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".

声波激励的超小型纳机电系统磁电天线

当前的小型天线依赖于电磁波的谐振,因此天线的尺寸与电磁波波长相关。典型的天线尺寸大于波长的1/10,而进一步缩小天线尺寸在近十年来都是一个公开的挑战。介绍一种通过悬浮铁氧/压电薄膜异质结构的声波激励纳机械磁电天线。这种磁电天线通过其在声波谐振频率处的磁电效应接收和发射电磁波。磁电天线中的体声波激发铁磁薄膜的磁化振荡,产生电磁波的辐射;反之,天线感应电磁波的磁场,得到压电电压输出。这种磁电天线(尺寸仅为波长的千分之一)比现有小型天线的尺寸小1到2个数量级,但性能却没有降低,在便携式无线通信系统中具有很大的应用潜力。