聚丙烯腈論文：碳纖維用聚丙烯腈溶液共聚合反應(yīng)研究.doc

聚丙烯腈論文：碳纖維用聚丙烯腈溶液共聚合反應(yīng)研究【中文摘要】碳纖維自上世紀(jì)六十年代開始發(fā)展以來(lái),以其比重小、強(qiáng)度高、模量高、耐高溫、耐腐蝕等一系列優(yōu)良特性,成為未來(lái)最具發(fā)展前景的材料之一。制備碳纖維的前驅(qū)體有很多,其中聚丙烯腈(PAN)基碳纖維的產(chǎn)量占到了90%以上。聚丙烯腈基碳纖維的生產(chǎn)可分為兩步：聚丙烯腈紡絲原液的制備和原絲的預(yù)氧化與炭化。其中的聚丙烯腈往往是丙烯腈和少量其它單體的共聚物,共聚物的合成是制備碳纖維的第一步,也是最為關(guān)鍵的環(huán)節(jié),其性能直接影響到碳纖維的性能。本論文采用高濃度的丙烯腈(AN)和少量衣康酸(IA)混合物為共聚單體,低濃度的偶氮二異丁腈(AIBN)為引發(fā)劑,在溶劑二甲基亞砜(DMSO)中,進(jìn)行丙烯腈溶液共聚合,制備高分子量的聚丙烯腈。通過(guò)測(cè)定不同溫度、引發(fā)劑濃度、共聚單體含量、總單含量下,經(jīng)過(guò)不同反應(yīng)時(shí)間條件所得到的AN-IA共聚物的轉(zhuǎn)化率,探討了上述因素對(duì)聚合反應(yīng)速率的影響。以DMF為溶劑,在30條件下,用烏氏粘度計(jì)測(cè)量各個(gè)反應(yīng)條件下所得共聚物的分子量,探討聚合條件對(duì)分子量的影響。經(jīng)過(guò)上述實(shí)驗(yàn),得到了轉(zhuǎn)化率30%以下,粘均分子量在30-100萬(wàn)的AN-IA共聚物。發(fā)現(xiàn)不同的條件下,聚合過(guò)程中聚合液及共聚物的形態(tài)差別較大。經(jīng)過(guò)定量測(cè)定,繪制了各個(gè)條件下反應(yīng)的轉(zhuǎn)化率-時(shí)間關(guān)系曲線。發(fā)現(xiàn)反應(yīng)速率和分子量均隨總單濃度的增大而增大,卻均隨衣康酸含量的增大而減小。溫度、引發(fā)劑含量的增大均使反應(yīng)速率顯著增大,卻使分子量減小,而反應(yīng)時(shí)間的增大雖使轉(zhuǎn)化率增大,但對(duì)分子量卻基本沒(méi)有影響。以衣康酸單正丁酯(MI)為共聚單體,中等濃度的偶氮二異丁腈(AIBN)為引發(fā)劑,在二甲基亞砜(DMSO)中,進(jìn)行AN-MI溶液共聚合。初步探討了IA的加入對(duì)共聚反應(yīng)的影響,并得到一組轉(zhuǎn)化率-時(shí)間關(guān)系圖。在各個(gè)不同溫度下,改變AN/MI配比,得到轉(zhuǎn)化率為10%以下的AN-MI共聚物。采用元素分析方法,得到共聚物中兩種單體單元的組成。分別采用Fineman-Ross法和Kelen-Tudos法對(duì)上述結(jié)果進(jìn)行分析,得到AN-MI共聚體系的競(jìng)聚率,并對(duì)所得結(jié)果進(jìn)行驗(yàn)證。發(fā)現(xiàn)Fineman-Ross法會(huì)得到競(jìng)聚率為負(fù)值的不合理結(jié)果,而采用Kelen-Tudos法所得結(jié)果與理論相比具有足夠高的相符度。在55-65下,測(cè)得的AN-MI共聚體系的競(jìng)聚率的值為rAN=0.660.71,rMI= 8.357.44。比較各個(gè)溫度下的結(jié)果,發(fā)現(xiàn)溫度對(duì)于競(jìng)聚率有微小的影響,隨著溫度的升高,競(jìng)聚率值均向1靠近,表明共聚反應(yīng)朝著理想共聚方向靠近?！居⑽恼縒ith the excellent characteristics such as low weight, high strength, high modulus, anti-high temperature, anti-erosion and so on, carbon fiber is widely used in the field of aeronautical and space technologies, transportation, sports supplies, civil construction, etc., making itself the most promising material in the coming decades.Several precursors can be used to produce carbon fibers, among which polyacrylonitrile (PAN) based carbon fibers has the best performance and share 90% in quantity. The production of PAN based carbon fibers can be divided into two steps:the production of PAN precursor and the pre-oxidation and carbonization of the precursor. The first step is the key point which can determine the quality of carbon fiber.In order to produce high molecular weight polyacrylonitrile, free-radical solution copolymerization of high concentration (about 50 wt%) of acrylonitrile (AN) as first monomer and itaconic acid (IA) as comonomer is carried out in dimethyl sulphoxide (DMSO), using low concentration (about 50 wt%) of azodiisobutyronitrile (AIBN) as initiator. The values of different factors such as temperature, the concentration of monomer, IA content in the monomer, and the concentration of AIBN are changed, the copolymer in those conditions in different reaction time is produced and the conversion of monomer was measured at each point of condition. Then, the viscosity average molecular weight of poly(AN-co-IA) prepared in each point of condition above was measured by Ubbelohde viscosity meter at 30, using DMF as solvent. The copolymer with viscosity average molecular weight of 3001000 thousand was produced, and the curve of conversion-time at each condition was drawn by the experiments above. It has been demonstrated that both reaction rate and viscosity average molecular weight are increased by the increasing of monomer concentration, while the same thing is otherwise with IA content. Reaction rate will increase dramatically with the increading of either temperature or AIBN content, while again, the same thing is otherwise with viscosity average molecular weight. Though conversion increases dramatically along with the polymerization time, viscosity average molecular weight changes slightly.Though the time can make conversion increase, it has little effect on viscosity average molecular weight.Monobutyl Itaconate (MI, also named Itaconic Acid Monobutyl Ester) is also introduced as another potential comonomer in the free-radical solution copolymerization of acrylonitrile, using medium concentration AIBN as initiator and DMSO as solvent under different temperatures of 50,55,60, and 65. By using different ratio of AN/MI, a series of poly(AN-co-MI) are preparared under low conversion (below 10%) at each temperature. The accumulated average composition of the copolymer was determined by elemental analysis, and then both Fineman-Ross method and Kelen-Tudos method were applied to calculate the reactivity ratio of the copolymerization system. It shows that the result of Fineman-Ross method is unreasonable because it has a negative value, while that of Kelen-Tudos method is reasonable because the practical experimental points coincide with the theoretical curve under each temperature. It shows that temperature has tiny influence on reactivity ratio, the value of reactivity ratio is about rAN=0.660.71,rmi=8.357.44 in the range of 5065, and with the increasing of the polymerization temperature, the reactivity ratios of AN and MI approach to unity, suggesting that the solution copolymerization of AN/MI has a tendency to ideal copolymerization.【關(guān)鍵詞】聚丙烯腈 溶液共聚 轉(zhuǎn)化率 粘均分子量 競(jìng)聚率【英文關(guān)鍵詞】Polyacrylonitrile solution copolymerization conversion viscosity average molecular weight reactivity ratio【備注】索購(gòu)全文在線加好友：1.3.9.9.3.8848 同時(shí)提供論文寫作一對(duì)一指導(dǎo)和論文發(fā)表委托服務(wù)本文為學(xué)術(shù)文獻(xiàn)總庫(kù)合作提供，無(wú)涉其他?！灸夸洝刻祭w維用聚丙烯腈溶液共聚合反應(yīng)研究摘要5-6Abstract6-7目錄8-11第一章 緒論11-21引言111.1 碳纖維的主要性能及應(yīng)用領(lǐng)域11-141.1.1 碳纖維的結(jié)構(gòu)及性能11-121.1.2 碳纖維的主要應(yīng)用領(lǐng)域12-141.2 聚丙烯腈基碳纖維的生產(chǎn)工藝概況14-171.2.1 聚合14-151.2.2 紡絲15-161.2.3 預(yù)氧化16-171.2.4 炭化171.3 聚丙烯腈的主要制備方法17-181.3.1 水相沉淀聚合171.3.2 溶液聚合17-181.4 聚丙烯腈基碳纖維技術(shù)的國(guó)內(nèi)外發(fā)展概況18-191.4.1 碳纖維技術(shù)在國(guó)外的發(fā)展181.4.2 我國(guó)在碳纖維技術(shù)發(fā)展上的差距18-191.5 本課題的研究意義及主要研究?jī)?nèi)容19-211.5.1 本課題的研究意義19-201.5.2 本課題的主要研究?jī)?nèi)容20-21第二章 理論基礎(chǔ)21-362.1 丙烯腈的自由基聚合基本理論21-272.1.1 自由基聚合機(jī)理21-242.1.2 自由基聚合動(dòng)力學(xué)24-272.2 二元自由基共聚合體系的競(jìng)聚率27-332.2.1 共聚物組成微觀方程的推導(dǎo)27-292.2.2 二元共聚競(jìng)聚率的測(cè)定方法29-312.2.3 競(jìng)聚率的影響因素31-332.3 粘度法測(cè)定聚合物的分子量33-362.3.1 聚合物的分子量33-342.3.2 聚丙烯腈溶液的本征粘度34-352.3.3 Mark-Houwink方程35-36第三章 溶液共聚合制備高分子量聚丙烯腈36-673.1 實(shí)驗(yàn)部分36-413.1.1