小分子物质在聚烯烃粒子内的传质

王文清等小分子物质在聚烯烃粒 子内的传质●15.Q小分子物质在聚烯烃粒子内的传质王文清②马青山冯连芳王凯(浙江大学材料与化工学院聚合反应工程国家重点实验室,杭州310027)通过实验与理论分析相结合，对小分子物质在聚合物粒子内的传质进行了研究。传质过程分为小分子物质在流体主体相与粒子孔洞间的传质和小分子物质在流体主体相与聚合物相间的传质。文中着重讨论”了不同条件对后一-过程的影响，并发现该过程虽然由孔洞内扩散阻力控制，但其规律可用传质系数的方法进行处理。文中还提出了一修正的Sherwood准数，对于小分子物质在流体主体相与聚合物间的传质，可用该准数与Reynolds准数很好地关联。关键词:传质小分子物质聚合物粒子中图分类号: TQ021.4A聚合物工业中，涉及小分子物质在聚合物中的曲折因子 A的关系为"，传质现象很多，如多相聚合反应、聚合物系脱挥、D. = D,(e/2)(1)增塑剂及其他添加剂的分散等。本研究所涉及的传其中. λ由下式给出2，质过程包括气相聚合反应和聚合物粒子的脱挥，它λ= of D(r)()dr(2)们共同的特点是由聚合物粒子和小分子物质组成的体系，体系压力为常压或低压(<1.013 x其中,f(r)为粒子内孔径密度分布函数, ε和10'kPa),体系温度比较低(T0. 03m/s时，粒子层D。有效扩散系数， m2/s .已经开始鼓动，所以属湍流传质。DL单体在粒子内扩 散系数, m2/s将Sh"对Re回归得到D。单体在聚合物内扩散系数, m2/sSh'= 0.017Re.s7(11)dp 粒子粒径，m回归结果如图6所示。由图可见，不同温度相E。吸收_扩散活化能， J/mol同气速下的Re和Sh'都相差很小。k Henry 系数, mol/ (m' ●Pa)0.121hy传质系数, s"M单体浓度, mol/m3 .。M。饱和浓度， mol/m'0.08eg00Mgg单体平衡浓度， mol/m'M。反应器内单体浓度， molm'0.04R传质速率, mol/ (m'●s)T温度,C0.00T，沸点,C20 25RT。玻璃化转变温度,T时间，s或min围6 Sh" 与Re回归结果Fig,6 Calculated reults of Sh" at diferent Re5。特征时间， su表观气速， m/s本研究用的是沸腾床传质,但是由上式可以看λ孔洞曲折因子出，Re的方次接近于0.5,这是层流传质的特征。p氮气密度，kg/m'这是因为小分子物质在聚合物粒子内的传质，其控μ氮气粘度，Pa.s制步骤是小分子物质在聚合物粒子空洞内的扩散，.Re Reynolds 准数而该步骤为层流传质,所以整个过程也表现出层流Se Schmidt 准数传质的特征。Sh"修正的 Sherwood准数I下转第56页]●56.化学工程2001 年第29卷第6期136.19 TnlebM. etal. Cstllizain of pocins under an exter12 NimuraN, Minezaki Y, et al. Polar structure of lysornal electic feld. ICirystal Cromth, 999, 200; 575.zyme agrgates in unseturated solurion delermined by20 YunYY, Neve RS. Cllis M W. The cfer of an eesmall-angle neutron scteringcontrast variation melthod..trie field on heat and mass trausfer for dieletric crstaliza-Crystal Growth, 199 200: 265.tin. Trus lchemE, 1997, 75, P'ant A: 668.13 BairdJ K. Theary o protein cytal muleation and growth21 LipusL, KopeJ, el l. Magneie water tealment forcontolld by solvent evaporation. 了Crystal Crowth,scale prevenion. HungJ Ind Chem, 1998. 26: 109.1999，204: 553.22 WakayamaN1, Ataka M, Abe H. Eiteer of a magetie14 Takeuchi H. Structure frmation during the crstlizationfield on the crslalization of hen lyozyme. 」Crystalinduction period of a sbhort chain molecule system: a morGrowth, 1997. 178: 653.lecular dynanics study. J Cherm Phys， 1998， 10923 SaakiC, Yohida E, etal. ffetr ol a magneic field on(13): 5614.the ersalization of biological maronpoleules. J Crystal15 CrantML Efets of temodynamie nideaity in proceinGrowth. 1997. 173: 231.crystal growth. J Crystal Crowth, 2000, 209: 13024 SuzkiC, YanagiyaS, et ul. Efer of a megnetie fed on16 WangYP, HanY, etal. Prolein cystal gowth in micro.the prolein rylalizain. Intemnatioul Sympoium on Ingarity using a liqpid liquid difusion method. Microgai- .lstrial Crslliatinn Waseda Unierit， Jpan.ty Sci Technol, 1996, 9 (4): 281.1998, 363.I7 McPbersn A. Recent advancs in the mingngieysal 25 AlakaM, KaohE, WakeyamaNl. Etea of the hoan-lization of bologial macomolecules. Trends in Biotech-geneous magnetic field on protein erysalization. J Crystalnology, 1997, I5 (6): 197.Crwth, 1997, 173: 592.18 Sohnel0, CarsideJ. Peipatin.n (xford: Butereorh. 26 Banel PA, etal. Laser seine for bomolcular cystaHeineman, 1992, 65.liation. 」Crystal Crowth, 1998, 191: 537.[上接第19页]10 Floyds, Huthinson RA, Ray W H. Polymeirzaton of参考文献Olefins throughb heterogencous calysis- V. J Appl PolymSei, 1986, 32: 5451.1 FloydS, Choi KR, TaglorTW, el al. Polyncrization of11 FloydS, Heiskanen T, Taylor 1 w. e1 al. Polymeiza-Olefins through heterngeneous catalysis- m.」Appl Polymtiomu of Olefins through beleogeneous catalysis-VI.」Ap-Sei, 1986 (32): 2935.pl PolymSei, 1987. 33: 1021.2 WangCr, Smith J M. Totuosily facors for difusion in 12 马青山 气相原位共聚制备粒状聚烯烃台金工程研究catalyst plls. AIChEJ. 1983, 29 <1): 132.[博士学位论文。。杭州:浙江大学化工系. 19993 Michaels AS, Bisler H J. Flow of gases through polyethy13 KimKJ, Choi K Y. Continuous olefin cplymerzrinene. J Polym Sei, 1961, 50: 413.with soluble Ziepler-Natta calalysts. AICnEJ, 1991, 37Michaels AS, Bixler H J. Slobliy of gaes in palyehy-(8): 1255.lene. J PolymSci, 1961, 50: 393.14 Hamba M. Han-AdebekunGC, Ray W H. Kinetic study5 Frensdod H K. Polymerization in expanding calyst parti.of gas phase olecfin polymerization with a TiCL//4/MgC1//cles. J PolymnSei, A-2, 1964, I: 341.2 catalyst I. Kinetie paraneter eination and mode!6 Takenchi Y, Okamure H. The role of difusion in the Xie-building J Polym Sci, A: Plym Chem， 1997. 35:gler polymerzaion of ethylene.」Chem Fng Japan, 1976,2075.9: 136.15 Singh D, Mrill R P. Molecular weight disnibution of po-7 LongR B. A particle growth thory for heterogneus Zie-lyetlhylene produced by Ziegler Natta eatalysts. Macromole-gler polyeriztion. Ind Eng Chem，1965, 4 (4): 445.xules, 1971,4 (5): 599.8 MeCal D W. Sicher w P. Difusion in ethylene poly.16 Y'emakov v A. Chunaerski N B. On the mechauism ofmers.0 Efects of temperature and pressure. J Am Chcmolein polymeriration by Zieler-Natta catalysts. PlastSoe, 1958. 80: 1861.Massy, 1970, 9: 7.9 Schmeal W R, Sret J R. Polymerization in expnding cat.17马青山， 冯连芳，张立锋等，丙烯为土单体的烯烃共alyst paricles. AIChEJ, 1971 (17) 5, 188.聚合金的研究，石油化工， 199 28 (10): 66.6..