Polystyrene degradable

Table V. Effect of Pore Size on GPC Degradation Polystyrene...

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]. 

A variety of methods have been used for microsphere formation including non-degradable polystyrene, poly(methyl methacrylate) (PMMA), and polyacrylamide (PAAm) microspheres, as well as PLLA, PGA, PGLA, polycyanoacrylate, starch, and protein microspheres, which would be more likely to be fully biodegradable [42, 110]. Measurable amounts of polystyrene [107] and PAAm microspheres [110] persist in the tissue for many weeks after administration. It seems likely, however, that PGA [108] and protein microspheres [110] may be degraded in vivo in a period of days. 

Degradable Polystyrenes. The Ecolyte "Fast" polystyrene foam has a higher concentration of photosensitive vinyl ketone comonomer than the Ecolyte "Slow" foam and as a result has a shorter irradiation time to embrittlement as listed in Table I. The "Fast" foam was brittle after one month outdoor exposure or 275 hr xenon arc irradiation. The outdoor exposure was facilitated by wind and rain erosion. Turning the sample over after 35 hr xenon irradiation lowered the embrittlement time to a remarkably short period of 70 hr considering the thickness and opacity of the foam. Similarly the "Slow" foam had its xenon embrittlement time reduced from 21+00 hr to only 600 hr by turning the foam over after each 2l+ hr irradiation period. To obtain a better idea of the rate of... 

Bio-Degradable Plastics Inc. recommend that their Sty-Grade resin concentrate be let-down 10 1 or 20 1 for use in formulating a Degradable polystyrene (2 ). 

Stevenson, W. White, J.R. Photo-sensitivity of recycled photo-degraded polystyrene. J. Mater. Sci. 2002, 37, 1091-1100. 

Donor molecules a,8-unsaturated carbonyl (polybutadiene degradation) polystyrene carbonyl polypropylene carbonyl... 

Table 3.127. Rate constant of degradation polystyrene samples degradation with different initial average chain lengths at different frequencies...

The existence of was demonstrated early by Staudinger in the 1930s [1,2] when he shear-degraded polystyrenes of different molecular weights in the solid state and in solution. A ball mill and a platinum jet were used, respectively. 

Fig. 4.3 Comparison of actual (left) and theoretical (right) distribution curves for ultra-sonically degraded polystyrene, original = 860,000. The values are for exposure times in minutes [32],...

Fig. 21. Differential distribution functions of ultrasonically degraded polystyrene. dm/dP differential distribution function of d ree of polymerization dm = mass of polymer having a degree of polymerizatkm betwee and P+dP initial molecular we My, = 411000, My d = 1.05 solvent tetrahydrofuran ultrasonic power of 48 watts at 20 kc/sec. Curves fe/f are expoi-moitah canesr ht are theoretical distribution functions calculated from pie de ation model. Param H of curves is time of irradiation (in min) iReC. (97)1...

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