Biodegradable polymers having good toughness were used as compatibilizers for the polymer blend system of poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) to replace the inorganic or non- degradable compatibilizers. Biodegradable polymers such as poly(butylene succinate) (PBS), poly(butylene adipate- co-terephthalate) (PBAT), and poly(hydroxybutylate-co-valerate) (PHBV) have capability to mix with PLA. Polymer blends of PLA/PBAT (70:30) were added with 1, 3 and 5 phr of PBS, PBSA and PHBV. It was found that thermal property of polymer blends slightly decreased, melting temperature (Tm) of the compositional polymers were almost not changed which indicated the phase separation of compositions. The melt flow of polymer blends increased with increasing amount of PBS while it was not changed with addition of PBSA and PHBV. Modulus of polymer blend with addition of 1 wt% PHBV was slightly increased while modulus of most of the polymer with addition of PBS and PBSA decreased. The results confirmed the phase separation of polymer components

Which is right, ΔH_m (J/g-paraffin wax) or ΔH_m (J/g-capsules) to understand thermal properties of microcapsules?

Poly(divinylbenzene) (PDVB) microencapsulated octadecane (OD) (PDVB/OD) for use as a heat storage material was prepared by the microsuspension polymerization of DVB/OD droplets, first generated by phase inversion emulsification (PIE). The influence of the surfactant on the colloidal stability, particle size and particle size distribution (PSD) was investigated. Capsules with a size of approximately 1.5 μm, a narrow PSD, and good colloidal stability throughout the polymerization were obtained using polyvinyl alcohol and sodium dodecyl sulfate as the surfactant and cosurfactant, respectively, in the process of PIE. The optical and scanning electron micrographs showed that the microcapsules have a spherical shape and display a dented surface. The thermal properties and thermal stability of the PDVB/OD microcapsules were determined using a differential scanning calorimeter (DSC) and thermogravimetric analyzer, respectively. From the DSC analysis, the onset melting temperature (T_m) of the encapsulated OD (22.6 °C) was slightly lower than that of the bulk OD (28.7 °C), while it was significantly different in the case of the crystallization temperature (T_c, 12.4 °C and 26.3 °C for encapsulated and bulk OD, respectively). The latent heats of melting (H_m, 192 J g⁻¹-OD) and crystallization (H_c, 195 J g⁻¹-OD) of the encapsulated OD were close to those of the bulk OD (215 and 220 J g⁻¹, respectively).

The microencapsulation of jasmine oil with polymethyl methacrylate (PMMA) was carried out by solvent evaporation method in oil in water (O/W) emulsion system. The oil phase was formed by the mixing of PMMA, jasmine oil and toluene and then dispersed in polyvinyl alcohol solution as stabilizer. After solvent evaporation, PMMA microcapsules with encapsulated jasmine oil were formed. The influence of weight ratio of PMMA:jasmine oil on the preparation of polymer capsule was studied. It was found that using 1:1 weight ratio of PMMA:jasmine oil, the polymer capsules could not prepared. The increase of PMMA content resulting in the formation of spherical PMMA microcapsules as in the case of 2:1 and 3:1 weight ratios. The amount of encapsulated jasmine oil and the encapsulation efficiency was measured with UV-visible spectroscopy. Approximately 72% encapsulation efficiency was obtained