Research on the Crystallization of the Surface Modified PEO Particles
|School||Tianjin Polytechnic University|
|Keywords||Surface-modified particles Polyoxyethylene Isothermal Crystallization Non-isothermal crystallization DSC|
According to the basic principle of the the Wurster experimental apparatus, the Wurster experimental design for improving means; in the Wurster experimental apparatus, the film formation method using the air suspension to the PEO particles subjected to a surface modification, the formation of surface-modified PEO particles of different size categories by DSC experiment and hot stage polarized light microscopy experiments PEO particles of different sizes of conduct such as mild non-such as isothermal crystallization experiments, study the the PEO particles at different temperatures, etc. isothermal crystallization process and different cooling rates PEO particles of non-such as temperature and crystallization process, and trying to find out the suitable resolution The cooling crystallization kinetic parameters of the equation. Experimentally proven to improve the Wurster experimental apparatus suitable for laboratory preparation of the surface-modified PEO particles. For particles in the PEO phase change occurs within the temperature interval, the finishing layer without the surface modification of the thermal effects of the PEO particles with a heat of fusion and heat of crystallization can be obtained surface-modified PEO particles content and the thickness of the finishing layer. The measured thickness of the modified layer with the microscope using phase change heat resulting surface-modified PEO particles surface-modified the PEO particles in the thickness of the finishing layer is consistent. Surface-modified particles of PEO spherulites met the modified layer until it fills the end of the limited space crystallization, without modification of PEO particles in spherulite growth after a period of time, collide with each other to squeeze until the end until it fills all the voids crystalline, surface; modified the PEO particles of crystalline half time and crystallization fastest time shorter; surface-modified the PEO particles and unmodified PEO particle size of less than 400 m, the surface-modified the PEO particles of crystalline peak position moves to the high temperature. Isothermal crystallization kinetics, as the temperature rises, the slower the rate of crystallization of PEO particles; increases with the molecular weight of PEO particles slow crystallization rate. Scattered off-the-shelf nuclear lead to surface modification of PEO particles isothermal crystallization process multiple crystallization peak. Non-isothermal crystallization process, as the cooling rate increases, the rate of crystallization of the PEO particles larger; composite crystallization rate increases. Avrami exponent n in each cooling rate close to 3. Surface-modified the PEO particles in the crystallization rate constant and the crystallization rate constant compared to the unmodified PEO particles in the initial stage of crystallization, the crystallization rate constant is smaller; in the later crystallization, the crystallization rate constant. Determine the nucleation or Avrami exponent n, K (T) as the Gaussian get crystallization kinetics differential equations more suitable to resolve the constant velocity cooling kinetics of non-isothermal crystallization parameters.