DEPOLYMERIZATION AND KINETICS OF DEPOLYMERIZATION OF POLYETHYLENE TEREPHTHALATE USING DIBUTYLTIN OXIDE CATALYST

Depolymerization of poly（ethylene terephthalate） （PET） was performed in the tubular bomb microreactor which contained the solution of PET in methanol and dibutyltin oxide at the temperature ranging from 433 K to 473 K, the reaction time from 5 to 45 min and the catalyst-to-PET ratio of 0.3%-2% by weight. The optimal condition for PET depolymerization catalyzed by dibutyltin oxide is the temperature of 443-453 K, the reaction time of 20-25 min and 0.8% by weight of catalyst. By using differential methods, the activation energy for the depolymerization process was found to be 154.05 kJ/mol in the temperature range from 433-463 K.     

Chemical Degradation of Amine-cured DGEBA Epoxy Resin in Supercritical 1-Propanol for Recycling Carbon Fiber from Composites

Chemical degradation of diglycidyl ether of bisphenol A（DGEBA） epoxy resin cured with an aliphatic amine in supercritical 1-propanol was investigated under different reaction temperature and time. The combination of GC-MS and LC-MS proved that the epoxy resin was decomposed to five main products including phenol, 4-isopropylphenol, 4-isopropenylphenol, bisphenol A, and 4,4’-（cyclopropane-1,1-diyl）diphenol. The 13C-NMR results verified the chemical structures of the degradation products. The change of the products′ yield with time was evaluated by an effective means of HPLC. In addition, the GPC analysis confirmed the formation of soluble low molecular weight clusters during the degradation reaction. A possible free-radical reaction mechanism was proposed for chemical depolymerization of the epoxy resin in supercritical 1-propanol. After the homolytic cleavage of the aromatic ether linkages, the resulting bisphenol A biradical either produced 4,4’-（cyclopropane-1,1-diyl）diphenol after intramolecular rearrangement or generated bisphenol A after capturing hydrogen from 1-propanol.     

STUDY ON METHYLDIETHANOLAMINE SYNTHESIS

Methyldiethanolamine was synthesized in a continuous pipe reactor.The effects of temperature,pressure,stay time and raw material compositionson the reaction results were examined.The results showed that the reaction ofmethylamine(MA)with ethylene oxide(EO)proceeded consecutively.Theproducts included methylethanolamine(MMEA),methyldiethanolamine(MDEA),and methylethanoldiethyleneglycolamine(MEDA)while EO reactingwith water produced little ethyleneglycol(EG)and diethyleneglycol(DEG).The optimum reaction conditions were chosen out through experiments as fol-lows:temperature,120—150℃;pressure,5.0—7.0 MPa;mole ratio of EO/MA,1.8—2.0;stay time,≥25 sec.     

A catalyst-free novel synthesis of diethyl carbonate from ethyl carbamate in supercritical ethanol

Diethyl carbonate has been synthesized via the alcoholysis of ethyl carbamate in supercritical ethanol under catalyst-free conditions.The influences of various parameters such as reaction temperature,reaction time,reaction pressure,ethanol/ethyl molar ratios and reaction loading volume on the yield of DEC were studied systematically.The experimental results indicated that the alcoholysis of ethyl carbamate was greatly improved in supercritical ethanol.The optimal reaction conditions were as follows：a reaction temperature of 573 K,a reaction time of 30 min,a reaction pressure of 13.2 MPa,an ethanol/ethyl carbamate molar ratio of 10 and a reactor loading volume of 285 μL respectively.The optimal yield of DEC was 22.9%.     

Thermodynamic analysis of combined reforming process using Gibbs energy minimization method: In view of solid carbon formation

Thermodynamic analysis was applied to study combined partial oxidation and carbon dioxide reforming of methane in view of carbon formation. The equilibrium calculations employing the Gibbs energy minimization were performed upon wide ranges of pressure (1-25 atm), temperature (600-1300 K), carbon dioxide to methane ratio (0-2) and oxygen to methane ratio (0-1). The thermodynamic results were compared with the results obtained over a Ru supported catalyst. The results revealed that by increasing the reaction pressure methane conversion decreased. Also it was found that the atmospheric pressure is the preferable pressure for both dry reforming and partial oxidation of methane and increasing the temperature caused increases in both activity of carbon and conversion of methane. The results clearly showed that the addition of O 2 to the feed mixture could lead to a reduction of carbon deposition.     

SYNTHESIS OF 1,2-ACEANTHRYLENEDIONE THROUGH ACYLATION OF ANTHRACENE WITH OXALYL CHLORIDE

Acylation of anthracene and oxalyl chloride in the presence of anhydrous AlCl3 was investigated. Pure 1,2-aceanthrylenedione, which is used as new functional macromolecule, was prepared by extraction and recrystallation. The structure of 1,2-aceanthrylenedione was identified by measure of melting point, GC/MS, FTIR and 1↑HNMR analyses. The influences of various parameters, such as solvent, dosage of catalyst, molar ratio of anthracene to oxalyl chloride, reaction temperature, and reaction time were studied. The anhydrous AlCl3 was found to catalyze the reaction with high yeild and good selectivity. When the reaction temperature is 303K, reaction time is 5h and molar ratio of anthracene to oxalyl chloride is 1：2, the yield and selectivity of 1,2-aceanthrylenedione is 83.8 % and 92.3% respectively.     

Egyptian heavy vacuum gas oil hydrotreating over Co-Mo/CNT and Co-Mo/γ-Al_2O_3 catalysts

The catalytic activity of CoMoS /CNT towards the Egyptian heavy vacuum gas oil hydrotreating was studied. The delivered CNT was functionalized with 6 mol /L HNO_3. The CNT were loaded with 12% MoO_3( by weight) and 0.7 Co /Mo atomic ratio with impregnation methods. The γ-Al_2O_3 catalyst was also prepared by impregnation method to compare both catalysts activities.The analysis tools such XRD,Raman spectroscopy,TEM,and BET were used to characterize the catalysts. The autoclave reactor was used to operate the hydrotreating experiments. The hydrotreating reactions were tested at various operating conditions of temperature 325-375 ℃,pressure 2-6 MPa,time 2-6 h,and catalyst /oil ratio( by weight) of 1 ∶75,1 ∶33 and 1 ∶10. The results revealed that the CoMoS /CNT was highly efficient for the hydrotreating more than the CoMoS /γ-Al_2O_3. Also, the hydrodesulfurization( HDS) increased with increasing catalyst /oil ratio. Additionally,results showed that the optimum condition was temperature 350℃,pressure 4 MPa,catalyst /oil ratio of 1 ∶75 for 2 h. Furthermore,even at low CoMoS /CNT catalyst /oil ratio of 1 ∶75,an acceptable HDS of 77.1% was achieved.     

Supercritical carbon dioxide assisted synthesis of amphiphilic graft copolymers based on poly(styrene-co-maleic anhydride) with methoxyl poly(ethylene glycol) side chains

Supercritical carbon dioxide（scCO₂） was used as a reaction medium in synthesizing amphiphilic graft copolymers composed of poly（styrene-co-maleic anhydride）（SMA） backbones and methoxyl poly（ethylene glycol）（MPEG） side chains via esterification.The synthesized copolymers were characterized by Fourier transform infrared spectroscopy（FTIR）,gel permeation chromatography（GPC）,¹H-NMR,thermo-gravimetric analysis（TGA） and differential scanning calorimetric analysis（DSC）.The gelation phenomenon was suppressed effectively by tuning reaction conditions.The influences of scCO₂ temperature and pressure on the conversion of anhydride were investigated.It was found that the highest conversion ratio occurred at 80℃under a constant pressure of 14 MPa or 26 MPa.With the increase of scCO₂ pressure,the conversion ratio increased first,and then leveled off.The conversion ratio of anhydride could be controlled by regulating the reaction conditions.It was also revealed that using low molecular weight MPEG brought a high conversion ratio of anhydride.     

AN INVESTIGATION ON KINETICS AND REACTIVE SPECIES IN ANIONIC TELOMERIZATION OF BUTADIENE INITIATED BY n-BUTYLLITHIUM/N, N, N'''', N''''-TETRAMETHYLETHYLENE DIAMINE

The polymerization rate of butadiene in toluene initiated by n-butyllithium and tetramethyl ethy-lene diamine as well as the micro-structure and degree of association of polybutadiene were deter-mined. The effect of TMEDA/n-BuLi (abbr. A/Li) and temperature on the polymerization rate,molecular weight, molecular weight distribution and structure of polybutadiene was investigated. Ac-tivation energy of the propagation reaction and chain transfer reaction, together with the chain trans-fer reaction rate constant were estimated. Kinetic parameters and contribution of different reactivespecies to polymerization rate were calculated by Nonlinear Least-Squares Method. A kinetic equa-tion was proposed. The mechanism of anionic chain transfer reaction was discussed.     

PREPARATION OF STARCH SUCCINATE WITH INTERMEDIATE DS BY AQUEOUS SLURRY REACTION

The succinylation of cornstarch by slurry reaction has been studied using sodium hydroxide as catalyst.Several reaction parameters affecting the succinylation were investigated including the concentration of starch in water,the ratio of succinic anhydride to starch,the reaction time and the reaction temperature,The favorable conditions for an intermediate degree of substitution(DS) and reasonably high reaction efficiency(RE) are pH 8.5-9.0,50% starch by weight to water.succinic anhydride to starch 1/1(w/w),reaction time 4h,reaction temperature 30℃ .Under these conditions,the DS of 0.45 and RE of 28% were achieved.The addition of an adequate amount of crosslinking agent imparted starch succinate water absorbency.     

聚碳酸酯在亚临界水中解聚的研究

采用间歇式高压反应装置研究聚碳酸酯(PC)在亚临界水中的解聚.在温度260～340℃、压力4.8～14.8 MPa、反应时间5～60min的反应条件下,考察了反应温度及反应时间对PC解聚率及主产物双酚A(BPA)和苯酚(PhOH)回收率的影响.产物分别采用傅里叶红外光谱(FTIR)、扫描电子显微镜(SEM)、气质联谱(...     

Effects of plastic additives on depolymerization of polycarbonate in sub-critical water

The effects of plastic additives on depolymerization of polycarbonate (PC) in sub-critical water were examined. Depolymerization of PC with two additives was carried out in an autoclave at temperatures from 533 to 613 K for reaction times ranging from 15 to 60 min. The additives used were a flame retardant (decabromodiphenyl ether, DBDPO) and a plasticizer (di-n-octyl phthalate, DnOP). The main products of PC depolymerization in the presence or absence of the additives were bisphenol A (BPA) and phenol, which were identified by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and gas chromatography mass spectrometry (GC-MS), and quantified by gas chromatography (GC). The addition of DBDPO accelerated the hydrolysis of PC while the addition of DnOP had the opposite effect, and both additives reduced the yield of BPA. The activation energy for PC depolymerization in sub-critical water was found to be lower with DBDPO additive than with DnOP.     

Chemical recycling of polycarbonate in high pressure high temperature steam at 573 K

Polycarbonate (PC) could be completely decomposed into its monomer, bisphenol A (BPA) with high pressure (not atmospheric pressure) high temperature steam (573 K) in 5 min reaction time. The maximum yield of BPA was about 80 mol% based on the starting PC. PC decomposition at 573 K in liquid water phase near the saturated pressure for the comparison. For 30 min in reaction in liquid water at 573 K residual PC still remained and the BPA yield was about 50% as maximum.     

Study on depolymerization of polycarbonate in supercritical ethanol

The characteristics of depolymerization of PC in supercritical ethanol were investigated in the range of 483-563 K by using a high-pressure batch autoclave reactor. Based on the qualitative and quantitative analyses of the products, a depolymerization-reaction model was proposed to explain the reaction mechanism, i.e. random scission and ester exchange reaction occurred simultaneously during the process of depolymerizaition of PC. It was suggested that the process of depolymerization consisted of subcritical region, transitional region and supercritical region. It was indicated that PC degraded with slow decrease of molecular weight determined by GPC and with the conversion of 7.5% at 513 K in subcritical region. While in the supercritical region, the molecular weight of PC decreased quickly and degraded completely in 30 min at 563 K. Continuous-distribution kinetics could be used to describe the mechanism of polymer degradation and the energy of activation for the random scission of PC in the supercritical region was 97.2 kJ/mol. Moreover, PC could be degraded completely into diethyl carbonate (DEC) and bisphenol A (BPA) with the yields of 89% and 90%, respectively, in supercritical region.     

超临界甲醇降解对苯二甲酸丁二酯的研究

作为一种综合性能优良的新型工程塑料,对苯二甲酸丁二酯(PBT)工程塑料及其各种合金在全球范围内已经广泛用于电子电气、汽车、机械及民用等各个领域,而中国是其中需求量最大的国家．     

含双酚芴聚碳酸酯的合成与光学性能

将具有负双折射系数的双酚芴{9,9-二[4-(2-羟乙氧基)苯基]芴, BPEF}与双酚A(BPA)共聚, 制备本征双折射率接近零的含双酚芴聚碳酸酯(共聚PC). 研究发现, 碱性强、 pK_a值大的催化剂可以缩小BPA和BPEF的活性差异, 有利于制备高分子量含双酚芴聚碳酸酯, 缩聚温度为265 ℃、 缩聚时间为40 min时产物具有较高的分子量和较低的黄变指数. BPEF和BPA投料比(摩尔比)为40/60时共聚体系的重均分子量可达39800, ¹H NMR和¹³C NMR测试证明分子链呈无规共聚结构. 随着BPEF含量的上升, 共聚PC的折射率从1.586提高到1.639, 本征双折射率从0.1948下降到-0.0102. 当BPEF摩尔分数为87%时, 共聚PC的本征双折射率低至0.0028, 非常接近零双折射.     

亚临界水萃取-高效液相色谱法测定聚碳酸酯水杯中双酚A和苯酚的迁移量

建立了亚临界水萃取-高效液相色谱同时测定聚碳酸酯(PC)水杯中双酚A和苯酚迁移量的方法。选择萃取温度120 ℃、萃取压力6.89 MPa(1000 psi)、静态萃取时间1 h、萃取1次对11种样品进行测定。双酚A的迁移量为6.81～11.16 μg/g。5种样品中未检出苯酚,其余样品中苯酚迁移量为3.25～6.08 μg/g。在优化的测定条件下,双酚A和苯酚在8 min内达到基线分离。双酚A和苯酚分别在0.05～20 mg/L和0.02～20 mg/L范围内线性关系良好,相关系数(r)均大于0.9997,检出限分别为7.6 μg/L和2.0 μg/L。日内及日间的重复性(以RSD计)分别小于5.21%及11.63%。传统的浸提法结果表明长时间浸提会使PC材料发生微弱水解。相比传统的浸提法,该方法的萃取效率提高了49～106倍。该方法简便、快速、环保,可用来测定PC水杯中双酚A和苯酚的迁移量。     

聚苯基膦酸双酚A酯的合成与表征

聚苯基膦酸双酚Ａ酯的合成与表征唐旭东陈晓婷王玉忠杨科珂王波（四川联合大学化学系成都６１００６４）吴大诚（四川联合大学轻纺学院成都６１００６５）关键词聚膦酸酯，阻燃剂，熔融缩聚，热性能聚膦酸酯类化合物是一类重要的磷系阻燃剂［１～３］，与传统的非聚...     

含1,2-亚乙基单元的双酚A聚碳酸酯非光气法合成和表征

以双酚A(BPA),碳酸乙二酯(EC)和碳酸二甲酯(DMC)为原料,制备双酚A二元醇(Ⅰ)和双酚A碳酸酯(Ⅱ),并用红外光谱与核磁共振波谱对其结构进行表征.通过Ⅰ与Ⅱ的共缩聚反应及Ⅱ的自聚实现了主链中含有—CH2CH2—单元的双酚A型聚碳酸酯(PC)的非光气法合成,用凝胶渗透色谱法(GPC)和TGA-DSC对PC的分子量和热性质进行分析.结果表明,Ⅱ在240℃自聚6h后产物的Mn可达17.6×103,主链中—CH2CH2—单元的引入,可以降低聚合物的Tg,提高其结晶性,所得聚合物具有良好的热稳定性.