Polymers purification

Polymerization Solvent. Sulfolane can be used alone or in combination with a cosolvent as a polymerization solvent for polyureas, polysulfones, polysUoxanes, polyether polyols, polybenzimidazoles, polyphenylene ethers, poly(l,4-benzamide) (poly(imino-l,4-phenylenecarbonyl)), sUylated poly(amides), poly(arylene ether ketones), polythioamides, and poly(vinylnaphthalene/fumaronitrile) initiated by laser (134—144). Advantages of using sulfolane as a polymerization solvent include increased polymerization rate, ease of polymer purification, better solubilizing characteristics, and improved thermal stabUity. The increased polymerization rate has been attributed not only to an increase in the reaction temperature because of the higher boiling point of sulfolane, but also to a decrease in the activation energy of polymerization as a result of the contribution from the sulfonic group of the solvent. 

In the polymer industry, post-reaction product treatment processes such as liquid-solid separation, drying, precipitation, particle size control, and polymer purification are very complex and costly. Future polymer plants should be designed such that process equipment can be easily and quickly converted to making new products at minimal cost and with... 

A strict vacuum-line technique was used for purifications of solvent, monomer, and initiator, preparation of solutions and polymerization. Polystyryllithium of a degree of polymerization of about 15 was prepared by using n-butyllithium and was used as a seed polymer. Purifications of reagents were most carefully carried out. See the original literature for details 17). 

In the second step (Scheme 1), 0.5 g azo-polysiloxane was dissolved in 7ml DMSO under stirring the necessary quantity of nucleobase (as a function of the imposed substitution degree) and -0.1 g K COj were added and then the reaction mixture was heated 9 h at 55°C (under nitrogen atmosphere). The polymer was precipitated in methanol and washed 3 times with methanol to eliminate the unreacted products and dried under vacuum. In the case of donor/acceptor groups, 0.5 g azo-polysiloxane was dissolved in 7 ml DMSO under stirring the necessary quantity of sodium phenoxide and 0.1 g Bu NHSO were added and then the reaction mixture was heated 4-5 h at 80°C. The polymer purification was similar. 

Poly(/V-vinylpyrrolidone) [9003-39-8] M (111.1) , crosslinked/25249-54-7/m >300. Purify it by dialysis, and freeze-drying. Also by precipitation from CHCI3 solution by pouring into ether. Dry it in a vacuum over P2O5. For the crosslinked polymer purification is by boiling for lOminutes in 10% HCl and then washing with glass-distilled water until free from Cl ions. Finally, Cl ions are removed more readily by... 

Polymer purification Residual HC stripping with wet nitrogen... 

A variety of methods have been employed to functionalize polyesters with bioactive molecules. One approach is to graft the biomolecule in polyester before it is subject to the electrospinning process. Grafting methods permit control of the extent of functionalization in all stages. However, using this method after electrospinning, a part of the bioactive molecules is located in the core of the fibers, inaccessible for the cells. Therefore, an additional step for polymer purification can be necessary. This step can increase the cost of scaffold production. 

From a manufacturing standpoint, the interfacial process is capital-intensive to purify the resin solution, isolate and dry the resin, and recycle solvents and brine. With melt transesterification, because it is a solventless process, the only recycle streams that must be dealt with are those related to the recovery of phenol for reuse in the production of DPC. Hence, there is no need to invest in solvent recovery infrastructure with the melt process, and polymer purification units and dryers can likewise be avoided. However, these investments are somewhat diminished by the investment required for the preparation and purification of DPC. 

Propylene polymerization processes, including slurry, gas-phase and liquid pool polymerization, have been reviewed by Lieberman and Barbe [70]. Progress in catalyst development is reflected by significantly simpU-fied polymerization processes and markedly reduced environmental pollution. As is apparent from Figure 18, which displays the general scheme of an olefin polymerization process, in gas-phase and Uquid pool processes hydrocarbon diluents and deactivations as well as polymer purifications steps are eliminated. Reactor granule technology forms... 

Sulfolane is used as a polymerization solvent for the production of polysulfones, polysiloxanes, polyphenylene ethers, and other polymers. Sulfolane is said to increase the reaction rates, afford easier polymer purification, and improved thermal stability. Sulfolane is a solvent for dissolving a variety of polymers for use in the fiber-spinning process. Cellulose and cellulose ester polymers can be plasticized with sulfolane to give improved flexibility and other physical property improvements [12,13]. Other application areas that have used sulfolane include electronic and electrical, textile-dye uses, curing of polysulfide sealant, and as a catalyst in certain synthetic reactions. 

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