PEL-SIL 9738 is useful in both frothed and rigid foam for the promotion of fine cell structure, which results in improved k-factor. PEL-SIL 9738 is a graft style non-hydrolyzable silicone polyether surfactant. The polyether pendants of this product are produced from ethylene oxide with no propylene oxide and the silicone backbone makes up 27% of the molecular weight. PEL-SIL 9738 is acetate capped so it has no hydroxyl functionality. It may be added to either the A or B side of rigid polyurethane foam formulations. Use levels for this type of foam can vary from 1 to 2 parts PEL-SIL 9738 per 100 parts polyol.