Preparation And Release Kinetic Of Pendimethalin Microcapsule

Microcapsule is researching hotspot now. Microcapsules of pendimethalin with a urea-formaldehyde resin wall were prepared by an in-situ condensation polymerization reaction in aqueous medium, and release rule was study by chromatogram analysis and bioassay.1. Microcapsules of pendimethalin with a urea-formaldehyde resin wall were prepared by an in-situ condensation polymerization reaction in aqueous medium. Several encapsulating parameters including dispersing and emulsifying agent, emulsification time, stirring speed, acidification time and curing temperature on microcapsule appearance quality such as encapsulation rate, particle size, and size distribution were investigated. Optimal reaction conditions were as follows: PAAS and SMA at weight ratio of 4:1(m/m), stirring for emulsifying at speed of 1500 rpm and last 60 min, acidifying for 90 min, and the curing temperature under 50℃for 90 min. Under these conditions, the average diameter of microcapsules was 9.6μm, uniform and spherical microencapsules of pendimethalin were obtained, and their encapsulation rate was above 99%.2. The quality specifications, including suspension rate and encapsulation rate, were measured after Pendimethalin 20% CS was prepared by an in-situ polymerization reaction in aqueous medium. All the results were up to standard. In additional, the encapsulation rate was above 99%, and suspension rate was above 85%. The changes of the encapsulation rate, content and suspension rate were determined after hot and cold storage. The rates of dehydration were determined too. After hot and cold storage, the encapsulation rate was still above 95%, suspension rate were above 82%, and the rates of dehydration were about 2%. The results showed that the specifications of pendimethalin 20% CS had no significant changes.3. The release velocity of microcapsule by gas chromatogram, at different core/wall ratios, different temperature, different moisture content. The results...