NUCLEATION PROCESS AND NUCLEATION MECHANISM OF MMA/BA SEEDED SEMI-CONTINUOUS EMULSION POLYMERIZATION

作者：Zhang Xinya^*; Sun Zhijuan; Jiang Qingmei; Chen Huanqin

来源：Acta Polymerica Sinica, 2009, 009(5): 409-418.

DOI：10.3724/sp.j.1105.2009.409

• Semi-continuous emulsion polymerization
• Nucleation mechanism
• Particles size and its' distribution
• Micellar nucleation
• Homogeneous nucleation

A water-insoluble dye (BL-S) was used as a probe to study the influence of some factors on the process of nucleation and nucleation mechanism in seeded semi-continuous emulsion polymerization. Some parameters were analysed for quantitative study on nucleation mechanisms, the parameters include the amount of dye incorporated into the resultant latex particles (P-dye), number of the resultant latex particles (N-p(c)) and the different numbers of particles which are formed by micellar nucleation (N-m) and homogeneous nucleation (N-h) The results of the study and analysis show that P-dye, N-h, N-m and N-h/N-p(c) all increase with Increasing initiator concentration [I], but N-m/N-p(c) decreases as N-m/N-p(c) = -0.0262 [I] + 0.8833, which can illuminate the proportion of homogeneous nucleation increases while micellar nucleation decreases with increasing [I] The influence of the emulsifier concentration [E] on nucleation mechanisms is different at different concentration range, when [E] equals to 0.7216 x 10(-2) mol.L-1, the proportion of homogeneous nucleation is equal to micellar nucleation, both of them are 50%. When [E] is greater than 0.7216 x 10(-2) mol.L-1, the nucleation time t(1/2) decreases and Nm/N-p(c) increases with increasing [E], N-h/N-p(c) decreases accordingly, and the proportion of micellar nucleation is larger than homogeneous nucleation, so that the micellar nucleation mechanism predominates gradually in the particle nucleation process; when [E] is less than 0.7216 x 10(-2) mol.L-1, the proportion of micellar nucleation is less than homogeneous nucleation, the main nucleation mechanism becomes to homogeneous nucleation. In the system of MMA/BA copolymerization, when f(MMA) increases from zero to 0.6, the value of Nm/N-p(c) decreases from 80.93% to 50%, which means that the proportion of micellar nucleation is larger than that of homogeneous nucleation, so that micellar nucleation plays a key role in the particle formation period. When f(MMA) increases from 0.6 to 1, N-m/N-p(c) is reduced to 40% and N-h/N-p(c) is raised to 60% but homogeneous nucleation is more important than micellar nucleation in this system. In addition,the t(1/2) is 12 min and 6 min for the conventional and seeded semi-continuous emulsion polymerization, respectively, but P-dye change is less. All these show that the both semi-continuous emulsion polymerization techniques only have some effect on the formation process of particles and the neculeation time,but little effect on their specific nucleation.

• 出版日期2009-5-20
• 单位华南理工大学