2,2-双(2-(口恶)唑啉)与苯酐联用改性回收PET的动态热性能研究

以扩链剂2,2-双(2-(口恶)唑啉)(BOZ)与苯酐(PA)联用改性回收PET,系统地考察了增黏改性后回收PET动态流变性能和动态力学性能的影响.结果表明,BOZ与PA联用的改性效果明显优于单用BOZ改性回收PET体系;但因扩链剂的加入,在PET分子链中引入的柔性链段而导致聚合物弹性模量下降.     

聚对苯二甲酸丁二醇酯的化学扩链改性研究

以 2 ,2′ -双 ( 2 -唑啉 ) (BOZ)为扩链剂 ,对聚对苯二甲酸丁二醇酯 (PBT)进行扩链改性 ,考察了反应时间、扩链剂用量对扩链效果的影响 ,测试了扩链后PBT的热失重、力学性能和DSC。结果表明 ,BOZ的用量为 0 .44 % ,反应时间 3～ 5min ,PBT的最大扩链效率可达 72 .9% ,PBT的特性粘数从 0 .83dL/g提高到 1.2 1dL/ g ,扩链后PBT热稳定性和力学性能都得到提高。     

反应挤出过程中PET扩链反应的研究

分别加入羧基加成型的双噁唑啉(BOZ)和羟基加成型的均苯四甲酸酐(PMDA)为扩链剂,考察了反应挤出前后PET特性黏度([η])和羧基值的变化情况。实验结果表明:BOZ的扩链效果不明显;PMDA能较大程度地提高PET的[η],但产品羧基值较高;BOZ和PMDA联用可得到高[η]低羧基值的产品,扩链效果最佳。当挤出机工艺条件为:反应段温度260℃、螺杆转速45 r/min、反应段压力1 kPa、BOZ和PMDA质量分数均为0.2%时,可得到[η]为0.90 dL/g,羧基值为25 mol/t的PET产品。     

双噁唑啉类扩链剂增黏回收的PET的研究

从扩链剂用量、反应时间分别研究了2,2一双（2-噁唑啉）（BOZ）与2,2-（1,3-苯撑）-双（2-噁唑啉）（PBO）对回收的聚对苯二甲酸乙二醇酯（PET）的扩链效果。结果表明：扩链剂量为理论量的3倍,反应时间为4～6rain时获得最大扩链效果。其中BOZ对PET特性黏数的提高效果较好,从0．61提高到0．80。利用红外差减光谱分析了BOZ与PET的扩链反应前后的结构变化,酰胺基团出现以及酯基增加、羧基减少证实了扩链反应的发生;而五元环的存在则表明反应过程是分两步进行的。利用差示扫描量热分析仪分析了残余扩链剂对产物热性能的影响;当扩链剂的添加量较低时,熔融过程中产物的相对分子质量进一步提高,结晶度下降;而当扩链剂添加量较高时,相对分子质量反而下降,结晶度上升。     

2，2-双（2-噁唑啉）改性回收PET的研究

以扩链剂2，2-双(2-噁唑啉)对回收PET进行扩链增粘，从特性粘度和羧值的变化考察了其扩链效果，并用DSC法研究了不同添加量噁唑啉对PET热性能的影响。结果表明：双噁唑啉对PET有一定的扩链效果，且影响PET的冷结晶行为。     

高特性粘度聚酯的研究—化学增粘法

合成了对聚酯树酯端基具有活性的扩链剂BOZ,研究了对聚对苯二甲酸乙二酯(PET)和聚对苯二甲酸丁二酯(PBT)的扩链反应过程,扩链反应时间和扩链剂用量等对特性粘度的影响。实验结果表明:合成的扩链剂对PET和PBT能起扩链增粘作用,使分子量提高。可得到特性粘度0.98的PET树脂和特性粘度1.62的PBT树脂。     

不同环氧值环氧树脂对回收PET扩链研究

采用不同环氧值的环氧树脂扩链剂对回收PET在密炼机中进行反应扩链,利用DSC、转矩流变仪和特性粘度测试对其扩链效果进行了分析和研究。结果表明,环氧树脂改性PET的DSC曲线无明显玻璃化转变和冷结晶峰,且环氧树脂环氧值越小,改性PET结晶速度越快,熔点越高;随着环氧树脂扩链剂含量的增大,扩链改性PET特性粘度先增大后减小,且环氧树脂环氧值越小,改性PET特性粘度越大;当环氧值为0.238的环氧树脂扩链剂EP1添加量为1.3%时,扩链效果最好,改性PET特性粘度达到0.977 d L/g。     

PET/LCP共混体系可纺性及其初生纤维结构

通过在 PET和热致性液晶高聚物 (TL CP)共混体系中加入扩链剂双 (2 -　唑啉 ) (BOZ)进行反应性共混纺丝 ,并对初生纤维的结构与性能进行了表征。发现由于扩链剂的作用 ,在 PET与 LCP之间的扩链反应生成部分具有嵌段结构的共聚酯 ,改善了体系的相容性和界面粘结性能 ,提高初生纤维的强度 ,但初生纤维的取向度降低 ,模量和伸长也降低。初生纤维的结晶性能几乎不发生变化     

PET回收料的改性研究

聚对苯二甲酸乙二醇酯回收料(简称R-PET)在回收过程中其各方面性能都有所下降,难以达到直接再利用的目的。因此在文中采用单扩链剂和双扩链剂联用的化学改性方法对R-PET改性,改性后粘均相对分子质量,热分解温度,加工时的平衡扭矩均有所提高,最终确定了改性的最佳配方。     

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。     

双噁唑啉化合物增容PET/PA66共混体系的研究

合成了双恶唑啉化合物（BOZ），制备了PET／PA66／BOZ共混物。用扫描电镜观察了共混物的形态，表明BOZ的加入改善了PET／PA66的相容性，BOZ是反应性的界面相容剂；测试了共混物的力学机械性能，结果显示BOZ在适合的添加量时，冲击强度、弯曲强度、拉伸强度、断裂伸长均有所提高。     

PET/TLCP扩链反应性共混物的热性能研究

研究了聚对苯二甲酸乙二酯（PET）和热致性液晶共聚酯60PHB／PET（含60％摩尔对羟基苯甲酸）体系在少量扩链剂双（2－Wu唑啉）（BOZ）存在下的反应性共混条件对共混物的玻璃化转变温度（Tg)、冷结晶温度（Tcc)、熔体结晶温度（Tmc)以及熔点（Tm)等热性能的影响。结果表明,BOZ对酯交换的促进作用使Tg升高;延长共混时间和提高共混温度使Tcc升高,Tmc和Tm下降,并受到BOZ加入量的显著影响。     

改性纳米SiO2对苯并恶嗪树脂摩擦性能的影响

用超支化聚硅氧烷修饰纳米SiO2粒子(HBPSi-SiO2),将其加入到苯并恶嗪(BOZ)树脂中制备了BOZ/HBPSi-SiO2复合材料,并与普通处理的纳米SiO2(Nano-SiO2)进行比较,研究了该复合材料的摩擦性能。结果表明,HBPSi-SiO2具有比Nano-SiO2更优异的减摩抗磨效果。相对于纯BOZ树脂,BOZ/Nano-SiO2复合材料的磨损率降低了59.4%,而BOZ/HBPSi-SiO2复合材料的磨损率降低了87.2%,摩擦系数也有所降低。     

Reactive blending of poly(ethylene terephthalate)(pet)/ poly(ethylene 2,6‐naphthalate)(pen). I: Effect of mixing conditions on chain structure

Reactive blending of poly(ethylene terephthalate)/poly(ethylene naphthalene 2,6dicarboxylate) with addition of 2,2'‐bis(1,3‐oxazoline) (BOZ) has been studied under various mixing conditions for the different compositions. The transesterification level, the sequence length of both PET and PEN short blocks, and the degree of randomness were estimated using¹H NMR. The results indicate that both mixing time and temperature are the primary factors controlling the transesterification, while the chain extender BOZ can significantly accelerate the transesterification between PET and PEN at 275°C. The composition also, to some extent, influences the transerification level as the mixing time is increased. As a consequence of transesterification proceeding, the sequence structures of the reactive blends are also markedly changed, which corresponds to a transfer from an initial block structure to a multiblock structure with higher randomness. The change in the microstructure of the reactive blends has also been analyzed by a Bernoullian statistics model. The effect of the BOZ on the intrinsic viscosity of the reactive blends is discussed.     

双噁唑啉化合物偶联聚酯的研究─—聚对苯二甲酸丁二酯的偶联反应

报告双唑啉化合物（ＢＯＺ）对聚对苯二甲酸丁二酯（ＰＢＴ）的偶联扩链的研究结果，表明与偶联聚对苯二甲酸乙二酯（ＰＥＴ）一样，特性粘数（［η］）在３～６ｍｉｎ迅速达到极大值，随后缓慢下降，ＰＢＴ熔点较低，故此反应可在较低温度下进行，偶联效率与ＰＥＴ的结果相近，以丁二酸为模型化合物考察表明偶联作用是在羧基进行，同时反应的最低温度可至１６４℃左右。     

Processing effects on poly(ethylene terephthalate) from bottle scraps

Processing of virgin and recycled poly(ethylene terephthalate) (PET) in a twin screw extruder evidences the degradative effect caused by thermal decomposition of poly(vinyl chloride) (PVC) and other impurities, e.g. adhesives, at the processing temperature. Lower melt viscosity and molecular weight, along with higher carboxylic end group concentration, were observed for recycled PET, the extent depending on PET purity. In an attempt to investigate the correlation between the kinetics of degradation phenomena and the level of thermomechanical stress, a novel dynamic method of evaluating thermal stability in processing conditions was developed. Such a method allows the achievement of long equivalent residence times while using lab-scale extruders. As a result of these experiments, PVC-rich recycled PET was shown to reach very low melt viscosity after less than 10 min in processing conditions, while virgin PET retained high viscosity even after 30 min.     

Recycling of poly(ethylene terephthalate) into closed‐cell foams

The increase of the elongational viscosity of recycled poly(ethylene terephthalate) (PET) is investigated with the aim of producing closed‐cell foams by means of a cost‐effective reactive extrusion technique. A recycled PET grade containing controlled contamination levels of polyvinyl chloride (PVC) and poylethylene (PE) is selected, and compared with virgin bottle‐grade PET as a reference. Reactive processing with a tetrafunctional epoxy additive induces randomly branched molecules with a lower degree of branching in recycled PET than in virgin PET, as shown by a molecular structure analysis. The corresponding increase in elongational viscosity is related to foaming experiments performed using supercritical CO₂ in a pressurized vessel. Observations of foam microstructures reveal that modified virgin PET forms closed‐cell structures under a large variety of foaming conditions, as opposed to unmodified virgin and recycled PET, which collapse as a result of insufficient elongational resistance. Closed‐cell foams are also obtained using modified recycled PET, providing that the temperature at which the pressure is released is lowered to 260°. Recycling of PET into closed‐cell foams is thus achieved, although the processing window is slightly reduced compared to virgin PET.