Styrene content bound

The samples of surface devulcanized reclaimed rubber made in this series of experiments were then compounded with a blend of virgin rubbers and cured. The blends were made by mixing 20 parts per 100 parts of rubber (phr) of the surface devulcanized reclaimed rubber samples with 70phr of Plioflex 1712 SBR, 30 phr of Budene 1254 polybutadiene rubber, about 9 phr of aromatic oil, about 70 phr of carbon black, about 2 phr of stearic acid, about 4 phr of wax, about 1 phr of accelerator, about 2 phr of zinc oxide, about 1.5 phr of sulfur, and about Iphr of antioxidant. The Plioflex 1712 has a bound styrene content of about 28.5% and was oil extended with about 37.5% of an... 

Ohamal ll l studied the effect of monomer ratio in EVA, SBR, and poly (styrene-butyl acrylate, SAE) latexes on the strengths of latex-modified mortars (Fig. 4.10). The monomer ratio affects the strengths of the latex-modified mortars to the same extent as the polymer-cement ratio. The maximum strengths of EVA- and poly(styrene-butyl acrylate)-modified mortars are obtained at a bound ethylene content of 13% and a bound styrene content of 55% respectively. The strengths of SBR-modified mortar increase with a rise in the bound styrene content. These results are similar to those obtained by Cherkinskii, et al.f i The tensile strength of the dry films made from SBR latexes increases sharply when the bound styrene content is raised, and there is a positive correlation between the strength of the films and the flexural strength of SBR-modified mortars with polymer-cement ratios above 10% as shown in Fig. 4.11.li l... 

Ohamat l found a nearly ten-fold increase in adhesion to ordinary cement mortar of SBR-modified mortar with a polymer-cement ratio of 20%, compared to unmodified mortar. In this case, the monomer ratio of the copolymer was important, and the high adhesion was attained at a bound styrene content of 70%. 

Figure 9.2 shows the effect of Fg on wet skid. If an increase in wet grip is required with minimum impact on rolling resistance, then a change in Tg is best accomplished via an increase in the vinyl-butadiene level rather than in the bound styrene content. Alternatively, if wear is of higher importance, Fg should be adjusted by a change in the bound styrene level. The optimum... 

Fraga [11] has also described an infrared thin-film area method for the analysis of styrene-butadiene copolymers. The integrated absorption area between 6.6 and 7.2 pm has been found to be essentially proportional to total bound butadiene, and is independent of the isomeric type of butadiene structure present. This method can be calibrated for bound styrene contents ranging from 25 to 100%. 

Styrene block copolymers are the most widely used TPEs, accounting for close to 45 percent of total TPE consumption worldwide at the close of the twentieth century. They are characterized by their molecular architecture, which has a hard thermoplastic segment (block) and a soft elastomeric segment (block) (see Fig. 3.2). Styrenic TPEs are usually styrene butadiene styrene (SBS), styrene ethylene/butylene styrene (SEES), and styrene isoprene styrene (SIS). Styrenic TPEs usually have about 30 to 40 percent (wt) bound styrene certain grades have a higher bound styrene content. The polystyrene endblocks create a network of reversible physical cross links that allow thermoplasticity for melt processing or solvation. With cooling or solvent evaporation, the polystyrene domains reform and harden, and the rubber network is fixed in position. ... 

The less expensive BR (made through the emulsion polymerization process) is also available. It is commonly referenced as EBR. The production volume of EBR is not nearly as large as BR from the solution process. Some of the cured property improvements realized from the use of high cis-BR are not as good when EBR is used. If EBR is considered as a substitute for high cis-BR from the solution polymerization process, care should be exercised to look for unintended consequences such as a loss in flex fatigue resistance, loss in wear (or abrasion) resistance, and an increase in rolling resistance. Some look at EBR as similar to SBR from the emulsion polymerization process except that its bound styrene content is zero. 

SBR/PVC blends with nitrile rubber (NBR) as a compatibilizer show improved mechanical properties at lower cost than NBR/PVC. i This was the conclusion of studies using a divinylbenzene cross-linked, hot-polymerized emulsion polymer with 30% bound styrene and a cold-polymerized emulsion polymer with 23% boimd styrene PVC with inherent viscosity from 0.86 to 1.4 NBR with Mooney viscosity from 30 to 86 acrylonitrile content of 23.5, 32.6, and 39.7% and ZnO, stabilizers, sulfur, and accelerators. ... 

A methanol extract of a weighed portion of the polymer is pyrolysed at 700°C and the pyrolysis products swept on to a gas chromatograph and then determined. For example if a styrene-butadiene copolymer is being examined then determination of 1,3 butadiene in the pyrolysis products enables the bound butadiene content of the copolymer to be determined. The procedure is calibrated against copolymers of known composition, or, alternatively against injections of the pure monomers. 

The advantage of the Py-GC-MS method over other methods for measuring styrene content of SBR copolymer is its relatively easy use for analysis of clear polymers as well as polymers containing process oils, fillers, and carbon black, and even cured rubbers. Moreover, the percent bound styrene obtained by this technique is not affected by changes of copolymer microstructure. Results of this work clearly show that the percentage of styrene obtained by this technique correlates very well with the results obtained by other methods. 

Abstract These test methods cover the synthetic rubber lattices ABR, BR, CR, HR, NBR, NCR, NIR, PBR, PSBR, SBR, SCR, SIR, synthetic rubber lattices with substituted carboxylic acid groups on the polymer chain, and reinforced synthetic mbber lattices. Covered tests include the procedure for collecting samples and determining total solid content, volatile unsaturates content, pH, surface tension, viscosity, coagulum, bound styrene, Mooney viscosity, mechanical stability, polystyrene reinforcement in contained polymer, and residual acrylonitrile content. Each test method contains information on material exceptions, apparatus, and test procedures. 

A solution of styrene in methanol to impregnate wood samples, followed by polymerization, was used by Furuno and Goto (1979). Penetration of the monomer into the cell wall was determined by solvent extraction of samples after polymerization. This removed lumen located polymer, whilst leaving the cell wall bound polymer in place. This showed that the concentration of cell wall bound polymer increased in proportion to the monomer content in methanol, up to a maximum of 80% of the monomer in the solvent. No cell wall penetration was observed for treatment with neat monomer. This was also found for bulking of the wood, as determined from external dimensions of the samples. Improvements in ASE were obtained as a result of the presence of cell wall bound polymer. To achieve similar ASE values with lumen located polymer required very high polymer loadings. 

Fig. 12.1.1 Dependence of order parameter, S. of the secondary polymer, spin-labeled poly (methyl methacrylate) (PMMA) and polystyrene (PST), bound to poly(maleic anhydride—styrene )-grafted silica on hexane content in ethyl acetate-hexane cosolvent. Numbers in parentheses are number average molecular weight of the secondary polymer. (From Ref. 48.)...

The polymer bound triphenylphosphine oxide was synthesized using established techniques from a macro reticular DVB/styrene copolymer, Amberlite XE-305 (10). The phosphorus content was determined gravimetrically using the Kjeldahl method (11). 

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