Wax-crystal modification for fuel oils by self-aggregating partially crystallizable hydrocarbon block copolymers

The quality of life partially depends on the ability to maintain the transp ortation of goods and people in an efficient and reliable fashion, even und er difficult climatic conditions. A well-known problem at low temperatures is the filter blockage of diesel fuel. Fuel oils contain alkanes that preci pitate at low temperature as large crystals or spherulites of wax in such a way as to form gels. Thereupon the fuel loses its ability to flow and the transportation system falters or is stopped. The lowest temperature at whic h the fuel will still flow is known as the pour point. As the temperature a pproaches that of the pour point, difficulties emerge in transporting the f uel through lines and pump. Furthermore, wax crystals can plug screens and filters at temperatures above the pour point; the so-called cold filter plu gging point. To combat this behavior various additives have been developed to depress the pour point or to decrease the size and alter the shape of th e wax crystals; e.g., smaller sized crystals are less likely to clog either screens or filters. This paper reports on the use of a crystalline-amorpho us diblock copolymer that performs, in its self-assembled state, as an effi cient nucleator for the wax in middle distillate fuels.