Compounding melt filtration

To 20 g of the above compound dissolved in 300 ml 95% ethanol In a Parr reaction vessel is added 1.5 g Adams catalyst, platinum dioxide, and the mixture shaken under hydrogen at 50 psi for 1 hour at ambient temperature. The mixture Is then filtered and the ethanol removed on a standard rotary evaporator. The resulting oil is dissolved in 200 ml ether and slowly added to 1,200 ml ether with continuous stirring. The product separates as crystals which are removed after 15 to 30 minutes by filtration. The compound melts at 148°C to 147°C and needs no further purification. 

To a mixture of 60 cc of benzene, 40 cc of pyridine and 17 g of hydrochloric acid salt of nicotinic acid chloride, was added 4.5 g of 2,2,6,6-tetramethylolcyclohexanol, and the whole mixture was refuxed at 75°C to 80°C for 2.5 hours. After the mixture was cooled water was added. Precipitate formed was separated by filtration, washed thoroughly with water and dried. Recrystallization from dilute acetic acid gave 14gof the final compound, melting point 177°Cto 180°C. 

The solvents were evaporated in vacuo, and the residue was taken up in 80 ml of 3M hydrochloric acid. After addition of 220 ml of water, the insoluble material was filtered off, washed with 100 ml of water and then dried. The insoluble material weighed 9.5 g and was mainly unreacted bromo compound. The filtrate was reacted with 50 ml of 7 M NaOH, extracted three times with methylene chloride (50 m -t 2 x 25 ml portions), dried over potassium carbonate, and then evaporated. The yield of residue was 26.8 g which corresponds to 71.4% of the theoretical yield. This residue was a colorless solidifying oil and was dissolved in 200 ml chloroform. Hydrogen chloride was bubbled in until a sample of the solution tested acidic to wet pH indicator paper. A precipitate was obtained and recovered by filtration. The precipitate was washed with chloroform and dried. The melting point was determined to be from 246 Cto247.5°C. 

The Vinyloop process is based on the selective dissolution of PVC used in composites applications like cable insulation, flooring, tarpaulins, blisters, etc. After removal of insoluble parts like metals, rubber or other polymers, the PVC is reprecipitated with all additives by introduction of a non-solvent component whieh will form with the seleetive solvent an azeotropie mixture. By using typical conditions, the process is able to reeover a pure PVC eompound powder ready for use without any additional treatment like melt filtration or a new pelletisation (speeific characteristics of the powder are average diameter of 400 microns and bulk density above 600 kg/ eub.m). All the solvents used are eompletely reeyeled and reused. PVC compounds recovered in the Vinyloop process can be reused in a closed-loop recycling scheme... 

Melt filtration systems are commonly employed in pigment master-batch production and in situations where the presence of defects in the compound may have a critical effect on its subsequent processing or properties. This is vitally important, for example, in fibre-spinning operations involving extrusion of polyester or polyamide through fine spinneret plates [162], and in minimizing breakdown of polymer cable insulation subjected to electrical stress [163]. 

A solution of 3-acetamino-adamantane-l-carboxylic acid (3.0 g) in 4 N sodium hydroxide (40 ml) was refluxed for 5 h. After cooling, the pH of the solution was adjusted to 7 with acetic acid. The crystalline precipitate was filtered off, washed with ethanol and dried to yield 2.20 g of the desired compound, melting point over 330°C. In order to purify the compound, 2.0 g of it was suspended in water (10 ml), 4 N NaOH (2 ml) was added, and the resulting solution filtered through a filter aid known under the registered trademark Dicalite. The filtrate was adjusted to a pH of 6.5 with acetic acid. The resulting crystalline precipitate was filtered off, washed with a little water followed by alcohol, and dried to yield 1.55 g of pure 3-amino-adamantane-l-carboxylic acid. 

The residue was subjected to azeotropic operation with toluene two times, and ether was added to the residue. The precipitate derived from trioxane was removed by filtration and washed with ether, and the combined ethereal solutions were concentrated under reduced pressure. The residue was dissolved in ethyl acetate, and the solution was washed with water and aqueous saturated solution of sodium chloride, was dried, and was concentrated to give 4 g of an oily material. The oily material was dissolved in 20 ml of methanol and to the solution was added 20 ml of aqueous 1 N solution of sodium hydroxide, and the mixture was stirred for 14 hours at room temperature. After removal of methanol under reduced pressure, water was added to the mixture, and this solution was acidified to pH 3 with aqueous 2 N hydrochloric acid. The mixture was extracted five times with ethyl acetate, and the ethyl acetate extract was dried and concentrated to give 3.5 g of crude crystals. After addition of ethanol to the crude crystals, the crude crystals were filtered. The filtrate was concentrated, and to the residue was added ethanol and ethyl acetate, and precipitate was collected by filtration. The combined amount of the crude crystals was 1.6 g. After the combined crude crystals were methylated with diazomethane, the reaction product was dissolved in 20 ml of ethyl acetate. To this solution was added 1.5 g of sodium acetate and 300 mg of 10% palladium-carbon, and the mixture was stirred for 2 hours under hydrogen. Then, the reaction product was filtered, and after addition of aqueous saturated solution of sodium hydrogen carbonate to the filtrate, the mixture was extracted two times with ethyl acetate. The extract was washed with an aqueous saturated solution of sodium chloride, dried, and concentrated to give 1.3 g of crude crystals. The crude crystals were recrystallized from ethyl acetate to yield 765 mg of the title compound (melting point 134-135°C, yield 43%). 

A suspension of 15.0 g (4.05 mol) of the reagent in 20 mL of freshly distilled benzene containing 0.250 g (1.36 mmol) of cyclododecanol is heated to 70 °C for 1.5 h. The solution is filtered through Celite (diatomaceous earth), the pellets are washed with 70 mL of benzene, and the combined filtrates are evaporated under reduced pressure to yield 0.226 g (90%) of cyclododecanone as colorless crystals, mp 56-59 °C. The pure compound melts at 59-61 °C. 

Extrusion with melt filtration can then be used as the ultimate way of purifying the material. Since each extrusion step exposes the material to thermomechanical cycles likely to further degrade the material, the number of extrusion steps should be kept to a minimum. For the final extrusion compounding, additives can be used to maintain or improve selected material properties, depending upon the composition and degree of degradation of the material. 

Because recycled plastics have had a first use and have been environmentally exposed, required conversion processes are often more stringent. For example, compounding may have to be done on a twin rather than a single-screw extruder for dispersive mixing. In addition, compounding purification steps such as devolatilization and melt filtration may be required for some recycled feedstock. Consequently, the compounding process can have a significant impact on the overall conversion cost. Another contributor to conversion cost is the compatibilizer additive. The most effective of these additives cost about 2.00 per pound. This adds 10 cents per pound of product at a 5% level of compatibilizer additive. 

Machinery used to prepare particulate-filled polymer composites may be classified in terms of the applied shear intensity and whether the operation is of a batch or continuous nature. Furthermore, most compounding processes are critically dependent on the efficiency of ancillary equipment to undertake various functions, including additive and polymer feeding, melt filtration and pelletising procedures. 

Melt filtration is commonly used during continuous melt compounding operations to enhance product quality, by reducing adverse effects from contaminants or unwanted... 

In cases where elimination of agglomerates is essential to ensure that optimum compound properties are achieved, melt filtration can be used. This is important in pigment masterbatch production or in coloured compounds to be spun into fibres, where agglomerates can lead to fibre breakage. Removal of impurities or large defect particles by melt filtration can also increase the fatigue life of FIDPE pipe and the resistance to breakdown of polymer subjected to an electrical stress [71, 72]. 

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