聚乙二醇的非等溫結晶動(dòng)力學(xué)研究

第16卷第3期含能材料Vol. 16. No. 32008年6月CHINESE JOURNAL OF ENERGETIC MATERIALSJune, 2008文章編號:10069941(2008)03030504聚乙二醇的非等溫結晶動(dòng)力學(xué)研究黨永戰,趙鳳起,高紅旭,胡榮祖,康冰西安近代化學(xué)研究所,陜西西安710065)摘要:用差示掃描量熱法(DSC)研究了聚乙二醇(PEG)的非等溫結晶動(dòng)力學(xué)。用 Ozawa法、 Jeziomy法和莫志深法處理了PEG的非等溫結晶數據。結果表明,PEG的非等溫結晶過(guò)程可用0awa動(dòng)力學(xué)方程描述,與 avrami動(dòng)力學(xué)方程不符,采用Owa法和莫志深法處理數據可得到較好的線(xiàn)性關(guān)系,PEG的結晶速率參數為0098。關(guān)鍵詞:物理化學(xué);聚乙二醇(PEG);非等溫結晶;動(dòng)力學(xué);差示掃描量熱法(DSC)中圖分類(lèi)號:T555;064文獻標識碼:A醇,廣東汕頭市西隴化工廠(chǎng),相對分子量200001引言2.2實(shí)驗條件聚乙二醇( polyethylene glycol,PEG)是用環(huán)氧乙試樣量,(5.43±0.25)mg;吹掃載氣,40mL·min1烷與水或乙二醇逐步加成聚合得到的水溶性聚醚,有(氮氣);熔融熱和溫度校正用銦作標準,熔融熱校正多種優(yōu)良特性而被廣泛應用。PEG作為NEPE推進(jìn)值為28.70J·g'。DsC的操作條件:快速升溫至劑的黏合劑賦予NEPE推進(jìn)劑較優(yōu)異的力學(xué)性能。70.0℃使PEG熔融,恒溫5mim,消除熱歷史后,分別含PEG的NEPE推進(jìn)劑是一類(lèi)硝酸酯增塑的聚醚推以5,3,2,1℃·min-降溫速率降至室溫。進(jìn)劑,是現役固體推進(jìn)劑中能量最高的一種31。PEG是一種結晶型高分子聚合物,為改善NEPE推進(jìn)劑低3結果與討論溫力學(xué)性能,避免NEPE推進(jìn)劑內部結晶缺陷的出現,3,1冷卻速率對結晶溫度的影響分析NEPE推進(jìn)劑在一些特定條件下的力學(xué)現象,為圖1為不同冷卻速率下PEG的DSC曲線(xiàn)。PEGPEG的生產(chǎn)和在其他領(lǐng)域的應用提供理論參考依據,試樣的結晶終止溫度(T)、結晶峰溫(T)和開(kāi)始結晶本工作用差示掃描量熱法(DC)考察了PEG的非等溫度(T,)與冷卻速率之間的線(xiàn)性關(guān)系見(jiàn)圖2。結晶溫溫結晶行為我們在考察等速降溫條件下PEG結晶行度都隨著(zhù)冷卻速率增大而降低,這是因為冷卻速率增為的同時(shí)用3種動(dòng)力學(xué)方法(Ozwa法、 ezion法和大時(shí),結晶溫度下降很快,高分子鏈在高溫下來(lái)不及作莫志深法)分析了PEG的非等溫結晶過(guò)程從不同規則排列,結晶熱效應在較低溫度下顯現結晶平衡需角度分析了PEG非等溫結晶特點(diǎn)。要在較寬溫度范圍才能達到。般認為高聚物的非等溫結晶過(guò)程較復雜,等溫3.2冷卻速率對結晶時(shí)間的影響結晶過(guò)程可用 Avrami方程來(lái)描述“。在非等溫結晶研究領(lǐng)域, Ozawa3導出了求取 Avram指數(n)的非由聚合物熔體降溫DsC曲線(xiàn)得特征溫度:結晶峰溫(T)、等溫結晶動(dòng)力學(xué)模型。 corny 6)提出了非等溫動(dòng)力開(kāi)始結晶溫度(T)和非等溫結晶過(guò)程峰面積達總面積學(xué)結晶能力的概念。近年來(lái),也有用描述等溫結晶過(guò)50%的溫度(Tn)。從T、T和B,由下式得半結晶時(shí)間:程的 Avrami公式導出非等溫結晶動(dòng)力學(xué)方法研究聚n =(t, - Tia)/B(1)酯、聚酰胺的非等溫結晶過(guò)程假設結晶放熱峰對稱(chēng),且不考慮曲線(xiàn)的非均衡性,則可用T代替T12,于是有2實(shí)驗部分1n=(7-7)/B2.1儀器和試樣對PEC的非等溫結晶過(guò)程,由特征結晶溫度計算的半美國TA公司2910型差示掃描量熱儀。聚乙二結晶時(shí)同(n)見(jiàn)表1將12的倒數對B作圖,得圖3所示直線(xiàn),直線(xiàn)斜收稿日期:2007-1205;修回日期:20080214基金項目:火炸藥燃燒國防科技重點(diǎn)實(shí)驗室基金(Na.914003010001)率d(1/ta)/dB被定義為結晶速率參數CRP( crystalli作者簡(jiǎn)介:黨水戰(1971-),男,博士,主要從事固體推進(jìn)劑配方和工 zationrate parameter),它表明PEG開(kāi)始結晶時(shí),結晶藝研究。e-mal: pecc@163.c0m含能材料16卷速率較慢,然后慢慢加快,約在t1達到最高,而到了后3.3用 Ozawa方程處理的PEG結晶動(dòng)力學(xué)期,結晶速率又降低。由圖3直線(xiàn)斜率求得PEC的0zawa方程是20世紀70年代出現的處理聚合物CRP值為0.098。非等溫結晶過(guò)程的方法,以聚合物結晶的成核和生長(cháng)為著(zhù)眼點(diǎn)導出了不同T時(shí)a(7)與B之間的關(guān)系式:5℃.m11-a(T)=exp[-k(T)/B8”(3)203℃mnr對式(3)進(jìn)行簡(jiǎn)單數學(xué)變換,得Ig[ -In(1-a(T))]= lgk(T)-nlgB (4)2℃mnr式中,a(T)為在溫度T時(shí)的相對結晶度;k(T)與成核方式、成核速率T、晶核生長(cháng)速率等因素相關(guān),是溫度的函數,稱(chēng)為冷卻結晶函數;n為 Avrami指數。在給定溫度的條件下,用1g[-ln(1-a(T))]對lg作圖,得圖4所示斜率為n的直線(xiàn)。圖1不同冷卻速率下PEG結晶過(guò)程的DSC曲線(xiàn)Fig. I DSC curves of the crystallization process31315Kof PEG at different cooling rates315.15K32115K32315K000408圖4不同溫度時(shí)PEG結晶過(guò)程的lg[-ln(1-a(T))]對lg的關(guān)系圖2冷卻速率對PEG結晶溫度的影響Fig4 Ig[ -In(1-a(T))] vs lgB relationship for the crystallizationFig 2 Effect of cooling rate on crystallization temperature of PEGprocess of PEG at different temperatures表1PEG的結晶特征溫度和半結晶時(shí)間Table 1 Crystallization temperature and由圖4得不同溫度時(shí)的n值結果見(jiàn)表2。由表2half-crystallization time of peG數據可見(jiàn),n為非整數,不同溫度下的n值和冷卻結晶B/C. miT/℃T℃7r/℃11a/min函數lhnk(T)值相差較大,說(shuō)明PEG結晶成核機理復47.6842,98雜,不同溫度下結晶機理有所不同39.145.79表2不同溫度時(shí)PEG的n和Ink(刀值Table 2 The Avrami exponent n and Ink(r)of PEG at different temperaturesT/K313.15315.15317.15319.15321.15323.15n1.0362.0222.8502.7353.1333.013nk(T)2.7483.2322.8931.198-0.371-2,4843.4用 Jeziorny方程處理的PEG結晶動(dòng)力學(xué)ezion法是直接把 Avrami方程推廣為解析等速變溫DSC曲線(xiàn)的方法,其實(shí)質(zhì)是先把聚合物的非等溫結晶過(guò)程按等溫結晶過(guò)程來(lái)處理,然后對所得參數進(jìn)行修正B℃mn圖3PEG的tB關(guān)系Avrami方程exp(-Zr")β relationship for PEG第3期黨永戰等:聚乙二醇的非等溫結晶動(dòng)力學(xué)研究可寫(xiě)成如下的線(xiàn)性形式a=0.40a=060Ig[-In(1-a)]= lgZ + mlgt式中,Z為復合結晶速率常數;m為 Avrami指數,與成核6a=020c=080機理和形成晶體的形態(tài)有關(guān)。以ln[-hn(1-a)]對lg作圖,從直線(xiàn)斜率得m,從截距得Z。由這種方法求出的z隨B而變化考慮到B的影響用下式對其進(jìn)行校正。(7)03Jeziorny把z作為表征非等溫結晶動(dòng)力學(xué)的參數。010203040506070809K. min圖BB與lg的關(guān)系5K. mintthe crystallization process of PEG表3用莫志深法計算的非等溫結晶動(dòng)力學(xué)參數Table 3 Non-isothermal crystallization parametersof PEG obtained by Mo Zhi-shen methodF(T)0.0.407.11圖5不同冷卻速率時(shí)PEG結晶過(guò)程的7.69g[-ln(1-a)]與l的關(guān)系0.800.828Fig.5 The Ig[ -In(1-a)]vs Igt relationship forthe crystallization process of PEG at different cooling rates結論用 Jeziomy方程處理的PEG結晶動(dòng)力學(xué)關(guān)系見(jiàn)圖5。(1)對不同B下PEC結晶過(guò)程的DSC曲線(xiàn)分析,由圖5可知,g[-hn(1-a(T)]與g在低結晶度時(shí)線(xiàn)探討了B對PEG結晶溫度和結晶時(shí)間的影響,求得性關(guān)系較好而在高結晶度會(huì )產(chǎn)生線(xiàn)性偏離。PEG相對PEG結晶速率參數(CR)為0.098分子量在2000左右,結晶初期,受成核控制。當結晶(2)PEG非等溫結晶過(guò)程可用 Ozawa方程和莫志度達到一定程度時(shí)體系粘度增大鏈段運動(dòng)困難結晶深法動(dòng)力學(xué)方程描述,而不能用 Jeziorny方法處理的受擴散控制,二次結晶導致了這種線(xiàn)性偏離。Avrami動(dòng)力學(xué)方程描述。3.5用莫志深法處理的PEG非等溫結晶動(dòng)力學(xué)(3)0zawa方程所得到的n隨著(zhù)B值的變化在莫志深等人把 Avrami方程和Ozwa方程結合,1.036-3.133之間變動(dòng)。通過(guò)莫志深法處理得到的同時(shí)考慮非等溫結晶過(guò)程中結晶時(shí)間與溫度的關(guān)系,得PEG非等溫動(dòng)力學(xué)參數F(T)在不同B下隨結晶度的IgB lgF(r)-algt(8)增大而增加,表明在單位時(shí)間內達到一定結晶度所需式中,F(T)=[K(T)/,表示單位結晶時(shí)間內體系的降溫速率在增加。達到某一結晶度時(shí)所需的降溫速率,表征樣品在一定結晶時(shí)間內達到某一結晶度時(shí)的難易程度,a=m/n參考文獻圖6為采用莫志深法獲得的lgB~lgt關(guān)系曲線(xiàn)。[1]王偉,尚丙坤胡少強,等,聚乙二醇穩定性研究的方法及抗氧劑選擇[].化學(xué)推進(jìn)劑與高分子材料,2004,2(5):39-41.由圖6可知,1B與lgt有較好線(xiàn)性關(guān)系,由直線(xiàn)的斜率WANG Wei, SHANG Bing-kun, HU Shao-qiang, et al. The study of和截距可分別求出a和F(T),結果見(jiàn)表3。PEG stability and the selection of antioxidants for PEC[J].Chemical從表3數據可見(jiàn),PEC的F(T)值隨結晶度增大Propellant Polymeric Material, 2004, 2(5):39-41而增加,表明在單位時(shí)間內達到一定結晶度所需的B[2]唐根郭翔龐愛(ài)民,等PEGN100彈性體單向拉伸斷裂行為在增加,即說(shuō)明其在一定結晶時(shí)間內達到某一結晶度J]含能材料,2007,15(4):356-358TANG Gen, GUO Xiang, PANG Ai-min, et al. Unilateral tension時(shí)的難易程度,β越大,結晶速率越慢。fracture behavior of PEG/N-100 matrix J]. Chinese Journal of含能材料第16卷Energetic Material( Hanneng Cailiao), 2007, 15(4): 356-358[6] Jeziorny A. Parameters characterizing the kinetics of the non-isother-[3]李靜峰,司馥銘.NEPE推進(jìn)劑燃燒性能調節技術(shù)研究[打.含能材料,2002,10(1):4-9[]. Polymer,1978,19:142-1144LI Jing-feng, SI Fu-ming. Study on modification technology of the[7]劉結平,莫志深玉臣等聚氧化乙烯(PEO)/聚雙酚A羥基醚combustion property of the NEPE propellant[ J]. Chinese Joumal of(PBHE)共混體系的非等溫結晶動(dòng)力學(xué)[J].高分子學(xué)報,1993Energetic Material( Hanneng Cailiao),2002, 10(1):4-9.4]邊界,葉勝榮,封麟先PET,PBT結晶過(guò)程 Avrami方程的探討LIU Jie-ping, Mo Zhi-shen, QI Yu-chen, et al. Kinetics of non[玎].高等學(xué)?；瘜W(xué)學(xué)報,200021(9):1481-1484isothermal crystallization of PEO/PBHE Blends[ J]. Acta PolymericaBIAN Jie, YE Sheng-rong, FENG Lin-xian. Investigation on avramisinica,1993(1):I-6equation of PET and PBT in crystallization[ J]. Chemical Joumal of [8] Schaaf E, Zimmermann H. Non-isothermal crystallization kinetics ofChinese Universities, 2000, 21(9): 1481-1484nucleated poly( ethylene terephthalate)[J]. J Chem Anal, 1988, 33[5]Ozawa T. Kinetics of non-isothermal crystallization [J]. Polymer053-10581971,12:150-158Non-isothermal Crystallization Kinetics of Polyethylene GlycolDANG Yong-zhan, ZHAO Feng ql, GAO Hong-xu, HU Rong-zu, KANG Bing(Xi'an Modern Chemistry Research institute, xi' an 710065, China)isothermal crystallization kinetics of polyethylene glycol PEG )was studied with differential scanningcalorimetry. The non- isothermal crystallization data of PEG was analyzed by the methods of Ozawa, Jeziorny, and Mo Zhi-shenResults show that the non-isothermal crystallization process of PEG may be described with Ozawa kinetie equation,but does notagree with Avrami equation processed in the Jeziomy method. The linearity of treating non-isothermal crystallization kinetic curvesmethod and MO Zhi-shen method is better. Parameter of crystallization velocity for PEC is 0.098Key Words: physical chemistry: polyethylene glycol( PEG ) non-isothermal crystallization; kinetics; differential scanningcalorimetry(DSC)(上接294頁(yè))Differential and Integral Isoconversional Non-linear Methods and theirApplication in Physical Chemistry Study of Energetic MaterialsV. Theory and Numerical Method Based on Kooij's FormulaHU Rong-zu, ZHAO Feng-qi, GAO Hong-xu'ZHANG Hai, ZHAO Hong-an, MA Hai-xia"(1. Xi' an Modern Chemistry Research institute, Xi'an 710065, China:3. College of Communication Science and Engineering, Northest University, Xi'an 710069, China;4. College of Chemical Engineering, Northwest University, Xi'an 710069, China)Abstract: Eight typical differential and integral isoconversional non-linear equations based on Kooij's formula for computing theapparent activation energy (E. )from isothermal and non-isothermal data were derived. The numerical methods of computing thealue of E. of decomposition reaction of energetic materials via the equations were presentedKey words: physical chemistry energetic materials; differential isoconversional non-linear method; integral isoconversional non-linear method; decomposition reaction; apparent activation energy