Polymers bottles

The carboxyl end can also thermally degrade to form vinyl end groups [22-24], which occur along with the formation of acetaldehyde (Figure 11). This is a side reaction that needs to be avoided, as acetaldehyde can taint mineral water and carbonated soft drinks if present at high levels (>20ppm) in the bottle polymer. Hence lower temperatures (around 160°C) are used in the SSP phase to minimise the formation of acetaldehyde. 

The optical properties of bottles are a matter of crystallinity affected by nucle-ation, depending on the content and size of light-scattering polymer solids. The purity of the raw materials and the cleanness of the reactors are prerequisites for satisfactory quality. Bottle polymer should display as little contaminations as possible. The detection of impurities is carried out by the same methods as mentioned above. Thorough filtration of the polymer is therefore mandatory. It should... 

Bottle polymer should have a minimum of contaminants, the determination of which is carried out by the same methods as mentioned above for fiber polymers. It should be noted that the quality of the TPA as a starting material has a significant influence on that of the polymer. The color is affected by the content of chemical impurities in the raw material, such as heavy metals, carboxyben-zaldehyde and toluenic acid. 

A very important factor of bottle polymer is its thermal stability, which depends on the conditions of its manufacture and the thermal history of the polymer. The amount of carboxylic end groups (CEGs) is a good indicator of the qualification of the chips. Continuously produced polymer should contain no more than 25 eq/kg CEG. Little differences between the TPA and DMT routes towards bottle polymers are observed. Chips from batch processes show higher CEG values (30meq/kg and more). The thermal stability depends on the use and efficiency, i.e. mainly the concentration, of stabilizers. 

Polyester granules (e.g., PET) are used for the production of bottle polymer, film (either video or wrapping), and fiber or filament. These types of polyester require quite a different system as the product first... 

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