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合成了聚(丙烯酸丁酯/丙烯酸钠)(PBA/ANa)齐聚物,并以此为乳化剂合成出聚丙烯酸丁酯(PBA)为核,聚甲基丙烯酸甲酯(PMMA)为壳的复合乳液,研究了单体配比、链转移到(DDM)的用量对齐聚物聚合阶段反应速率的影响,温度、引发剂用量对复合乳液聚合速率的影响,齐聚物用量、核层交联剂的用量以及滴加速度对聚合速率的影响。结果表明,在合成齐聚物时,随着从含量的增多,能有效地提高转化率;引发剂浓度的增加能有效提高核层聚合反应速率,但是对壳层反应速率影响不大;合适的单体滴加速率有利于反应的进行。 相似文献
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高THF/Li体系丁二烯—苯乙烯聚合反应动力学研究 总被引:1,自引:0,他引:1
在环己烷熔剂中,以正丁基锂为引发剂,在较高含量的THF/Li存在下对丁二烯、苯乙烯均聚及丁苯共聚的聚合动力学进行了研究,结果表明,丁二烯均聚反应速率随着反应温度的升高及THF添加量的增加而增大;而THF添加量对苯乙烯均聚影响规律与其相反,在丁苯共聚中,随着THF加入量的增加动力学曲线表明,聚合反应速率呈下降趋势,且其变化规律与苯乙烯均聚规律相似。 相似文献
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悬浮聚合法色粉制备条件及树脂性能控制 总被引:8,自引:0,他引:8
研究了超声波及颜料颗粒铁黑和碳黑对苯乙烯聚合过程的影响。结果表明,超声波对苯乙烯聚合过程的影响可分为三个阶段,在聚合反应前期,超声波引发聚合作用显著,对苯乙烯聚合有加速作用:在聚合反应中期,超声波降解作用加强,使聚合反应速率降低:在聚合反应后期,由于聚合体系的粘度增大,超声波引发聚合作用显著而加速反应过程。铁黑颗粒加入聚合体系,会阻碍链自由基的扩散,因而加快聚合反应;碳黑颗粒对聚合过程的影响与加入量有关,碳黑加入量低于1%(wt)时,碳黑颗粒造成的空间效应会阻碍链自由基的扩散,使反应加速;碳黑加入量高于5%(wt)时,由于碳黑素面活性基团对自由基的捕捉作用而使反应减速。实验研究了悬浮聚合法色粉制备过程中温度、引发剂浓度和颜料颗粒对聚合树脂分子量分布、熔融特性的影响。结果表明,聚合温度或高或引发剂用量增加,聚合树脂的分子量减小,软化点降低,熔融指数增大;加入碳黑可降低聚合树脂分子量,加入铁黑可显著提高树脂分子量,且均能显著增大分子量多分散系数;加入铁黑颗粒,色粉的软化点升高,熔融指数减小。通过参数调节,可有效控制树脂的熔融特性。 相似文献
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本文以废旧聚酯瓶为原料,采用固相缩聚的方法,合成了特性粘度0.7-1.2范围的高分子量PET,使回收的聚酯瓶得以重新被利用。研究了聚合温度,聚合时间,原料颗粒度,真空度等对固相聚合速度的影响。初步探讨了固相聚合的机理和较佳的工艺参数,为废旧聚酯瓶的回收打下了基础。 相似文献
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PET固相缩聚反应机理的研究 总被引:5,自引:1,他引:5
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。 相似文献
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Continuous production of polyester‐poly(ethylene terephthalate) resins in melt‐phase and solid‐state reactors
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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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A numerical method to seek a solution for the solid-state polycondensation (SSP) proces has been proposed to analyze the mechanism of SSP. Results expound that, for the industrial SSP process of PET, the overall reaction rate in a single pellet is appropriately simulated by the diffusion and reaction rate jointly controlling the model. From the core to the surface the SSP rate increase monotonically due to a gradual reduction of the concentration of such by-products as ethylene glycol and water. However, the SSP rate at any location within the pellet is constrained between two purely reaction rate controlling cases. © 1995 John Wiley & Sons, Inc. 相似文献
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分析了目前过磷酸钙的生产过程,认为在过程后续阶段反应环境不利于硫酸和磷矿间进行质量交换。为搭建一个平台使硫酸和磷矿粉之间的反应渠道始终畅通,提出无熟化过磷酸钙工艺与二水物磷酸生产过程类似,通过提高矿粉细度和搅拌强度,降低硫酸浓度和反应温度,达到提高转化率的目的。过磷酸钙生产新工艺取消了化成、熟化工序,环保,节能,符合当前产业政策。 相似文献
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利用固相聚合生产装置,研究了共聚PET固相聚合反应温度、停留时间、氮气流量、催化剂含量、基础切片端羧基含量对增粘的影响。结果表明:在一定的工艺条件下,产品粘度随反应温度提高、停留时间的延长及催化剂含量的增大而增大;当气固比大于0.3时,增大氮气流量对增粘速率不再产生影响。 相似文献
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Ben Duh 《应用聚合物科学杂志》2003,89(12):3188-3200
The solid‐state polymerization (SSP) of poly(trimethylene terephthalate) (PTT) has been studied and compared with that of poly(ethylene terephthalate) (PET). Because PTT and PET share the same SSP mechanism, the modified second‐order kinetic model, which has successfully been used to describe the SSP behaviors of PET, also fits the SSP data of PTT prepolymers with intrinsic viscosities (IVs) ranging from 0.445 to 0.660 dL/g. According to this model, the overall SSP rate is ?dC/dt = 2ka(C ? Cai)2, where C is the total end group concentration, t is the SSP time, ka is the apparent reaction rate constant, and Cai is the apparent inactive end group concentration. With this equation, the effects of all factors that influence the SSP rate are implicitly and conveniently incorporated into two parameters, ka and Cai. ka increases, whereas Cai decreases, with increasing SSP temperature, increasing prepolymer IV, and decreasing pellet size, just as for the SSP of PET. Therefore, the SSP rate increases with increasing prepolymer IV and increasing SSP temperature. The apparent activation energy is about 26 kcal/mol, and the average SSP rate about doubles with each 10°C increase in temperature within the temperature range of 200–225°C. The SSP rate increases by about 30% when the pellet size is decreased from 0.025 to 0.015 g/pellet. Compared with PET, PTT has a much lower sticking tendency and a much higher SSP rate (more than twice as high). Therefore, the SSP process for PTT can be made much simpler and more efficient than that for PET. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3188–3200, 2003 相似文献