polyethylene glycol MW 4000

wt%		log P (dynes/cm^2)

5.0		5.98
10.0		6.29
15.0		6.64
20.0		6.86
25.0		7.11
30.0		7.23
35.0		7.40

An equation that fits this data is the following.

log P = a + b * (wt%) ^ c

where a = 4.93, b = 0.50 and c = 0.45

Note that it should be applied only over the range of pressures measured.