Precipitation of n-alkanes at low temperatures is the main factor that affects the cold flow properties of diesel fuel. In order to improve the clod flow properties of diesel fuel, maleic anhydride-methyl benzyl acrylate copolymer (MA-MB) were synthesized and modified with long-chain fatty amine and long-chain fatty alcohol (RNH 2 and ROH, R = C 14 , C 16 , C 18 ) to obtain a series of aminated copolymers R 1 MA-MB (R 1 = N 14 , N 16 , N 18 ) and esterified copolymers R 2 MA-MB (R 2 = C 14 , C 16 , C 18 ). These copolymers were characterized by gel permeation chromatography (GPC), Fourier transform infrared (FTIR) spectroscopy, and proton nuclear magnetic resonance ( 1 H NMR), and the oil affinity and oil solubility were studied by the static contact angle. The influences of them used as pour point depressants (PPDs) on the cold flow properties of diesel fuel were investigated. Results indicate that the esterified copolymers exhibit a better depression effect in depressing the solid point (SP) and cold filter plugging point (CFPP) than that of aminated copolymers. Among that, C 14 MA-MB exhibited the most considerable reduction on the SP and CFPP by 24 and 8 °C at 500 ppm addition, respectively. In addition, the depression mechanism was explored by differential scanning calorimetry, rheological analysis and polarizing optical microscopy. The analysis shows that C 14 MA-MB changed the crystal behaviors by modifying the crystal growth direction, restraining the crystal accumulation, and retarding the formation of large crystals, thus enhancing the cold flow properties of diesel fuel. Therefore, the synthesized copolymers are the highly effective PPDs of diesel fuels.
Meiying Huang,Lijun Gao,Jiuying Feng,Xuyi Huang,Zengquan Li,Zetian Huang,Lingyun Wang
Poly(propylene carbonate) (PPC) from CO2 and propylene oxide (PO) has wide potential applications as a degradable “plastic”. However, the thermal stability and mechanical properties of PPC cannot meet most of the application requirements. Herein, we focus on improving these properties. A (maleic anhydride/cis-1,2,3,6-tetrahydrophthalic anhydride) (MA/THPA) oligomer containing several cyclocarboxylic anhydride groups, which can copolymerize with PO, has been readily synthesized and used as the third comonomer to prepare PPC with cross-linked networks. The gel contents increase from 16 to 42% with increasing MA/THPA oligomer feed contents from 0.5 to 4 wt % of PO. The formation of cross-linked networks in PPC greatly improves the thermal, mechanical, and dimensional properties. The 5% weight-loss degradation temperature increases from 217 °C to nearly 290 °C before and after cross-linking, which ensures that PPC does not decompose in melt processing. The tensile strength of the copolymer is in the range of 22.2–44.3 MPa with elongation at break of 11–312%. The maximum tensile strength is improved by 143% compared to that of PPC. When the MA/THPA oligomer feed is above 3 wt % of PO, the hot-set elongation of the copolymer at 65 °C decreases more than 10 times when compared with that of PPC, and the permanent deformation is close to 0, while it is 145% for PPC. The dimensional stability is improved sharply. It can overcome the cold flow phenomenon of PPC. The improvement of the above comprehensive properties is of great significance to the practical application of PPC in various fields.
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