苯乙烯-马来酸酐共聚物对20%除虫脲悬浮剂分散稳定性的影响

Effect of Styrene-Maleic Anhydride Copolymer on the Dispersibility of 20%Diflubenzuron Suspension Concentrate

以过氧化苯甲酰为引发剂,采用溶液共聚法在不同温度下合成了一系列苯乙烯-马来酸酐共聚物,经磺化制得不同相对分子质量的聚苯乙烯-马来酸酐磺酸钠(SSMA)。通过测定平均粒径、Zeta电势、黏度等考察了SSMA对20%除虫脲悬浮剂分散稳定性的影响。结果表明,最佳分散剂为75℃聚合得到的SSMA,其质量分数为3%时,水悬浮剂的分散稳定性最好;当pH=9时SSMA分子完全电离,能为颗粒提供较大的空间势垒,水悬浮剂分散稳定性最好;Na+或Ca2+压缩颗粒界面的双电层,降低Zeta电势的绝对值,使颗粒因带电量减少而聚结,导致水悬浮剂分散稳定性变差;当离子浓度相同时,Ca2+的聚沉能力强于Na+,添加Ca2+后的水悬浮剂的分散稳定性更差。

With benzoyl peroxide as initiator, a series of styrene-maleic anhydride copolymer was prepared by solution copolymerization under different temperatures. Polystyrene-maleic anhydride sulfonic acid sodium（SSMA） with different relative molecular mass was obtained by sulfonated the polystyrene-maleic anhdride. The dispersibility of 20% diflubenzuron suspension concentrate was identified by assaying and analyzing the diameter of particles, Zeta potentials and viscosities. The results showed that the optimal dispersant was SSMA, which was prepared at 75 ℃, and the most suitable concentration was 3%. At pH=9, the dispersion stability of suspension concentrate was the best due to the strong steric hindrance provided by completely ionizing of the molecules. Na＋ or Ca2＋ was able to decrease the absolute value of Zeta potential by compressing the electronic double layer thickness of particles surface, which could lead to particles aggregation due to the reduction of electric quantity and ultimately deteriorate the dispersive effect of suspension concentrate. If the ions concentration were the same, the coagulation capacity by Ca2＋ was stronger than that of Na＋, and the dispersion stability of suspension was worse after adding Ca2＋.