Polycarbonate degradation products

Troev et al. (see, e.g., [80,81]) degraded polyurethanes (microporous elastomers or flexible foams) via exchange reactions between urethane groups and alkoxy groups of phosphonic or phosphoric acid derivatives using dialkyl phosphonates or trialkyl phosphates. The potential application of the oligomeric liquid products is similar to that of the polycarbonate degradation products [29], i.e., for flame retardant formulations and polymer modification. 

Bisphenol A is used as a raw material to make polycarbonate and epoxy adhesives and can coatings. It is also used in flame-retardants, in unsaturated polyesters and in polyacrylate resins. Many foodstuff containers are made of these resins, including containers for oven and microwave cooking. Recent studies have shown that bisphenol type compounds have both mutagenic and cytotoxic properties [84]. Nerin et al. developed a fast screening method based on SPME and HPLC with fluorescence detection suitable for the analysis of several bisphenol derivatives and their degradation products in aqueous canned foods such as tuna, olives and corn [85]. The best results were obtained with carbowax and PDMS/DVB fibers. The detection limits were between 0.7 and 2.4ngmL while RSDs were between 14 and 32%. After the extraction parameters were optimized, the method was applied to... 

The photo-Fries products are not present in significant amounts in solid polycarbonate degraded under normal weathering conditions. 

SIM curves for representative degradation products and TIC curved observed for (a) PBT, (b) brominated polycarbonate (Br-PC), and (c) FR-PBT measured by TPPy-MS, from Ref. 33. The italic numbers in parentheses represent the peak heights. 

Polymers shown to possess immunostimulatory properties in the form of their degraded products are the polyiminocarbonates (Kohn et al, 1986), based on a variation of classical polycarbonates (8). The only stractural... 

Another advantage of the melt process is that it avoids the use of chlorinated solvents. Trace levels of residual chlorinated solvents can be a concern for polycarbonate used in applications such as water bottles [16]. The solvent levels are very low in manufactured polycarbonate and become even lower during subsequent melt processing into articles however use of the melt process avoids the issue entirely. Both processes have the potential for residual BPA and BPA is a degradation product of polycarbonate, especially degradation by hydrolysis. There is currently some concern about the health effects of BPA and the topic is the subject of much scientific debate and many studies [17]. 

The interaction and relative role of the three mechanisms has not yet been explained, nor has the chemical structure of the compounds crucial for yellowing. Investigations of a non-stabilized polycarbonate, exposed to outdoor weathering in Florida for four years, indicate more than 40 different degradation products. The majority of these are degradation products caused by photo-oxidation, whereas... 

Processes were developed in recent years in order to recover raw materials from poly(ethylene terephtalate) (PET) and polycarbonate (PC) by hydrolysis. The main focus was the recovery of terephthalic acid and ethylene glycol besides other products such as benzene, salts of terephthalic acid and oxalic acid. Processes developed for PET are also valid for polyesters such as poly(butylene terephthalate) (PBT) and poly(ethylene 2,6-napthalene dicarboxylate) (PEN). The recovery of bisphenol-A (BPA) from PC requires more sophisticated methods due to the low stability of BPA at high temperatures. Often phenol and isopropenyl phenol are obtained as degradation products of BPA. 

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