A Unified Theoretical Treatment on Statistical Properties of the Semi-batch Self-condensing Vinyl Polymerization System

We present a novel generating function (GF) method for the self-condensing vinyl polymerization (SCVP) system with any initial distribution of preexisted polymers.Such a method was proven to be especially useful to investigate the semi-batch SCVP system allowing a sequence of feeding operations during the polymerization.Consequently,the number-,weight-,and z-average molecular weights as well as dispersity index of hyperbranched polymers can be explicitly given,which are determined by predetermined feeding details and conversions in each polymerization step.These analytical results are further confirmed by the corresponding Monte Carlo simulations.Therefore,the present GF method has provided a unified treatment to the semi-batch SCVP system.Accordingly,hyperbranched polymers with desired properties can be prepared by designing feeding details and presetting conversions at each step based on the present GF method.     

Analysis of semibatch emulsion polymerization: role of ultrasound and initiator

In this work semibatch miniemulsion was carried out wherein the effect of free radicals produced by ultrasound and an external addition of initiator was examined. Influence of different variables on polymerization rate and polymer particle size has also been investigated. Over a range of 0-4% (by wt) initiator, the polymerization rate was found to increase over a range of 0.56-1.33 g L⁻¹ min⁻¹. Similarly monomer concentration range (7.2-15 wt.%) changed the polymerization rate from 1.33 to 2.61 g L⁻¹ min⁻¹. Under optimum parametric conditions polymer particle size 50 nm were obtained with a narrow size distribution. Syndiotactic phase of PMMA was observed by controlling the formulation recipe. Although, number of reports could be found in the literature [9], [13], [17], [18], [20] and [22] related to batch emulsion polymerization, this experimental data could be useful for the production of large scale monodispersed PMMA latex as all of the scale-up and design parameters have been qualitatively addressed.     

分批投料模式下加核自缩合乙烯基体系的Monte Carlo模拟

通过Monte Carlo 模拟方法对加核自缩合乙烯基体系在分批投料模式下的聚合行为进行研究, 考察了引发核的加入时间及分批投料方式对超支化高分子的重均分子量及多分散指数的影响. 研究结果表明, 不同的分批投料方式对超支化高分子的重均分子量和多分散性具有显著的调控作用. 通过调整投料方式、 投料次数、 引发核官能度和转化率等因素, 可以得到分子量较高且多分散性较好的超支化高分子.     

High-molar mass acrylamide-co-diacetoneacrylamide graft copolymers as viscosity enhancer for polymer flooding oil recovery

One of the most widely applied enhanced oil recovery processes is the polymer flooding, in which aqueous solution of polymer viscosifier is introduced in oil reservoirs to increase the recuperation of the remaining oil. From the current challenges of this process, it can be referred to a high cost of materials regarding their substantially required amount and the low impact on the mobility ratio during the process due to the reduction of solution viscosity at high temperatures and high salinity environments. The purpose of this study is to investigate the concept of acrylamide-based thermosassociating copolymer (TAP), with a specific morphology and chemistry (hydrophilic main backbone made of polyacrylamide with grafted amide functionalized pending chains) as viscosity enhancer at harsh conditions of high temperature and salinity. For that aim, a specific TAP microstructure was targeted (very high molar mass linear polymer chains with improved copolymer homogeneity). It is achieved in this study throughout applying the reaction engineering approach, such as synthesis in semi-batch mode or/and in heterogeneous dispersed media. As a result, the synthesized TAP presented excellent behavior as viscosity enhancer especially under high temperature and salinity conditions with improved performance in comparison to TAP synthesized by a conventional solution polymerization approach and to actual commercial high molar mass acrylamide-based polymer.