification and reaction among isophorone diisocyanate (IPDI), dimethylol propionic acid (DMPA) and nitrocellulose (NC). The WNC was characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and thermal gravimetric analysis (TGA), etc. The WNC dispersion has Z-average particle size of 133 nm approximately and distribution index of 0.152. It is indicated by TEM that the cured WNC particles show a core-shell structure, in which hydrophobic component is encapsulated by the hydrophilic carboxyl. FTIR confirms that the reactions (i.e. IPDI and NC, IPDI and DMPA) have occurred, the - NCO group of IPDI has been consumed totally and the backbone of NC is retained. TGA reveals that the cross-linked WNC film has better thermal resistance, and the water resistance measurement confirms that it has weaker water-sensitivity.