Research On The Drag Reducing Agents Of Pentene/Alpha Olefin Bipolymer And Terpolymer

Fluid transportation is the important segment of industrial production with wide application.Pipeline transportation is the main transporting pattern.DRAs（drag reducing agents）are a kind of chemical additives to reduce liquid flow friction and to increase flow rate,the use of drag reduction agent can save energy and increase transportation effect obviously.As the demand of oil is rising,the study of DRAs used for pipeline transportation of crude oil is becoming more and more important.Nowadays,production technology of drag reducer was monopolized by the company of United States and Germany,the use of drag reducer in our country depend on import.The linear flexible macromolecule polymer has better drag reduction effect,α-olefin polymer is currently widely used in crude oil drag reduction with good drag reduction effect.In this paper,the alkenes with short chain were introduced to react with alkenes with long chain,in order to damage the regularity of the polymer chain and decrease the crystallinity of synthetic copolymer.Using α-olefin as polymerization monomers,high-molecular binary copolymer of α-pentene/dodecene bipolymer and α-pentene/α-octene/α-dodecene terpolymer were synthesized by solvent polymerzation with TiC_l4/MgC_l2 as main catalyst and Al（i-Bu）₃ as cocatalyst,this is the first time use α-pentene as the material preparing drag reduction agent.The influence of polymerization method,solvent species and adding method of the main catalyst on the synthetic process and drag reduction efficiency was investigated.The drag reduction efficiency of the terpolymer was evaluated by an indoor loop pipeline experimental apparatus.Effects of polymerization conditions on the drag reduction efficiency of copolymer were also investigated.The orthogonal test and response surface methodology were used to optimize the polymerization technology.The polymers was characterized by13C-NMR,FT-IR and XRD.Besides,the influence of the way adding catalyst on drag reducing efficiency（DR）and polymerization technology were investigated.To prepare the α-pentene/dodecene bipolymer,it is better to use solutionpolymerization than bulk polymerization,using cyclohexane as solvent is better than n-hexane.There is few influence between adding the the main catalyst before and after it dissolve in solvent,on the whole,it is better to adding the main catalyst directly into the polymer solution.The optimum polymerization conditions to synthesize α-pentene/dodecene bipolymer were: 0.05 mL α-pentene,16 mL dodecene,0.08 g main catalyst,0.2 mL cocatalyst and 5 ℃,the drag reduction rate is 57.62%.The optimum polymerization conditions to synthesize α-pentene /α-octene/α-dodecene terpolymer were: 0.07 mL α-pentene,dodecene: octane = 4,0.07 g main catalyst,0.4 mL cocatalyst,when the dosage of the terpolymer is 10 g·m^-3,the drag reduction rate is 59.79%.The crystallinity of synthetic copolymer were significantlt decreased due to the introduction of α-pentene,the solubleness was much better than α-dodecene polymer and α-octene/α-dodecene bipolymer,the drag reduction rate（DR）was improved.The ability for different α-olefin to enter into the unit cell is different,branch chain with carbon atom number less than 5 can enter into the lattice.There are 3carbon atom on the branch chain of the α-pentene,it can enter into the lattice easily in the high-speed polymerization process,act as the expansion of the lattice and the obvious increase of lattice parameters.After adding the α-pentene the arrangement of polymer molecular chain become relatively loose,so that damaged the regularity of the polymer chain,the crystallinity of synthetic copolymer decreased.There are 6carbon atom on the branch chain of the α-octene,they are difficult to enter into the lattice in the high-speed polymerization process,most of them are excluded from the outside of the lattice.Excess α-pentene can compete active centres of the catalyst withα-octene and α-dodecene,result in the decreasing of the molecular weight of the copolymer,which may lead to the a poor drag reduction performance.