Reactor surfactants, types

Particle nucleation and particle growth are important steps in emulsion polymerization because they affect the overall polymerization rate and polymer properties. Thus, initiator concentration and surfactant type/concentra-tion have significant effects on the polymerization kinetics. In a batch emulsion process, particle nucleation and growth steps can be separated to some extent by employing a multistage reaction process. In a continuous process, both particle nucleation and growth steps occur simultaneously unless a seed reactor is provided to separate these two effects. In general, latex particle size distributions obtained by batch and continuous processes are quite different. 

There is an extensive amount of data in the literature on the effect of many factors (e.g. temperature, monomer and surfactant concentration and types, ionic strength, reactor configuration) on the time evolution of quantities such as conversions, particle number and size, molecular weight, composition. In this section, EPM predictions are compared with the following limited but useful cross section of isothermal experimental data ... 

For the use of surfactant for remediation of the hydrophobic aromatic dyes polluted soil or sediment, based on the results presented in this thesis, the solubility enhanced of CAD by surfactant follow by photolytic destruction is a promising method. A further study to examine the application of this technique in different type of soil or sediments to solve the real world problem. Finally, a continuous pilot scale reactor for the dyes removal by both ACO and surfactant soil remediation is needed as a next step to further develop. 

Fractional gas holdup is an indication of the effective interfacial area in any gas-liquid system. Detailed discussion on fractional gas holdup in stirred reactors is available in Section 7A.5. Analogous to other parameters, the gas holdup is also a function of the operating parameters (superficial gas velocity, type of impeller and its size/position in the reactor, etc.) and system properties (liquid-phase viscosity, surface tension, solid density and loading, presence of surfactant, etc.). As discussed in Section 7A.5, YawaUcar et al. (2002a) have been able to obtain a unique correlation for the gas holdup using the concept of relative dispersion N/N ... 

At times, it is necessary to add a quantity of material all at once to a reactor in which an emulsion is already polymerising. For example, a relatively small amount of functional monomer could be added to a latex near the end of the polymerisation to produce a functionalised particle surface. Such a process is known at the shot-growth method (283). This method is often used in emulsifier-free polymerisations (69, 360) that contain no surfactant (but do use highly water-soluble, surface-active, functional monomers instead). During the early stages of emulsifier-free polymerisation, the particle size is determined primarily by the amount and type of initiator (such as potassium persulfate) and functional monomer (such as sodium styrene sulfonate). Latexes made in this manner tend to be narrow in size distribution. At high conversion (approximately 90%) an additional quantity or shot of functional monomer is added, and it chemically binds at the surface of the... 

Sonochemical Synthesis of M50 Type Steel Nanopowders. A dispersion of 15g (0.0765 mol) of Fe(CO)5, 0.66g of Cr(EtxC6H6-x)2, 0.75g (0.0015 mol) of CpMo(CO)3 and 1.0 g of polyoxyethylene sorbitan trioleate (surfactant) in dry decalin was sonicated at 50% amplitude for 7h at room temperature in a sonochemical reactor fitted with a condenser and gas inlet and outlet tubes connected to a mercury bubbler. The color of the solution turned dark and then black within a few minutes and this reaction mixture was sonicated until the formation of shiny metallic particles was observed on the walls of the reaction vessel. The sonication was then stopped and the decalin solvent was removed from the reaction flask via vacuum distillation. Fine black powder (Yield 4.448g) remained at the bottom of the reactor, which was then isolated, transferred to a vial and coated with mineral oil before the compaction. 

Abstract A new type of interfacial additive has been developed by the authors recently. The molecules of amphiphilic character are capable of forming chemical bonds at both the polar and the apolar sides. These reactive surfactants have been synthesised in a specially designed computer-controlled reactor system. The aim of the development was to combine the advantages of nonre-active surfactants and reactive coupling agents, making possible an... 

---