Effect of molecular weight on the solidification rates of poly (alpha-methylstyrene) emulsions
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摘要: 为研究分子量对聚--甲基苯乙烯（PAMS）空心微球的乳液微封装制备过程中乳液固化速率的影响，实验采用分子量为300~800 kgmol-1的3种PAMS作为油相，测量在聚乙烯醇（PVA）和聚丙烯酸（PAA）两种外水相环境下，PAMS/氟苯（FB）乳液直径、油相浓度和FB扩散通量随固化时间的变化。结果表明，随PAMS分子量减小，PAMS油相浓度上升趋势变慢，FB扩散通量的峰值在分子量为300 kgmol-1时达到最小。因此，可通过降低PAMS分子量的方式来延长乳液的固化时间，从而降低FB的扩散速率，使乳液有足够时间调整形变有利于获得良好的微球球形度。Abstract: To research the effect of molecular weight on the solidification rates of the emulsion particles in the microencapsulation process of poly (-methyl styrene) (PAMS) hollow shells, three different kinds of PAMS with molecular weights 300, 440 and 800 kgmol-1 respectively as oil phase were further studied. In the curing process, the diameter of PAMS/FB droplets, the PAMS concentration and the evolution of FB diffusion flux under PVA and PAA solution were experimentally measured. The results show that the PAMS concentration increased slowly with the decreasing molecular weight. Especially, the summit of FB diffusion evolution flux achieved the minimum when the molecular weight of PAMS was 300 kgmol-1. Therefore, the curing time could be prolonged by reducing the molecular weight of PAMS and the diffusion rates of FB could be accordingly decreased, and during the key phase of the solidification process of double emulsions, the droplets could have enough time to adjust to obtain better sphericity.
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Key words:
- poly (alpha-methylstyrene) /
- solidification /
- diffusion flux /
- emulsion
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