尼龙6固相聚合的计算机模拟(英文)

建立了尼龙 6固相聚合过程动力学模型 ,并用实验数据进行了验证。考查了模型参数对固相聚合尼龙 6聚合度和多分散性指数的影响 ,分析固相聚合过程诸多的影响因素对尼龙 6聚合度及多分散性指数的影响。利用此模型 ,分析了固相聚合一定时间后水浓度、数均聚合度在颗粒半径方向上的分布     

尼龙6固相聚合研究进展

对尼龙 6固相聚合方法与特点、工艺流程、动力学与机理的各种影响因素、粒子的粘结现象、模型化等进行了较系统综述 ,并提出了尼龙 6固相聚合模型化以及催化剂等需进一步研究的几点建议。     

尼龙6固相聚合模型及计算机模拟研究

根据尼龙6固相聚合反应机理,建立了由可逆化学反应和小分子扩散共间控制的尼龙6固相聚合动力学模型,并确定了其动力学和热力学参数。通过计算机模拟实验表明,聚合反应温度越高,预聚体尺寸越小,预聚体初始相对分子质量越高,越有利于固相增粘反应,有利于固相聚合尼龙6相对分子质量的增加。     

尼龙6固相聚合建模与计算机仿真

在一定假设基础上建立了尼龙６固相聚合过程模，并用实验数据验证了模型的正确性，结果表明随着固相聚合时间的延长，数均聚合度Ｕｎ增加。     

PET的固相聚合

利用固定床反应器研究聚对苯二甲酸乙二酯（ＰＥＴ）预聚体颗粒在Ｎ２流场中的固相聚合，探讨了聚合温度和Ｎ２流速对聚合反应速率的影响，实验中解决了高温聚合时物料的粘结问题；利用ＤＳＣ分析固相聚合过程中聚合物结晶结构的变化；建立了动力学模型描述了小分子不稳定扩散和化学反应速率共同控制下的聚合反应历程；计算结果较好的反映了工艺操作条件对固相聚合反应的影响。     

提升固相聚合装置生产负荷的工艺探讨

对固相聚合装置的工艺进行优化,提高了仪化股份公司瓶片事业部产能为40 kt/a的Buhler固相聚合装置生产负荷,产品质量达到优等品要求;对固相聚合装置的产品乙醛含量的影响因素进行工艺初步探讨。     

固相聚合PET及饮料瓶的热性能研究

应用 DSC、 TGA和 TMA研究了固相聚合 PET树脂的双重熔融行为、热稳定性及瓶坯、包装瓶的结晶性能和膨胀性。结果表明 ,固相聚合 PET树脂在不同升温速度下的双重熔融行为反映出树脂结晶结构的完整性 ,可为确定固相聚合生产的工艺条件提供参考。对具有不同结晶性能和热稳定性的固相聚合 PET树脂 ,其制坯及吹瓶工艺条件应作必要调整。     

高性能聚芳酯纤维的研制和表征

介绍了热致性液晶聚芳酯纤维的制备。选用双酚A、对苯二甲酸、间苯二甲酸为单体进行熔融聚合,制得具有不同相对分子质量的双酚A-对/间苯二甲酸共聚酯,探索了后续固相聚合工艺,研究了后续固相聚合对原熔融聚合物相对分子质量、热性能以及力学性能的影响。原聚合物再经固相聚合及不经固相聚合的两种聚芳酯在不同的纺丝和热处理工艺条件下,可以获得力学性能相近的聚芳酯纤维,为进一步研制热致液晶型聚芳酯纤维生产路线提供可靠的工艺数据。     

聚(对苯二甲酸乙二醇酯-co-对苯二甲酸异山梨醇酯)预结晶及固相聚合研究

研究了不同异山梨醇(ISB)含量的聚(对苯二甲酸乙二醇酯-co-对苯二甲酸异山梨醇酯)(PEIT)共聚酯预结晶及固相聚合工艺。探讨了温度、时间与PEIT共聚酯预结晶温度、固相聚合反应速率之间的关系;利用差式扫描量热仪(DSC)分析研究PEIT共聚固相聚合前后的热性能变化情况。结果表明:随着ISB用量的增加,PEIT共聚酯结晶困难,预结晶时间增加,固相聚合反应速率减慢;随着温度升高,PEIT共聚酯固相聚合反应速率加快,但仍慢于聚对苯二甲酸乙二醇酯(PET);固相增粘后PEIT共聚酯玻璃化转变温度(Tg)与ISB含量呈线性上升关系。     

国外动态

<正> 据Zimmer称,已与ICI纤维公司签定了提供PET固相聚合设备的合同,估计1983年中将开始运转,日产57吨。固相聚合可显著提高有光纤维切片的质量:切片粘度符合要求,低乙醛含量。所得切     

聚乳酸固相缩聚模型

提出了聚乳酸固相缩聚的反应-扩散综合模型,该模型中考虑了可逆酯化反应和热降解反应.并由实验数据拟合得到了不同温度下各反应的速率常数以及水的扩散系数,进而得到它们的活化能;模拟了不同因素对固相缩聚过程的影响.研究表明在较低的温度下,热降解反应的影响较小,可以忽略;而在较高温度下,其影响显著.水的扩散速率对聚乳酸分子量的增长影响很大;小粒径颗粒有利于制备高分子量聚乳酸.     

PET固相缩聚反应机理的研究

对ＰＥＴ固相聚合的反应机理进行了较深入地研究。并首次对副产物ＥＧ表面扩散控制机理进行了探讨。通过研究发现：固相聚合机理与温度、预聚体尺寸、惰性气体的流量（或真空度）有关。当反应温度较低时（如１６０～１８０℃），ＰＥＴ固相聚合总是化学反应控制的过程。当反应温度较高（如≥２２０℃），且预聚体的尺寸较大时，ＰＥＴ的固相聚合实际上是由副产物ＥＧ从样品内部向表面的扩散控制的。当反应温度较高，且预聚体的尺寸很小（如几十微米）时，又惰性气体流量较小（或真空度较差），ＰＥＴ固相缩聚反应为副产物ＥＧ从样品表面向外的扩散所控制；若惰性气体流量较大（或真空度较好），反应又转化为化学反应控制。     

PBT的固相缩聚

对固相缩聚的机理和影响因素进行了介绍。认为聚对苯二甲酸丁二酯 ( PBT)是一种重要的工程塑料 ,高的分子质量使其性能得到提高。作为生产 PBT高粘切片的有效方法 ,固相缩聚依赖于化学 (可逆化学反应 )和物理 (小分子的扩散 )两个过程     

Kinetics of the solid‐state polymerization of nylon‐6

The kinetics of the thermally induced solid‐state polymerization (SSP) of nylon‐6 were examined in both a fixed‐bed reactor and a rotary reactor. Factors such as the regulator content, the reaction temperature and time, the particle size, the type and geometry of the nylon‐6 prepolymer, the nitrogen gas flow rate, the water content of the nitrogen gas flow, and the polymerization process were studied. The results showed that the regulator content, the reaction temperature and time, and the particle size were the primary factors, and that the others were negligible. Moreover, the SSP rate and number‐average molecular weight (M_n) increased with increasing reaction temperature and time and decreasing particle size. The SSP rate and M_n had maximum values with increasing regulator content in an experimental range of 0.03–0.07 wt %. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 616–621, 2002; DOI 10.1002/app.10341     

尼龙6固相聚合中试试验研究

通过工厂中试实验研究,探讨了中试规模下聚合反应时间、反应温度、预聚体初始黏度等因素对尼龙6固相聚合的影响,确定了尼龙6固相增黏的工艺操作条件为:最佳温度175￣185℃,停留时间48h。     

Experimental and modeling study of the solid state polymerization of poly(ethylene terephthalate) over a wide range of temperatures and particle sizes

The solid state polymerization (SSP) of poly(ethylene terephthalate) was studied experimentally over a wide range of pellet sizes and temperatures. A comprehensive model was developed. It considered polycondensation, degradation and polycondensation of vinyl end groups together with diffusion. The reaction rate constants, diffusivities and the corresponding activation energies were obtained through parameter identification using experimental data. The effects of the reaction temperature and pellet size on the SSP time were also investigated. A decrease in the particle size decreases the concentration of the vinyl end groups and narrows the concentration distribution of end groups inside poly(ethylene terephthalate) particles. A decrease in the size of pellets also favors diffusion. Nevertheless it is preferable that the size of pellets be between 1 and 2 mm because too small pellets bring about difficulties with preparation and handling. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Solid-state polycondensation of poly(ethylene terephthalate) modified with isophthalic acid: kinetics and simulation

The kinetics for the solid-state polycondensation (SSP) of poly(ethylene terephthalate) modified with isophthalic acid at the protection of nitrogen gas was studied in the paper. A kinetic model controlled by the reversible chemical reactions and the three dimension diffusions of small molecule by-products has been established. The kinetic parameters of the SSP of PET at different temperatures, including the forward rate constants of transesterification reaction (k₁) and esterification reaction (k₂), the diffusion coefficients of EG (D₁) and water (D₂), the concentrations of EG (g_s) and water (w_s) on the surface of PET chips in SSP, and the activation energies of these kinetic parameters were obtained by experiments and solution of the model. Using the model and the kinetic parameters, the SSP of poly(ethylene terephthalate) modified with isophthalic acid can be simulated with good accuracy. In addition, the influences of nitrogen gas flow rate, the chip dimension and the carboxyl end-group concentration of the PET prepolymer on the molecular weight of PET after SSP, and the change of the EG concentration of PET chips with reaction time were also studied by simulation.     

Effects of sorption modes on the transport and physical properties of nylon 6

The presence of low molecular weight molecules in a polymeric matrix often has a marked effect on material properties. Knowledge of specific penetrant distributions and component interactions is important for an elucidation of structure-property relationships, plasticization phenomena, and any modification of structure induced by the presence of penetrants. The sorption-mode characteristics of water, methanol, and ethanol in Nylon 6 films have been investigated by the application of the differential sorption method. The sorption and diffusion behavior were interpreted in terms of clustering theory with suitable account being made for penetrant molecular size and hydrogen-bonding capability. The examination of transport and mechanical properties of these films indicates a pronounced dependence of those properties on the concentration of penetrants. The effect of penetrant cluster formation at characteristic concentrations of sorbed penetrant is to decrease the concentration dependence of both diffusion and mechanical relaxation processes in the case of alcohols. The onset of water clustering apparently only affects the mechanical relaxation process. The samples were further characterized by DSC, X-ray diffraction and density measurements to detect any significant changes in the structure of Nylon 6 induced by the penetrant conditioning.