Preparation and Properties of Spray Polyurea Elastomer for Aquaculture Foam Floating Balls

[Objectives] This study was conducted to develop a polyurea elastomer which can be sprayed on the surface of expanded polystyrene (EPS) floating balls, so as to improve the surface strength and service life of the floating balls. [Methods] The effects of the types and amounts of isocyanate, chain extenders and polyether polyols on the gelation rate, adhesion and wear resistance of polyurea elastomer were investigated, and it was finally determined the preparation process of polyurea elastomer using liquid isophorone diisocyanate (IPDI) and amino-terminated polyether (D2000) as the main raw materials, dimethylthiotoluene diamine (E300) as the chain extender and silica as the wear resistance modifier through two-step solution polymerization of prepolymerization and chain extension. [Results] The physical properties and chemical resistance tests of spray polyurea elastomer showed that it had good physical properties and acid and alkali resistance, and could meet the requirements of spraying and protection of EPS floating ball surface in marine environment. [Conclusions] Polyurea elastomer coating can improve the aging resistance, wear resistance and acid and alkali resistance of EPS floating balls, and prevent them from being fragile and floating randomly to form marine floating garbage which results in "white pollution".

Shell-formation mediated surface composition of uniform two-component microparticles fabricated by micro-fluidic spray drying: Effect of component size and solubility

This work is aimed to study the effects of component size and solubility on the surface composition of spray dried(SD)uniform two-component particles fabricated by micro-fluidic spray dryer.Various precursor liquid consisting of small molecular of methionine(Met,33 g/L)or lysine(Lys,739 g/L)and large-sized silica(12 nm)were prepared by adjusting the mass ratio of components.X-ray energy disper-sive results showed that the respective enrichment degree(De)of Met and Lys on the surface of SD-M1S9 and-L1S9 prepared at 150 C were 182±9% and 125±14%.The De of hydrophobic Met for SD-M1S1 and-M9S1 were 46±9% and 4±2%,respectively,whereas relative hydrophilic Lys mainly distributed internal of the particle meanwhile the De of silica on the surface for SD-L1S1 and-L9S1 were 17±4%and 12±1%,respectively.Drying temperature(120 and 180℃)showed more apparent effect on the De of amino acid for the particles of less amino acid.The possible formation mechanism of surface composition and the surface composition impact on the wettability of particles were explored.These results provide new guidance for manufacturing functional SD powders with various components.