王文清等小分子物質(zhì)在聚烯烴粒 子內(nèi)的傳質(zhì)●15.Q小分子物質(zhì)在聚烯烴粒子內(nèi)的傳質(zhì)王文清②馬青山馮連芳王凱(浙江大學(xué)材料與化工學(xué)院聚合反應(yīng)工程國家重點(diǎn)實(shí)驗(yàn)室,杭州310027)通過實(shí)驗(yàn)與理論分析相結(jié)合，對小分子物質(zhì)在聚合物粒子內(nèi)的傳質(zhì)進(jìn)行了研究。傳質(zhì)過程分為小分子物質(zhì)在流體主體相與粒子孔洞間的傳質(zhì)和小分子物質(zhì)在流體主體相與聚合物相間的傳質(zhì)。文中著重討論”了不同條件對后一-過程的影響，并發(fā)現(xiàn)該過程雖然由孔洞內(nèi)擴(kuò)散阻力控制，但其規(guī)律可用傳質(zhì)系數(shù)的方法進(jìn)行處理。文中還提出了一修正的Sherwood準(zhǔn)數(shù)，對于小分子物質(zhì)在流體主體相與聚合物間的傳質(zhì)，可用該準(zhǔn)數(shù)與Reynolds準(zhǔn)數(shù)很好地關(guān)聯(lián)。關(guān)鍵詞:傳質(zhì)小分子物質(zhì)聚合物粒子中圖分類號: TQ021.4A聚合物工業(yè)中，涉及小分子物質(zhì)在聚合物中的曲折因子 A的關(guān)系為"，傳質(zhì)現(xiàn)象很多，如多相聚合反應(yīng)、聚合物系脫揮、D. = D,(e/2)(1)增塑劑及其他添加劑的分散等。本研究所涉及的傳其中. λ由下式給出2，質(zhì)過程包括氣相聚合反應(yīng)和聚合物粒子的脫揮，它λ= of D(r)()dr(2)們共同的特點(diǎn)是由聚合物粒子和小分子物質(zhì)組成的體系，體系壓力為常壓或低壓(<1.013 x其中,f(r)為粒子內(nèi)孔徑密度分布函數(shù), ε和10'kPa),體系溫度比較低(T0. 03m/s時(shí)，粒子層D。有效擴(kuò)散系數(shù)， m2/s .已經(jīng)開始鼓動，所以屬湍流傳質(zhì)。DL單體在粒子內(nèi)擴(kuò) 散系數(shù), m2/s將Sh"對Re回歸得到D。單體在聚合物內(nèi)擴(kuò)散系數(shù), m2/sSh'= 0.017Re.s7(11)dp 粒子粒徑，m回歸結(jié)果如圖6所示。由圖可見，不同溫度相E。吸收_擴(kuò)散活化能， J/mol同氣速下的Re和Sh'都相差很小。k Henry 系數(shù), mol/ (m' ●Pa)0.121hy傳質(zhì)系數(shù), s"M單體濃度, mol/m3 .。M。飽和濃度， mol/m'0.08eg00Mgg單體平衡濃度， mol/m'M。反應(yīng)器內(nèi)單體濃度， molm'0.04R傳質(zhì)速率, mol/ (m'●s)T溫度,C0.00T，沸點(diǎn),C20 25RT。玻璃化轉(zhuǎn)變溫度,T時(shí)間，s或min圍6 Sh" 與Re回歸結(jié)果Fig,6 Calculated reults of Sh" at diferent Re5。特征時(shí)間， su表觀氣速， m/s本研究用的是沸騰床傳質(zhì),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,這是層流傳質(zhì)的特征。p氮?dú)饷芏?，kg/m'這是因?yàn)樾》肿游镔|(zhì)在聚合物粒子內(nèi)的傳質(zhì)，其控μ氮?dú)庹扯龋琍a.s制步驟是小分子物質(zhì)在聚合物粒子空洞內(nèi)的擴(kuò)散，.Re Reynolds 準(zhǔn)數(shù)而該步驟為層流傳質(zhì),所以整個(gè)過程也表現(xiàn)出層流Se Schmidt 準(zhǔn)數(shù)傳質(zhì)的特征。Sh"修正的 Sherwood準(zhǔn)數(shù)I下轉(zhuǎn)第56頁]●56.化學(xué)工程2001 年第29卷第6期136.19 TnlebM. etal. 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