共查询到17条相似文献,搜索用时 209 毫秒
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PET固相缩聚反应动力学研究 总被引:2,自引:1,他引:1
建立了综合考虑 PET固相缩聚化学反应、小分子副产物物理扩散、大分子结晶三方面的 PET固相缩聚动力学模型 ,并用文献报道的实验测定数据验证该模型。运用该模型 ,研究了水、乙二醇、乙醛小分子副产物的含量与分布及其对固相缩聚的影响 ,从乙醛含量分布图可以得出 ,随着反应时间的延长 ,切片内各层乙醛含量降低不明显 相似文献
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PET固相缩聚反应动力学模型 总被引:5,自引:1,他引:4
总结了PET 固相缩聚反应的原理及其反应动力学,综述了国内外研究PET 固相缩聚动力学模型的进展。指出单纯考虑化学反应或小分子扩散的模型都是不全面的,应该用化学反应过程和物理扩散过程共同控制的模型来描述固相缩聚反应。 相似文献
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十四烷辅助下聚酯的固相缩聚 总被引:2,自引:0,他引:2
在200~240℃研究了聚对苯二甲酸乙二醇酯(PET)在十四烷辅助下的固相缩聚反应.结果表明,溶剂辅助下的固相缩聚(分散相固相缩聚)的反应速度较传统气相环境中的固相缩聚更快,最佳反应温度为230℃左右.随着反应温度的升高,分散相固相缩聚得到的PET切片的熔点和结晶度也相应提高.分散相固相缩聚前后PET切片的孔隙率并未发生明显变化.用苯酚处理之后的PET孔隙率增加,有利于小分子扩散,使缩聚反应速率加快.聚合物在十四烷中溶胀导致链活动性增强可能是分散相固相缩聚分子量提高的主要原因. 相似文献
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系统地研究了粉末聚酯(PET)固相缩聚,得到了有效的干燥结晶条件:140℃干燥120 min,180℃再结晶45 min,切片含水率低于30μg/g;研究了反应温度,粉末粒径和N2流量对PET固相缩聚的影响,分析粉末固相缩聚存在N2流量阈值的机理。结果表明:反应温度越高,颗粒越小,固相缩聚反应速度越快;粉末 PET预聚体在一定温度下固相缩聚,存在N2流量阈值。在此流量下,达到该温度下的该粒径粉末的最大界面扩散速率和固相缩聚的最大反应速度。相同反应温度下,粉末粒径越小,阈值N2流量越大。 相似文献
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连续式PET固相缩聚移动床反应器具有显著的分布参数特性,由于建模简化或过程时变等原因使得所建模型参数不精确,导致反应器状态的估计失真。首先采用正交配置方法离散PET固相缩聚过程的偏微分方程模型,然后基于改进的平方根不敏Kalman滤波算法(ISR-UKF),设计自适应联合估计器,同时获得参数和状态估计值。实验结果表明,参数估计结果合理,状态估计精度较高且稳定性好;并获得了频率因子、活化能近似值和有效系数随反应温度动态变化的规律,表明所提出的联合估计器能获得较好的实际应用效果。 相似文献
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针对大型连续PTA直接酯化法PET工艺过程装置,以Aspen Plus和Polymers Plus为模型开发工具,建立了以反应和传质过程机理为基础的稳态模型。结果表明:该模型中包括了酯化反应、缩聚反应、二甘醇生成反应、链降解反应和乙醛生成等主副反应,且考虑了端羧基对酯化反应的自催化效应;更重要的是模型考虑了酯化阶段PTA在酯化反应器中的溶解过程和终缩聚阶段小分子的脱挥,并建立了小分子脱挥的传质系数与缩聚反应器内聚合度、黏度、温度和搅拌器转速等的关联;在此模型基础上模拟研究了第一酯化反应操作温度对各反应器出口指标的影响,指出酯化段的酯化率有一个适宜的控制范围。 相似文献
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The relative merits of the moving packed bed, fluidized bed, and stirred bed reactors for solid-state polycondensation are discussed along with methods for improving these designs. A general model to describe continuous solid-state polymerization reactors is then developed and illustrated by a case study of a moving packed bed reactor showing the relative importance of operating variables. The model also predicts the dynamic behavior in response to several process inputs. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1775–1788, 1998 相似文献
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Continuous production of polyester‐poly(ethylene terephthalate) resins in melt‐phase and solid‐state reactors 下载免费PDF全文
Chi‐Chin Chen 《Polymer Engineering and Science》2017,57(5):505-519
A simple reaction model has applied net polycondensation rates to predict the steady‐state performance of three distinct continuous processes for manufacturing polyester‐PET resins. A net melt‐phase polycondensation rate was described by the simple second‐order kinetics. A net solid‐state polycondensation rate was assumed to follow the modified second‐order kinetics with respect to active end group concentration. A moving‐packed bed requires a longer residence time to deal with the diffusion‐limited SSP of standard pellets or challenging pastilles. The calculations and data showed low IV pastilles to have much slower diffusion‐controlled SSP rates than medium IV pellets. The tanks‐in‐series model demonstrated a narrow RTD in a gas fluidization bed with five mixing stages. Higher reaction temperatures may significantly increase the low diffusion resistance SSP rates of smaller beads or micro‐pellets in a gas‐fluidized reactor. The reaction‐controlled SSP of micro‐beads becomes apparent at 230°C. The high IV melt resins may challenge the slow reaction rates of Ti or Al‐catalyzed SSP resins. The efficacy of catalyst promoters on Ti activity enhancement may depend upon various ligands in Ti glycolate, Ti citrate, or titanic acid. The thermo‐oxidative stability of Ti or Al‐catalyzed resins may decrease at higher hot air drying temperatures (188°C or above). POLYM. ENG. SCI., 57:505–519, 2017. © 2016 Society of Plastics Engineers 相似文献
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N. M. Ghasem 《化学工程与技术》2001,24(10):1049-1057
The two‐phase model developed for the UNIPOL polyethylene process is improved by introducing polymer diffusion resistance, this means modelling of polyethylene fluidized bed reactors has been examined on two levels, at small scale of individual polymer particle, and macroscale of the whole reactor. The model utilizes the multigrain model that accounts for the reaction rate at catalyst surface to explore the static and dynamic bifurcation behavior of the fluidized bed catalytic reactor. Detailed bifurcation diagrams are developed and analyzed for the effect of polymer growth factor and Thiele modulus (the significance of the porous medium transport resistance is characterized by Thiele modulus) on reactor dense phase monomer concentration and reactor temperature as well as polyethylene production rate and reactor single pass conversion for the safe temperature region. The observations reveal that significant diffusion resistance to monomer transport exists, and this can mask the intrinsic rate constants of the catalyst. The investigation of polymer growth factor indicates that, the nascent stage of polymerization is highly gas phase diffusion influenced. Intraparticle temperature gradients would appear to be negligible under most normal operating conditions. 相似文献
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以已投产的年产万吨级连续固相缩聚装置生产工业丝级涤纶增黏切片实测的反应条件为依据,从原料切片、反应温度、停留时间、循环氮气纯度及流量等因素对固相缩聚反应的影响,详细地对连续固相缩聚生产工业丝级涤纶增黏切片的生产工艺加以探讨。 相似文献
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通过比较卧式和立式增黏反应器对聚酯液相增黏反应的影响,自主设计研制了生产能力为29 t/d的立式液相增黏反应器;将聚酯切片螺杆加热熔融后的熔体进行增黏反应,探讨了液相增黏工艺条件,并对比分析了液相增黏与固相缩聚后纺制的涤纶工业丝的性能。结果表明:聚酯液相增黏后的熔体特性黏数达1.05 dL/g,b值小于3,端羧基浓度约25 mol/t;增黏后的熔体进行直接纺丝,生产的涤纶工业丝的各项性能指标均能达到固相缩聚熔融纺丝工艺的同等水平,断裂强度为8.33 cN/dtex,断裂伸长率为15.4%;液相增黏技术具有设备投资省、能耗和运行成本低等特点。 相似文献
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采用回收聚酯(PET)瓶片,通过液相增黏直接纺丝生产涤纶工业丝,探讨了再生聚酯直纺涤纶工业丝的成套设备和工艺技术。结果表明:对干燥设备和螺杆挤压机进行改造,利用双级熔体预过滤器和液相增黏系统,聚酯瓶片再生增黏后特性黏数可达(0.85±0.01)dL/g;该成套设备的关键是采用单轴式液相增黏反应器;调整纺丝和拉伸工艺,直接纺丝生产的涤纶工业丝线密度为1 189 dtex,断裂强度为7.98 cN/dtex,断裂伸长率为14.66%,达到了常规固相增黏法生产的涤纶工业丝的性能指标。 相似文献