浅谈容量法测定瓶级聚酯切片端羧基的影响因素

本文对用容量法测试瓶级聚酯切片(以下称瓶片)端羧基含量的影响因素进行了研究,结果表明,可以适当增加样品的称样量、提高样品的均匀性、缩短样品溶解时间,并通过对人员定期进行终点颜色统一校准、测定样品时带标等控制手段,提高容量法测定瓶级聚酯切片端羧基的准确度和精密度。     

浅谈瓶片端羧基值测试方法的修改

从方法选择,样品制备,溶剂选择,样品调节,样品溶解条件,称样量,标准溶液的浓度,适用范围、精密度和偏差等方面对瓶用PET树脂国标的端羧基值分析方法各操作细节进行了研究,提出了国标修订的建议。     

瓶级聚酯切片生产中的黏度控制

论述了瓶级聚酯切片生产过程中,通过控制基础切片黏度、端羧基含量、切片外观尺寸等指标,调整固相缩聚(SSP)的反应温度、停留时间、氮气流量以及循环氮气中的碳氢含量等参数,控制瓶片黏度的方法。     

不同端基PBS的合成与降解性研究

利用熔融溶液相结合的方法,调节反应物比例得到了不同端基的聚丁二酸丁二醇酯(PBS).利用滴定法测定不同样品的羧基值,用乌氏黏度计测定不同样品的特性黏度,降解实验测定降解率随时间的变化情况.结果显示,特性黏度大小的顺序是:等物质的量比>羧基封端>羟基封端,羧值大小的顺序是:羧基封端>等物质的量比>羟基封端,降解率大小的顺序是:羟基封端>羧基封端>等物质的量比.     

瓶用聚酯切片固相增黏行为研究

设计不同配方的瓶用基础切片,进行固相增黏研究;得出增黏后产品主要性能指标的变化规律是:二甘醇含量、熔点变化不大;端羧基含量下降7．0-12．0 mol/t;冷结晶温度上升6-7℃、熔融冷却结晶温度下降8-10℃。工业化生产过程与小试实验结果基本相同,可以用小试实验方法预测工业化生产。     

瓶级PET切片生产中的品质控制

主要介绍了瓶级PET切片生产中影响产品品质的各个因素,包括色值、黏度、乙醛含量、间苯二甲酸含量、端羧基值、结晶度等。指出了各影响因素控制方法,对提高相关产品指标以及工艺优化提出了建议。     

直纺长丝工艺中聚酯熔体端羧基值控制的工业研究

本文从工业生产的实践出发对杜邦聚酯技术直接纺工艺中端羧基控制进行了研究。通过对熔体端羧基值对无油长丝端羧基、粘度及纺丝加工影响的分析 ,阐明了聚酯端羧基控制范围 ;通过摸索三个反应釜工艺条件对端羧基值的影响 ,找出了端羧基工业控制的有效途径 ,为同类技术装置生产提供了依据     

钛系催化剂的瓶级PET切片工程化生产

应用钛系聚酯催化剂LT181在25万t连续缩聚PET生产线工程化生产瓶级PET切片。对切片的特性黏度、端羧基值、色值、乙醛含量、二甘醇含量进行检测分析,钛系催化剂能取得和锑系催化剂相似的技术指标。     

英国粘接杂志第34卷1～4(1991)目录及文摘(续)

可再使用的干胶粘剂:用端羧基丁腈橡胶和氯丁橡胶的自硫化混合物进行铝—铝粘接: 氯丁橡胶和端羧基丁腈橡胶的自硫化混合物能够用于铝—铝粘接的胶粘剂,其剥离强度取决于胶粘剂的固化程度、试验温度和端羧基丁腈橡胶的羧基含量。在模塑硫化时间低于15分钟的情况下,重复剥离模塑后发现,该胶粘剂可以再使用。关键词干胶粘剂再使用铝—铝粘接自硫化橡胶共混物固化程度     

回收PET的增粘研究

分别使用均苯四甲酸二酐（PMDA）、环氧树脂及两者的混合物作为回收PET瓶的扩链剂,利用反应挤出技术在同向双螺杆挤出机中反应,研究回收PET瓶烘干时间、扩链剂种类、扩链剂用量对PET产物的特性粘度、端羧基的质量摩尔浓度的影响。实验结果表明：均苯四甲酸二酐（PMDA）和环氧树脂均对PET有一定的扩链作用,且二者合用时扩链效果更佳,反应后PET的特性粘度由0．45dl／g提高到0．58dl／g,摩尔质量也显著提高;随着干燥时间增加,改性的回收PET样品的特性粘度增加的幅度较大;其中单独使用环氧树脂为扩链剂时,可以使反应后的PET端羧基的质量摩尔浓度显著下降。     

瓶级PET切片色相b值的影响因素

从瓶级PET切片的生产实际出发,通过分析该切片色相b值的影响因素,提出了控制原材料品质、添加剂的含量、生产工艺,是得到色相b值较好的瓶级PET产品的保证。     

大容量热灌装瓶级PET的开发

通过寻找瓶片的分子结构参数及超分子结构与瓶片使用性能及加工性能之间的关系,找到影响大容量热灌装瓶级PET切片产品品质的主要工艺控制因素,并对工艺进行优化,通过改变原料配方和调整工艺参数,生产出了能够满足吹大容量(700 mL)以上热灌装瓶级PET产品。     

纤维级PET切片国家标准及产品品质评价

介绍了纤维级聚酯切片新版产品标准GB/T14189-2008修订的主要变化。从特性黏度、二甘醇含量、熔点、端羧基值、色度、凝聚粒子、粉末等方面,对纤维级聚酯切片的抽检结果进行了分析。提出了企业可制定指标严于国家标准的内控标准。     

Identification of rheological and structural characteristics of foamable poly(ethylene terephthalate) by reactive extrusion

The reactivity and efficiency of five low molecular weight multifunctional anhydride and epoxy compounds as chemical modifiers of a bottle grade poly(ethylene terephthalate) (PET) resin were evaluated by reactive extrusion under controlled conditions. The two dianhydrides and the three epoxy compounds were used at concentrations based on stoichiometry derived from the measured carboxyl and hydroxyl end group contents of the base resin. Measures of melt viscosity, melt strength, intrinsic viscosity and carboxyl group content were used as criteria of the extent of the modification. Correlations of die pressure with extrudate swell during extrusion, and melt flow index (MFI) with melt strength by off‐line testing of the extrudates permitted the ranking of the modifiers according to their chain‐extending/branching efficiency. For some systems molecular weight increases (related to die pressure/MFI/intrinsic viscosity) accompanied by broadening of the molecular weight distribution (related to die swell/melt strength) were considered excessive. Extrusion foaming experiments with one particular dianhydride modifier that increased the intrinsic viscosity of the resin from 0.71 to 0.9 dl g^?1 indicate that production of low‐density foams by a process involving one‐step reactive modification/gas injection foaming is feasible, at conditions not significantly different from those employed in the simple reactive modification of the PET resin. The rheological and structural parameters determined in this work may be used as criteria to specify PET foamable compositions in terms of types and concentrations of modifiers. Copyright © 2004 Society of Chemical Industry     

End‐group determination in poly(ethylene terephthalate) by infrared spectroscopy

A complete infrared (IR) spectroscopy experimental procedure was used to determine end‐group concentrations of poly(ethylene terephthalate) (PET). The correlations of the hydroxyl and carboxyl units were derived independently for accurate calibration results. The intermediate monomer of PET, bis(hydroxyethyl terephthalate), was used to prepare hydroxyl end‐group standards and titration measurements were used to determine the carboxyl content for the carboxyl end‐group standards. A double‐Gaussian form equation was defined to account for the interference between the hydroxyl and the carboxyl absorbance peaks in the PET IR spectrum. Some deviation was found from the assumption traditionally used for end‐group determination, stating that carboxyl and hydroxyl are the only end‐group units available in PET. © 2002 Society of Chemical Industry     

Processing characteristics of poly(ethylene terephthalate): hydrolytic and thermal degradation

The effects of poly(ethylene terephthalate) (PET) resin moisture content and temperature exposure have been investigated in terms of material changes resulting from the injection moulding process. Two resins with initial carboxyl contents of 10 µeq/g PET and 20 µeq/g PET have been analysed. Preforms processed at different resin moisture contents and processing temperatures of 280, 290 and 300 °C were evaluated in terms of carboxyl end‐group concentration using a titration method. Intrinsic viscosities of the performs were also measured by solution viscosity. Mathematical models describing the relationships of carboxyl end‐group concentration and intrinsic viscosity to the processing conditions were generated from the experimental data. Carboxyl end‐groups formed were compared for both resins and shown to be dependent on initial carboxyl content in the resin. Reducing the initial carboxyl content in the resin has been shown to increase its hydrolytic stability. The hydrolytic effect on the overall molecular weight drop was separated from the thermal/thermal‐oxidative degradation and shown to be dependent on both the processing temperature and the resin moisture content. © 2002 Society of Chemical Industry     

热灌装瓶级PET切片加工性能的影响因素

对辽化聚酯厂生产的PET瓶片进行分析测试,从瓶片的分子结构参数与瓶片使用性能及加工性能之间的关系进行了分析,找到影响大容量热灌装瓶级PET切片产品品质的主要工艺控制因素,并对工艺进行了优化。