Bei Gong,Wenxia Liu,Xueshuai Chen,Hua Tan,Xiuli Zhang,Huili Wang,Dehai Yu,Guodong Li,Zhaoping Song
Stabilizing alkenyl succinic anhydride (ASA) emulsions using fine particles instead of cationic starch have attracted much attention in recent years. Herein, starch nanocrystals (SNCs) made from maize starch by H 2 SO 4 hydrolysis were used to co-stabilize ASA emulsions with fluorescent carbon dots (CDs) made hydrothermally from gelatin. The introduction of CDs can significantly enhance the stability and reduce the droplet size of SNC-stabilized ASA-in-water emulsions. Consequently, the sizing performance of the SNC-stabilized ASA emulsion is significantly improved by increasing the CD-to-SNC mass ratio. SNC and CD co-stabilized ASA emulsions show much better sizing performance than starch and CD co-stabilized ASA emulsions, achieving their best sizing performance at a CD-to-SNC mass ratio of 80%. Meanwhile, the morphology of SNC/starch and CD co-stabilized ASA emulsions can be traced under UV excitation.
Hua Tan,Wenxia Liu,Dehai Yu,Haidong Li,Martin A. Hubbe,Bei Gong,Wei Zhang,Huili Wang,Guodong Li
Alkenyl succinic anhydride (ASA) is a widely used paper sizing agent that is applied in the form of oil-in-water (o/w) emulsions in order to impart a water-resistant character to the resulting paper. To obtain stable o/w emulsions of ASA, laponite, a highly hydrophilic synthetic clay, was selected as the stabilizer after it had been modified with tetramethylammonium chloride (TMAC), a quaternary ammonium salt with the shortest possible hydrocarbon groups. It was found that the TMAC moderately neutralized the negative charges of laponite particles, lowered the apparent viscosity, but enhanced the turbidity of laponite aqueous dispersion by enhancing the hydrophobicity of the laponite particles, favoring adsorption of laponite particles on the ASA–water interface. Meanwhile, the TMAC significantly decreased the interfacial tension between ASA and water/aqueous laponite dispersion, promoting the formation of an emulsion with small droplets. When the added amount of TMAC reached 1 wt% based on laponite, the as-prepared ASA emulsion had small droplet size, low viscosity and uniform droplet size distribution, and exhibited good creaming/coalescence stability. By using TMAC to modify laponite nanoparticles , the hydrolysis stability and sizing performance of ASA emulsion were also improved.
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