共查询到19条相似文献,搜索用时 418 毫秒
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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 相似文献
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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。 相似文献
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固相聚合PET及饮料瓶的热性能研究 总被引:7,自引:2,他引:5
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。 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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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。 相似文献
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PA6固相聚合——相对分子质量研究 总被引:1,自引:1,他引:0
本文对PA6固相聚合(SSP)过程中影响聚合产物相对分子质量(RMW)的因素进行了研究.结果表明:RMW随RMW调节剂用量增加稍微增加后再迅速减小;聚合时间增加,则PA6的RMW开始迅速增加,随后逐渐减慢. 相似文献
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Jian‐Jun Xie 《应用聚合物科学杂志》2002,84(3):616-621
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 (Mn) increased with increasing reaction temperature and time and decreasing particle size. The SSP rate and Mn 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 相似文献
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Constantine D. Papaspyrides 《Polymer International》1992,29(4):293-298
Low reaction rates and distinct transition phenomena from the solid to the melt state restrain solid state polymerisation (SSP) reactions of nylon salts for industrial application. To alleviate these problems, catalysts containing nylon salts are employed. In this study, hexamethylenediammonium adipate (HMA) particles were used containing a strictly controlled amount of catalyst, either phosphoric acid, sulphuric acid or boric acid. The results show considerable acceleration of the reaction rate, especially in the presence of boric acid, while the solid state character of the process is maintained throughout the total course of the reaction. Comparative polymerisation runs were monitored both by end-group and quantitative water determinations of the reacting material to exclude any accumulation of the water of polycondensation within the reacting particles. The results obtained support further the mechanism proposed for the transition solid-melt in SSP runs of nylon salts in the absence of catalysts. In the latter case extended water accumulation is the rule. 相似文献
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KwanHan Yoon Malcolm B Polk Byung G Min David A Schiraldi 《Polymer International》2004,53(12):2072-2078
The crystal structures of nylon‐6 and nylon‐6/clay fibers were investigated on annealing and drawing. Annealing increased the γ‐crystalline form of both fibers, as indicated by the DSC curves, and its effect was dominant in nylon‐6/clay fiber. On drawing, the γ‐crystalline form was easily converted into the α form in nylon‐6, whereas it was still observed at a relatively high spin‐draw ratio in nylon‐6/clay fiber. However, although the α‐crystal form was dominant in nylon‐6, the γ‐crystal form was dominant in nylon‐6/clay with annealing and drawing, on the basis of the XRD data. The fast crystallization rate of nylon‐6/clay compared with pure nylon‐6 was confirmed, on the basis of the Avrami exponent. The initial modulus of nylon‐6/clay fiber was 30 % higher than the neat nylon‐6 fiber. The reinforcing effect of clay on the dynamic storage modulus was observed. Copyright © 2004 Society of Chemical Industry 相似文献
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Nylon 6,6 resins, in the form of pellets, were solid state polymerized in the temperature range of 160–200°C in a fixed‐bed reactor under flowing nitrogen for times of 0–4 h. The kinetics of the solid state polymerization (SSP) of nylon 6,6 were examined by the evaluation of pertinent rate expressions and the selection of the most suitable one for describing the apparent overall process. The Flory‐theory‐based kinetic models were the most effective both for this study's data and for data previously published on SSP of different polyamides. Accordingly, SSP rate constants and activation energies were derived, and process parameters, such as the temperature and time, were investigated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 671–681, 2005 相似文献
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Thermal Properties of methyl methacrylate (MMA), ethyl methacrylate (EMA) and n-butyl methacrylate (n-BMA) grafted onto nylon 6 fibre with various graft levels were investigated by thermogravimetric analysis (TGA) and differential thermal analysis (DTA) and the results compared with that of parent nylon 6 fibre. It was found that the initial decomposition temperatures (IDT) of the grafted samples were lower than that of the parent nylon 6 fibre. On the other hand with all the three monomers, there was an increase in overall thermal stability followed by subsequent decrease with increase in the graft level. Among the grafted samples both the IDT and IPDT (initial procedural decomposition temperature) followed the order MMA-g nylon > EMA-g nylon < n-BMA-g nylon Differential thermal analysis shows a depression in glass transition temperature (Tg) as well as in melting temperature (Tm). In the case of the MMA and EMA grafted samples, the depression is small over a wide range of graft level. In the case of the n-BMA grafted samples, the depression is higher. A wide melting range was obtained in the grafted samples. Flammability studies also showed that with an increase in the graft level as well as an increase in the alkyl chain the ease of flammability increased as expressed by limiting oxygen index (LOI) values. The possible reasons for the phenomena occurred have been discussed. 相似文献
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With trimesinic acid as a molecular weight regulator, the hydrolytic polymerization of ?‐caprolactam was carried out, and nylon‐6 or polyamide‐6 with three‐branched chains was obtained. Through a systematic study of the effects of conditions such as the reaction time and concentration of trimesinic acid on the polymerization, we found that the conversion of caprolactam was almost insensitive to the initial concentrations of the regulators, but the relative viscosity of the polymer decreased with increasing trimesinic acid. Characterization investigations showed that differential scanning calorimetry curves changed from a single peak for normal nylon‐6 to one main peak and one shoulder or one small peak for the branched polymer; the melting point of the star‐shaped nylon‐6 decreased with an increasing amount of trimesinic acid, whereas its crystallization temperature was higher than that of linear‐chain nylon‐6. A wide‐angle X‐ray diffraction study indicated that the crystal structure of the star‐shaped nylon‐6 still belonged to the α form, and the crystallizability of the branched polymer with an elevated amount of trimesinic acid during polymerization did not seem to be weakened; the characteristic absorption of infrared spectra provided indirect evidence for the existence of branched chains in the polymer. Moreover, the mechanical properties of star‐shaped nylon‐6 and linear‐chain nylon‐6 were compared. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3184–3193, 2001 相似文献