Multi-microtubes formation and simulation of nanocellulose-embedded cryogel microspheres
The large-scale preparation of nanocellulose-embedded cryogel microspheres can be realized by crystallization pore-forming and low-temperature polymerization in a multi-microtube reactor.In this process,the formation of hydroxyethyl methacrylate monomer solution embedded with nanocellulose through multi-microtube reactor is the primary condition.It is of great significance to study the dynamic characteristics of the forming process.Using high-speed imaging and computational fluid dynamics(CFD)simulation methods,the droplet formation process of hydroxyethyl methacrylate embedded with different proportions(1%,3%,5%of monomer mass)of nanocellulose at different inlet flow rates(6,8,10 mm·s-1)was visualized.The effects of nanocellulose content on droplet formation,droplet diameter distribution,necking line length,droplet falling speed and other factors were investigated.The results show that the hydroxyethyl methacrylate droplets embedded with nanocellulose undergo stretching and compression processes after forming and dripping in a multi-microtube reactor,and finally stabilized into a spherical shape.The measured droplet diameter and necking line length were positively correlated with the cellulose concentration in the monomer solution.The increase of cellulose content increased the viscosity and surface tension coefficient of the monomer solution,thus increasing the droplet size and necking line length.The simulation results are basically consistent with the experimental results.The difference of droplet diameter is 2.1%—6.3%,and the difference of necking line length is 7.2%—11.9%.In the amplification simulation of droplet formation,the average droplet diameter is 3.98 mm and the average necking line length is 4.14 mm at the inlet velocity of 10 mm·s-1.Finally,a multi-microtube reactor was used to successfully prepare nanocellulose chimeric crystalline microspheres.The effective porosity of the microspheres can reach more than 80%,and the absolute dry porosity is close to 90%.It is an ideal carrier for the field of biological separation and the adherent growth of microorganisms.
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