聚对苯二甲酸二甲酯/聚2,5-呋喃二甲酸二甲酯嵌段聚酯的合成与表征

以生物基单体2,5-呋喃二甲酸、乙二醇为原料合成聚2,5-呋喃二甲酸乙二醇酯(PEF)。采用熔融酯交换法以PEF聚酯部分取代聚对苯二甲酸乙二醇酯(PET),制备了系列PET-b-PEF嵌段共聚酯。通过核磁共振仪(NMR)、差示扫描量热仪(DSC)、热失重仪(TGA)、X射线衍射仪(XRD)等技术手段表征了共聚酯的结构和性能。结果表明,该系列共聚酯的玻璃化转变温度(Tg)在75.8~80.3℃之间,且随着PEF链段质量分数的增加,PET-b-PEF嵌段共聚酯的Tg先降低后升高,结晶度和熔融温度逐渐降低。当PEF链段含量高于15%时,共聚酯没有结晶峰。该系列共聚酯具有良好的热稳定性,起始分解温度在392.2~407.9℃之间,与所制备的PET起始分解温度403.3℃接近。且当共聚酯中PEF链段含量低于15%时,起始分解温度均在407℃左右,优于PET的热稳定性。     

生物可降解聚丁二酸/苯基丁二酸丁二醇酯系列共聚物的合成及其结晶行为

合成了一系列聚丁二酸/苯基丁二酸丁二醇共聚酯(PBSBS),利用DSC、1H-NMR和X射线等测试手段对共聚物组成、热力学性能、结晶性能、等温结晶行为进行了表征和研究.结果表明,含苯基的共聚单元的引入显著改变了聚丁二酸丁二醇酯(PBS)的热力学性能4,利用Hoffman-Week曲线得到的共聚物平衡熔点随共聚组分含量的增加显著降低,玻璃化转变温度则明显升高,结晶熔点符合无规共聚物的Flory方程.此外,利用Avrami方程对均聚物PBS以及共聚物PBSBS-10分别进行了等温结晶行为研究,结果表明共聚使结晶速率降低,PBS和PBSBS-10的Avrami指数分别介于2.8~3.0和2.7~2.9之间,结晶方式为三维生长异相成核,X射线测试结果表明共聚不影响晶体结构.     

非晶聚对苯二甲酸乙二酯的制备与表征

通过单体酯交换法和聚 2 ,6 萘二甲酸乙二酯 (PEN)与低分子量PET酯交换的方法分别合成了一系列NPA/TPA/EG和IPA/TPA/EG共聚酯 .随着NPA或IPA单元含量的增加 ,等温结晶速度迅速降低 ,共聚物的结晶性降低甚至非晶化 .由NMR分析得知单体酯交换法与聚合物酯交换法得到的共聚酯NPA/TPA/EG序列分布相近 ,链结构都接近完全无规 .由DSC结果分析 ,随共聚单体含量的增加 ,熔点和熔融热降低 ,结晶度也随之降低 .当NPA或IPA含量达到 2 0 %时 ,可以得到非晶的共聚酯 (APET) .本文还对共聚物组成与结晶温度的关系进行了表征     

甲基取代的新型聚醚醚酮及其共聚物的合成、表征和性能研究

设计合成了一种甲基侧基取代的可溶性聚芳醚酮均聚物PETMDEK,同时合成了一系列不同比例的无规共聚物PETMDEK-PEDEK,考察了共聚组成对聚合物性能的影响.随着共聚物中可溶性PETMDEK组分的不断增加,其聚集态结构也发生变化,出现从结晶→液晶→结晶→无定形固体的转变,同时溶解性也由可溶向不溶转变.本文还侧重研究了PETMDEK组分摩尔分数为20%的无规共聚物的热致液晶行为.     

短链支化聚乙烯的合成与表征

合成了两类结构明确的乙烯共聚物, 通过FTIR, GPC, ¹H NMR和¹³C NMR表征了产物的分子结构, 分别研究了分子量和短链支化含量对两类共聚物结晶性能的影响. 采用阴离子聚合制备分子量(M_w)20000~110000、分子量分布为1.1的1,2-结构摩尔分数为7%左右的聚丁二烯. 加氢反应后得到乙烯/1-丁烯模型共聚物的熔点和结晶度随着分子量的增加而下降. 采用茂金属催化剂Et[Ind]₂ZrCl₂催化乙烯与1-己烯共聚合, 制备分子量为100000左右, 共聚单体摩尔分数为0~5.5%的乙烯/1-己烯共聚物, DSC结果表明其熔点和结晶度随着共聚物中1-己烯含量的升高而降低.     

ABS/PET/PETG合金非等温结晶动力学

以聚对苯二甲酸乙二醇酯-1,4-环己烷二甲醇酯(PETG)作为丙烯腈-丁二烯-苯乙烯(ABS)/聚对苯二甲酸乙二醇酯(PET)合金的增容剂,探讨了PETG用量对合金力学性能的影响,并通过差示扫描量热(DSC)仪研究了PET,ABS/PET和ABS/PET/PETG的非等温结晶动力学过程,使用Jeziorny法对合金的非等温动力学数据进行分析,计算得到相应动力学参数.研究结果表明,随着PETG加入量的增多,合金的冲击性能和断裂伸长率明显增加,拉伸强度和弯曲强度稍有降低,结晶度降低,结晶速率稍有降低.     

含氟两亲接枝共聚物的制备及其结晶行为

采用大分子单体技术合成了一系列以聚乙二醇为支链、甲基丙烯酸六氟丁酯为主链的含氟两亲接枝共聚物(PHFMA-g-PSPEG)。用1HNMR和凝胶色谱(GPC)对制备的大分子单体和两亲接枝共聚物的结构进行了表征。利用示差扫描量热法(DSC)、X射线衍射(XRD)和偏光显微镜(POM)测试技术对含氟两亲接枝共聚物的结晶行为进行了研究。DSC和XRD结果表明,随着共聚物中含氟链段质量分数的增加,其结晶温度(Tc)和结晶度(Xc)均降低,而结晶熔融温度(Tm)先减小后增加。POM发现,随着共聚物中含氟链段质量分数的增加,其结晶速度减慢,共聚物形成清晰球晶的能力减弱,当共聚物中含氟链段质量分数为57%时,含氟两亲接枝共聚物已不能形成清晰的球晶。     

芘标记磺酸基聚电解质在水与DMSO中的荧光光谱

合成了芘标记单体N-(芘基)甲基-2-甲基丙烯酰胺(PyMA),其与2-丙烯酰胺基-2-甲基丙磺酸(AMPS)、N,N-二甲基丙烯酰胺(DMAA)共聚,得到含PyMA摩尔分数为0.1%、AMPS摩尔分数F_AMPS分别为0.033～0.896的芘标记磺酸基聚电解质.在DMSO和水中,F_AMPS<0.449时芘标记聚电解质的荧光光谱与PyMA的荧光光谱基本相同;当F_AMPS≥0.449时,芘的[0,1]和[0,3]跃迁的发射强度大幅度增强.芘标记的I₁/I₃值随聚电解质电荷密度增加逐渐减小,且随聚电解质浓度增加也减小,表明聚电解质体系中通过电离基团间吸引形成了分子主链的聚集.     

含噻吩单元的间苯共聚物及其电致发光性能

采用NiCl2催化的Yamamoto缩聚反应将不同比例的含噻吩单体与间苯单体共聚,合成了聚(5-(2-乙基己氧基)-1,3-苯撑-co-(2,5-二苯撑-4-基-噻吩))(PmP-DPT),并测试了4种不同比例共聚物的紫外-可见光吸收光谱,光致发光光谱和LED器件的电致发光光谱,系统地表征了共聚物的光电性能。结果表明,噻吩的加入形成了新的发光中心,实现了从间苯链段到含噻吩发光中心的有效能量转移,当噻吩摩尔分数约为1%时,可得到效率为0.47%的色坐标(CIE)为0.17和0.13的蓝光PLED器件。当噻吩摩尔分数为10%时,可得到效率为2.59%的色坐标(CIE)为(0.21,0.36)的蓝绿光PLED器件。     

PET/HBA/TA/HQ四元共聚酯形态及相结构的研究

研制了一套蚀刻方法并对聚对苯二甲酸乙二醇酯/对羟基苯甲酸/对苯二甲酸/对苯二酚(PET/HBA/TA/HQ)体系的共聚酯液晶试样断面进行蚀刻,并用扫描电镜观察,发现此类共聚酯中存在两相结构.当PET摩尔分数小于50％时,分散相呈球状且富含PET,连续相富含全芳族链段;当PET摩尔分数等于或大于50％时,分散相和连续相结构发生颠倒,连续相富含PET,分散相球状粒子富含全芳族链段且为纤维状结构.因此可以断言,用熔融缩聚方法制备的PET/HBA/TA/HQ四元共聚酯不是无规共聚物,而是嵌段共聚物.     

EFFECT 0F INTERFACIAL ADHESION ON CRYSTALLIZATION AND MECHANICAL PROPERTIES OF POLY (ETHYLENE TEREPHTHALATE)/GLASS BEAD COMPOSITES

The interfacial adhesion between poly (ethylene terephthalate) (PET) and glass beadwas investigated by scanning electron microscope and parallel-plate rheometer. Effect ofinterfacial adhesion on the crystallization and mechenical properties of PET/glass beadcomposites was also studied by differential scanning calorimeter and mechanical testers.The results obtained indicate that the glass bead has a heterogeneous nucleation effecton the PET crystallization. Although better interfacial adhesion is advantageous to theincrease of the tensile strength of the composite, yet it is unfavorable to the crystallizationof PET. It should be pointed out that the crystallization rate of filled PET is always higherthan that of pure PET, regardless of the state of interfacial adhesion.     

Blends of Polypropylene and Syndiotactic 1,2-Polybutadiene:Morphology,Crystallization Behaviors and Mechanical Properties

Morphologies,crystallization behavior and mechanical properties of polypropylene（PP）/syndiotactic 1,2-polybutadiene（s-1,2 PB）blends were investigated.Morphology observation shows the well dispersed domains of s-1,2 PB in PP matrix with the rather small domain sizes from 0.1 to 0.5μm when the s-1,2 PB content increases from 5%to 20%（mass fraction）in the blends,and the phase structure tends to become co-continuous as s-1,2 PB content further increases.Crystallization temperature（Tc）of PP component in the blends is fluctuated with the variation of s-1,2 PB content in the blends.Compatibilization,to some extent,between the two components is inferred from the examination of both morphology and crystallization behavior.Improvement of impact strength of PP toughened by s-1,2 PB becomes significant only in the case of s-1,2 PB content above 20%（mass fraction）.     

Structure and properties of compatibilized recycled poly(ethylene terephthalate)/linear low density polyethylene blends

Blends of recycled poly(ethylene terephthalate) (R-PET) and linear low density polyethylene (LLDPE) were compatibilized with poly(styrene-ethylene/butyldiene-styrene) (SEBS) and maleic anhydride-grafted poly(styrene-ethylene/butyldiene-styrene) (SEBS-g-MA). Effects of compatilizer were evaluated systematically by study of mechanical, thermal and morphology properties together with crystallization behavior of PET. Tensile properties of the blends were improved effectively by the addition of 10 wt% SEBS-g-MA, elongation at break and charpy impact strength were increased with the increasing content of compatilizer. SEBS-g-MA is more effectual on mechanical properties of R-PET/LLDPE blends than SEBS. DSC analysis illustrates crystallinities of PET and LLDPE were increased by compatilizer at annealing condition. WAXD and FT-IR spectra show that annealing influences crystallization behavior of PET. Different compatilizer content results in different morphology structure, in particular, higher SEBS-g-MA content can induce the formation of a salami microstructure.     

The study on grafting comonomer of n-butyl acrylate and styrene onto poly(ethylene terephthalate) film by gamma-ray induced graft copolymerization

Poly(ethylene terephthalate) (PET) film was successfully grafted with n-butyl acrylate and styrene comonomer through gamma-ray induced graft copolymerization. The degree of grafting (DG) and the composition of grafted side chain were characterized by ¹H NMR. It was found that St can inhibit the homopolymerization of BA effectively and increase the DG when the concentration of comonomer mixture is kept constant. The proportion of St to BA in grafted side chain has a positive dependence on the feed ratio of St, which ultimately approaches the feed ratio. The thermal properties of poly(ethylene terephthalate)-graft-poly(n-butyl acrylate-co-styrene) (PET-g-P(BA-co-St)) films were investigated by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). The T_g of PET decreases with the DG, indicating that the grafted P(BA-co-St) copolymer has good compatibility with PET backbone.     

Miscibility of Semi-flexible Thermotropic Liquid Crystalline Copolyesteramide with Polyamide 66

IntroductionIn sl'tu polymer composites containing liquid crystalline polymers(LCPs) have attractedconsiderable attention in the past'decades['--'j. But the development of in sl'tu composites is restricted by two factors. First, the melting temperatures of thermotropic liquid crystallinepolymers (TLCPs) are generally higher than those of the commodity engineering resins. Athigh processing temperatures, these resins tend to become unstable, thereby, causing seriousproblems during fiber spinn…     

三元共聚液晶聚酯酰亚胺/PET共混体系结构与性能研究

通过熔融共混的方式,将实验室自行设计合成的三元共聚热致液晶聚酯酰亚胺(PPDI)与聚对苯二甲酸乙二酯(PET)进行共混,制备一系列不同液晶聚合物含量的共混体系.采用示差扫描量热仪(DSC)、广角X-射线衍射仪(WAXD)和动态力学性能分析仪(DMA)对共混体系的结构与性能进行表征.结果表明,共混体系中两组份之间具有良好...     

Thermal properties of random copolyesters of PET and 3- and 3,5-bromo-substituted p-hydroxybenzoic acids. II

Melt-polycondensation of poly(ethylene terephthalate) (PET) and 3-bromo-p-acetoxybenzoic acid or 3,5-dibromo-p-acetoxybenzoic acid in different mole ratios yielded random copolyesters. The copolyesters have higher T_gs than PET because of an increase in mol % of the substituted p-oxy-benzoate units and follow Wood's equation for copolymer T_gs. Using this equation, we calculated the T_gs of the homopolymers of 3-bromo-p-oxybenzoate and 3,5-dibromo-p-oxybenzoate, which are not available experimentally, to be 113 and 123°C, respectively. Up to certain percentages of the comonomer composition the copolyesters exhibited cold crystallization and melt transitions which we attribute to the crystallizable segments of PET. The variation in melting temperatures in the composition of the copolymer was explained by Flory's theory. The differences in the melting behavior of the polymer, annealed at various crystallization temperatures for a constant time interval, throws light on the morphological changes that took place in it. Using the Hoffman and Weeks method, we determined the extrapolated equilibrium melting temperatures of these copolyester which were used to calculate the enthalpy of melting for the crystallizable units.     

Effect of pressure on the crystallization of poly(ethylene terephthalate)

The effect of pressure on the crystallization of poly(ethylene terephthalate) (PET) was studied. The Instron capillary rheometer was adapted as a high-pressure/high-temperature dilatometer to carry on experiments up to 40,000 psi. Isothermal measurements of PET melt density were made with a precision of ±0.5%. Analysis of the kinetics of crystallization of PET melt at high pressures reaffirmed the existence of low Avrami exponents and their noninteger values. To rationalize the crystallization mechanism with the observed low exponents it is proposed that an appropriate increase in pressure would effectively reduce the free volume of a crystallizable substance to a point at which an alteration of the crystallization mechanism or nucleation mode could occur. It is further shown that PET clearly exhibits two different and sharply defined stages of crystallization behavior at pressures above 10,000 psi. Based on the Avrami equation, the fraction of uncrystallized polymer for the initial stage is defined as an empirically determined function of time and pressure. There is good agreement between the predicted and experimental values over the pressure range investigated.     

Some simulations on crystallinity in a typical linear low-density polyethylene

Crystallinity in ethylene/1-hexene copolymers, a type of linear low-density polyethylene, was investigated by Monte Carlo simulations. The comonomer distributions generated in the simulated chains and the melting temperatures of real chains were used to estimate the minimum crystallite thickness, which is the critical quantity for simulating crystallization in any type of polymer. Simulated values of this thickness were in good agreement with values calculated from Raman longitudinal acoustic mode (LAM) spectroscopy, except for very low 1-hexene mole fractions, where there were presumably complications from high melt viscosities and chain entanglements. The use of this information in estimating properties of these copolymers is illustrated by some preliminary results on the effects of varying amounts of this comonomer on the sizes and numbers of the polyethylene crystallites.     

Polydispersity of ethylene sequence length in metallocene ethylene/α‐olefin copolymers. II. Influence on crystallization and melting behavior

In this work, crystallization and melting behavior of metallocene ethylene/α‐olefin copolymers were investigated by differential scanning calorimetry (DSC) and atomic force microscopy (AFM). The results indicated that the crystallization and melting temperatures for all the samples were directly related to the long ethylene sequences instead of the average sequence length (ASL), whereas the crystallization enthalpy and crystallinity were directly related to ASL, that is, both parameters decreased with a decreasing ASL. Multiple melting peaks were analyzed by thermal analysis. Three phenomena contributed to the multiple melting behaviors after isothermal crystallization, that is, the melting of crystals formed during quenching, the melting‐recrystallization process, and the coexistence of different crystal morphologies. Two types of crystal morphologies could coexist in samples having a high comonomer content after isothermal crystallization. They were the chain‐folded lamellae formed by long ethylene sequences and the bundlelike crystals formed by short ethylene sequences. The coexistence phenomenon was further proved by the AFM morphological observation. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 822–830, 2002