The kinetics of the emulsifier free seeded polymerization of butadiene at 60 O C in SmithEwart interval I11 was investigated using sodium peroxodisulfate as initiator. The aim of this work was to measure the propagation rate coefficient (k,) of butadiene at 60 "C in emulsion polymerization. Modelindependent techniques to measure propagation rate coefficients like spatially intermitted polymerizationsl-3 ("rotating sector" and "laser flash" photolysis) have not been used for butadiene so far since network formation prevents acquiring the necessary data from GPC. All experiments were conducted in the presence of tertdodecylmercaptan, as is usual in industrial practice. The fractional conversion was b d on gravimetrically calibrated on-line densitometry and was found to be highly accurate. By analogy with the well-known Ugeletad plots, the product of the propagation rate coefficient (k,) and the average number of radicale per particle (e) versus seed latex particle diameter clearly shows Smith-Ewart case I and case I1 regimes. From a constancy in values of kpR (case I1 regime) in this plot, a value for k, could be calculated that was 3 times larger than the current literature value. It was found that negligible "thermal background initiation" is present in the butadiene system. Two linear regions in polymerization rate are observed in interval 111. Model calculations are presented in excellent agreement with the experimental data. From these calculations a value of the rate coefficient for transfer to monomer, k,,, could be estimated.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.