Polystyrene solution degradation

Fig. 2.13 Mechanochemistry of polystyrene solutions degradation index DI as a function of the product of time t times the shift factor a. The symbols represent different polymers and conditions [58].

The polymer should be dissolved at room temperature [28]. Magnetic stirring devices or laboratory shakers are recommended to aid dissolution. Excessive temperature or ultrasonic devices may cause the polymer to degrade. Polystyrene solutions prepared with solvents such as THF are very stable, as long as MW < 500,000 g mol 1. However, it is a good practice to analyze polymer solutions within 24 hr of their preparation [28]. 

Hunston, D. L., and Zakin, J. L., Flow-assisted degradation in dilute polystyrene solutions,... 

Kanwal F, Liggat JJ, Pethrick RA (2(X)0) Ultrasonic degradation of polystyrene solutions. 

Fig. 5 Degradation effects of a high-molecular-weight polystyrene solution during laminar flow through a porous medium...

Figure. 3.391. Influence of the pressure on the degradation rate of polystyrene solutions in benzene [1159] (in psi) (a) variant 1- (A) 15 (A) 30 (j) 80 ( ) 150 (o) 225 ( ) 300 (x) 450 (b) variant 2 (via a mercury column). The same meaning of symbols (c) Value of constant K in function of pressure excess for (o) gaseous excess pressure ( ) excess pressure exerted via a mercury column. Condition frequency 500 KHz intensity 10 W/cm. ...

The degradation of polystyrene in a chlorobenzene solution in the presence of dioxygen and initiator also occurs with the rate vs v [140,141], However, the vs/b ratio was found to be much less than unity. 

As a check to confirm that no extraneous non-polymer-attached catalytic species were present, the following experiment was performed. Polystyrene without attached cyclopentadiene was exposed to Co2(C0)e, extracted using a Soxhlet extractor and dried in vacuo in exactly the same manner as was used to synthesize 5. When used under the above Fischer-Tropsch reaction conditions, these treated, white polystyrene beads did not discolor, release any detectable species into solution, cause a CO/H2 pressure drop, or result in the formation of any detectable amounts of methane. These observations argue against the presence of small amounts of occluded Co2(C0)e or C04 (CO) 12 which could conceivably have been active or precursors to active species. It should be noted that the above clusters were reported to be essentially inactive under Fischer-Tropsch conditions (140°C, toluene, 1.5 atm., 3/1 H2/CO, three days) leading to mere traces of methane (11). The lack of products under our conditions also indicates that, at least in the absence of resin-bound CpCo(C0)2 or its derivatives, the polystyrene support did not degrade. 

Biaxially oriented polystyrene film, 23 408 Biaxial viscosity, 21 718 Bibenzyl solution, VDC polymer degradation in, 25 717 Bibliographic patent information, 18 212 Bibutyltin dichloride, 24 820 Bicarbonates, 12 66... 

The ultrasonic degradation of an air saturated toluene solution of polystyrene is greater than when the solution is degassed. 

Rabek and Ranby (22) have shown that a free radical induced degradation of polystyrene occurs in the presence of oxygen, that leads to rapid chain scission. Benzoyl radicals derived from Type 1 initiators abstract hydrogen atoms from the polymer and thereby start a chain degradation process. Berner, Kirchmayr and Rist (6) and others have shown that when initiator I is irradiated in solution, the benzoyl radical abstracts a hydrogen from the surrounding solvent to form benzalkdehyde and a free radical. 

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... 

Polystyrene latices can be prepared by the dispersion polymerisation of styrene in alcohol/water mixtures containing polyelectrolytes. The experimental data obtained lend support to the hypothesis that the polymerisation mechanism which operates is analogous to that which occurs in the non aqueous dispersion polymerisation of methyl methacrylate in solutions of degraded... 

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