Virgin PET

Similar to virgin PET, solid-state polycondensation (SSP) is the method of choice to increase the molecular weight in mechanical recycling processes. 

The cost for recycled PET has to be lower than virgin PET bottle material, even at low virgin prices. 

As an example for process succession D, the Buhler bottle-to-bottle process fulfils all of the requirements listed above. Acetaldehyde levels are even below those of virgin PET (Figure 4.23). 

Table 4.3 Typical specifications for reclaimed flakes, recycled PET pellets and virgin PET pellets...

The chips sell for about 25 to 35 cents per lb for PET (with less than 100 ppm of aluminum), and 17 to 25 cents per lb for HDPE. In comparison, virgin PET costs about 50 to 60 cents per lb, and HDPE resins about 40 cents per lb. The center combines these and other factors in evaluating the financial aspects of operating a plant. "In our engineering... 

Figure 8-5 Concentration profile for the migration of chlorobenzene in and from an impurified PET core layer into a virgin PET barrier layer and a food simulating liquid F.

This PET recyelate is used mainly in the nonfood sector, because of hygienic concerns. Small amounts of recyclate are used in bottle-to-bottle applications. In the sandwich process a core of recyclate is coated inside and outside by virgin PET. In this case up to 40% recyclate can be used. 

Similar compatibilization has been achieved through radiation, without any specific additives, involving recycled and virgin PET and radiation oxidized HDPE [10],... 

BURILLO G., HERRERA-FRANCO P. ET AL., Compatibilization of recycled and virgin PET with radiation-oxidized HDPE, Radiat. Phys. Chem., 63, 241 - 244, 2002. 

One of the major problems associated with the neutral hydrolysis method is that most of the impurities initially present in the PET waste remain in the TPA produced by the reaction. Therefore, complex and intensive purification operations are needed to obtain TPA with properties similar to the commercial grades. A hydrogenation step has been proposed as a method for the removal of impurities and colour found in the TPA produced by PET neutral hydrolysis.60 TPA precipitated from the hydrolysis medium is slurried in water and cata-lytically hydrogenated at 260-290 °C and a pressure of 65-82 atm for around 1 h. Palladium supported on carbon is one of the preferred catalysts for this hydrogenation step. This treatment leads to a colour level and fluorescence properties in the produced TPA similar to those of the commercially available virgin PET. 

A similar result for PPE/PET blends has been reported by Liang and Pan [1994]. The authors found the cold crystallization temperature, T in the dispersed PET phase to be markedly lower than that of the virgin PET, indicating that PPE may partly act as nucleating agent to promote the nucleation of the PET component. 

Recycled PET is used for an inner layer of new, 5-layer Coca-Cola bottles. The outer layers are virgin PET, separated from the inner by two thin layers of PA-m XD6... 

In an open reaction vessel, potassium hydroxide has been used for PET depolymerization with success. Complete degradation was accomplished in 8 min in 1-butanol, in 4 min in 1-pentanol, and in 7 min in 1-hexanol working at a constant microwave power of 500 W in a scientific apparatus. This method yielded as products (after acidification) terephthalic acid and ethylene glycol of sufficient purity to be reused as monomers for the synthesis of virgin PET (Scheme 3.14). In most cases, similar reactions under conventional heating required up to 8 h at reflux. ... 

These processes for PET yield materials that can be used interchangeably with virgin PET, and several companies have received letters of no objection for these processes. 

Figure 10.8. Comparison of the impacts of virgin PET, recycled PET and PLA on human health, ecosystem quality, climate change and non-renewable resources [KUM10]...

With regard to the errviromnental impacts of errergy consumption and etrrissions of pollutants and carbon dioxide, it is generally accepted that recycling is beneficial whatever the material (glass, steel, alttminttm, paper, cardboard). Errviromnental benefits have also been verified for polymers. In the case of PET, total substimtion of virgin PET with recycled PET rednces CO2 emissiorrs by 27% [HOP 09]. 

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