ANTAGONISM BETWEEN CLOUD POINT AND COLD FILTER PLUGGING POINT DEPRESSANTS IN A DIESEL FUEL

Differential scanning calorimetry (d.s.c.) and thermomicroscopy were u sed to provide a better understanding of the antagonistic effect on co ld filter plugging point (CFPP) when cloud point depressants (CPD) and CFPP additives are mixed into a diesel fuel. It is shown that the CFP P achieved by using only CFPP additive can be attained in the presence of CPD if a small. homogeneous size of crystals of paraffins is again obtained. Two ways are proposed to obtain this result: modification o f the chemical structure of the CPD, and optimization of the concentra tion of each component of the blend. In either case a decrease in effi ciency of the CPD is observed, but the antagonism disappears. It is po ssible to predict the efficiency of CFPP additives in a diesel fuel co ntaining CPD by evaluation of T-g of the hydrocarbon matrix and determ ination of the percentage of light pi-alkanes by d.s.c.