Drying

PET is hygroscopic, acceptation that it absorbs baptize from its surroundings. However, if this 'damp' PET is again heated, the baptize hydrolyzes the PET, abbreviating its resilience. Thus, afore the adhesive can be candy in a abstraction machine, it have to be dried. Dehydration is accomplished through the use of a anhydrous or dryers afore the PET is fed into the processing equipment.

Inside the dryer, hot dry air is pumped into the basal of the alembic absolute the adhesive so that it flows up through the pellets, removing damp on its way. The hot wet air leaves the top of the alembic and is aboriginal run through an after-cooler, because it is easier to abolish damp from algid air than hot air. The consistent air-conditioned wet air is again anesthetized through a anhydrous bed. Finally, the air-conditioned dry air abrogation the anhydrous bed is re-heated in a action boiler and beatific aback through the aforementioned processes in a bankrupt loop. Typically, balance damp levels in the adhesive have to be beneath than 50 locations per actor (parts of baptize per actor locations of resin, by weight) afore processing. Dryer abode time should not be beneath than about four hours. This is because dehydration the actual in beneath than 4 hours would crave a temperature aloft 160 °C, at which akin hydrolysis would activate central the pellets afore they could be broiled out.

PET can aswell be broiled in aeroembolism air adhesive dryers. Aeroembolism air dryers do not reclaim dehydration air. Dry, acrimonious aeroembolism air is broadcast through the PET pellets as in the anhydrous dryer, again appear to the atmosphere.