Unsaturated polyester degradation products

UNSATURATED POLYESTER RESINS ON THE BASE OF CHEMICAL DEGRADATION PRODUCTS OF PET WASTE FOR VARNISHES... 

Thermoset plastics have also been pyrolysed with a view to obtain chemicals for recycling into the petrochemical industry. Pyrolysis of a polyester/styrene copolymer resin composite produced a wax which consisted of 96 wt% of phthalic anhydride and an oil composed of 26 wt% styrene. The phthalic anhydride is used as a modifying agent in polyester resin manufacture and can also be used as a cross-linking agent for epoxy resins. Phthalic anhydride is a characteristic early degradation product of unsaturated thermoset polyesters derived from orf/io-phthalic acid [56, 57]. Kaminsky et al. [9] investigated the pyrolysis of polyester at 768°C in a fiuidized-bed reactor and reported 18.1 wt% conversion to benzene. 

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... 

A series of poly(alkylene phthalate)s and some unsaturated polyesters were also investigated by Py-GC. The major pyrolysis products for these polyesters were the associated diols and anhydrides, such as phthaUc anhydride and maleic anhydride, as well as the products formed through the six-membered cyclic transition state. Moreover, various kinds of cyclic ethers and cyclic esters were also observed in considerable quantities. The general scheme of the degradation of poly(alkylene phthalatejs is shown in Figure 5.3. ... 

PPF is an unsaturated hnear polyester (Eig re 1) that degrades into fumaric acid and propylene glycol, both biocompatible degradation products. Many formulation methods have been proposed for orthopaedic applications. Once PPF is produced, it can be crosslinked through the fumarate double bond widi a vinyl monomer. Various filler particles can be incorporated to create porosity, increase mechanical properties, and enhance osteoconductivity. This mixture creates a moldable paste suitable for filling irregularly shaped bone defects that hardens in a short period of time. This review describes the many metliods used to synthesize and characterize PPF, and explores possible applications. 

The color of the polymer can also be affected by inappropriate reaction conditions in the polymerization process, such as temperature, residence time, deposits of degraded polymer or the presence of oxygen. Degradation of polyesters and the generation of chromophores are thermally effected [29b, 29c, 39], The mechanism of thermal decomposition is based on the pyrolysis of esters and the formation of unsaturated compounds, which can then polymerize into colored products. It can be assumed that the discoloration takes place via polymerization of the vinyl ester end groups or by further reaction of AA to polyene aldehydes. 

Poly(propylene fnmarate) (PPF) is an unsaturated linear polyester which degrades via bulk hydrolysis. The products of its degradation are propylene glycol, poly(acrylic acid-fumaric acid), and fumaric acid which occur naturally as part of the Krebs cycle. ... 

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