Styrenated oils, analysis

Treatment of a solution of 55cCu(OTf)2 complex with a stoichiometric amount of PhI=NTs in CH2C12 resulted in rapid uptake of the insoluble iodinane. This complex, when treated with styrene, provided aziridine in quantitative yield in the same selectivity (37% ee) as the catalytic reaction (in CH2C12 at 25°C, 36% ee), Eq. 59. Addition of toluene at -78°C resulted in deposition of the complex as an oil. Analysis of the supernatant liquid revealed that <5% Phi was present, suggesting that the iodobenzene was still part of the complex. Unfortunately, this material resisted repeated attempts at crystallization. Whatever its true nature, it seems that this complex is not a classical copper nitrenoid (77). 

Although PFE lacks a proven total concept for in-polymer analysis, as in the case of closed-vessel MAE (though limited to polyolefins), a framework for method development and optimisation is now available which is expected to be an excellent guide for a wide variety of applications, including non-polyolefinic matrices. Already, reported results refer to HDPE, LDPE, LLDPE, PP, PA6, PA6.6, PET, PBT, PMMA, PS, PVC, ABS, styrene-butadiene rubbers, while others may be added, such as the determination of oil in EPDM, the quantification of the water-insoluble fraction in nylon, as well as the determination of the isotacticity of polypropylene and of heptane insolubles. Thus PFE seems to cover a much broader polymer matrix range than MAE and appears to be quite suitable for R D samples. 

Analysis of a large number of styrenated linseed oils showed that parallels, drawn between these two lines, indicate immediately the percentage of styrene in the products. 

An alternative method was also studied. This involved ratioing the intensity of the 698 cm 1 styrene band to the intensity of the 2921 cm-1 C-H stretching vibration. Since oils and other additives would interfere with this approach they were extracted with acetone. Vacuum oven drying was then necessary to remove all traces of acetone prior to PA analysis. Otherwise the PA spectrum would be that of acetone rather than that of the rubber since the gas phase spectrum of the acetone would overwhelm that of the solid phase rubber. This technique allowed both solution and emulsion SBR to be analysed by a common method. The results can be expressed by a least squares linear regression equation over the range of 5%-40% styrene in SBR. 

Clough and Ramirez (15) have also reported that for an iron catalyst the optimal steam to oil molar ratio is ca. 10. The plots in Figure 3 indicate that as this ratio is increased, higher conversions to styrene are attainable. Since only one reaction is considered in the analysis, the conversion criterion is used instead of a yield criterion. It should be noted that this analysis does not take into account cost considerations. 

Polymerization of styrene in each of the three types of microemulsions was performed using a water soluble initiator, potassium persulfate (K2S208), as well as an oil-soluble initiator, AIBN. As desired, solid polymeric materials were obtained instead of latex particles. In the anionic system, the cosolvent 2-pentanol or butyl cellosolve separates out during polymerization. Three phases are always obtmned after polymerization. The solid polymer was obtained in the middle with excess phases at the top and bottom. GC analysis of the upper phase indicates more than 80% 2-pentanol, while Karl-Fisher analysis indicated more than 94% water in the lower phase. Some of the initial microemulsion systems have either an excess organic phase on top or an excess water phase as the bottom layer. GC analysis showed the organic phase to be rich in 2-pentanol. However, the volume of the excess phase is much less in the initial system than in the polymerized system. 

Although unified chromatography still has to find its own applications niche, it has been already used for the analysis of a wide variety of samples from aromatic hydrocarbons, styrene, esters, phthalates, crude oil, amines, household wax, pesticides in vegetable oils and many others [11,14-16]. Its major application in the near future will certainly be centered in the analysis of complex samples such as environmental samples, biological fluids, forensic chemistry, and so forth. In this case, there is a need for more than one separation mode because the sample might contain volatile, semi-... 

Another approach to anisotropic materials is to measure the bulk expansion of material using dilatometry (Fig. 6). The technique was used extensively to study initial rates of reaction for bulk styrene polymerization in the 1940s, an experiment which the author has used in his thermal analysis class on TMA. By immersing the sample in a fluid (normally silicon oil) or... 

In a typical experiment, styrene (180 mg, 1.74 mmol) was admixed with clayfen or clayan (300 mg) in a glass tube. The reaction mixture was placed in an oil bath for 15 min or irradiated for 3 min in an alumina bath inside an unmodified household microwave oven (900 W) at its medium power. On completion of the reaction, followed by TLC examination (hexane-EtOAc, 4 1, v/v), the product was extracted into dichloromethane (45 mL), the combined organic extract dried with anhydrous sodium sulfate and solvent removed under reduced pressure. The relative amounts of product distribution were calculated from GC-MS analysis. Alternatively, the crude material was chromatographed on a silica gel column and eluted with hexane-EtOAc (4 1, v/v) to afford the pure product (147 mg, 57%). 

In view of the wide application of Py—GC in industry and research, the development of techniques and equipment for automatic analysis by this method is of great practical interest. An automatic Py—GC system was developed by Coulter and Thompson [69] for Curie-type cells with a filament for specific application in the tyre industry. A typical analysis involves the identification and determination of polymers in a tyre material sample. The material of a tyre is essentially a mixture of polymers, most often natural rubber (polyisoprene), synthetic polyisoprene, polybutadiene and butadiene-styrene copolymer. A tube is normally made of a material based on butyl rubber and a copolymer of isobutylene with small amounts of isoprene. In addition to the above ingredients, the material contains another ten to twelve, such as sulphur, zinc oxide, carbon black, mineral oil, pine pitch, resins, antioxidants, accelerators and stearic acid. In analysing very small samples of the tyre material, the chemist must usually answer the following question on the basis of which polymers is the tyre made and what is their ratio The problem is not made easier by the fact that cured rubber is not soluble in any solvent. 

To demonstrate the livingness of styrene-acrylonitrile random copolymerizations, TEMPO (0.084 g) and BPO (0.101 g) were dissolved in 30 mL of styrene and 10 mL of acrylonitrile. The reaction mixture was stirred and purged with argon. The flask was sealed, lowered into a oil bath at 125 C and the mixture allowed to reflux. Periodically the flask was removed from the bath, cooled and a sample withdrawn for GPC analysis. To measure the composition of the copolymers, a series of polymerizations taken to low conversion were done in a Parr pressure reactor. The total moles of monomer were kept constant at 0.55, and the relative amounts of the two monomers were adjusted to vary the mole fraction of acrylonitrile from 0.1-0.9. 

Both polystyrene samples contained an ester and a mineral oil type of lubricant together with a phenolic antioxidant. The lubricants have little absorption in the 280-300 nm region and do not interfere in either method of analysis at the 5-10% concentrations at which they are used in polystyrene formulations. The absorption spectrum of the phenolic antioxidant, however, shows a sharply decreasing non-linear absorbance in the 280-300 nm region and contributes significantly to the background absorption of the test solution in the direct UV spectroscopic method. This invalidates the baseline correction procedure and leads to erroneous styrene monomer values. In the distillation procedure, however, the test solution used for spectroscopy does not contain the phenolic antioxidant and there is no interference in the determination of styrene monomer. 

To circumvent interference from the extending oil, no internal chromatographic standard was used to check response. Polymer standards were prepared. These were made by incorporating the oil and antioxidant into unstabilised polybutadiene or styrene-butadiene resin cement at typical levels of concentration. These preparations were then air-dried to a dry polymer condition. For analytical purposes, 10.0 0.01 gram of polymer were ethanol extracted in a Soxhlet apparatus using 165 ml of solvent for 16 hours. The extract solution was then concentrated to about 10 ml volume and taken up in the appropriate solvent to a 50 ml volume and used for chromatographic analysis of the antioxidant. 

ATRP of styrene is carried out in a Schlenk ask loaded with CuBr to which styrene (much in excess of [St] [CuBr] = 30 1 ratio), phenyl ether (solvent), and N,N,N, N, N"-pentrme1iiy diethylene triamine (PMDETA) are added and stirred for 15 min to allow catalyst formation. To the reaction mixture, cooled in an ice bath, the difunctional initiator (P3-I) is added and heated at 90°C in an oil bath till the monomer conversion (measured by H-NMR analysis) corresponding to the target DP of 30 is reached. [The ATRP reactions are stopped at a relatively low (less than 50%) monomer conversion to circumvent loss of bromide end functionality because of termination processes (cf. Problem 12.2).] To quench the polymerization, the reaction mixture is cooled and diluted with CHCI3. 

The reaction of carbenes with olefins to form cyclopropyl derivatives has been used to modify elastomers. Pinazzi and Levesque and Berentsvich et al. found that carbene addition had a significant influence on the properties of polydienes. Thermogravimetric analysis (TGA), flammability and oil resistance in NR and dichlorocarbene modified styrene butadiene rubber (DCSBR) blends were investigated by thermogravimetrie analysis as a funetion of different composition. The TGA plots confirmed the better thermal stability and flame resistance of DCSBR as well as its blends with NR. The amount of DCSBR in the blend significantly affected the properties of blends. 

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