Effects of Mixed Costabilizers on the Ostwald Ripening of Styrene Miniemulsion : CA/n-alkanes

• Main Authors: Ratna Herly Safitri, 何瑞娜
• Other Authors: Chorng-Shyan Chern
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/3qzq6d

碩士 === 國立臺灣科技大學 === 化學工程系 === 100 === The effect of costabilizer concentration on the Ostwald ripening rate of various miniemulsion systems comprising styrene (ST) as monomers, and stabilized by either Cetyl Alchohol (CA), n-alkanes, or mixed CA with n-alkanes (Decane, Dodecane, Hexadecane from lilik’s data, Octadecane, and Tetracosane) was investigated. The miniemulsions were prepared by dispersing ST in water using surfactant (SDS) and either CA , n-alkanes or mixed CA/n-alkanes than homogenize using sonicator. For ST/CA miniemulsion system determined at costabilizer volume fraction (??) in the range of 0.005-0.05 and for ST/n-alkanes in the range (??) in the range of 0.005-0.02. The results showed that miniemulsion droplets decrease in diameter with increasing costabilizer concentration. The Ostwald ripening rate data only follow Kabalnov’s equation at low costabilizer volume fractions. At higher costabilizer volume fractions, they deviated significantly as the costabilizer volume fraction was increased. For miniemulsions stabilized using mixed costabilizer (CA and n-alkanes) were determined at the costabilizer volume fraction in the range of 0.005-0.02 with the composition CA: n-alkanes= 0:1; 0.2:0.8; 0.35:0.65; 0.5:0,5; 0.65:0.35; 0.8:0.2; 1:0. The average droplet size increases with time in every composition. The K1 value is found decrease with increasing the molar ratio of CA to n-alkanes. The effectiveness of n-alkanes in suppressing Ostwald ripening decreases by increasing the molar ratio of CA in the miniemulsions system and vice versa. However, n-alkanes is still more dominant in retarding the ostwald ripening rate than CA in the mixed costabilizer miniemulsion system. The role of the mixed costabilizers of CA and n-alkanes in retarding Ostwald ripening occurring in the three component disperse phase styrene monomer miniemulsion was investigated. All the results that are self consistent with one another justify the validity proposed pseudo two component dispersion phase miniemulsion model. The predictions obtained from the modified Kabalnov equation severely deviate from the Ostwald ripening rate data for the three-component disperse phase ST miniemulsions with CA/n-alkane = 0.5/0.5. Mix costabilizer of CA with longer chain of n-alkanes (Octadecane and Tetracosane) give an synergetic effect showed from the data close to non linear equation than linear equation. It competes with mix costabilizer of CA with shorter chain of n-alkanes, it result no synergetic effect. It means the single costabilizer give the best work to retarding Ostwald ripening rate than combinantion of CA with shorter chain n-alkanes (Decane and Dodecane). While in the middle, combination of CA-Hexadecane give the average value, the same difference to non linear equation and linear equation.