The research project has carried out technical studies where plastic parts with defined material and additive recipes have been exposed to air, tap water or sea water at various temperatures and pressures.

The results show that plastic systems for marine applications needs specially tailored stabiliser systems. 

Some key conclusions from our studies were

• There are less remaining AO’s in all samples aged in sea water, 90°C at 30 bars compared with the same materials at 1 bar.
• At 110°C the results show much higher AO conc. after dry ageing than after wet ageing.

At dry conditions the depletion rate of AO1010 and AO 1330 are comparable. At wet conditions the depletion rate of AO1010 is much quicker. 

All in all it is still possible to design an underwater PP solution with the right AO composition for lifetime > 25 years.

• Figure - OIT of samples aged in air at 110°C vs. sea water at 90°C.
• The figure shows that the remaining stability is much less for sea water exposed samples even if the exposure in air is made at higher temperature.
• OIT = Oxidation Induction Time is a measure of the polymer resistance to degradation.