Why does DOA give better low-temperature flexibility?
Because of its backbone. Phthalate and terephthalate plasticisers carry a rigid benzene ring at the centre, which limits how freely the molecule can rotate and therefore how much chain movement it can permit as temperature falls. Adipates have a flexible fully aliphatic six-carbon chain instead, which keeps PVC pliable to around minus 40 degrees Celsius.
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What is the trade-off for that cold performance?
Permanence. The smaller, more mobile aliphatic molecule is more volatile and more readily extracted by oils and fats than an equivalent phthalate, so it migrates out faster and the article stiffens sooner. For that reason DOA is frequently used in a blend with a more permanent plasticiser rather than alone.
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Why is DOA used in cling film?
Because the film must stay flexible and clingy at refrigeration temperature, where a phthalate-plasticised film would stiffen and lose its cling. The same reasoning applies to freezer bags and to cold-climate cable and hose, all of which need the plasticiser to keep working well below normal ambient.
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Is DOA the same as DEHA?
Yes. DOA, dioctyl adipate, and DEHA, di(2-ethylhexyl) adipate, refer to the same material, CAS 103-23-1. As with the octyl phthalates, the generic octyl designation is ambiguous, so the CAS number should be used when specifying to avoid confusion with other adipate esters.
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