Acrylics, solvent extraction

Transition metal oxides or their combinations with metal oxides from the lower row 5 a elements were found to be effective catalysts for the oxidation of propene to acrolein. Examples of commercially used catalysts are supported CuO (used in the Shell process) and Bi203/Mo03 (used in the Sohio process). In both processes, the reaction is carried out at temperature and pressure ranges of 300-360°C and 1-2 atmospheres. In the Sohio process, a mixture of propylene, air, and steam is introduced to the reactor. The hot effluent is quenched to cool the product mixture and to remove the gases. Acrylic acid, a by-product from the oxidation reaction, is separated in a stripping tower where the acrolein-acetaldehyde mixture enters as an overhead stream. Acrolein is then separated from acetaldehyde in a solvent extraction tower. Finally, acrolein is distilled and the solvent recycled. 

Applications As the basic process of electron transfer at an electrode is a fundamental electrochemical principle, polarography can widely be applied. Polarography can be used to determine electroreductible substances such as monomers, organic peroxides, accelerators and antioxidants in solvent extracts of polymers. Residual amounts of monomers remain in manufactured batches of (co)polymers. For food-packaging applications, it is necessary to ensure that the content of such monomers is below regulated level. Polarography has been used for a variety of monomers (styrene, a-methylstyrene, acrylic acid, acrylamide, acrylonitrile, methylmethacrylate) in... 

There have also been several papers [61-63] on the importance of carefully establishing the reaction mechanism when attempting the copolymerization of olefins with polar monomers since many transition metal complexes can spawn active free radical species, especially in the presence of traces of moisture. The minimum controls that need to be carried out are to run the copolymerization in the presence of various radical traps (but this is not always sufficient) to attempt to exclude free radical pathways, and secondly to apply solvent extraction techniques to the polymer formed to determine if it is truly a copolymer or a blend of different polymers and copolymers. Indeed, even in the Drent paper [48], buried in the supplementary material, is described how the true transition metal-catalyzed random copolymer had to be freed of acrylate homopolymer (free radical-derived) by solvent extraction prior to analysis. 

The first palladium catalyzed reaction reported in an ionic liquid, by Kaufmann in 1996, was a Heck reaction.15 A series of aryl bromides were efficiently coupled with n-butyl acrylate in tributylhexadecylphosphonium bromide ([Ci6PBu3]Br) and tetrabutylammonium bromide ([NBu4]Br) to afford the trans-cinnamates in yields of over 90% in some cases (Scheme 1). Product isolation was achieved by distillation from the ionic liquid or by solvent extraction. 

Membrane technology may become essential if zero-discharge mills become a requirement or legislation on water use becomes very restrictive. The type of membrane fractionation required varies according to the use that is to be made of the treated water. This issue is addressed in Chapter 35, which describes the apphcation of membrane processes in the pulp and paper industry for treatment of the effluent generated. Chapter 36 focuses on the apphcation of membrane bioreactors in wastewater treatment. Chapter 37 describes the apphcations of hollow fiber contactors in membrane-assisted solvent extraction for the recovery of metallic pollutants. The apphcations of membrane contactors in the treatment of gaseous waste streams are presented in Chapter 38. Chapter 39 deals with an important development in the strip dispersion technique for actinide recovery/metal separation. Chapter 40 focuses on electrically enhanced membrane separation and catalysis. Chapter 41 contains important case studies on the treatment of effluent in the leather industry. The case studies cover the work carried out at pilot plant level with membrane bioreactors and reverse osmosis. Development in nanofiltration and a case study on the recovery of impurity-free sodium thiocyanate in the acrylic industry are described in Chapter 42. 

PA-6 (100-0) / SAN (0-100) or ABS / SMA (14 or 25% MA) (0-10) or imidized acrylate copolymer with 1 % MA content or SAN-co-IPO (1% oxazoline) double-extrusion on SSE / torque rheometry / mechanical properties / selective solvent extraction / SEM / lap shear adhesion / SAN + SMA double-extruded in separate step followed by extrusion with PA Triacca etal., 1991... 

Description The general flow diagram comprises six main sections reaction, quench, solvent extraction, crude acrylic acid recovery, raffinate stripping and acrylic acid purification. 

Solvent extraction (3) Liquid-liquid extraction is used to separate water and AA. The top of the extractor is forwarded to a solvent separator. The extractor bottom Is sent to the raffinate stripper (5) to recover solvents. Crude acrylic acid (CAA) is separated from the solvents by distillation. The overhead vapor is condensed in an internal thermoplate condenser. The two-phase condensate is separated. The organic phase is recycled. The aqueous phase is sent to the raffinate stripper (5). The column bottom, mostly AA and acetic acid, is routed to the CAA separator (4). 

Characterization of the graft copolymer by solvent extraction indicates that a substantial amount of the epoxy resin and of the acrylic are free. About 47% of the epoxy resin is ungrafted, 61%... 

Synthesis of epoxy-acrylic graft copolymer using free radical means was described. Characterization of the graft copolymer by solvent extraction indicated that the graft copolymer is consisted of the following ... 

PET (75)/PBT (25)/various phosphite condensing agents (0-5 %) Internal mixer at 275-280 °C/GPC/DSC/ torque rheometry/viscometry/selective solvent extraction/phosphoms analysis/ effect of PET end-group concentrations/ FTIR for end-groups concentration/effect of phosphite structure/model study with OH -t COOH-terminated acrylic polymer/ detailed mechanistic study Jacques et al. 1993, 1996a, b, 1997... 

PC (50-30)/imidized acrylate copolymer (77 % glutarimide, 19 % MMA, 3 % MAA, 2 % glutaric anhydride) (70-50) Internal mixer at 260-270 °C or solution casting/ETlK/optical microscopy/SEM/ TEM/SEC/model reactions/selective solvent extraction/comparison to blends with PMMA or with imidized acrylate copolymer cmitaining different imide levels, or no acid or anhydride/details of reaction mechanism Debier et al. 1995, 1997a, b... 

ERA (30-50)/PS-co-butyl acrylate-co-(t-butylperoxy methacryloyloxyethyl carbonate) (70-50) Brabender mixer at 180 °C/selective solvent extraction/effect of temperature on grafting efficiency/also blends of peroxide-containing polymer with PP Moriya et al. 1988 (see also Moriya et al. 1989)... 

This method proved valuable in the examination of a sample of acrylic sheet known from elemental analysis to contain phosphorus. Dry vacuum distillation of the polymer and solvent extraction both yielded a liquid, which, on direct infrared examination, proved to be an impure material containing phosphate or phosphite. The vacuum distillate at 200 °C was submitted to gas-liquid chromatographic examination on a 1.8 m (6.35 mm diameter) column packed with 30% w/w of silicone E301 on Celite maintained at 130 "C. A sample of the main component was taken by method 3 and the infrared spectrum obtained was readily identified as that of triethyl phosphate. 

The principal monomer used in the manufacture of superabsorbent polymers is acrylic acid. Acrylic acid is made by the oxidation of propene in two steps (5). First, propene is oxidized to acrolein, and then the acrolein is further oxidized to aciylic acid. Different mixed metal oxide catalysts are used for each step to optimize the yield and selectivity of the oxidation reactions. Technical-grade acrylic acid is isolated from the steam-quenched reaction gas by means of solvent extraction and distillation, and is used principally in the fiirther preparation of acrylate esters. The technical-grade acrylic acid is further purified by distillation or by crystallization from the melt to afford the polymerization-grade monomer. 

In case of printing paste, more than 5% w/w volatile organic compounds (VOCs) should not be permitted. These include acrylates, styrene monomers like acrylamide, butadiene, polyols, acrylonitrile, formaldehyde, hydrocarbons, ahphatic hydrocarbons (C10-C20), ammonia, etc. MSDS for printing formulation has to be supplied, and the testing can be done by solvent extraction and GC-MS methods. There is a restriction on the use of plastisols in printing binders and restricted phthalates including PVC. The threshold limit is 0.1%. 

In PVC technology certain polymeric additives can be considered as process aids. These polymers have a similar composition to those used as impact modifiers in PVC formulations but are more compatible and so are primarily included to ensure more uniform flow and hence improve surface finish. Such process aids include ABS, chlorinated polyethylene, MBS, EVA-PVC graft polymers and acrylate-methacrylate copolymers. As these are usually found in unplasticised PVC, direct analysis of the product by IR will usually indicate the presence of those that have a distinctive spectmm as no masking by plasticiser will take place. However, even rigid PVC can contain a small amount of phthalate and so it is advisable to carry out a solvent extraction to clean up the matrix first. Where the process aid (e.g., chlorinated polyethylene) has a relatively bland spectmm, a technique such as NMR will be required to both detect and quantify it. NMR will usually be required to quantify the other types as well, unless the spectrum is very distinctive and standards of known composition are available. 

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