Aggregation behaviour of PE-PEP copolymers and the winterization of dieselfuel

Results from multicontrast SANS investigations of aggregates that form on c ooling a solution of polyethylene(PE)-polyethylenepropylene(PEP) block copo lymer in decane are reported. The PE-cores form extended crystalline platel ets covered by a "brush" of PEP-"hairs" on both sides. Added wax (paraffin) is taken up by these aggregates. Decane may be considered as a model for d iesel fuel and the waxes as contaminants in diesel fuel that crystallize at low temperatures and clog the filters of engines. It is explained why comp ounds of the PE-PEP family efficiently reduce the minimum temperature down to which these fuels may be used by directing the walt precipitation/nuclea tion into aggregates that are small enough to pass the filters. (C) 2000 El sevier Science B.V. All rights reserved.