Fractionation with resins

Although most aromatic modified C-5 resins are typically higher softening point resins, certain appHcations, such as adhesives, require lower softening points. Copolymerization of a C-8—C-10 vinyl aromatic fraction with piperylenes in the presence of a C-4—C-8 mono-olefin chain-transfer stream yields resins with softening points ranging from 0—40°C (44). A particular advantage of these Hquid resins is the fact that they eliminate the need for plasticizers or oils in some pressure sensitive adhesive appHcations. 

Chemical Properties and Reactivity. LLDPE is a saturated branched hydrocarbon. The most reactive parts of LLDPE molecules are the tertiary CH bonds in branches and the double bonds at chain ends. Although LLDPE is nonreactive with both inorganic and organic acids, it can form sulfo-compounds in concentrated solutions of H2SO4 (>70%) at elevated temperatures and can also be nitrated with concentrated HNO. LLDPE is also stable in alkaline and salt solutions. At room temperature, LLDPE resins are not soluble in any known solvent (except for those fractions with the highest branching contents) at temperatures above 80—100°C, however, the resins can be dissolved in various aromatic, aUphatic, and halogenated hydrocarbons such as xylenes, tetralin, decalin, and chlorobenzenes. 

The lac resin is associated with two lac dyes, lac wax and an odiferous substance, and these materials may be present to a variable extent in shellac. The resin itself appears to be a polycondensate of aldehydic and hydroxy acids either as lactides or inter-esters. The resin constituents can be placed into two groups, an ether-soluble fraction (25% of the total) with an acid value of 100 and molecular weight of about 550, and an insoluble fraction with an acid value of 55 and a molecular weight of about 2000. 

The heavy-end portions (usually called heavy fractions) of bitumen (e.g. asphaltenes, preasphaltenes) can exist both in a random oriented particle aggregate form or in an ordered micelle form, peptized with resin molecules (16.17). In their natural state, asphaltenes exists in an oil-external (Winsor s terminology) or reversed micelle. The polar groups are oriented toward the center, which can be water, silica (or clay), or metals (V, Ni, Fe, etc.). The driving force of the polar groups... 

The analysis of organic materials by GC/MS requires a pretreatment of the sample, one important step being the extraction of the compounds of interest from the matrix. This is crucial with resinous materials from historical objects due to the uniqueness of such samples and to the small amount of the organic fraction usually contained in them. This means the extraction methods must be highly efficient. The methods generally adopted can be divided into three main groups ... 

The EEM profiles of fractions obtained by the isolation procedure of the DOM by the XAD resins showed that a fractionation was effective and the XAD-8 eluate is highly representative of the original DOM. Emission scan spectra of DOM and its fractions are featureless, whereas synchronous scan spectra show that the isolation procedure is efficient in separating the original DOM into fractions with different fluorescence properties. The synchronous scan spectra obtained with a wavelength offset of 20 nm present multicomponent samples such as the DOM fractions from landfill leachate. 

S-Acetylthiocholine chloride [6050-81-3] M 197.7, m 172-173" The chloride can be purified in the same way as the bromide, and it can be prepared from the iodide. A few milligrams dissolved in H2O can be purified by applying onto a Dowex-1 Cf resin column (prepared by washing with N HCl followed by CO3— free H2O until the pH is 5.8). After equilibration for lOmin elution is started with CO3 —free distilled H2O and 3ml fractions are collected and their OD at 229nm measured. The fractions with appreciable absorption are pooled and lyophilised at 0-5°. Note that at higher temps decomposition of the ester is appreciable hydrolysis is appreciable at pH >10.5/20°. The residue is dried in vacuo over P2O5, checked for traces of iodine (cone H2SO4 and heat, violet vapours are released), and recrystd from propan-l-ol. [Clinica Chim Acta 2 316 1957],... 

Step 5. Adjust pH to 1.0 with HC1 to precipitate humic acid. Separate humic and fulvic acids by centrifugation. Rinse humic-acid fraction with distilled water until AgN03 test shows no Cl . Dissolve humic acid in 0.1 N NaOH and hydrogen saturate by passing solution through cation-exchange resin in H-form. 

The reaction for making methyl-r-butyl ether proceeds quickly and highly selectively by reacting a mixed butene-butane fraction with methyl alcohol in the liquid phase on a fixed bed of an acidic ion-exchange resin catalyst (Fig. 1). 

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