Structural Regulation And Influence Of Polytetradecyl Methacrylate Copolymers On Low Tem-perature Fluidity Of Diesel Fuel

At low temperature,wax crystals precipitate out and grow continuously to form a three-dimensional network structure bonded with each other,which makes diesel lose its low temperature fluidity.The low temperature fluidity of diesel affects its normal use in extreme environment.Adding pour point depressants（PPDs）is a simple and effective method to regulate the low temperature fluidity of diesel,but the depressive effect of these polymers is always influenced by their molecular structure and polarity.In order to obtain a high efficient PPDs for improving the low temperature fluidity of diesel,in this paper,the structure of poly（tetradecyl methacrylate）was modified by polar monomers with different structures and used as PPDs.The mechanism of polymers in diesel was investigated by POM,DSC and rheological analysis.The main research contents are as follows:（1）A series of comb copolymers of tetradecyl methacrylate-benzylacetone(C₁₄MC-BAE),tetradecyl methacrylate-methyl cinnamate(C₁₄MC-MCA)and tetradecyl methacrylate-3-benzoyl acrylate(C₁₄MC-EBLA)was synthesized by molecular structure regulation.The inhibition effects of these copolymers on solid point（SP）and cold filter pour point（CFPP）of diesel were studied,and compared with previous reports.The results indicated that,the carbon-based monomer closer to the benzene ring on the side chain had better inhibition effect.When the molar ratio of the monomer was 9:1,these PPDs had the best inhibition effect on CFPP and SP of diesel.Among them,as the dosage was at 2000 ppm,C₁₄MC-EBLA（9:1）reduced the CFPP and SP of diesel by 12 and 15 ^oC,respectively.In addition,the morphology and crystallization behavior of wax crystals before and after adding PPDs were studied by POM,DSC and rheological analysis.（2）A series of copolymers with different proportions was synthesized by tetraceutical methacrylate(C₁₄MC)with acrylamide（AM）,phenylacrylamide（NPA）,N,N-dimethyl acrylamide（DMAM）,diacetone acrylamide（DAAM）and N-（hydroxymethyl）acrylamide（NMA）.These copolymers were added to diesel and the SP and CFPP of diesel samples were tested.The results showed that,acrylamide containing hydroxyl groups could better improve the depressive effect of polymer on diesel.thereinto,C₁₄MC-NMA（6:1）at 2000 ppm reduced SP and CFPP of diesel to-23 and-41 ^oC,respectively.In addition,POM,DSC and rheological analysis were used to study the influence of low temperature fluidity of diesel before and after adding polymers.（3）Ternary polymer C₁₄MC-EBLA-NMA with different proportions was prepared by polymerization of C₁₄MC,EBLA and NMA,and used as pour point depressants.The results showed that,the polar groups in the polymer acted synergistically to reduce the CFPP and SP of diesel.C₁₄MC-EBLA-NMA achieved the best depressive effect at 12:1:1 and 1500 ppm,which increasingΔCFPP andΔSP by 10 and 16 ^oC,respectively.The low temperature fluidity of diesel before and after polymer addition were analyzed by POM,DSC and rheology analysis.