Polyethylene terephthalate hydrolysis

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)... 

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... 

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. 

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. 

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)... 

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. 

Recently, a new approach using enzymes to modify material (or nanomaterial) surfaces has been developed. This approach utilizes enzymatic hydrolysis or degradation to mildly etch the material surfaces and thus CTeate desirable surface structures or properties [45]. Many polymers, including polyvinyl chloride (PVC), polyaayloni-trile, polyethylene terephthalate, and polyamides, have been modified by this method. In a recent study, PVC tubes were soaked in Rhizopus arrhizus lipase to create nanometer surface features that exhibited antibacterial properties [60]. Enzymatic modification demonstrates great potential and promise for biomedical and nanomedicine applications due to its biocompatible, environmentally friendly, and simple process. 

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. 

However, some last minute experimentation aimed at improving the hydrolytic stability of the polyethylene terephthalate backbone lead to bisphenol-A polycarbonate. The simple molecule, guaiacol carbonate, provided the key to this transition since it was known to be very resistant to hydrolysis. This lead to the concept of preparing bis-guaiacol polycarbonate as the basis for a more hydrolytically stable wire enamel. There was no bis-guaiacol in the stockroom so bisphenol-A was selected as a model. 

Hydrolysis reactions have been widely reported in NCW for low-molecular-weight molecules as well as for polymeric materials. Mandoki reported a process for depoly-merizing condensation polymers using NCW without addition of bases or acids. More particularly, polyethylene terephthalate, polybutene terephthalate, nylon 6, and nylon 66 were hydrolytically depolymerized (Fig. 9.25). 

In the preparation of polyester for compositional analysis by NMR spectroscopy, much higher rates of hydrolysis are achieved by refluxing polyethylene terephthalate with a... 

Ester groups occur in a wide range of polymers (e.g., polyethylene terephthalate) and in copolymers such as, for example, ethylene vinyl acetate. The classical chemical method for the determination of ester groups, namely, saponification, can be applied to some types of polymer. For example, copolymers of vinyl esters and esters of vinyl esters and esters of acrylic acid, can be saponified in a sealed tube with 2 M sodium hydroxide. The free acids from the vinyl esters were determined by potentiometric titration or gas chromatography. The alcohols formed by the hydrolysis of the acrylate esters were determined by gas chromatography. Vinyl acetate ethylene copolymers can be determined by saponification with 1 N ethanolic potassium hydroxide at 80 C for 3 hours and back titration with standard acid or by saponification with p-toluene sulfonic acid and back titration with standard acetic acid [49, 50]. 

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