PMMA degradation

Polymethyl methacrylate (PMMA) degrades under irradiation and becomes more soluble due to main chain scission. The degradation can be greatly reduced by the addition of 10% of various additives, such as aniline, thiourea, or benzoquinone. PMMA is an example of a nongelling polymer it does not form a three-dimensional network structure under irradiation. ... 

PMMA degradation determines a general decrease of mechanical performances of the material while the other phenomena may have beneficial effects even if rubber cross-linking can produce a decrease in the strain at break. These mechanisms, however they work, determine a decrease in the strain at break and a slight increase of the yield stress upon further irradiation. The different responses of the system varying the rubber nature is clearly attributable to the different effects of ionizing radiation on the rubber, which affect the final structure of PMMA-rubber blend. 

Cross-finked PS PMMA degraded in exposed areas. 

It is noticeable that PMMA degradation is accelerated only by a few admixtures, and perhaps it is an additional reason for a well-known durability of this... 

Dental prosthetic material, modified PMMA, degraded [8] ... 

Comparison of the physical blend, Nafion-H/PMMA, with the ph mically combined copolymers. The degradation of Nafion-H/PMMA blends and 2-SEM/MMA copolymers both show significant char formation, indicating that the methyl methacrylate units of both interact with the sulfonic acid groups. As illustrated in the Schemes, the process by which this occurs is different but the end result is that MMA is incorporated into the char rather than simply producing monomer as is seen in PMMA degradation. 

UV studies of PC samples at different extents of dehydrochlorination have revealed that the predominant absorption are characteristic of trienes. This is to be expected if random loss of HCl occurs by the nonradical mechanism shown in Scheme 26. PC does not accelerate PMMA degradation in PC/PMMA blends,which is also consistent with a nonradical dehydrochlorination. 

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