马来酸酐和富马酸对聚丁二酸丁二酯的改性研究

在聚丁二酸丁二酯(PBS)分子主链中添加带有不饱和键的马来酸酐(MAH)和富马酸(FA)单体,得到了含有不饱和键的,具有顺、反结构的PBS基共聚物。通过广角X射线衍射、热重分析、差示扫描量热分析和拉力测试等分析手段,研究了不同结构共聚物的性能。结果表明,随着MAH和FA含量的增加,两种改性后的PBS基共聚物的晶粒尺寸减小;玻璃化转变温度都有所降低;共聚物的热稳定性都略有降低,但高于300℃,仍具有良好的热稳定性;共聚物的拉伸强度差异较大,但断裂伸长率明显提高。在PBS主链中形成顺、反结构的两种单体的添加对PBS基共聚物性能的影响没有太大差别。     

乙烯—醋酸乙烯酯共聚物的化学接枝改性

综述了乙烯－醋酸乙烯酯共聚物的化学接枝方法,重点探讨了乙烯－醋酸乙烯酯与马来酸酐的接枝原因,并对接枝物的表征及应用加以论述。     

低聚合度、低醇解度聚乙烯醇的合成与性能研究——I.低聚合度聚醋酸乙烯酯的合成

以甲醇为溶剂,偶氮二异丁腈(AIBN)为引发剂,采用自由基聚合方法合成了低聚合度聚醋酸乙烯酯,并对其结构进行了表征。讨论了聚合时间、引发剂用量、物料配比、聚合温度等因素对聚合率的影响,获得了相对较佳的工艺参数。     

马来酸酐接枝细菌纤维素改性聚乳酸研究

制备了马来酸酐接枝细菌纤维素（BC-g-MAH）,然后采用溶液浇铸法将BC-g-MAH与聚乳酸（PLA）制备成复合材料,通过红外光谱、差示扫描量热分析、拉伸实验和热失重分析等测试手段,研究了由PLA与不同含量BC-g-MAH制备成的复合材料的结构和性能。结果表明,MAH对BC进行了成功的接枝,制得的BC-g-MAH与 PLA具有较好的界面相容性;随着BC-g-MAH含量的增加,改性后的复合材料的结晶度、拉伸强度和拉伸模量较纯PLA有较大提高;BC-g-MAH含量为 20 %（质量分数,下同）时,复合材料的结晶度、拉伸强度和拉伸模量较纯PLA分别提高了17.1 %、69.4 %和428.4 %,复合材料热稳定性能也有了显著增强。     

Blends of Poly(ether imide) and Styrene Sulfonic Acid Based Polymer: Thermal,Mechanical and Ionic Conduction Behavior

Dense membranes based on poly(ether imide) (PEI) and poly(styrene sulfonic acid-co-maleic acid) (PSSAMA) was obtained by extrusion and compression molding. Blends with different PSSAMA content (1, 3, 5, and 10 wt%) were prepared. Their morphology was investigated by scanning electron microscopy (SEM) and their thermal properties by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic-mechanical analysis (DMA). Two glass transition temperatures (T_g) (100 and 216°C) appeared when high contents of PSSAMA were added to PEI, indicating that the polymers form an immiscible system. TGA curves showed that the first weight loss occurred above 400°C for all blends, indicating a good thermal stability. Water uptake measurements have shown that the membranes presented low swelling when compared with Nafion®. The proton conductivity of the membrane with 10 wt% of PSSAMA obtained bv impedance measurements was 0.006 × 10^?2 S·cm^?1.     

Miscibility Studies of Poly (vinyl acetate) and Cellulose Acetate

Polymer blends of poly (vinyl acetate) (PVAc) with cellulose acetate (CA) have been prepared by solution blending, and their miscibility has been investigated by using physical techniques. Viscosity, density, and ultrasonic velocity for blend solutions at different percentages of the blend composition have been measured at 30°C. The results are discussed.     

Poly(ethylene‐co‐vinyl acetate) blends with phenoxy

EVA was blended with phenoxy over the whole range of composition using a twin‐screw Brabender. Two‐phase separation caused by EVA crystallization was observed in the EVA‐rich blends and the dispersed domain of EVA was not clearly shown in the phenoxy‐rich blends. Differential scanning calorimetry (DSC) showed that the glass transition temperature (T_g) of EVA was increased by 5–10°C in the EVA‐rich blends but the T_g of phenoxy was superposed over the melting behavior of EVA. X‐ray diffraction measurement indicated that EVA crystallization was restricted in the phenoxy‐rich blends and the EVA crystal structure was influenced by incorporation of phenoxy into the EVA‐rich blends. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 227–236, 1999     

Poly(2-hydroxyethylmethacrylate-co-2-folate ethylmethacrylate) and Folic acid/Poly(2-hydroxyethylmethacrylate) Solid Solution: Preparation and Drug Release Investigation

Poly(2-hydroxyethylmethacrylate-co-2-folatethylmethacrylate) was synthesized by free radical polymerization of 2-hydroxyethylmethacrylate with 2-folatethylmethacrylate and folic acid/poly(2-hydroxyethylmethacrylate) solid solutions was prepared by mixing folic acid with poly(2-hydroxyethylmethacrylate) using the solution casting method. The structure and the homogeneity distribution of folic acid in the polymer matrix are characterized by different methods. The diffusion behaviors of water and folic acid through poly(2-hydroxyethylmethacrylate-co-2-folatethylmethacrylate) and poly(2-hydroxyethylmethacrylate) matrixes were found obey to the Fick models. The in vitro cytotoxicity assessed by microculture tetrazolium test assay and the antioxidant activity of poly(2-hydroxyethylmethacrylate-co-2-folatethylmethacrylate) systems determined by 1,1-diphenyl-2-picryl-hydrazyl method revealed no significant toxicity of these systems and has excellent free radical scavenger property which can be as safe candidate in drug-carrier system. The solubility enhancement of folic acid in different pH media is also investigated and the results obtained reveal a maximum of 399–400?mg?L^?1. The release dynamic of folic acid from the poly(2-hydroxyethylmethacrylate-co-2-folatethylmethacrylate) containing 5?mol% of folic acid and that from folic acid/poly(2-hydroxyethylmethacrylate) system containing 10?mol% of folic acid have the best intestine/stomach ratio.     

Permeation of Oxygen and Nitrogen Gases through Poly(ethylene-co-vinyl acetate) Membranes

The transport of oxygen and nitrogen gases through uncrosslinked and crosslinked poly(ethylene-co-vinyl acetate) membranes has been analyzed. Poly(ethylene-co-vinyl acetate) was crosslinked by dicumyl peroxide and benzoyl peroxide. Neat sample showed a lower permeation coefficient due to the crystalline nature. The crystalline nature was supported by X-ray diffraction analysis. The difference in the permeation behavior of the two crosslinked samples was correlated with crosslink density. Crosslink density was calculated using equilibrium sorption method. Differential scanning calorimetry analysis also supports the different permeation behavior of the crosslinked samples. The O₂/N₂ selectivity of the membranes was estimated. The influence of the crosslink density and size of penetrants on permeation were analyzed. The effect of free volume on the gas barrier properties was investigated by positron annihilation lifetime spectroscopy.     

Poly(2-hydroxyethyl methacrylate) (PHEMA)/poly(styrene-co-acrylamide) (PSAm) blends: miscibility and hydrogel properties

The blend miscibility of poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(styrene-co-acrylamide) (PSAm) was studied by DSC. A ‘miscible window’ was found in the range 47–57 mol% of acrylamide in blending PSAm with PHEMA (1:1 w/w) and was analysed by the mean-field theory. The water content and permeability coefficients of proteins were measured. The results show that the water content of the blends depends on the composition of PSAm and the blends, and the behaviour of blends swollen in water in Fickian type. However, the permeability of the solutes not only related to water content, but was also affected by phase behaviour. Controlled release of somatotropin from a cylindrical device coated with PHEMA/PSAm was achieved.     

温度和封端剂马来酸酐对聚碳酸亚丙酯相对分子质量的影响

考察了加工温度和封端剂马来酸酐（MAH）含量对聚碳酸亚丙酯(PPC)黏均相对分子质量的影响。结果表明,PPC对温度非常敏感,加工温度在120 ℃以上时,其黏均相对分子质量就有很大的下降,温度越高,下降得越多;少量的MAH对PPC的封端作用就很明显,加工温度相同时,MAH的添加量越多,对PPC的封端作用越强,但MAH的添加量不宜超过1 %。     

Effect of tacticity of poly(methyl methacrylate) on the miscibility with poly(vinyl acetate)

The results of the miscibility between the chemically similar polymers poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc) published so far show inconsistent statements concerning miscibility. The problems may be due to differences in molecular weights, tacticity, and preparation methods of the polymers. This investigation was carried out by using either chloroform or tetrahydrofuran (THF) as solvent to prepare the blends, because to our knowledge, nobody has reported any tacticity effect of PMMA on the miscibility with PVAc. Therefore, in this article, different tactic PMMAs were used to mix with PVAc and their miscibility was studied calorimetrically. The results showed little effect of solvent and tacticity. PMMA and PVAc were determined to be almost completely immiscible because of the observation of two T_g's. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 35–39, 2004     

聚乳酸的化学合成与应用

简述了近年来聚乳酸(PLA)尤其是聚左旋乳酸(PLLA)的化学合成方法(缩合聚合和开环聚合)及其结构与性能,并对这类材料的应用和发展作了展望。     

Studies on the miscibility and phase structure in blends of poly(epichlorohydrin) and poly(vinyl acetate)

The miscibility of atactic poly(epichlorohydrin) (aPECH) with poly(vinyl acetate) (PVAc) was examined under two different conditions: (i) in dilute solution, using vicometeric measurements and (ii) as cast films, using differential scanning calorimetric (DSC) and FT-infrared spectroscopy. Phase separation on heating, i.e. lower critical solution temperature (LCST) behavior of the aPECH/PVAc blends was examined by the measurement of transmitted light intensity against temperature. From viscosity measurements, the Krigbaum-Wall polymer-polymer interaction (ΔB) was evaluated. The DSC results show that the aPECH/PVAc blends are miscible as evidenced by the observation of a single composition-dependent glass-transition temperature (T_g) which is well described by the Couchman and Gordon Taylor models. The Flory-Huggins interaction parameter (χ₁₂) calculated from the T_g-method was negative and equal to −0.01, indicating a relatively low interaction strength. The FT-IR results match very well with those of DSC. The cloud point phenomenon is thermodynamically driven but phase separation, once taken place, is diffusion controlled in normal accessible time.     

聚对苯二甲酸甲二酯的热分解行为及其动力学研究

研究了惰性气氛下聚对苯二甲酸甲二酯(PMT)的非等温热分解行为及其动力学,并与聚对苯二甲酸丁二酯 (PBT)进行了对比。研究发现,PMT的热降解过程包括两个主要失重阶段,其热分解反应不是一级反应。第一阶段的起始分解温度较低是由于产物的分子链末端基中含有Br或Cl能催化聚合物的降解反应;第二阶段为分子链主体的热分解过程,由于分子链中苯环的密度较大,分子链的热稳定性比具有较低苯环密度的PBT要高。而PBT的降解失重过程仅为一个阶段,为一级反应。     

Thermal Behavior of Isotactic Poly(propylene)/Maleated Poly(propylene) Blends

This paper analyzes the thermal and thermo‐oxidative degradation behavior, phase separation, melting, and crystallization of blends consisting of isotactic poly(propylene) (IPP) and poly(propylene) grafted with maleic anhydride (PP‐g‐MA). It has been established that, depending on the blend composition and crystallization/preparation procedure, the blends of IPP and PP‐g‐MA can either co‐crystallize or evidence phase separation. This conclusion has been attained by comparing the DSC results of crystallization under dynamic and isothermal conditions with X‐ray diffraction results. On the basis of the obtained results, the optimum mixing ratios have been established as 95–85 wt.‐% IPP/5–15 wt.‐% PP‐g‐MA. Thermo‐oxidative behavior has been studied by thermogravimetry and differential thermal analysis.

     

新型聚离子液体的制备及其捕获CO_2性能研究

CO2的捕获和封存是当前关注的重要问题。采用自由基聚合制备了一种新型聚离子液体,聚四亚乙基五胺丙烯酸盐(PTEPAA),并对其捕获CO2性能进行了研究。结果表明,PTEPAA捕获CO2具有捕获容量高、速度快、高度可逆的特点,在低温捕获的CO2可以在高温下有效解吸,捕获/解吸过程可以重复进行,PTEPAA可再生。每个捕获/解吸循环,每克PTEPAA可以分离大约0.24克CO2。PTEPAA作为一种新型固态CO2捕获材料,在烟气及燃气脱碳领域表现出良好的应用潜力。     

Fractional Crystallization Kinetics of Poly(ethylene oxide) in Its Blends with Poly(butylene succinate): Molecular Weight Effects

The fractional crystallization kinetics and phase behavior of PEO with different molecular weights (MWs) in its miscible crystalline/crystalline blends with PBS are studied. Both fractional crystallization kinetics and phase segregation of PEO in PBS/PEO blends are dramatically influenced by its MW. PEO with a medium MW (20 kDa) shows a significant fractional crystallization in the blends with PBS crystallized at a high T_IC,PBS, which, however, is dramatically depressed in the blends with a very low or high MW of PEO. This indicates that the PEO component with a medium MW is more ready to segregate into the interlamellar region of PBS crystals than those with a very low or high MW. The MW‐dependent fractional crystallization kinetics and phase segregation of PEO component in the PBS/PEO blends are discussed.

     

部分水解聚醋酸乙烯酯的制备及其分离苯/环己烷混合物的渗透汽化特性

聚醋酸乙烯酯（PVAc）经醇解反应制备了不同水解度的聚醋酸乙烯酯（PHPVAc）,并探索了PHPVAc水解度、成膜技术、测试条件对膜渗透汽化性能影响的规律.实验发现,改变膜材料的水解度、铸膜溶剂组成、操作温度以及料液组成可以调节膜的分离性能,获得较佳的分离效果.     

PHB和PHBV增韧、增塑改性研究进展

总结了近年来国内外关于聚羟基丁酸酯(PHB)和聚羟基丁酸酯-co-羟基戊酸酯共聚物(PHBV)在增韧和增塑改性方面的研究进展。通过应力-应变行为和冲击强度等性能指标,对弹性体、酚类化合物、反应性增韧、超高相对分子质量聚乙二醇、淀粉、羟基烷酸酯、热处理等增韧改性方法和效果、改性产物进行了评述；通过熔点、玻璃化转变温度、冷结晶温度等性能指标,对共聚改性、中小相对分子质量聚乙二醇、环氧大豆油等增塑剂增塑改性方法、效果以及改性产物进行了详细介绍。最后对PHB和PHBV生物降解材料的发展前景进行了展望。