Polystyrene benzene solutions

Fig. 113.—Comparison of observed entropies of dilution (points and solid lines with results calculated for ASi according to Eq. (28) (broken line). Data for polydimethyl-siloxane, M =3850, in benzene, A (Newing ), obtained from measured activities and calorimetric heats of dilution. Entropies for polystyrene (Bawn et in methyl ethyl ketone,, and in toluene, O, were calculated from the temperature coefficient of the activity. The smoothed results for benzene solutions of rubber, represented by the solid curve without points, were obtained similarly.

Amination (11) and solution carbonation (8) reactions were carried out as described previously. For solid-state carbonations, a benzene solution of poly(styryl)lithium was freeze-dried on the vacuum line followed by introduction of high-purity, gaseous carbon dioxide (Air Products, 99.99% pure). Analysis and characterization of polymeric amines (11) and carboxylic acids (8) were performed as described previously. Benzoyl derivatives of the aminated polystyrenes were prepared in toluene/pyridine (2/1. v/v) mixtures with benzoyl chloride (Aldrich, 99%). 

Photolytic. Irradiation of styrene in solution forms polystyrene. In a benzene solution, irradiation of polystyrene will result in depolymerization to presumably styrene (Calvert and Pitts, 1966). 

Values for k were obtained using the retention time of hexamethyl benzene as to. Values for k e were obtained employing tne retention time of the completely excluded solute polystyrene (t(e)o) (Mol. Wt.83,000). t(e)o was also employed for the measurement of the linear mobile phase velocity. 

Figure 3 shows the effect on the viscosity of polystyrene samples irradiated (X > 305 nm) in benzene solution in the presence of initiator I-III. The degradation of the polymer is caused by free radicals generated from the initiators. There is also a significant difference between the three initiators. Initiator I has a stronger absorption band between 300 and 400 nm than the... 

Figure 3. Intrinsic viscosity of polystyrene samples, irradiated in benzene solution in the presence of initiator I-III. Polystyrene concentration 7.69x10 2 M, photoinitiator concentration 2.31 x 10-3 Ml p Pure polystyrene initiator I initiator II A initiator III. (Reproduced with permission from Polym. Deg. Stability Ref. 21).

Figure 4. Intrinsic viscosity of polystyrene samples irradiated in benzene solution under various conditions. Polystyrene concentration 7.69x 10-2 M and initiator I concentration 3.12x 10-3 M. vacuum nitrogen saturated air saturated V oxygen saturated 3.12 3 / 3-tert-butyl-4-hydroxyanisole 3.12x 10-3 M 1.4-diazobicyclo(2.2.2)-octane (DABCO).

Fig. 8.10. Viscosity-shear rate master curve for concentrated polystyrene-n-butyl benzene solutions. The data were obtained for molecular weights ranging from 160000 to 2400000 concentrations from 0.255 to 0.55 gm/ml, and temperatures from 30° C to 60° C (155)...

The thermal decay process of the radicals is a bimolecular reaction. The decay rate increases with increasing temperature. At 100° C, a half-life of 12 minutes has been observed for methyl methacrylate popcorn radicals. A fast decay rate takes place when the dry popcorn is swollen in a liquid such as benzene. That means that during the proliferous growth process, when the polymer is swollen by the monomer, a decay process also occurs, and a stationary radical concentration in the growing polymer popcorn results. A liquid that does not swell the polymer (for example, methanol for polystyrene) does not influence the decay rate. A much higher rate of radical decay is obtained with a benzene solution of diphenylpicrylhydrazil. The reaction rate between the polymer radical and inhibitor radical may be measured. 

The ultrasonic irradiation of a mixture of polymers also produces block copolymers, when chain fragments combine with each other and cross termination is predominant in the case of a benzene solution of polymethyl methacrylate and polystyrene, Henglein showed that 33% of the radicals produced combine (101). 

The block-polymers containing a middle block of polystyrene and two blocks of polyethylene oxide have some unusual properties. They are soluble in methyl ethyl ketone and cannot be precipitated from this solvent by methanol. Addition of water produces a slight cloudiness but still no precipitation although the block polymer is not soluble in pure water. The polymer is also soluble in benzene, but addition of water to this solution causes its precipitation. On the other hand, neither homopolystyrene nor homo-polyethylene oxide or their mixtures are precipitated from benzene solution by addition of water. This strange behaviour is explained by Richards and Szwarc (45) in terms of hydrogen bonding which depends on the chemical potential of water in the aqueous layer and therefore also in the benzene solution. 

Some adducts may reduce the rate of propagation to such a low value that the pertinent chain will be considered "dead", at least within the time of the experiment. Studies of Welch (50) have shown that butyl lithium initiated growing polystyrene may associate with BuLi in benzene solution, and the associated ends are too unreactive to contribute to the polymerization. However, the associated ends are in equilibrium with the... 

Figure 4. Critical concentrations, g25, of phase separation for block copoly-mers and polymer mixtures in benzene solutions at 25°C as functions of the polystyrene molecular weight...

The only product obtained by the copolymerization of styrene and maleic anhydride in acetone was the alternating copolymer even in the presence of more than equimolar quantities of either styrene or maleic anhydride. However, as shown by the data in Table I, larger quantities were obtained than could be accounted for by the formation of the alternating copolymer when excess styrene was used for the copolymerization in benzene solutions. In addition to the precipitates, there was also a trace of benzene-soluble product, which was shown to be polystyrene by infrared spectrometric (28) and pyrolytic gas chromatographic techniques (26). 

Unlike the alternating copolymer, these high yield benzene-insoluble products were not completely soluble in acetone, but they were soluble in a mixture of acetone-benzene (2 1). However, unlike polystyrene, they were precipitated essentially completely when excess benzene was added to the acetone-benzene solutions. In contrast when excess benzene was added to a mixture of polystyrene and the alternating copolymer in an acetone-benzene solution, the copolymer precipitated and the polystyrene remained in the benzene-rich solvent. The polystyrene was recovered from this solution by adding excess methanol. 

Fjuita (16) studied the viscosity behavior of a polystyrene/ethyl-benzene solution to obtain the variation of free volume with changing polymer concentration. This work suggested a value of v ... 

The reaction of polymerization of the NCA by the aminated polystyrene or polybutadiene is carried out in absence of moisture, at room temperature, in DMF or benzene solution, using a total concentration in NCA and aminated polyvinyl block of 2%22,24. ... 

The rotational correlation times of a benzene solution of a nitroxide imbibed in polystyrene of varied crosslinking density and the analogous compound covalently attached to the chains of the crosslinked polystyrene were measured. In the latter case the modified polystyrene matrix was also equilibrated with benzene. An estimate of the influence of crosslinking density on the internal viscosity can be obtained... 

K 17 Kurosaki, S., T. Sudo and S. Watanabe Sedimentation, diffusion and viscosity of polystyrene fractions in benzene solutions. J. Chem. Soc. Japan, Pure Chem. Sect. 73, 789 (1952). 

Labelled polystyrene-14C (PS-14C) was the adsorbate. Two batches were prepared by an identical procedure with only one of them containing radioactive 14C. The labelled polymer was used for the adsorption measurements, whereas the unlabelled polymer was used for the determination of the solution properties. The polystyrene was prepared by emulsion polymerization of redistilled styrene. In order to remove unreacted monomer the polystyrene was freeze-dried from benzene solution. 

A small molecule mimic of polystyrene (cumene) was dissolved in benzene at a concentration of 1 M available benzylic H-atoms. When /er/-butoxy radicals were introduced, the ratio of acetone to /er/-butanol was 11. However, when /er/-butoxy radicals were introduced into benzene solutions containing polystyrenes of various molecular weights at the same molar concentration of benzylic H-atoms, the acetone /er/-butanol ratio dropped precipitously as the molecular weight of the polystyrene increased (Figure 24.2). 

For polystyrene (benzene solution) we used a diagram of Marzolph and Schulz (22). The values for PMMA (solvent CHCI3) were obtained with the formula (7)... 

Hunston and Reischman showed that the contribution of 25 ppm of a 2 x 10 polystyrene in benzene solution to DR was negligible when added to 2.5 ppm of a 7 X 10 polystyrene (Fig. 3), demonstrating that a small amount of high-MW polymer dominates DR behavior in a mixture. ... 

Poly(styryl)lithium (> 15,000) In benzene solution was reacted with excess ethylene oxide In the presence of N,N,N, N -tetramethyl-ethylenedlamlne (TMEDA, [TMEDA]/[Li] 3.2). After 12 days at 25-30 C, size exclusion chromatographic analyses Indicated no significant ethylene oxide polymerization. Hydroxyethylated polystyrene was recovered in essentially quantitative yleU. 

Isotactic polystyrene. Isotactic polystyrene was prepared by heating a 10% solution of styrene in benzene at 60° for 24 hours in the presence of a catalyst prepared in the presence of monomer from equimolar amounts of (C2H5)3A1 (heptane solution) and T1CI3-AA (heptane suspension). The reaction mixture was diluted with benzene and poured into an excess of isopropanol. The resulting precipitate was dissolved in warm methylene chloride. The solution was filtered and added to hot methyl ethyl ketone. The solution was concentrated and cooled to obtain the isotactic polymer in the form of a white powder that was washed with methyl ethyl ketone and dried under vacuum. Final purification was achieved by reprecipitation of the polymer from benzene solution into methanol, followed by drying at 60° under vacuum. 

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