氨纶废丝醇解工艺探讨

以一缩二乙二醇为醇解剂,二月桂酸二丁基锡为催化剂对氨纶废丝进行了醇解。重点分析了醇解时间、催化剂用量、氨纶废丝与醇解剂质量比等工艺条件对回收聚四氢呋喃二元醇(回收PTHF)性能和结构的影响。结果表明,当温度不变时,增加醇解时间、催化剂用量、醇解剂与氨纶废丝比例仅可以在一定程度上提高回收PTHF的收率和纯度。     

氨纶废丝的醇解产物分析

以二甘醇为醇解剂,以二月桂酸二丁基锡为催化剂对氨纶废丝进行了醇解,醇解产物冷冻后分成两层,上层为白色蜡状醇解产物、下层为棕色液体。对白色蜡状醇解产物进行了红外光谱、核磁共振测试,对棕色液体进行了高效液相色谱—质谱联用测试。结果表明:白色蜡状醇解产物主要为聚醚多元醇;棕色液体除了过量的二甘醇以外,主要含有二甘醇-异氰酸酯加成化合物。     

PET废丝常压醇解工艺研究

以乙二醇(EG)为降解剂,以醋酸锌为催化剂对聚对苯二甲酸乙二醇酯(PET)废丝进行醇解,研究了在常压下醇解反应条件对醇解率、醇解产物回收率的影响,对醇解产物进行了红外(IR)、热重-差示扫描量热(TG-DSC)以及扫描电子显微镜(SEM)分析.结果表明:PET废丝在常压下进行醇解反应,当EG:PET废丝:醋酸锌质疑比为...     

熔纺氨纶废丝的回收再利用

采用升温红外光谱分析法,探讨了熔纺氨纶废丝在升温过程中分子链断裂的机理。在此基础上,提出在磷酸三乙酯介质中,以乙酰胺对废丝进行热降解,使其获得重新加工的性能的方法。进一步,将降解产物与新鲜的聚四氢呋喃二醇(PTMG)混合,然后与甲苯二异氰酸酯(TDI)进行反应,制成了再生聚氨酯薄膜。     

应用微波法对废PET进行醇解的研究

研究了一种应用微波技术在常压下对废PET催化降解以实现化学回收的方法。考察了在微波作用下,醇解温度、物料配比、催化剂含量及醇解剂官能度对废PET降解程度及降解产物的影响,并利用红外光谱仪对降解产物的化学结构进行了分析。结果表明:综合考虑废PET的醇解程度、醇解产物的性能以及经济成本因素,选定的最佳工艺条件是微波功率500W时,醇解时间15min、反应温度220℃、二甘醇与废PET的质量比为1.25、醋酸锌用量0.2%;其他反应条件不变,将醇解剂改为甘油和二甘醇的混合醇,混合醇与废PET的质量比为1.5,当二甘醇与甘油质量比为1:1时,醇解产物羟值最高,可以达到477mg/g;实验所得的废PET的二甘醇醇解产物是羟基封端分子链含有醚键的聚酯多元醇。     

聚碳酸酯在乙二醇中的可控醇解

为了实现聚碳酸酯(PC)的有效回收和循环利用,以乙二醇为醇解剂,醋酸锌为催化剂,二氧六环为溶剂,用溶液法对PC进行降解反应。利用34正交实验研究反应温度、反应时间、醋酸锌及乙二醇用量对PC醇解反应的影响程度。考察反应温度、反应时间、PC重复链节与乙二醇物质的量比、催化剂及溶剂的类型和用量等条件对PC醇解行为的影响。通过傅里叶红外光滑和黏度法对产物进行分析。正交设计实验的直观和方差分析得出四个因素对PC醇解反应的影响顺序为:反应温度>反应时间>乙二醇用量>醋酸锌用量,通过设定特定的条件,得到不同摩尔质量的产物,实现PC的可控醇解。     

氨纶废丝的醇解及产物分析

以辛酸亚锡为催化剂,以丙三醇为醇解剂对废旧氨纶丝进行解聚。醇解产物经过冷冻后分为两层,上层为浅褐色的蜡状固体,下层为棕色液体。对萃取后蜡状产物进行了红外光谱分析;对下层棕色液体进行了高效液相-质谱联用分析。分析表明:上层产物主要为聚四氢呋喃;下层产物种类较复杂。     

废旧涤棉混纺织物的循环醇解工艺研究

以经过致密化处理的废旧涤棉军装(废旧涤棉)为原料,以乙二醇(EG)为醇解剂,通过改变EG与废旧涤棉的配比、醇解时间、醇解液循环使用次数等研究了废旧涤棉的醇解效率,以及不同循环次数对醇解产物对苯二甲酸乙二醇酯(BHET)和涤棉织物中的棉纱性能的影响。结果表明:在废旧涤棉与EG质量比为1∶(10~12),废旧涤棉与Na_2CO_3质量比为1∶0.003,反应温度196℃,反应时间1 h的醇解条件下,醇解液可以循环使用,最佳循环使用次数为4,醇解后产物绝大部分仍为BHET单体,醇解物产率高于60%;醇解后棉纱表面虽有一定程度破坏,但其断裂强度最高仍达1.76 c N/dtex,满足开松再纺纱的要求,可实现棉纱的二次回收利用。     

废PET醇解产物及在聚氨酯弹性体合成中的应用

以醋酸锌或3A分子筛为催化荆、一缩二乙二醇(DEG)为醇解剂,降解废聚对苯二甲酸乙二醇酯(PET),得到PET醇解产物;再用此废PET醇解产物合成聚氨酯弹性体(PUEs).讨论了醇解催化剂种类、nDEG:nPET重复单元、醇解产物添加量对PUEs性能的影响,同时采用TIG、DSC、X-射线衍射等分析手段对PUEs进行表...     

聚碳酸酯树脂的醇解反应及机理研究

以醋酸锌(Zn(Ac)_2)为催化剂、乙二醇(EG)为醇解剂、四氢呋喃(THF)为溶剂,考察了不同醇解反应时间和温度条件下不同来源聚碳酸酯(PC-1、PC-2)树脂的醇解反应规律,得到相应的重均分子量与醇解反应速率参数,并通过红外特征吸收峰的变化推测其醇解反应机理。结果表明:延长反应时间、提高反应温度,PC的醇解率逐渐增大,重均分子量逐渐下降;其重均分子量的变化值(1/M_(wt)-1/M_(w0))与反应时间呈一级反应动力学规律;醇解反应速率常数随温度升高而增大,PC-1的醇解反应速率常数大于PC-2的,二者的醇解反应活化能分别为30.42kJ/mol和45.51kJ/mol。从降解机理来看,PC的醇解降解反应主要发生于碳酸酯键以及芳环-亚异丙基键接处。     

Studies of glycolysis of poly(ethylene terephthalate) recycled from postconsumer soft‐drink bottles. II. Factorial experimental design

Glycolysis temperature, glycolysis time, and amount of catalyst are important factors affecting the glycolysis of recycled poly(ethylene terephthalate) (PET) flakes. A 2³ factorial experimental design is applied to study the main, two‐factor interaction, and three‐factor interaction effects of glycolysis temperature, glycolysis time, and amount of catalyst on the glycolysis of recycled PET flakes. In this study cobalt acetate is used as the glycolysis catalyst. The sequence of the main effects on the glycolysis conversion of the recycled PET flakes in ascending order is glycolysis time < glycolysis temperature < amount of catalyst. The sequence of the two‐factor interaction effects on the glycolysis conversion of the recycled PET flakes in ascending order is glycolysis temperature versus the glycolysis time < glycolysis time versus the amount of catalyst < glycolysis temperature versus the amount of catalyst. The three‐factor interaction effect is significantly related to the glycolysis conversion of the recycled PET flakes. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 956–962, 2001     

Viscoelastic and thermal decomposition behaviors of polytetrahydrofuran binder prepared using glycerin as a crosslinking modifier

Polytetrahydrofuran (PTHF) is an effective binder ingredient used for improving the performance of propellants. PTHF becomes sufficiently rubbery for use as a binder with the addition of an adequate crosslinking modifier. This study investigated the viscoelastic and thermal decomposition behaviors of the PTHF binder prepared using glycerin as a crosslinking modifier, as well as the influence of the molecular weight of PTHF on the characteristics of the PTHF binder. The curing behavior of the PTHF binder was suitable for the manufacture of propellants, and the superior tensile properties of the PTHF binder made it suitable for use as a propellant binder. The degree of crosslinking of the samples decreased as the molecular weight of the PTHF increased. The PTHF binder has unique dynamic mechanical properties owing to its melting and chemical structure, and these properties were dependent on the molecular weight of PTHF. The glass transition temperature (T_g) and the loss tangent at T_g decreased as the molecular weight of the PTHF increased. The temperature and frequency dependence of the PTHF binder were influenced by the melting point of PTHF. The viscoelastic properties of the binder prepared using PTHF with a molecular weight of 650 followed the time–temperature superposition principle. The activation energy for the relaxation of this binder varied remarkably at the melting point of PTHF. The thermal decomposition behavior indicated that at low temperatures, the consumption rate of the binder with low‐molecular‐weight PTHF was slightly larger than that of the binder with high‐molecular‐weight PTHF. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Study of glycolysis of poly(ethylene terephthalate) recycled from postconsumer soft‐drink bottles. III. Further investigation

A modified glycolysis reaction of recycled poly(ethylene terephthalate) (PET) bottles by ethylene glycol (EG) was investigated. Influences of the glycolysis temperature, the glycolysis time, and the amount of catalysts (per kg of recycled PET) were illustrated in this study. The manganese acetate was used as a glycolysis catalyst in this study. Bis‐2‐hydroxyethyl terephthalate (BHET) and its dimer were predominately glycolysis products. It was found the optimum glycolysis temperature is 190°C. And the best glycolysis condition is 190°C of glycolysis temperature, 1.5 h of glycolysis time, and 0.025 moles of manganese acetate based on per kg of recycled PET. If the best glycolysis condition is conducted, the glycolysis conversion may be as high as 100%. For a given reaction time (1.0 h), the ln(% glycolysis conversion) is linear to 1/T (K^?1) and the activation energy (E) of glycolysis reaction is around 92.175 kJ/(g mole). The glycolysis conversion rate increases significantly with increasing the glycolysis temperature, the glycolysis time, or the amount of manganese acetate (glycolysis catalyst). Thermal analyses of glycolysis products were examined by a differential scanning calorimetry (DSC) and a thermogravimetric analysis (TGA). According to the definition of a 2³ factorial experimental design, the sequence of the main effects on the glycolysis conversion of the recycled PET, in ascending order, is the glycolysis time (0.18) < the amount of catalyst per kg of the recycled PET (0.34) < the glycolysis temperature (0.40). Meanwhile, the prediction equation of glycolysis conversion from the result of a 2³ factorial experimental design is ? = 0.259+0.20X₁+0.09X₂+0.17X₃+0.06X₁ X₂+0.145X₁X₃+0.05X₂X₃+0.035X₁X₂X₃. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2004–2010, 2003     

Studies of glycolysis of poly(ethylene terephthalate) recycled from postconsumer soft‐drink bottles. I. Influences of glycolysis conditions

The glycolysis of recycled poly(ethylene terephthalate) flakes by ethylene glycol (EG) is investigated. Bis‐2‐hydroxyethyl terephthalate (BHET) and oligomers are predominately glycolysis products. The influences of glycolysis temperature, glycolysis time, and the amount of catalyst (cobalt acetate) are illustrated. The BHET, dimer, and oligomers are predominately glycolysis products. The optimum glycolysis temperature is found to be 190°C. If a 190°C glycolysis temperature, 1.5‐h glycolysis time, and 0.002 mol glycolysis catalyst (cobalt acetate) are used, the glycolysis conversion is almost 100%. The glycolysis conversion rate increases significantly with the glycolysis temperature, glycolysis time, and the amount of cobalt acetate. Thermal analyses of glycolysis products are examined by differential scanning calorimetry. In addition, the chemical structures of glycolysis products are also determined by a Fourier transform IR spectrophotometer. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 943–948, 2001     

黏合剂结构对胶片及推进剂力学性能的影响

为了阐明黏合剂结构对推进剂力学性能的影响,采用动态力学和单项拉伸试验方法,研究了几种典型聚酯聚醚黏合剂结构对推进剂力学性能的影响。结果表明,在不含增塑剂情况下,聚四氢呋喃(PTHF)胶片具有更高的伸长率,聚己内酯-四氢呋喃嵌段聚酯醚(HTCE)和聚己内酯(PCL)具有更高的强度;PCL、HTCE和PTHF胶片的储能模量(E′)和损耗模量(E″)依次降低,其玻璃化转变温度(T_g)分别为-43.94、-61.99和-66.98℃。增塑剂降低了链段解冻运动过程中的内耗阻力,使胶片的玻璃化温度大幅降低,PTHF、PCL和HTCE的T_g分别为-67.66、-72.27和-77.10℃,PCL的储能模量和损耗模量最高,PTHF储能模量大于HTCE、HTCE和PCL胶片的力学性能优于PTHF。推进剂的T_g由高到低顺序为PTHF、PCL、HTCE,分别为-55.27、-56.16和-57.91℃;PTHF的储能模量最大,在低温下抗冲击性能和韧性最差;HTCE推进剂的储能模量和损耗模量最低,黏合剂体系的弹性较好、损耗较低;PCL的储能模量、损耗模量和内耗峰面积均较高,在宽温度范围内的刚性和冲击韧性较好。     

活性炭负载磷钨酸催化合成聚四氢呋喃

活性炭为载体制备了负载型磷钨酸催化剂,研究其在环氧氯丙烷的引发作用下催化四氢咬喃开环聚合的反应工艺.考察了反应时间、反应温度、四氢呋喃与环氧氯丙烷的质量比、催化剂的活化温度及催化剂用量对收率的影响,并分析了催化剂活性降低的原因.研究表明,最优反应条件为:反应时间为4h,反应温度为50℃,四氢呋喃与环氧氯丙烷的质量比为1...     

Sustainable rigid polyurethane foams based on recycled polyols from chemical recycling of waste polyurethane foams

The preparation and characteristics of rigid polyurethane foams (RPUFs) based on recycled polyol obtained by glycolysis of waste RPUF scraps from end-of-life refrigerators were investigated. To deactivate the amine adducts derived from isocyanates, the recycled product obtained after depolymerization was chemically modified via addition polymerization of propylene oxide. Two kinds of recycled polyols with different hydroxyl values and viscosity were blended with conventional virgin polyether polyol to prepare the RPUFs. The effects of the recycled polyols on the physical properties of RPUFs such as cell structures, compressive strength, thermal conductivity, and limiting oxygen index were discussed. It was found that the RPUFs from recycled polyols showed superior compressive strength, thermal insulation property, and self-extinguishing property compared with conventional control foam. The results of this study reveal that the recycled polyols could be used as feedstock for RPUFs with superior performance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47916.     

Mechanical Characteristics and Thermal Decomposition Behaviors of Polytetrahydrofuran Binder with Glycerol Propoxylate (Mn=1500) as a Crosslinking Agent

Polytetrahydrofuran (PTHF) is an effective binder ingredient for improving propellant performance, although it is not an energetic material. PTHF becomes sufficiently rubbery for use as a binder when a triol is added as a crosslinking modifier. In this study, glycerol propoxylate (GPO), with a molecular weight of 1500, was used as a crosslinking modifier, and the curing behavior, tensile properties, and thermal decomposition behaviors of the PTHF binder with GPO were investigated. A PTHF (M _n=650)/GPO blend with a PTHF/GPO mole ratio (ξ ) less than or equal to 4 and a PTHF (M _n=1400)/GPO blend with ξ ≤1 were used as propellant binders. The curing behaviors and mechanical properties of the PTHF/GPO blends were influenced by the molecular weight of PTHF and ξ , while the thermal decomposition behaviors were not affected. It was found that the PTHF/GPO blends had higher initial viscosity, longer pot life, and unique mechanical properties compared to those of the PTHF blends supplemented with GPO (M _n=260).     

Modeling of glycolysis of flexible polyurethane foam wastes by artificial neural network methodology

The glycolysis process as a useful approach to recycling flexible polyurethane foam wastes is modeled in this work. To obtain high quality recycled polyol, the effects of influential processing and material parameters, i.e. process time, process temperature, catalyst‐to‐solvent (Cat/Sol) and solvent‐to‐foam (Sol/Foam) ratios, on the efficiency of the glycolysis reaction were investigated individually and simultaneously. For the continuous prediction of process behavior and interactive effects of parameters, an artificial neural network (ANN) model as an efficient statistical‐mathematical method has been developed. The results of modeling for the criteria that determine the glycolysis process efficiency including the hydroxyl value of the recycled polyol and isocyanate functional group conversion prove that the adopted ANN model successfully anticipates the recycling process responses over the whole range of experimental conditions. The Cat/Sol ratio showed the strongest influence on the quality of the recycled polyol among the studied parameters, where the minimum hydroxyl value was obtained at a medium amount of the assigned ratio. For the consumed polyurethane foam, a higher value of this ratio led to an increase in the hydroxyl value and isocyanate conversion. © 2015 Society of Chemical Industry