Hydrolysis of polyethylene terephthalate

Nimchua T, Punnapayak H, Zimmermann W (2007) Comparison of the hydrolysis of polyethylene terephthalate fibers by a hydrolase from Fusarium oxysporum LCH I and Fusarium solani f. sp. pisi. Biotechnol J 2 361-364... 

Bacillus sp. (Nitro-benzyl- esterases) Hydrolysis of polyethylene terephthalate) oligomers [61, 62]... 

Eberl, A., Heumann, S., Bruckner, T., Araujo, R., Cavaco-Paulo, A., Kaufmann, F., Kroutil, W., and Guebitz, G.M. (2009) Enzymatic surface hydrolysis of polyethylene terephthalate) and bis(benzoyloxyethyl)... 

Nechwatal, A., Blokesch, A., Nicolai, M., Krieg, M., Kolbe, A., Wolf, M., and Gerhardt, M. (2006) A contribution to the investigation of enzyme-catalysed hydrolysis of polyethylene terephthalate) oligomers. Macromol. Mater. Eng., 291 (12), 1486-1494. 

As already described, the mechanochemical degradation of polyethylene terephthalate takes place mainly at the heteroatomic links (the weakest), while the breaking of —C—C— links is less pronounced. In wet media there is also a mechanochemically activated hydrolysis. 

Using a similar method, we examined the reaction of polyethylene terephthalate with NaOH. The reaction is shown in Figure 14. In contrast to the polyimide case, this hydrolysis causes chain cleavage. Because a water rinse completely removes the Na, we used a more complex scheme to study the kinetics. 

The concern about possible contamination of food containers means that they can be recycled to only nonfood contact uses in the United States. To reuse polyethylene terephthalate in contact with food, it must be broken down, purified (to remove metal compounds, colors, and such), and resynthesized (14.2). This has been done by hydrolysis, methanolysis, and glycolysis.162 (The solvolysis can be complete in 4-10 min when microwaves are used with a zinc acetate catalyst.163) (For nonfood uses, such as the use of polyethylene terephthalate in magnetic tapes, it may be sufficient to melt the polymer and filter out the chromium or iron oxides.164)... 

Hydrolysis in polyethylene terephthalate at temperatures of 100 to 120 °C and a relative humidity of 100% takes place approx. 10,000 times faster than thermal degradation, and 5,000 times faster than oxidation in air in the same temperature range. Just 0.01 wt.-% content of effectively acting water at elevated temperatures (100 C) causes a noticeable decrease in molecular mass and viscosity as well as in mechanical properties because of hydrolytic cleavage. This is important in particular for the manufacturing of PET with high molecular masses by solid-phase condensation [774]. 

The rate of hydrolysis reactions depends both on the protons as well as on the concentration of absorbed water. There is a direct proportionality between the rate of hydrolysis and water concentration. Dry polyethylene terephthalate absorbs moisture very quickly, depending on exposure time, particle shape, crystallinity, and relative humidity. Analogous to low-molecular carbonic acid esters, hydrolysis in polyethylene terephthalate is an autocatalytic reaction as long as acids or bases do not catalyze reactions [969]. 

Hsuan, Y.G., Koemer, R.M., 2005. Evaluation of the hydrolysis behavior of polyethylene terephthalate yams. In Rathje, E.M. (Ed.), Geo-Frontiers, ASCE/GI Conference. Geotechrucal Special Publications 130-142 GRI 18, January 24-27, Austin, Texas, pp. 3981—3985. 

In semi-cristalline polymers, rate-enhancement under stress has been frequently observed, e.g. in UV-photooxidation of Kapron, natural silk [80], polycaprolactam and polyethylene terephthalate [81]. Quantitative interpretation is, however, difficult in these systems although the overall rate is determined by the level of applied stress, other stress-dependent factors like the rate of oxygen diffusion or change in polymer morphology could occur concurrently and supersede the elementary molecular steps [82, 83], Similar experiments in the fluid state showed unequivocally that flow-induced stresses can accelerate several types of reactions, the best studied being the hydrolysis of DNA [84] and of polyacrylamide [85]. In these examples, hydrolysis involves breaking of the ester O —PO and the amide N —CO bonds. The tensile stress stretches the chain, and therefore, facilitates the... 

Polyethylene terephthalate (PET) is one of the most important commercial thermoplastic polyesters, which has been on the market since 1977 and is widely used in both industrial and household applications. Under specific conditions, plastics can be converted into their primary components for use in other chemical processes by chemical recycling. PET is a thermoplastic, and so recycling by chemical methods, which converts it into primary components, can be achieved. This study examines the optimal routes of the existing chemical methods. For chemical recycling, acidic hydrolysis is used and PET is converted into terephthalic acid (TPA) and... 

Depolymerization, e.g., polyethylene terephthalate and cellulose hydrolysis Hydrothermal oxidation of organic wastes in water Crystallization, particle formation, and coatings Antisolvent crystallization, rapid expansion from supercritical fluid solution (RESS)... 

DuPont offers a family of biodegradable polymers based on polyethylene terephthalate (PET) technology known commercially as Biomax. Proprietary monomers are incorporated into the polymer, creating sites that are susceptible to hydrolysis. At elevated temperatures, the large polymer molecules are cleaved by moisture into smaller molecules, which are then consumed by naturally occurring microbes and converted to carbon dioxide, water and biomass. Biomax can be recycled, incinerated or landfilled, but is designed specifically for disposal by composting. 

Biomax. Biomax is a family of aliphatic/aromatic polyesters based on polyethylene terephthalate and manufactured by DuPont. A combination of hydrolysis and microbial action breaks down the polymer, and some grades have been certified as compostable. Reportedly, as many as three different proprietary aliphatic monomers may be incorporated into the polymer. ... 

Another important area of polymer modification with subcritical and supercritical water is the hydrolysis of polycondensation polymers such as polyethylene terephthalate (PET), polyurethanes, and nylons for conversion to their monomers [ 37]. Specifically, in supercritical water, 91 % monomer recovery (terephthalic acid) is achieved at 400 °C and 400 bar in less than 15min reaction times [38]. Studies of these reactions using a hydrothermal diamond anvil cell to follow the phase changes during the reaction of PET... 

NMR spectroscopy has been applied to the determination of ester groups in polyethylene terephthalate (PET) [45]. A blend of a protic solvent (dimethyl sulfoxide), sodium hydroxide, and methanol hydrolyses ester groups in this polymer much more rapidly than do hydrolysis reagents previously used. 

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