Solvent cleaning polymers

Cleaning fabrics, quartz rods for light guide fibers, residues in microelectronics Removal of monomers, oligomers, and solvent from polymers Fractionation... 

Although atmospheric contamination of the polymer is generally minimal, it can be extensive because the dry polymer has a high affinity and capacity for almost all organic components. This situation is one of the reasons why the cleaned polymers are stored under an organic solvent such as methanol (78). With proper storage, the atmospheric contamination can be maintained well below interference levels. This situation is not the case for impurities from the polymerization process. 

It is generally known that to obtain pure fractions from a mixture of different plastics is a more expensive process than separation of simple clean polymers, in plant. Therefore, it is anticipated that the separation of a municipal mixed plastic waste should be the most challenging. In such a fraction, traces of foods, labels, dirt (size mm), solvents (alcohols, petrol etc.), metals, low molecular weight products of different origins etc. could be found. Some of the sorting methods used are listed in Table 1. 

Solid Samples Cut a piece approximately 2 in. x 3 in. x 5 in. from the corner of a polymer bale, and pass it through a cold mill, set at least V4 in. open, four times, reversing the sample on each pass. Cut the sample into two pieces at least 1 in. from the edge to expose clean polymer, and then dice approximately 2 g of the clean polymer or cut into small strips. Transfer 1.5 g, accurately weighed, into a 4-oz bottle fitted with a polyethylene cap, add 25.0 mL of the AMS-Solvent Solution, cap tightly, and agitate on a mechanical shaker until the polymer dissolves. 

The PFG NMR solvent suppression approach as discussed in this work removes all solvent peaks, impurities from the solvents, residual monomers, and small molecules reaction byproducts. As a result, the PFG NMR method permits the acquisition of a clean spectrum of polymers by LC-NMR and GPC-NMR. One can detect a signal such as the methoxy signal of pMMA (3.6 ppm) in THF which also resonates at about the same frequency. This is not possible with other well established techniques such as WET since the suppression is applied at selected solvent frequencies and all signals, solvent and polymer, in the vicinity of those frequencies will be eliminated. 

Cleaning polymer reactors, engines, machinery paint removers Water flushable. Removes vinyl, polyurethane, ABS. polystyrene, and other resin deposits. Residues usj ly dissolve vwlh mild agitation. Easily recovered. Can be used to improve formulations tor paint reriKivers ba on nonflammable solvents. Has synergistic effect in cold cleaners. 

These materials often have the same, or close to the same, chemistry as the base polymer. Therefore, they are often difficult to detect with ESCA or other analytical techniques. Typically the contaminants can be present in layers Inm to lOnm thick, even after solvent cleaning. They just continue to diffuse to the surface after solvent cleaning. Polyethylene is a particularly bad polymer for this problem. 

Most of the contaminants can be removed by an aqueous detergent wash or by other solvent cleaning possibly associated with mild liquid etching. However, care must be taken with cleaning fluids because they may be adsorbed into the polymer structure causing it to swell and possibly to craze on drying. 

Having produced the polymer in cells as a dilute aqueous fermentation broth, the next step is to isolate and purify it. The traditional method of achieving this is to evaporate most or all of the water by freeze- or spray-drying and then extract the PHB with a suitable organic solvent such as chloroform," methylene chloride1,2-dichloroethane," pyridine" or propylene carbonate.Alternatively, the polymer may be extracted into the organic phase directly from the fermentation broth if a solvent with very low water uptake such as 1,2-dichloroethane is used and emulsion formation is avoided. The cell debris may then be removed by filtration in the former case or by flotation in the latter to recover a clean polymer solution. 

Chlorine s most important use is as bleach in the manufacture of paper and cloth. It is also used widely as a chemical reagent in the synthesis and manufacture of metallic chlorides, chlorinated solvents, pesticides, polymers, synthetic rubbers, and refrigerants. Sodium hypochlorite which is a component of commercial bleaches, cleaning solutions, and disinfectants for drinking water, wastewater purification systems, and swimming pools—releases chlorine gas when it comes in contact with acids. 

Py-GC/MS and GC-MS - Separation and quantitative determination of pyrolysis products. - Extremely sensitive tool not only for ordinary solvent soluble polymers, but also for intractable cured polymers with three-dimensional networks. - Discrimination of isobaric pyrolysis compounds. - Detects only low-molecular-weight (up to mlz 600) and stable compounds. - Experimental methods have to be optimised for diverse polymer samples. - Time-consuming cleaning cycles. 

Features Exc. cleaning easy formulation compat. with most additives including alkalies, acids, solvents, metasilicates, polymers, anionics, cationics Regulatory Kosher... 

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