poly(oxy-1,2-ethaandiyl), α-(1-oxooctadecyl)-ω-(1-oxooctadecyloxy)-, (250 mol EO gemiddelde molaire verhouding ###>Poly(oxy-1,2-ethanediyl), .alpha.-(1-oxooctadecyl)-.omega.-(1-oxooctadecyloxy)-, (250 mol EO average molar ratio)