We are compounding special LDPE masterbatches with triethanolamine-based additives. After mid-term storage we observe an undesired browning of the product, which is caused by TEA oxydation (Maillard-type reactions). We tried to add specific TEA antioxidants but without significant results (the high extrusion temperature makes them ineffective). Can you suggest me any antioxidant suitable for triethanolamine and effective at 150 - 190 °C?
Extrude with CO2 injection to plasticate the polymer at lower temperature, example : foaming is made at 108°c exiting the die.
The less you additive the better, reactions are temperature catalyzed
Cheers
Cristo Bou thank you for your answer!
Indeed, we are using a twin-screw extruder to process LD-PE granules with our additives (volatile corrosion inhibitors, including triethanolamine). We know that temperature is the main issue, and we also found that sulfur-based antioxidants are suitable for triethanolamine color stabilization up to 80 °C (we successfully tested it). Unfortunately, the extrusion of polyethylene needs T > 150 °C and in these conditions our sulfur-based antioxidants do not work properly (some side-reactions occur between S and our additives).
Do you have any other suggestion for us?
Many Thanks!
Donato
PS: to overcome the color issue we can remove the triethanolamine (we tried it and it works), but we prefer to save this additive in our formulation.
Try with some water , this also has plasticating effect and partial foaming of your blend , but reactions could be also with your other additives.
You welcome
Regards
Cristo
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