Natural Ester

Paper

Standard

Temperatures

Duration

Results

Not specified [16]

Kraft paper and pressboard

ASTM D6802

110˚C, 140˚C, 160˚C and 185˚C

The samples have been aged during 336 h at 110˚C, then 336 h and 140˚C, next 336 h at 160˚C, finally 336 h at 185˚C for a total of 1344 h

Initially, the rate of degradation products dissolved in natural ester is higher than in mineral oil. The increase in temperature and aging duration reversed this trend.

Rapeseed and palm oils [22]

Kraft paper and pressboard

ASTM D6802

130˚C

100, 250, 500, 1000, and 1500 h

Overall increase in DDP during the first 1000 hours (rapeseed highest, palm oil and mineral oil least).

This tendency was reversed during the latter aging period, with mineral having the highest DDP, followed by palm oil and finally rapeseed.

Soya bean oil [17]

TUK and Nomex-910

ASTM D6802

120˚C, 150˚C and 180˚C

48, 72 and 96 h

The rate of degradation products dissolved in the oil is higher for impregnated Nomex compared to TUK.