共查询到17条相似文献,搜索用时 132 毫秒
1.
生物可降解聚丁二酸/甲基丁二酸丁二酯系列共聚物的合成和表征 总被引:3,自引:0,他引:3
摘要合成了一系列聚丁二酸/甲基丁二酸丁二醇共聚酯(PBSM), 利用DSC, 1H NMR和X射线衍射等方法对共聚物组成、 热学性能、 结晶性能、 等温结晶行为进行了研究. 结果表明, 引入甲基丁二酸共聚单元较为显著地改变了聚丁二酸丁二酯(PBS)的热学性能, 利用Hoffman\|Weeks方程得到的共聚物平衡熔点随共聚物的组分含量增加而降低, 玻璃化转变温度亦有所降低, 熔点则符合无规共聚物的Flory方程. 此外, 利用Avrami方程分别研究了均聚物PBS及共聚物PBSM-20的等温结晶行为, 结果表明, 在所研究的温度范围内, 聚酯结晶速率随温度升高而降低, PBS和PBSM\-20的Avrami指数分别介于2.8~3.0和2.7~3.0之间, 结晶方式为三维生长异相成核, 而X射线衍射测试结果表明晶体结构几乎不变. 相似文献
2.
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. 相似文献
3.
聚丁二酸丁二醇酯的自成核结晶行为 总被引:1,自引:0,他引:1
利用差示扫描量热仪(DSC)研究了自成核对聚丁二酸丁二醇酯(PBS)的结晶行为的影响. 研究结果表明, PBS的有效自成核温度处理区间为118~120 ℃. PBS经自成核处理后结晶温度提高, 可以在100~118 ℃温度区间内迅速结晶. 同时, 研究了自成核处理后样品在100~104 ℃范围内的等温结晶行为、动力学过程及熔融行为. 结果表明, 随着等温结晶温度的升高, 结晶速率变慢, 熔融曲线出现多重熔融峰. Hoffman-Weeks方程分析结果表明, 自成核处理对PBS的平衡熔点没有影响. Avrami等温结晶动力学方程适合分析自成核处理样品的等温结晶动力学过程, 获得其动力学参数K与n, 其中n值偏大的原因在于自成核的样品结晶生长点增多. 根据Arrhenius方程, 计算获得PBS自成核处理后等温结晶活化能为-286 kJ/mol. 相似文献
4.
5.
6.
7.
聚丁二酸丁二酯/纳米二氧化硅共混体系的结晶和动态力学性能研究 总被引:3,自引:0,他引:3
用溶液共混法制备了聚丁二酸丁二酯(PBS)/纳米二氧化硅(nano-SiO2)复合材料,并通过DSC、XRD、TEM和DMTA对其结晶、微观结构和动态力学性能进行了研究.DSC与XRD结果表明,在PBS中加入纳米SiO2,提高了PBS的结晶温度,并随着nano-SiO2含量的增加呈正相相关性,从纯PBS的67.7℃提高到含5%nano-SiO2时的73.3℃;在空气淬火条件下,提高了复合材料中PBS的结晶度,在nano-SiO2含量为2%时达到42.4%;TEM照片表明SiO2与基体PBS的界面模糊,表明二者之间具有一定的相互作用;这种相互作用和复合材料结晶性能的变化使PBS/nano-SiO2复合材料的储能模量和损耗因子均高于纯PBS.上述结果表明在PBS中添加适量的nano-SiO2,能显著提高PBS的结晶和动态力学性能. 相似文献
8.
9.
10.
单轴取向聚对苯二甲酸乙二酯非等温结晶动力学研究 总被引:2,自引:0,他引:2
采用等速升温DSC方法对单轴取向聚对苯二甲酸乙二酯 (PET)的结晶过程进行了研究 ,发现单轴取向PET的冷结晶峰表现为多重结晶峰 .等温DSC方法的研究结果进一步证实结晶重峰的存在 .为此 ,本文提出了一种依据非等温DSC曲线解析高聚物结晶动力学参数的新方法 .对单轴取向PET的研究结果表明 ,与其他方法相比较 ,由新方法计算出的理论曲线与实验数据能更好地吻合 .单轴取向PET的总的结晶过程由三个子结晶过程组成 .根据不同拉伸比 ,各个子过程的Avrami指数和质量分数的变化 ,对结晶机理进行了解释 .与各向同性PET样品相比 ,单轴取向PET在低温部分的结晶速率明显增快 相似文献
11.
Yongxiang Xu Jun Xu Baohua Guo Xuming Xie 《Journal of Polymer Science.Polymer Physics》2007,45(4):420-428
The crystallization behavior of biodegradable poly(butylene succinate) and copolyesters poly(butylene succinate‐co‐propylene succinate)s (PBSPS) was investigated by using 1H NMR, DSC and POM, respectively. Isothermal crystallization kinetics of the polyesters has been analyzed by the Avrami equation. The 2.2‐2.8 range of Avrami exponential n indicated that the crystallization mechanism was a heterogeneous nucleation with spherical growth geometry in the crystallization process of polyesters. Multiple melting peaks were observed during heating process after isothermal crystallization, and it could be explained by the melting and recrystallization model. PBSPS was identified to have the same crystal structure with that of PBS by using wide‐angle X‐ray diffraction (WAXD), suggesting that only BS unit crystallized while the PS unit was in an amorphous state. The crystal structure of polyesters was not affected by the crystallization temperatures, too. Besides the normal extinction crosses under the POM, the double‐banded extinction patterns with periodic distance along the radial direction were also observed in the spherulites of PBS and PBSPS. The morphology of spherulites strongly depended on the crystallization temperature. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 420–428, 2007 相似文献
12.
Xiaoqing Liu Chuncheng Li Dong Zhang Yaonan Xiao 《Journal of Polymer Science.Polymer Physics》2006,44(6):900-913
This article investigated the melting behaviors, crystallization kinetics, and spherulitic morphologies of poly(butylene succinate) (PBS) and its copolyester (PBSR) modified with rosin maleopimaric acid anhydride, using wide‐angle X‐ray diffraction, differential scanning calorimeter (DSC), and polarized optical microscope. Subsequent DSC scans of isothermally crystallized PBS and PBSR exhibited two melting endotherms, respectively, which was due to the melt‐recrystallization process occurring during the DSC scans. The equilibrium melting point of PBSR (125.9 °C) was lower than that of PBS (139 °C). The commonly used Avrami equation was used to describe the isothermal crystallization kinetics. For nonisothermal crystallization studies, the model combining Avrami equation and Ozawa equation was employed. The result showed a consistent trend in the crystallization process. The crystallization rate was decreased, the perfection of crystals was decreased, the recrystallization was reduced, and the spherulitic morphologies were changed when the huge hydrogenated phenanthrene ring was added into the chain of PBS. The activation energy (ΔE) for the isothermal crystallization process determined by Arrhenius method was 255.9 kJ/mol for PBS and 345.7 kJ/mol for PBSR. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 900–913, 2006 相似文献
13.
Licheng Tan Yiwang Chen Weihua Zhou Huarong Nie Xiaohui He 《Polymer Degradation and Stability》2010,95(9):1920-149
A series of aliphatic biodegradable poly(butylene succinate-co-dl-lactide) (PBSLA) copolyesters were synthesized with the aim of improving the degradation rate of poly(butylene succinate) (PBS) by incorporation of dl-oligo(lactic acid) (OLA) into the PBS molecular chains. The composition and sequential structure of the aliphatic copolyesters were investigated by proton nuclear magnetic resonance (1H NMR) spectroscopy. The crystallization behaviors, the crystal structure and morphology of the copolyesters were investigated by using differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and polarizing optical microscopy (POM), respectively. The results indicate that the crystallization of the copolyesters was restricted by the incorporation of lactide (LA) units, which further tuned the mechanical properties of the copolyesters. The copolyesters could form complete spherulites and exhibit the same crystal structure as that of PBS. Enzymatic study indicated that the copolyesters with higher content of LA units degraded faster, and the degradation began in the amorphous regions and then in the crystalline regions. The morphology and the resulting degradation products of the copolyesters were investigated by scanning electron microscopy (SEM) and 1H NMR analysis during the degradation process. 相似文献
14.
Biodegradable poly(butylene succinate) (PBS) and layered double hydroxide (LDH) nanocomposites were prepared via melt blending in a twin-screw extruder. The morphology and dispersion of LDH nanoparticles within PBS matrix were characterized by transmission electron microscopy (TEM), which showed that LDH nanoparticles were found to be well distributed at the nanometer level. The nonisothermal crystallization behavior of nanocomposites was extensively studied using differential scanning calorimetry (DSC) technique at various cooling rates. The crystallization rate of PBS was accelerated by the addition of LDH due to its heterogeneous nucleation effect; however, the crystallization mechanism and crystal structure of PBS remained almost unchanged. In kinetics analysis of nonisothermal crystallization, the Ozawa approach failed to describe the crystallization behavior of PBS/LDH nanocomposites, whereas both the modified Avrami model and the Mo method well represented the crystallization behavior of nanocomposites. The effective activation energy was estimated as a function of the relative degree of crystallinity using the isoconversional analysis. The subsequent melting behavior of PBS and PBS/LDH nanocomposites was observed to be dependent on the cooling rate. The POM showed that the small and less perfect crystals were formed in nanocomposites. 相似文献
15.
Synthesis,characterization and isothermal crystallization behavior of poly(butylene succinate)‐b‐poly(diethylene glycol succinate) multiblock copolymers 下载免费PDF全文
In order to modify the properties of poly(butylene succinate), poly(diethylene glycol succinate) (PDGS) segment was incorporated by chain‐extension reaction of dihydroxyl‐terminated PBS and PDGS precursors using hexamethylene diisocyanate as a chain extender to form PBS‐b‐PDGS multiblock copolymers. The chemical structure and basic physical properties of the multiblock copolyesters were characterized by nuclear magnetic resonance spectroscopy, differential scanning calorimeter (DSC), wide angle X‐ray diffraction, and tensile testing. The results suggested that the incorporation of PDGS segments would increase the elongation at break of PBS significantly while decrease its melting temperature and crystallization temperature slightly. The isothermal crystallization kinetics studied by DSC and polarized optical microscopy indicated that the crystallization rate of the multiblock polymers decreased gradually with increasing PDGS segment content while the crystallization mechanism kept unchanged and the spherulitic growth rate of the multiblock copolymers decreased gradually with increase in PDGS content due to its diluent effect to the crystallization of PBS segments. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
16.
Faxue Li Xinjian Xu Qinghui Hao Qiaobo Li Jianyong Yu Amin Cao 《Journal of Polymer Science.Polymer Physics》2006,44(12):1635-1644
In this work, new investigations on the effect of comonomer sequential structure on the thermal and crystallization behaviors and biodegradability have been implemented for the biodegradable poly(butylene succinate‐co‐butylene terephthalate) (PBST) as well as aliphatic poly(butylene succinate) (PBS). At first, these copolyesters were efficiently synthesized from dimethyl succinate and/or dimethyl terephthalate and 1,4‐butanediol via condensation polymerization in bulk. Subsequently, their molecular weights and macromolecular chain structures were analyzed by gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) spectroscopy. By means of differential scanning calorimeter (DSC) and wide‐angle X‐ray diffractometer (WAXD), thermal and crystallization behaviors of these synthesized aromatic–aliphatic copolyesters were further explored. It was demonstrated that the synthesized copolyesters were revealed to have random comonomer sequential structures with thermal and crystallization properties strongly depending on their comonomer molar compositions, and that crystal lattice structures of the new crystallizable copolyesters shifted from the monoclinic crystal of semicrystalline PBS to triclinic lattice of the poly(butylene terephthalate) (PBT) with increasing the terephthalate comonomer composition, and the minor comonomer components were suggested to be trapped in the crystallizable component domains as defects. In addition, the enzymatic degradability was also characterized for the copolyesters film samples. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1635–1644, 2006 相似文献