不同软段长度PBT-co-PBS-b-PEG嵌段共聚物的合成与表征

用熔融缩聚法合成了一系列具有不同软段长度的聚对苯二甲酸丁二酯 (PBT) co 聚丁二酸丁二酯(PBS) b 聚乙二醇 (PEG)嵌段共聚物 (PTSG) ,考察了PEG分子量 (Mn(PEG) )及PBS摩尔分数 (MPBS)对材料性能的影响 实验表明 ,随Mn(PEG)增加 ,缩聚反应时间延长 ,所得产物分子量均呈较为对称的单峰分布 ,多分散性指数小于 2 0 硬段序列结构分析显示 ,随MPBS 增加 ,PBT平均序列长度减小 ,而PBS平均序列长度增加 ,二者呈无规分布 .受组成及硬段平均序列长度变化影响 ,材料内部呈微观相分离状态 ,DSC曲线上可分别观察到软、硬段熔点及玻璃化转变温度 ;硬段熔点及结晶度随MPBS升高而降低 ,主要是受其平均序列长度变化及共晶作用所致 .材料断裂延伸率及降解速率均随Mn(PEG)及MPBS增加而增加 ,可见提高软段长度及降低硬段结晶度等均能有效改善共聚物高分子链的柔韧性及亲水性 ,赋予共聚物更好的降解性能 .     

聚乙二醇/聚对苯二甲酸丁二醇酯聚醚酯弹性体的合成与表征——不同硬段长度对材料性能的影响

以熔融缩聚法合成了一系列基于聚乙二醇 (PEG) 聚对苯二甲酸丁二醇酯 (PBT)的聚醚酯热塑性弹性体 ,用NMR、IR、DSC及力学性能测试等方法表征了材料的结构及性能 .讨论了在相同软段长度情况下 ,不同硬段长度对材料结构与性能的影响 .实验表明 ,随着体系中硬段PBT长度的减小 ,弹性模量、抗拉强度降低 ,特性粘度、吸水量及断裂形变量增加 ,材料性能良好可调     

聚(对苯二甲酸丁二醇酯-co-对苯二甲酸环己烷二甲醇酯)-b-聚乙二醇嵌段共聚物的合成与表征

用熔融缩聚法合成了一系列聚(对苯二甲酸丁二醇酯-co-对苯二甲酸环己烷二甲醇酯)-b-聚乙二醇嵌段共聚物(PBCG),用NMR,GPC,DSC,TGA及力学性能测试等方法表征了材料的结构与性能.GPC分析显示,共聚物分子量均具有较为对称的单峰分布,多分散性指数低于1.70.13CNMR谱结果表明,随PCT摩尔分数(xPCT)从10%增至60%,PBT平均序列长度由4.02降到1.41;而PCT平均序列长度则由1.17升至2.50,二者呈无规分布.受硬段平均序列长度及结晶能力影响,硬段熔点及结晶度在xPCT为20%～30%处均达到最小值,可能是硬段间形成共晶所致.TGA分析显示,引入芳香族聚酯组分PCT确可提高材料的热稳定性.力学性能测试说明,降低结晶度有利于提高材料的断裂延伸率,相反,则有助于增强弹性模量,断裂强度及屈服强度.     

生物可降解共聚物聚丁二酸/对苯二甲酸丁二醇酯(PBST)的序列结构及结晶性研究

制备了高分子量的聚丁二酸丁二醇酯．并通过与对苯二甲酸二甲酯的无规共聚调节其生物可降解性及力学性能．得到了具有优良机械性能和不同生物降解速度的一系列共聚物．并对共聚物序列结构、热力学性能、结晶性进行了研究．结果表明．该共聚物为无规共聚物．PBS和PBT分别结晶．共聚物的结晶熔点符合无规共聚物的Flory方程．     

相同软硬段质量配比聚醚酯弹性体PEG/PBT的结构与表征

以熔融缩聚法合成了一系列聚乙二醇（PEG）／聚对苯二甲酸丁二醇酯（PBT）聚醚酯热塑性弹性体，用NMR，FTIR，DSC及力学性能测试等方法表征了材料的结构及性能。讨论了在相同软硬段质量配比下，不用软硬段长度对材料性能的影响。结果表明，随着软段PEG长度增加，硬段PBT长度相应增长，弹性模量基本保持不变，抗拉强度，屈服应力及特性粘度增加。     

聚己内酯-聚丙交酯-聚醚三元共聚高分子微粒及其降解的研究

用乳化－ 溶剂蒸发法制备了聚己内酯－ 聚丙交酯－ 聚醚三元无规共聚物微粒,且与用相同方法制备的聚己内酯（ＰＣＬ） 和聚己内酯－ 聚醚嵌段共聚物微粒的形态进行了比较,讨论了材料的亲水性,以及三元无规共聚物中亲水性聚醚链段的长度及含量对所形成微粒形态的影响。研究结果表明,随着聚合物由疏水性向亲水性转变,所生成微粒的形态则从光滑、多孔、到不规则变化。证明了三元无规共聚物多孔微粒的形成是由于亲水的聚醚链段向水相取向所致。在３７ ℃、ｐＨ７ ．４ 的缓冲液中进行了三元无规共聚物微粒的降解,结果表明,随着降解时间的延长, 三元无规共聚物的分子量逐渐下降,且其中的聚醚链段含量有明显的降低。     

对苯二甲酸丁二酯-ε-己内酯多嵌段共聚物中硬链段的受限结晶

用差示扫描量热法（DSC）,广角X射线衍射（WAXD）,傅立叶变换红外光谱（FTIR）等技术研究了对苯二甲酸丁二酯-ε-己内酯（PBT—PCL）多嵌段共聚物中硬链段的受限结晶。结果表明,PBT—PCL共聚酯中软硬链段在非晶区的混容性比较好,不同组成的样品均显示出一个玻璃化转变温度;对硬段含量超过50%的共聚酯来说,硬链段可以结晶,而软链段不能结晶;由于硬链段的受限特点,BT硬链段的结晶受软链段的影响和制约,其结晶能力随硬段序列长度的增加而逐渐增大。     

聚己内酯—聚丙交酯—聚醚三元共聚高分子微粒及其降解的 …

用乳化－溶剂蒸发法制备了聚己内酯－聚丙交酯－聚醚三元无规共聚物微粒,且与用相同方法制备的聚己内酯（ＰＣＬ）和聚己内酯－聚醚嵌段共聚物微粒的形态进行了比较。他材料的亲水性,以及三元无规共聚物中亲水性聚醚链段的长度及含量对所形成微粒形态的影响。研究结果表明,随着聚合物由疏水性向亲水性转变,所生成微粒的形态则从光滑、多孔、到不规则变化。证明了三元无规共聚物多孔向亲水性一粒的形成是由于亲水的聚醚链段向水相     

真菌BFM-X1对聚丁二酸丁二醇酯薄膜的降解过程

对菌株Bionectria sp.BFM-X1(简称BFM-X1)分别利用不同碳源对聚丁二酸丁二醇酯(PBS)薄膜的降解情况及降解后的残留膜进行了观察分析,揭示PBS薄膜的微生物降解过程.结果表明:菌株分别以PBS乳剂、葡萄糖、大豆油及甘油为唯一碳源时均能有效降解PBS薄膜；降解过程表现为表面失去光泽期、裂纹状结构期、破碎期和完全降解期4个阶段,并存在迟滞期,且葡萄糖碳源下的降解速率快于其他碳源的；菌株的菌丝能在PBS膜表面上扩展生长是该菌株降解PBS的前提,真菌的寄生作用是前期降解的主要动力；降解过程中胞外酶的水解作用使聚合物的酯键水解,生成可被菌株同化吸收的小分子；菌株BFM-X1对PBS薄膜的降解首先发生在膜表面,非结晶部分先于结晶部分被降解.     

聚二甲基硅氧烷-聚对苯二甲酸酚酞酯嵌段共聚物的合成及表征

用低温溶液法合成了以聚二甲基硅氧烷(PSX)为软段、聚对苯二甲酸酚酞酯(PAE)为硬段的〔-(AB)_n〕型多嵌段共聚物。对共聚物结构的表征表明,使用该方法可得到硅氧烷含量可控的分子量较高的共聚物。随软段长度及含量的不同,既可得到弹性体也可得到较坚硬的材料。共聚物具有两相结构、较好的力学性能、耐热性及成膜性。     

Performance of biodegradable microcapsules of poly(butylene succinate), poly(butylene succinate-co-adipate) and poly(butylene terephthalate-co-adipate) as drug encapsulation systems

Poly(butylene succinate) (PBSu), poly(butylene succinate-co-adipate) (PBSA) and poly(butylene terephthalate-co-adipate) (PBTA) microcapsules were prepared by the double emulsion/solvent evaporation method. The effect of polymer and poly(vinyl alcohol) (PVA) concentration on the microcapsule morphologies, drug encapsulation efficiency (EE) and drug loading (DL) of bovine serum albumin (BSA) and all-trans retinoic acid (atRA) were all investigated. As a result, the sizes of PBSu, PBSA and PBTA microcapsules were increased significantly by varying polymer concentrations from 6 to 9%. atRA was encapsulated into the microcapsules with an high level of approximately 95% EE. The highest EE and DL of BSA were observed at 1% polymer concentration in values of 60 and 37%, respectively. 4% PVA was found as the optimum concentration and resulted in 75% EE and 14% DL of BSA. The BSA release from the capsules of PBSA was the longest, with 10% release in the first day and a steady release of 17% until the end of day 28. The release of atRA from PBSu microcapsules showed a zero-order profile for 2 weeks, keeping a steady release rate during 4 weeks with a 9% cumulative release. Similarly, the PBSA microcapsules showed a prolonged and a steady release of atRA during 6 weeks with 12% release. In the case of PBTA microcapsules, after a burst release of 10% in the first day, showed a parabolic release profile of atRA during 42 days, releasing 36% of atRA.     

Alkaline-solution-induced crystallization in poly(butylene terephthalate)

Subtle crystalline structure changes of poly(butylene terephthalate) (PBT) specimens treated with an alkali solution at room temperature were investigated with the grazing incidence X-ray diffraction (GIXRD) analysis method. A new phenomenon was found: the aqueous alkali solution induced the crystallization of the PBT polymer. Under the GIXRD analysis condition of an incidence angle of 1°, the penetration depth of the X-ray in PBT was less than 80 μm, and this agreed well with the rough theoretical estimation. The alkali solution adopted in this study was an aqueous sodium hydroxide solution, which had a concentration of 2.5 N. Dissolved quantities of the surface layers during the alkaline treatment were found to be small. No appreciable intrinsic viscosity change due to the alkaline treatment was detected. Possible factors that might contribute to the crystallization, such as water absorption and a chemical reagent effect, were examined, and a plausible explanation for the phenomenon was developed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1938–1948, 2004     

Heat capacity of poly(butylene terephthalate)

The low‐temperature heat capacity of poly(butylene terephthalate) (PBT) was measured from 5 to 330 K. The experimental heat capacity of solid PBT, below the glass transition, was linked to its approximate group and skeletal vibrational spectrum. The 21 skeletal vibrations were estimated with a general Tarasov equation with the parameters Θ₁ = 530 K and Θ₂ = Θ₃ = 55 K. The calculated and experimental heat capacities of solid PBT agreed within better than ±3% between 5 and 200 K. The newly calculated vibrational heat capacity of the solid from this study and the liquid heat capacity from the ATHAS Data Bank were applied as reference values for a quantitative thermal analysis of the apparent heat capacity of semicrystalline PBT between the glass and melting transitions as obtained by differential scanning calorimetry. From these results, the integral thermodynamic functions (enthalpy, entropy, and Gibbs function) of crystalline and amorphous PBT were calculated. Finally, the changes in the crystallinity with the temperature were analyzed. With the crystallinity, a baseline was constructed that separated the thermodynamic heat capacity from cold crystallization, reorganization, annealing, and melting effects contained in the apparent heat capacity. For semicrystalline PBT samples, the mobile‐amorphous and rigid‐amorphous fractions were estimated to complete the thermal analysis. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4401–4411, 2004     

Reversible melting in poly(butylene terephthalate)

Crystallized samples of poly(butylene terephthalate) (PBT), examined in the melting region by means of temperature modulated differential scanning calorimetry (TMDSC), show reversible fusion. The analysis of the complex heat capacity reveals that the fusion of poor crystallites can follow temperature modulation more easily than perfect crystals, in agreement with the findings recently reported in the literature, and that the amount of reversible melting decreases with increasing the modulation frequency.     

聚丁二酸丁二醇酯的研究进展

聚丁二酸丁二醇酯(PBS)是一种具有生物相容性和生物降解性的脂肪族聚酯,其在药物控制释放、手术缝合线等生物医药领域有广阔的应用前景.本文综述了PBS的合成、改性方法及其作为药物缓释载体的应用.提出今后PBS研究的重点将集中在功能化基团的引入、合成路线的简化、成本的降低及其改性后材料的相关性能等方面.     

Thermal decomposition of poly(butylene terephthalate)

Detailed results of the overall thermal degradation of poly(butylene terephthalate) are reported. Laser microprobe analysis and dynamic mass spectrometric techniques were used to identify the primary volatile degradation products and initial pyrolysis reactions that control polymer degradation. A complex multistage decomposition mechanism was observed which involves two major reaction pathways. Initial degradation occurs by an ionic decomposition process that results in the evolution of tetrahydrofuran. This is followed by concerted ester pyrolysis reactions that involve an intermediate cyclic transition state and yield 1,3-butadiene. Simultaneous decarboxylation reactions occur in both decomposition regimes. Finally, the latter stages of polymer decomposition were characterized by evolution of CO and complex aromatic species such as toluene, benzoic acid, and terephthalic acid. Activation energies of formation for the main pyrolysis products were determined from the dynamic measurements of the major ion species and indicate values of E = 27.9 kcal/mole for the production of tetrahydrofuran and E = 49.7 kcal/mole for the production of butadiene.     

Effects of crystallization temperature and blend ratio on the crystal structure of poly(butylene adipate) in the poly(butylene adipate)/poly(butylene succinate) blends

The effects of crystallization temperature and blend ratio on the polymorphic crystal structures of poly(butylene adipate)(PBA) in poly(butylene succinate)(PBS)/poly(butylene adipate)(PBS/PBA) blends were studied by means of differential scanning calorimetry(DSC), wide-angle X-ray diffraction(XRD) and atomic force microscopy(AFM). It was revealed that the polymorphism of PBA can be regulated by the blend ratio even in a non-isothermal crystallization process. The results demonstrate that high temperature favors flat-on α crystals, while low temperature contributes to edge-on β crystals. It was also found that the effect of blend ratio on the crystallization mechanism of PBA is well coincident with that of the crystallization temperature. The increment of PBS content in the PBS/PBA blend gives rise to more β-form crystals of PBA. For those PBS/PBA blends with low PBA content, the interlamellar phase segregation of PBA makes its molecular chains so difficult to diffuse from one isolated microdomain to another that high crystallization temperature and sufficiently long crystallization time will be required if the PBA α-type crystals are targeted.     

Hydrolytic Degradation and Monomer Recovery of Poly(butylene succinate) and Poly(butylene succinate/adipate) in the Melt

Aliphatic dicarboxylic acid/aliphatic diol‐derived polyesters, poly(butylene succinate) and poly(butylene succinate/adipate), have been hydrolytically degraded in the melt in high‐temperature and high‐pressure water over a wide temperature range of 180–300 °C for periods of up to 30 min. The formation/decomposition of succinic acid (SA), adipic acid (AA), and butane‐1,4‐diol (BD), plus the molecular weight change of PBS and PBSA were then investigated. SA and AA were recovered at maximum yields of 65–80%, whereas BD was recovered at a maximum yield of only 30%, probably because of its decomposition. The obtained results were compared with those reported for aliphatic hydroxycarboxylic acid‐derived polyesters and aromatic dicarboxylic acid/aliphatic diol‐derived polyesters.

     

Shear-induced non-isothermal crystallization of poly(butylene adipate-co-terephthalate)

The influence of shear on non-isothermal crystallization of commercial poly(butylene adipate-co-terephthalate) (PBAT) was investigated. PBAT melt was sheared at 130 and 150 °C at rates of 10–100/s, and then cooled. The crystallization was followed by a light depolarization technique, whereas the crystallized specimens were analyzed by DSC, 2D-SAXS, 2D-WAXS, PLM and SALS. Shear flow shifted crystallization to higher temperature, and the effect was augmented by lower temperature of shearing as well as by higher shear rate and strain. Crystallization peak rate temperature of PBAT, sheared at 130 °C for 5 min at 100/s, increased by up to 12 °C. However, no evidence of crystal orientation due to shear was found, indicating that the shear induced the point-like nucleation. Only a small increase of melting peak temperatures, by up to 2–5 °C, was observed for the specimens sheared at the highest rates (≥50/s).     

三元乙丙橡胶环氧化增韧聚对苯二甲酸丁二酯的研究

三元乙丙橡胶环氧化增韧聚对苯二甲酸丁二酯的研究王学会，张会轩，王新华，王志刚，蒋俊光，姜炳政（吉林工学院化工系，长春，１３００１２）（中国科学院长春应用化学研究所）关键词三元乙丙橡胶，环氧化，ＰＢＴ，增韧作用，共混物聚对苯二甲酸丁二酯（ＰＢＴ）具有优...