BaTiO3 nanoparticles with extremely high loading are chemically bonded with silicone rubber via “thiol–ene click”, leading to superior dielectric properties.
Summary
Novel microencapsulated phase change materials (MEPCMs) composed of the lead tungstate (PbWO4) shell and paraffin core were designed for shielding of gamma radiation as well as thermal energy storage. Such MEPCMs were prepared via self‐assembly methods and in‐situ precipitation. The PbWO4 shell with excellent photon attenuation can give the resulting MEPCMs an acceptable gamma radiation shielding capability. The chemical composition and structure of microcapsules samples were studied by X‐ray diffractometer (XRD) and Fourier‐transform infrared spectroscopy (FTIR). The effects of different core/shell mass ratios on the surface morphology and microstructure of the MEPCMs were determined by scanning electron microscopy (SEM), energy‐dispersive spectrometer (EDS), and transmission electronic microscopy (TEM). It was confirmed that the microcapsules exhibit a distinct core‐shell structure and a perfect spherical shape. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to present thermal stability and thermal‐storage capability of MEPCMs. A high‐purity germanium gamma spectrometer to measure the attenuation coefficient of the microcapsules for gamma rays showed that the MECPMs has good γ‐rays‐shielding property. The multifunction microcapsules in this study have great potential applications for building energy conservation as well as wearable personal protection in nuclear energy engineering.
A kind of silicone rubber (SR)/paraffin (Pa)@silicon dioxide (SiO 2 )@polydopamine (PDA) phase-change composite was prepared in this work. The double-shelled Pa@SiO 2 @PDA phase-change microcapsules were constructed by oxidative self-polymerization of dopamine (DA) in Tris-HCl buffer solution. The effect of the DA content on the properties of Pa@SiO 2 @ PDA microcapsules and SR/Pa@SiO 2 @PDA composites was researched. Due to the protective effect of SiO 2 , PDA layer, and SR matrix, the SR/Pa@ SiO 2 @PDA composites have good leak-proofing performance, and the leakage rate of SR/Pa@SiO 2 @PDA-2 is as low as 0.45%. Phase-change enthalpies of the Pa@SiO 2 @PDA microcapsules and SR/Pa@SiO 2 @PDA composites are reduced slightly with increasing DA content. Meanwhile, the composites displayed improved mechanical strength. The tensile strength of SR/Pa@SiO 2 @PDA-2 can be up to 0.560 MPa, which is 1.85 times higher than the tensile strength of pure SR/Pa@SiO 2 because the interface compatibility between Pa@SiO 2 microcapsules and SR is improved through hydrogen bonding between the abundant groups on the PDA surface and the matrix. Moreover, the rough surface of the PDA-modified microcapsules also enhances the interface interaction through physical "interlocking". The new kind of SR/Pa@SiO 2 @PDA composite can be used for thermal management.
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