Preparation And Performance Of Starch Based Waterborne Polyurethane Coated Fertilizer Materials

Waterborne polyurethane has good comprehensive performance that has no pollution and good working environment. In recent years, waterborne polyurethane has become a hotspot in research of chemical fertilizer coated materials. In this paper, the synthesis method is the solvent method of self-emulsifying. Waterborne polyurethane emulsion and waterborne polyurethane membrane are prepared using Poly-adipic acid glycol ester dibasic alcohol(PEA), 2,4-tolylene diisocyanate (TDI) as the main raw material,2,2-Bis(hydroxymethyl)propionic acid (DMPA) as hydropHilic chain extender. Starch based waterborne polyurethane emulsion and biodegradable starch based waterborne polyurethane membrane are prepared using water as dispersion medium, starch as material by the hybrid method. The optimal reaction conditions are determined by the appearance and centrifugal stability of the waterborne polyurethane emulsion, and the tracking test of NCO content. The results show that the optimal reaction conditions are that preparation of waterborne polyurethane for prepolymers polymerization temperature is 70℃, prepolymers polymerization time is 3.5 h, emulsifying temperature is 25 ℃.The optimal formula of reactants can be settled according to the appearance, centrifugal stability, viscosity, particle size of the waterborne polyurethane emulsion and the Infrared spectrum testing, surface water contact Angle, thermal stability of waterborne polyurethane membrane. The results show that the optimal formula of reactants of waterborne polyurethane are that R is 3-5, DMPA content is 5%～7%, the degree of 100%.Degradation behavior of starch based waterborne polyurethane membrane is detected by two methods that national standard degradation and soil burial degradation.The degradation behaviors of starch based waterborne polyurethane membrane is analyzed by measuring CO2 release quantity and weight loss rate and surface morpHology observation. The results show that the degradation behavior of starch based waterborne polyurethane membrane can be influenced by the tarch content, starch way, soil moisture and soil pH.The starch content is higher, degradation rate is faster. the degradation rate that starch based waterborne polyurethane membrane of starch content respectively are 0%,30%,40% respectively reached 4.84%,6.02% and 6.55% at 21 d in national standard degradation; the degradation rate that starch based waterborne polyurethane membrane of starch content respectively are 0%,10%,20%,30% respectively reached 12.96%,15.85%,17.28% and 24.64% at 43 d in soil burial degradation; Gelatinized starch’s starch based waterborne polyurethane membrane degradation degree and the speed is greater than without the gelatinization of starch’ s. The degradation rate respectively is 20.01% and 6.55% at 21 d in national standard degradation. In lower humidity of soil, degradation of starch based waterborne polyurethane membrane rate is higher. The degradation rate of the starch content of 30% starch based waterborne polyurethane membrane respectively reached 19.65% and 20.30% at 30 d in respectively the high humidity and low humidity of soil in soil burial degradation. The degradation rate of starch based waterborne polyurethane membrane is higher in acid soil than in neutral soil degradation rate is high. The degradation rate of the starch content of 30% starch based waterborne polyurethane membrane respectively reached 20.30% and 20.73% at 30d in respectively neutral soil and acid soil.