Stannous-acetylacetonate:A new catalyst for poly(trimethylene terephthalate) synthesis

Stannous-acetylacetonate was prepared efficiently and characterized by ^1H NMR and FT-IR. Its catalytic activity for poly（trimethylene terephthalate） （PTT） synthesis was investigated. By this catalyst, the degree of esterification of pure terephthalic acid was up to 91.7% after reaction at 260 ℃ for 2 h, while the intrinsic viscosity and content of terminal carboxyl groups of the corresponding PTT polymerized at 260 ℃, 60 Pa for 2 h was 0.8816 dL/g and 17 mol/t,respectively. Stannous-acetylacetonate was more active and promising than tetrabutyl titanate and stannous octoate for PTT synthesis.

Thermal degradation and isothermal crystalline behavior of poly(trimethylene terephthalate)

Poly（trimethylene terephthalate） （PTT） is an excellent fiber material. Its thermal degradation and isothermal crystalline behaviors were in this study investigated using thermogravimetric analysis （TGA）, thermogravimetric analysis-Fourier transform infrared spectroscopy （TGA-FTIR） analysis, differential scanning calorimetry （DSC） and X-ray diffraction （XRD）. The thermal degradation mechanism of PTT follows Mclafferty rearrangement principle. The PTTwithintrinsicviscosity（IV） of 0.74 dL/g has a maximum crystallinity of about 55% at 190 ℃, as demonstrated by DSC and XRD measurements consistently.

Banded Spherulites Grown from Poly(trimethylene terephthalate) Solution-cast Film

Various morphologies of poly（trimethylene terephthalate） （PTT） solution-cast thin films at different crystallization temperatures were investigated by polarized light microscopy （PLM）,atomic force microscopy （AFM） and transmitted electron microscopy （TEM）.In the range of 110-150 ℃,banded spherulite occurred and banding space gradually decreased along the radial direction from the primary nucleation site.Between 160 and 170 ℃,normal non-banded spherulite was found.Above 170 ℃,banded configuration occurred again.Lamellar growth direction of banded spherulite was determined to the crystal a-axis.

基于熔喷非织造材料的温度传感器制备及其传感性能

为结合织物的柔软性、舒适度和耐磨性制备低成本、高性能的可穿戴温度传感器,以超声波处理工艺将不同浓度比的聚(3,4-乙烯二氧噻吩)-聚苯乙烯磺酸(PEDOT:PSS)和碳纳米管(CNTs)共同负载在聚对苯二甲酸丁二酯(PBT)熔喷非织造材料表面,制备了PEDOT:PSS/CNTs/PBT熔喷非织造材料的温度传感器。借助扫描电子显微镜、X射线衍射仪和傅里叶变换红外光谱仪对温度传感器的微观形貌、化学结构进行表征与分析,并对其热稳定性能、传感性能和力学性能进行测试与研究。结果表明,所制备的温度传感器在25~80℃范围内,灵敏度可达-0.71%/℃,响应时间较快(18 s),线性度较好(R^(2)=0.99),迟滞度低至4.98%,具有良好的重复使用性及长期稳定性,并且在37~38℃的温度范围内感应精度可达0.1℃。所制备的温度传感器能够对环境温度和人体表面温度进行实时稳定监测,具有广阔的应用前景。

基于奇数碳软链段PBT基弹力丝的制备及结构性能

通过分子结构和聚合工艺设计合成了基于奇数碳软链段(聚三亚甲基醚二醇,PO3G)的聚对苯二甲酸丁二醇酯(PBT)基弹性体(PBT-PO3G),并分别以PO3G质量分数为20%和30%的PBT-PO3G为原料,采用熔融纺丝法制备弹力丝。通过与偶数碳软链段(聚四氢呋喃醚二醇,PTMG)质量分数为30%的PBT基弹性体(PBT-PTMG)及其弹力丝进行对比,探究奇数碳软链段结构对弹性体和弹力丝热力学性能的影响规律。结果显示,PBT-PO3G弹性体和弹力丝的回弹性优于PBT-PTMG,这是因为奇数碳软链段不易结晶。当牵伸倍数为2.5时,PO3G质量分数为30%的PBT-PO3G弹力丝的断裂强度为1.25cN/dtex,在定伸长10%条件下循环拉伸10次,回复率达93%。研究结果可为聚醚酯在弹性纤维领域的应用提供借鉴。

Stannous oxalate: An efficient catalyst for poly(trimethylene terephthalate) synthesis

A complete study on the catalytic activity of stannous oxalate for poly(trimethylene terephthalate) (PTT) synthesis via esterification method is carried out by comparison to the well known catalysts (tetrabutyl titanate (TBT), dibutyltin oxide (Bu2SnO), and stannous octoate (SOC)). Their catalytic activity in the esterification process is monitored by measuring the amount of water generated, while intrinsic viscosity (IV) and content of terminal carboxyl groups (CTCG) are used as the index in the polycondensation process. Stannous oxalate shows higher activity than the other catalysts. Decrease in reaction time and improvements in PTT property are observed. The higher catalytic activity of stannous oxalate is attributed to its chelate molecular structure.

Miscibility and Isothermal Crystallization of Poly(L-lactide) and Poly(trimethylene carbonate) Blends

Miscibility, isothermal crystallization kinetics, and morphology of poly（L-lactide）/poly（trimethylene carbonate） （PLLA/PTMC） crystalline/amorphous blends were studied by differential scanning calorimetry （DSC） and optical microscopy （OM）. The heterogeneity of OM images and an unchanged glass transition temperature showed that PLLA was immiscible with PTMC. During isothermal crystallization, the crystallization rate of PLLA improved when the PTMC content was low （≤ 20%）. However, when the PTMC content was high （≥ 30%）, the crystallization rate decreased significantly. The reason of these nonlinear changes in crystal kinetics was analyzed according to the nucleation and growth process by virtue of a microscope heating stage. The isothermal crystallization morphologies of the blends were also studied by polarized optical microscopy and the results confirmed the conclusions obtained from crystallization kinetics.

A study on the double melting behavior of poly(trimethylene terephthalate)

Double melting behavior of poly(trimethylene terephthalate) (PTT) was studied in detail by means of differential scanning calorimetry (DSC) and optical microscopy. The results indicate that the low-temperature melting peak of PTT at ca. 218℃ for the samples crystallized isothermally at 203℃ is associated with the melting of crystals produced by secondary crystallization, while the high-temperature melting peak of it at about 227℃ is related to the melting of the crystals produced by primary crystallization. The results further demonstrate that the PTT crystals growing non-isothermally during cooling process are thermodynamically unstable and can undergo structure reorganization during the DSC heating scan. The reorganized crystals melt at temperature higher than the crystals produced by secondary crystallization at 203 ℃. Consequently, for the non-fully crystallized samples, the crystals grown during cooling also exhibit contribution to the high-temperature melting peak.

Enzymatic ring-opening copolymerization of trimethylene carbonate and ethylene ethyl phosphate

Enzymatic ring-opening copolymerization of trimethylene carbonate (TMC) and ethylene ethyl phosphate (EEP) are performed in bulk at 100°C using porcine pancreas lipase (PPL) or candida rugosa lipase (CL) as catalyst. The factors affecting the yield and molecular weights such as catalyst concentration, polymerization time and monomer feed ratio are investigated. The random copolymers obtained have molecular weight ranging from 3200 to 10200. The glass transition temperature (T g) of the copolymers decreases from ?28 to ?41.7°C, with the increase of the EEP content in the feed from zero to 5:10. Degradation tests show that the degradability of the copolymers is improved by introduction of the EEP unit into the copolymer chain.

Studies on the rheological, phase morphologic, thermal and mechanical properties of poly(trimethylene terephthalate)/ ethylene propylene diene monomer copolymer grafted with maleic anhydride/metallocene polyethylene blends

The rheological,phase morphologic,thermal andmechanicalpropertiesofpoly(trimethyleneterephthalate)/metallocene polyethylene(PTT/mPE)blends in the presence of ethylene propylene diene monomer copolymer grafted with maleic anhydride(EPDM-g-MAH)as compatibilizer are studied by means of a capillary rheometer,scanning electron microscopy(SEM),differential scanning calorimetry(DSC)and thermogravimetric analyzer(TGA).Results suggest that the compatibility of PTT/mPE blends is improved greatly after the addition of a compatibilizer.The radius of the dispersed phase in the system decreases greatly when the compatibilizer is added into the blend.When the amount of compatibilizer exceeds 8 wt-%,the size of dispersed phase becomes larger again.This phenomena could be attributed to the higher viscosity of the EPDM-g-MAH phase,which is dispersed more difficulty in the PTT phase of lower viscosity,thus the mixing efficiency is apparently decreased during the melt blending process.Moreover,the melt viscosity of the blend reaches the maximal value in case of 4 wt-%compati-bilizer content,above which it would decrease again.This result is associated with the generation of more and bigger dispersed phase inside the bulk phase,thus the grafting efficiency at the interface is decreased,which could result in lower viscosity.The DSC results suggest that the mPE component shows a nucleating effect,and could increase the overall degree and rate of PTT crystallization,while the addition of a compatibilizer might slightly diminish these effects.In addition,the blend with 4 wt-%compatibilizer shows the best thermal stability.Furthermore,the Izod impact strength and the tensile strength at room temperature of the blend are also markedly improved by the addition of a 4–8 wt-%compatibilizer.

Study on the crystal morphology and melting behavior of isothermally crystallized composites of short carbon fiber and poly(trimethylene terephthalate)

The spherulites of the short carbon fiber(SCF)/poly(trimethyleneterephthalate)(PTT)compositesformedin limited space at designed temperatures,and their melting behaviors were studied by the polarized optical microscopy,atomic force microscopy(AFM),and scanning electron microscopy(SEM),respectively.The results suggest that SCF content,isothermal crystallization temperatures,and the film thicknesses influence the crystal morphology of the composites.The dimension of the spherulites is decreased with increasing SCF content,but whether banded or nonbanded spherulites will form in the composites is not dependent on SCF content.However,the crystal morphology of the composites depends strongly on the temperature.When the isothermal crystallization temperatures increase from 180℃ to 230℃,the crystal morphology of SCF/PTT composites continuously changes in the following order:nonbanded→banded→nonbanded spherulites.Disconti-nuous circle lines form in the film when the film thickness increases from 30 to 60μm.Basing on the SEM observation,it is found that these circle lines are cracks formed due to the constriction difference of the different parts of the spherulites.These cracks are formed when the film is cooled from the isothermal crystallization temperature to the room tempera-ture at a slow cooling rate;while they will disappear gradually at different temperatures in the heating process.The crack will appear/disappear first around the center of the spherulite when the film was cooled/heated.The nontwisted or slightly twisted lamellas will reorganize to form highly twisted lamellas inducing apparent banded texture of the spherulites.

PTT/EPDM-g-MAH/mPE共混体系的相形态与流变行为

研究了聚对苯二甲酸丙二酯码来酸酐接枝三元乙丙橡胶／茂金属聚乙烯共混体系（PTT／EPDM-g-MAH／mPE）的相形态和流变行为。结果表明，增容剂EPDM-g-MAH可以明显改善PTT与mPE的相客性，但含量超过4％时分散相的数日增加、尺寸增大。PTT／EPDM-g-MAH／mPE共混物熔体为假塑性流体，表现黏度随剪切速率的增加而降低；当EPDM-g-MAH的含量在0％～16％范围内时，共混物的非牛顿指数先减小后增加再减小；表现黏度、粘流活化能先增加后减小，并在4％时出现极值。

聚对苯二甲酸丙二醇酯的合成

系统研究了PTT合成条件对PTT产品质量的影响,分析和讨论了缩聚反应的放大效应。结果表明,酯化反应中应该使用催化剂,PDO/PTA摩尔比以1.8～2为宜。温度对缩聚反应进程有较大影响,在较低温度下以缩聚主反应为主,当温度高于260℃时,反应经历两个阶段,初期以缩聚主反应为主,后期以大分子链的热裂解为主。1,3-PDO的纯度、丙醛含量和加热色度对PTT质量影响较大。改善反应釜的脱灰效果,是解决合成中放大效应的关键因素。

离聚体Surlyn对PET/PA-6共混物的相容性及形态结构的影响

通过偏光显微镜（ Ｐ Ｌ Ｍ ）观察、扫描电镜（ Ｓ Ｅ Ｍ ）观察、动态力学分析（ Ｄ Ｍ Ａ）和广角 Ｘ 射线衍射分析（ Ｗ Ａ Ｘ Ｄ），研究了离聚物 Ｓｕｒｌｙｎ 对 Ｐ Ｅ Ｔ／ Ｐ Ａ６ 共混物的相容性及形态结构的影响。实验结果表明，在以 Ｐ Ｅ Ｔ 为主体的 Ｐ Ｅ Ｔ／ Ｐ Ａ６ 简单共混物中，两者的相容性很差。 Ｐ Ｅ Ｔ、 Ｐ Ａ６ 是分别结晶的，不生成共晶。加入离聚体 Ｓｕｒｌｙｎ 后，改善了共混物无定形区和晶区的相容性，增加了界面粘接力，使分散相 Ｐ Ａ６ 的尺寸减小、分布趋向均匀。当 Ｓｕｒｌｙｎ的含量达到 ６％ 时，其增容效果最好。

离聚物surlyn对PET/PA66共混物性能的影响

采用傅里叶红外光谱、差示扫描量热法考察了离聚物surlyn对聚对苯二甲酸乙二醇酯/聚酰胺66(PET/PA66)共混物结构、结晶性能的影响;通过低角频率下流变性能测试、力学性能测试以及热变形温度测试,考察了离聚物对该共混物流变性能、力学性能、耐热性能的影响。结果表明,加入离聚物surlyn增加了界面的粘接力和分子间的链缠结,使共混物的相容性得到了提高,其中以离聚物surlyn含量为10%(质量分数,下同)时效果较好;随着sur-lyn含量的增加,共混物的热变形温度和结晶性能降低,冲击强度、拉伸强度和弯曲强度增加。

PTT非等温结晶动力学研究

采用差示扫描量热仪对PTT进行非等温结晶研究。利用不同动力学模型对其结晶过程进行处理, 并将PTT与PET及PBT的非等温结晶过程进行对比。结果表明:Jeziorny方程和Ozawa方程都可以很好的 描述PTT,PET,PBT的非等温结晶过程;采用结合Avrami方程和Ozawa方程的处理方法,得到了3种聚酯的 结晶速率的大小关系:PBT>PTT>PET。通过计算Ziabicki结晶能力参数,得到3种聚酯的结晶能力的顺序 为:PBT>PTT>PET。

PEN短纤维增强PTT复合材料的流变性能及力学性能

研究了聚对苯二甲酸丙二酯(PTT)/聚对萘二甲酸乙二酯(PEN)短纤维复合材料的流变行为和力学性能,讨论了复合材料的组成、剪切应力和剪切速率及温度对熔体流变行为、熔体黏度的影响,以及不同配比复合材料的力学性能。结果表明,PTT/PEN短纤维复合材料熔体为假塑性流体,熔体表观黏度随着温度升高而下降,且熔体黏度随着PEN短纤维含量增加而不断上升。随PEN短纤维加入量的增加,复合材料的拉伸强度、断裂强度、弹性模量均明显提高,无缺口冲击强度略有提高,说明PEN短纤维的加入对PTT起到了明显的增强作用而不降低材料的韧性。

PET/PTT共混体系的结晶熔融行为

对PET/PTT共混体系的DSC热分析结果表明,在共混体系中两组分形成各自的晶体,呈现各自的熔点Tm,但两种聚合物各自的结晶过程是彼此受对方影响的。从形态和热力学两方面对共混体系的熔点下降行为进行了解释,根据N ish i-W ang方程的计算结果,PET/PTT共混体系的相互作用能密度和相互作用参数都为负值,表明PET/PTT共混体系在熔融态是热力学稳定的相容体系,在该体系中,PET和PTT分子间存在着密切的相互作用。

环状碳酸酯锡粉催化开环聚合

首次利用锡粉对环状碳酸酯 ( 1,3 -三亚甲基碳酸酯 ) ( TMC)进行催化开环聚合 ,研究了催化剂种类 ,催化剂的用量 ,反应时间 ,反应温度 ,单体纯度对聚合结果的影响 .GPC检测结果表明 :用金属锡粉做催化剂 ,能得到 Mn max=5 70 0 0 ( Mw/ Mn=1.6)的线型高分子量聚碳酸酯 ( PTMC) ,而锌粉则没有明显的催化活性 .单体纯度对聚合物分子量无明显影响 .

聚对苯二甲酸丙二醇酯(PTT)的研究

新型聚酯材料聚对苯二甲酸丙二醇酯 (PTT)是一种极有应用潜力的聚合物 ,但在非纤维领域的研究与应用才刚开始。本文简要概述了其发展状况 ;详述其结构、性能特点 ;