Xylene soluble fraction

The resins used to study the influence of EP/PP viscosity ratio were provided by SOLVAY. Samples, PPEP3 and PPEP4, are reactor blends produced in gas-phase by a two-stage polymerization process. They differ by the viscosity ratio between the EP and the PP phases which corresponds to the ratio of the solution intrinsic viscosities of the xylene-soluble fraction (mainly EP) and the xylene-insoluble fraction (mainly crystalline PP). Disks of these resins were injection molded and analyzed by TEM and by AFM and FMM. 

Atactic PP is soluble in a hydrocarbon solvent such as xylene, but isotactic PP is not. An accepted industrial method for measuring isotacticity is to determine the amount of xylene-soluble fraction in a given PP. Finally, it may be noted that the techno-commercial feasibility of the industrial manufacture of syndiotactic PP depends on finding unique applications of such a polymer. 

CHARACTERIZATION. The intrinsic viscosity of the soluble fractions was determined in toluene at 30 C. The MAH content of the soluble fractions was determined by heating a 0.5-1.0g portion in refluxing water-saturated xylene for 1 hr and titrating the hot solution with 0.05N ethanolic KOH using 1% thymol blue in DMF as indicator. 

Some studies relative to the influence of Lewis bases,124-127 1,3-diethers in particular,125-127 and the MgCl2 support have also been recently reported. The dependence of the industrially relevant isotactic indexes on the chemical structure of the 1,3-diether donor has been rationalized in the assumption that donor coordination competes with Ti catalytic species formation and xylene-insoluble (highly isotactic) and xylene-soluble (poorly isotacUc) fractions are mainly obtained by polymerization on (100) and (110) cuts, respectively.127... 

There are indications that pure naphthalene (a constituent of mothballs, which are, by definition, toxic to moths) and alkylnaphthalenes are from three to 10 times more toxic to test animals than are benzene and alkylbenzenes. In addition, and because of the low water solubility of tricyclic and polycyclic (polynuclear) aromatic hydrocarbons (i.e., those aromatic hydrocarbons heavier than naphthalene), these compounds are generally present at very low concentrations in the water-soluble fraction of oil. Therefore, the results of this smdy and others conclude that the soluble aromatics of crude oil (such as benzene, toluene, ethylbenzene, xylenes, and naphthalenes) produce the majority of its toxic effects in the enviromnent. 

Thomas and Delfino (1991) equilibrated contaminant-free groundwater collected from Gainesville, FT with individual fractions of three individual petroleum products at 24-25 °C for 24 h. The aqueous phase was analyzed for organic compounds via U.S. EPA approved test method 602. Average m-i-p-xylene concentrations reported in water-soluble fractions of unleaded gasoline, kerosene, and diesel fuel were 8.611, 0.658, and 0.228 mg/L, respectively. When the authors analyzed the aqueous-phase via U.S. EPA approved test method 610, average m+p-xylene concentrations in water-soluble fractions of unleaded gasoline, kerosene, and diesel fuel were lower, i.e., 6.068, 0.360, and 0.222 mg/L, respectively. 

Source As m-i-p-xylene, detected in distilled water-soluble fractions of 87 octane gasoline, 94 octane gasoline, and Gasohol at concentrations of 7.00, 20.1, and 14.6 mg/L, respectively (Potter, 1996) in distilled water-soluble fractions of new and used motor oil at concentrations of 0.26 to 0.29 and 302 to 339 pg/L, respectively (Chen et al, 1994). The average volume percent and estimated mole fraction in American Petroleum Institute PS-6 gasoline are 4.072 and 0.04406, respectively (Poulsen et al., 1992). Diesel fuel obtained from a service station in Schlieren, Switzerland contained m -xylene at a concentration of 336 mg/L (Schluep et al., 2001). 

The lithiated polyethylene copolymer was then suspended in hexane or THF solvent. The graft-from reactions were carried out in slurry solution by reacting the lithiated polyethylene copolymer with anionic polymerizable monomers, such as styrene and p-methylstyrene. After certain reaction time, 10 ml of isopropanol was added to terminate the graft-from reaction. The precipitated polymer was filtered and then subjected to fractionation. Good solvents for backbone and side chain polymers were used during the fractionization, using a Soxhlet apparatus under N2 for 24 hours. The soluble fractions were isolated by vacuum-removal of solvent. Usually, the total soluble fractions were less than 5 % of the product. The major insoluble fraction was PE graft copolymer, which was completely soluble in xylene or trichlorobenzene at elevated temperatures. 

Calculated from the data reported by D. Hardin and S. Sikorsky (46) for a compound having [Mfjf + 11.99 (neat) m) Benzene insoluble, decalin soluble fraction n) Ethyl acetate soluble fraction p) For the optical purity of the models see Tables 9 and 15 q) Referred to one monomeric unit r) In xylene solution. 

Solubility behavior of the copolymers in methylene chloride was examined by preparing a 103 solution in warm methylene chloride and allowing the solution to stand for two days at room temperature. The precipitate, if any, was filtered off under nitrogen pressure using a 0.45/t Millipore filter, washed with cold methylene chloride, and dried under vacuum. The soluble fraction was recovered by precipitation with methanol. A similar procedure was followed with m-xylene a 10% solution of the copolymer was heated overnight on a steam bath, the precipitate filtered off, dissolved in chloroform, and reprecipitated with methanol. 

The soluble and insoluble fractions were examined separately. The insoluble fraction, which made up 35% of the total, had the NMR spectrum expected of a DPP-rich block copolymer, with a sharp methyl proton signal and only one strong signal, at 8 6.46 ppm (PPP), in the aromatic backbone region. The composition, from comparison of the integrated intensities of the methyl and backbone proton signals, was 82 mole % DPP and 18% MPP. The soluble fraction had the spectrum expected of a block copolymer with about 65% MPP units. Since a coprecipitated blend was separated almost quantitatively into the pure homopolymers with m-xylene under these conditions, the copolymer is characterized as a block copolymer. 

The stoichiometry used to synthesize the first polymer can in principle lead to a completely crosslinked and insoluble polymer however, when xylenes were used as solvent, a 60% yield of soluble precursors were obtained. When octane was used as solvent, the soluble fraction was only 40-50%. The second polymer type, which in principle should give only linear materials, also gave 50-60% yields of soluble precursor. 

The chemical composition of the soluble fraction of the first polymer was SiC1.96B0.54H5.i4 and that of the second polymer was SiC3.26Bo.93H7.o3. Oxygen contents were 3-4 wt%. Some of the xylene solvent appears to be incorporated in the polymers as evidenced by the presence of aromatic peaks in the proton NMRs. TGA of the first polymer... 

Due to the relatively high water solubility, monoaromatic hydrocarbons and phenolic compounds are among the most frequently identified water pollutants. Monoaromatics like benzene, toluene and the xylenes, are the main constituents of the water soluble fraction of gasoline and other oil products, and they are widely used as solvents. Phenohcs often occur in coimection with creosote and tar pollution in groimd water and else in mai types of industrial process water discharge (Cooper and Wheatstone, 1973). Fmthermoie, they are often identified as intermediary metabolites in the degradation of other aromatic compoimds. 

The analysis of the soluble fractions indicates that the nonrecrystaUiz-able material obtained in xylene is essentially atactic material (II = 0.33 by NMR), whereas Q and particularly C7 soluble fractions are mixtures of lower molecular weight atactic and isotactic chains giving consequently a bad estimation of the mean isotacticity level of the sample and, in addition, this result depends on the molecular weight [3]. 

The MAH contents of the xylene-soluble and xylene-insoluble fractions were determined by heating a 1-2 g sample in refluxing xylene to dissolve or swell the polymer and then, on conversion of succinic acid to anhydride units, to remove a xylene-water azeotrope in a Dean-Stark tube. The xylene solution or suspension was cooled to about 60 C and 0.5N methanolic KOH was added through the condenser. The mixture was refluxed for 1.5 hrs, cooled and titrated with a 0.25N isopropanolic HCl solution to a phenolphthalein end point. 

Pure p-xylene and water were equihbrated at 25°C. The absorbance of the aqueous layer measured in a 1cm cell at A =274nm (due to p-xylene) was 0.884. A solution of p-xylene, mole fraction x =0.686, and n-dodecane, similarly treated, gave absorbance A=0.749. Assuming that both Beer s and Henry s laws hold for p-xylene in water and that n-dodecane is insoluble in water, what was the activity coefficient of p-xylene in the solution with n-dodecane (Neglect the small solubility of water in p-xylene.)... 

Table I Main characteristics of the resin used in the present study elastomer content, resin viscosity in the melt (Melt Flow Index) and viscosity ratio between the xylene soluble and the xylene insoluble fractions.

The products were fractionated by successive extraction with a series of solvents and the solubility behaviors were compared with that of the corresponding homopolymers prepared under the same conditions. A typical result of the fractionation of the PB sample is listed in Table 3. It can be seen from the result that the solubility of the PB sample is much different from that of a mixture of the two homopolymers. It is worthy to mention that the propylene homopolymer was completely dissolved after extracting by boiling toluene, but the fractions of xylene extract and residual of the PB sample still contain propylene units 38.0 and 45.2 mol%, respectively. Furthermore, the IR spectra of all the fractions except the ether-soluble fraction exhibit the absorption band of trans-1,4 polybutadiene crystalline at 770 cm and absorption band of polypropylene crystalline at 841 cm as shown in Fig.8, indicating the presence of long butadiene-butadiene sequences and long propylene-propylene sequences. 

A sample which had been heated in bulk at 150°C for 3 h (see Fig. 5) was treated with boiling xylene for a long period of time. A gel fraction was actually found whose IR spectrum, obtained on a film compression-molded at 150°C, shows a high content of anhydride. In contrast, the soluble fraction, recovered from xylene, shows an IR spectrum similar to that of the starting material, i.e., before any heat treatment, with a very small anhydride band. We can conclude that the bulk cyclization reaction proceeds via an inter-chain anhydride formation, which is a bimolecular process. A similar treatment with boiling xylene was made on a sample of EPR-g-MES after solution cyclization. Also in this case the sample shows a small gel fraction which presents at IR analysis no differences from the soluble fraction, thus indicating that both mechanisms of inter- and intra-chain anhydride formation can occur in this case, even if the monomolecular mechanism is preferred, due to the dilution of the system. 

Ciyst lliz tion. Low temperature fractional crystallization was the first and for many years the only commercial technique for separating PX from mixed xylenes. As shown in Table 2, PX has a much higher freezing point than the other xylene isomers. Thus, upon cooling, a pure soHd phase of PX crystallizes first. Eventually, upon further cooling, a temperature is reached where soHd crystals of another isomer also form. This is called the eutectic point. PX crystals usually form at about —4° C and the PX-MX eutectic is reached at about —68° C. In commercial practice, PX crystallization is carried out at a temperature just above the eutectic point. At all temperatures above the eutectic point, PX is stiU soluble in the remaining Cg aromatics Hquid solution,... 

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 reaction of EPR with dicumyl peroxide (DCP) at 180°C yielded a fraction insoluble in cyclohexane at 22 C. The presence of maleic anhydride (MAH) in the EPR-DCP reaction mixture increased the amount of cyclohexane-insoluble gel. However, the gel concentration decreased as the DCP concentration increased. The MAH content of the soluble polymer increased when either the MAH or the DCP concentration increased. The molecular weight of the soluble polymer increased with increasing MAH concentration and decreased with increasing DCP concentration in the reaction mixture. The products from the EPR-DCP and EPR-MAH-DCP reactions were soluble in refluxing xylene and were fractionated by precipitation with acetone. The presence of stearamide in the EPR-MAH-DCP reaction increased the amount and the molecular weight of the cyclohexane-soluble polymer. 

The polymer formed in the reaction of EPR with 0.5 wt-% DCP at 180 C, in the presence or absence of 5 wt-% MAH, was completely soluble in refluxing xylene, although it contained a fraction insoluble in cyclohexane at 22 C. The EPR and EPR-g-MAH were fractionated by addition of the xylene solution to acetone. 

The complete solubility in refluxing xylene of the EPR and EPR—g—MAH produced by reaction with DCP at 180°C suggests that treatment with cyclohexane at 22°C does not separate the crosslinked polymer from the uncrosslinked polymer but rather fractionates the uncrosslinked polymer based on molecular weight. Alternatively, the lightly crosslinked polymer is swollen and the crosslinks are broken in refluxing xylene. 

FIGURE 3.1.1.4.1 Logarithm of mole fraction solubility (In x) versus reciprocal temperature for o-xylene. 

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