聚己内酯/硝基纤维素共混体系结晶行为的研究

通过对聚己内酯／硝基纤维素共混体系的热分析、傅立叶变换红外光谱的研究，证实了该共混体系在聚己内酯含量较高时，是一个热力学相容的体系，同时两组分之间存在强的氢键相互作用。在此体系中聚己内酯长成了清晰规整的环带球晶。聚己内酯结晶形态随结晶温度和共混物组成的变化表明，在共混体系中聚己内酯结晶速率与非晶第二组分的扩散速率存在一定的匹配关系，是影响环带球晶形成的重要因素。     

聚ε-己内酯结晶形态的研究

采用DSC测试了聚ε-己内酯(PCL)的结晶温度(TC)和熔融温度(Tm)。同时采用偏光显微镜(POM)探讨了结晶时间的影响,发现结晶时间的改变只能够改变其晶体的尺寸,对其结晶形态并没有太大的影响。最后采用原子力显微镜(AFM)讨论了基底材料、溶剂和过冷度对PCL结晶形态的影响。结果表明:基底材料对PCL结晶形态的影响是比较显著的,PCL在硅片上呈棒状,在云母和涂有碳膜的云母上呈树枝状。溶剂对PCL结晶形态的影响明显,其结晶形态的差别与蒸汽压有关。在不同的温度下PCL结晶形态都成树枝状晶体,且分枝宽度随着过冷度的降低而增加。     

聚己内酯和乙基纤维素共混体系的环带球晶及液晶形态

聚己内酯（ＰＣＬ）中加入与其有一定混溶性的非晶组分乙基纤维素（ＥＣ）,可明显影响其长环带球晶的行为．表明具有低混溶性及某种分子间相互作用的二元共混体系ＰＣＬ／ＥＣ仍能在一定温度范围内形成环带球晶;良好的混溶性,强的分子间相互作用并非是二元共混体系中ＰＣＬ长环带球晶不可缺少的因素．通过偏光显微镜发现ＰＣＬ的加入有利于乙基纤维素／二氯乙酸溶液中液晶相的形成,用Ｆｌｏｒｙ关于棒状分子无规线团溶剂三元体系的理论对其进行了讨论．     

聚羟基丁酸酯环带球晶的形貌研究

聚羟基丁酸酯 ( PHB)是一种由细菌合成的手性高分子材料 ,其分子结构具有高度的规整性 [1] ,球晶比较大 (直径可达几毫米 ) ,是研究高分子结晶行为和形态的理想材料 [2 ] .在偏光显微镜下 ,Bauer[3]和 Martinez- Salazar等 [4 ] 曾在 PHB球晶上观察到消光带和同心的环线 .在聚环氧乙烷 [5] 和小分子液晶4-氰基 - 4 -癸氧基联苯的球晶上 [6 ] 也观察到了同心环线 .但这些工作都把同心环线归结为裂缝 ,并未提供证据 .事实上 ,偏光显微镜的低分辨率及其透视特点 [7] ,使之无法真实反映材料的表面形貌 ,因而也无法区分裂缝和台阶 .我们对光…     

聚己内酯-环糊精包合物对聚己内酯结晶行为的影响

采用溶液共混的方法制备了α-环糊精(α-CD)和聚己内酯(PCL)的包合物PCLIC,用X射线衍射和红外光谱对其结构进行了表征,并研究了α-CD、β-CD和PCLC对PCL结晶行为的影响,结果表明线性PCL穿入α-环糊精分子内腔形成了隧道状晶体结构,而且PCLIC对PCL具有明显的异相成核作用,其成核效率比α-CD和β-CD高.     

聚己内酯和丙烯腈-苯乙烯无规共聚物的共混物生成环带球晶中的几个新现象

聚己内酯（ＰＣＬ）和丙烯腈－苯乙烯无规共聚物（ＳＡＮ）的共混物的相容性和形态曾被广泛研究［１～４］．ＰＣＬ的结晶形成球晶结构，其和ＳＡＮ共混，在熔体中结晶时不但可观察到Ｍａｌ－ｔｅｓｅ十字消光，而且存在非常明显的明暗交替的周期性环带状结构，称之为“环...     

聚己内酯接枝淀粉纳米晶的制备

本文通过异氰酸酯与端羟基聚己内酯反应制备端异氰酸酯基预聚体,再接枝到淀粉纳米晶表面,制备了端基分子量可控的聚己内酯接枝淀粉纳米晶。分别用FTIR和1HNMR对所制备的聚己内酯接枝淀粉纳米晶进行表征,结果表明有少量聚己内酯接枝到淀粉纳米晶表面。XRD结果表明,接枝少量聚己内酯的淀粉纳米晶的晶型和结晶度基本不变。聚己内酯接枝淀粉纳米晶的熔融温度由115℃左右提高到122℃左右,并且温度范围变宽。浸润性实验表明,聚己内酯接枝淀粉纳米晶与水不浸润,其表面已具有疏水性。聚己内酯仅接枝在淀粉纳米晶的表面,改善了淀粉纳米     

聚己内酯接枝淀粉纳米晶的制备

通过异氰酸酯与端羟基聚己内酯反应制备端异氰酸酯基预聚体,再接枝到淀粉纳米晶表面,制备了端基分子量可控的聚己内酯接枝淀粉纳米晶。分别用FTIR和1H NMR对所制备的聚己内酯接枝淀粉纳米晶进行表征,结果表明,有少量聚己内酯接枝到淀粉纳米晶表面。XRD结果表明,接枝了少量聚己内酯后的淀粉纳米晶的晶型和结晶度与未接枝的淀粉纳米晶基本一致。聚己内酯接枝淀粉纳米晶的熔融温度由115℃左右提高到122℃左右,并且温度范围变宽。浸润性实验表明,聚己内酯接枝淀粉纳米晶与水不浸润,其表面已具有疏水性。聚己内酯仅接枝在淀粉纳米晶的表面,改善了淀粉纳米晶表面的疏水性能和与聚酯类聚合物的界面相容性。聚己内酯接枝淀粉纳米晶有望用于可降解聚酯类高分子材料,如聚乳酸(PLA)、聚己内酯(PCL)、聚丁二酸丁二醇酯(PBS)等,改善其力学性能和生物降解性能等。     

聚己内酯在聚己内酯/聚乙烯基甲基醚共混体系中的结晶研究

通过示差扫描量热(DSC)、广角X射线衍射(WAXD)、小角X射线散射(SAXS)研究了聚己内酯(PCL)/聚乙烯基甲基醚(PVME)共混体系中PCL的结晶行为.研究结果表明,共混聚合物中PCL的结晶度几乎不随体系的组成而发生变化.共混物中PVME的存在没有改变PCL的晶体结构,但是随着PVME含量的增加,片晶之间的距离则大,这主要是由于非晶层增厚引起的.     

左旋聚乳酸/聚(ε-己内酯)共混物在取向聚乙烯基底上的附生结晶行为

利用电子显微镜结合电子衍射研究了左旋聚乳酸/聚(ε-己内酯)(PLLA/PCL)共混物在取向聚乙烯(PE)基底上的结晶行为.纯PLLA在取向PE基底上能够附生结晶,主要形成分子链相互垂直的片晶结构.PCL在PE基质上也能发生附生结晶,导致两者分子链平行.PLLA/PCL共混物在取向PE基底上结晶的形态结构依赖于共混组成.在PLLA含量大于95 wt%时,PCL不影响PLLA与PE的附生结晶行为.当PCL含量增加至10 wt%时,PLLA在PE上的附生结晶行为受到了一定程度的影响.当PCL含量超过40 wt%时,PLLA在PE上的附生结晶被抑制,取而代之是PCL在PE取向基质上附生结晶,产生两者分子链平行的取向片晶.另外,在PLLA含量在50 wt%~30 wt%之间时,体系产生明显的微相分离,微相分离并不影响PCL与PE的附生结晶,在PCL的富集区仍然发生平行链附生结晶,而PLLA的富集区结构变得模糊.当PLLA含量少于20 wt%时,微相分离不明显,少量PLLA应该分散在PCL片晶间的非晶区.     

Crystallization Behavior and Dynamic Mechanical Properties of Poly(ε-caprolactone)/Octaisobutyl-Polyhedral Oligomeric Silsesquioxanes Composites Prepared via Different Methods

Two octaisobutyl-polyhedral oligomeric silsesquioxanes(oib-POSS)reinforced biodegradable poly(ε-caprolactone)(PCL)composites were prepared via two different methods,i.e.,melt compounding and solution casting,which were named as m PCL/oib-POSS and s PCL/oibPOSS,respectively,in this work.Oib-POSS dispersed finely in both composites;moreover,oib-POSS aggregates were larger in m PCL/oib-POSS than in s PCL/oib-POSS.Despite the different preparation methods,oib-POSS obviously promoted the crystallization of PCL,especially in s PCL/oib-POSS,but did not modify the crystal structure of PCL.The storage moduli of PCL were improved significantly in both composites.PCL/oib-POSS composites with enhanced crystallization behavior and improved dynamic mechanical properties were successfully prepared through both methods;moreover,the solution casting method was more effective than the melt compounding method.     

聚醚酯/蒙脱土复合材料的结晶动力学和结晶形态

有机－无机复合材料是近来材料科学发展的热点,无机物对基体的结晶行为有很大的影响［１,２］．聚醚酯嵌段共聚物的高弹性依靠硬段结晶形成的物理交联点［３,４］,因而任何影响结晶的因素必然导致其性能的变化．通过聚醚酯与蒙脱土的复合,研究聚醚酯的结晶行为的变化...     

Direct Comparison of Crystal Nucleation Activity of PCL on Patterned Substrates

A sample containing different regions with poly(ε-caprolactone)(PCL), oriented polyethylene (PE), and oriented isotactic polypropylene (iPP) films in contact with glass slide has been prepared to be observed in the same view field in an optical microscope and the crystallization of PCL in different regions during cooling from 80 °C down to room temperature at a rate of 1 °C·min^-1 was studied. The results showed that the crystallization of PCL started first at the PE surface and then at the iPP surface, while its bulk crystallization occured much later. This indicates that though both PE and iPP are active in nucleating PCL, the nucleation ability of PE is stronger than that of iPP. This was due to a better lattice matching between PCL and PE than that between PCL and iPP. Moreover, since lattice matching existed between every (hk0) lattice planes of both PCL and PE but only between the (100)PCL and (010)iPP lattice planes, the uniaxial orientation feature of the used PE and iPP films resulted in the existence of much more active nucleation sites of PCL on PE than on iPP. This led to the fact that the nucleation density of PCL at PE surface was so high that the crystallization of PCL at PE surface took place in a way like the film developing process with PCL microcrystallites happened everywhere with crystallization proceeding simultaneously. On the other hand, even though iPP also enhanced the nucleation density of PCL evidently, the crystallization of PCL at iPP surface included still a nucleation and crystal growth processes similar to that of its bulk crystallization.     

Studies on functional properties of PCL films modified by electron radiation and TAIC additive

Investigation of the effect of electron radiation and triallyl isocyanurate (TAIC) on the functional properties of poly(ε-caprolactone) (PCL) films was the aim of the present paper. The mechanical properties from static tensile tests, resistance to strain at elevated temperatures, permeability of oxygen and water vapor, shrinkage, luminous transmittance, haze and surface free energy were determined. It was found that irradiation of PCL containing TAIC induces larger and more distinct changes in the film properties with regard to the irradiation of PCL with no TAIC. This fact results from formation of a crosslinked structure, in which TAIC participates in linking of PCL macromolecules. The extent of observed changes essentially depends on the magnitude of the electron radiation dose. It was also found that films obtained exhibit a two-phase structure (crosslinked and non-crosslinked) in the case of samples with TAIC, and structural changes associated with elongation of macromolecules, formation of branched structures or polymer degradation in the case of samples with no this compound.     

The Crystallization and Melting Behaviors of PDLA-b-PBS-b-PDLA Tri-block Copolymers

In this study,the poly(D-lactide)-block-poly(butylene succinate)-block-poly(D-lactide)(PDLA-b-PBS-b-PDLA)triblock copolymers with a fixed length of PBS and various lengths of PDLA are synthesized,and the crystallization behaviors of the PDLA and PBS blocks are investigated.Although both the crystallization behaviors of PBS and PDLA blocks depend on composition,they exhibit different variations.For the PDLA block,its crystallization behaviors are mainly influenced by temperature and block length.The crystallization signals of PDLA block appear in the B-D 2-2 specimen,and these signals get enhanced with PDLA block length.The crystallization rates tend to decrease with increasing PDLA block lendth during crystallizing at 90 and 100°C.Crystallizing at higher temperature,the crystallization rates increase at first and then decrease with block length.The crystallization rates decrease as elevating the crystallization temperature.The melting temperatures of PDLA blocks increase with block lengths and crystallization temperatures.For the PBS block,its crystallization behaviors are mainly controlled by the nucleation and confinement from PDLA block.The crystallization and melting enthalpies as well as the crystallization and melting temperatures of PBS block reduce as a longer PDLA block has been copolymerized,while the crystallization rates of the PBS block exhibit unique component dependence,and the highest rate is observed in the B-D 2-2 specimen.The Avrami exponent of PBS crystallites is reduced as a longer PDLA block is incorporated or the sample is crystallized at higher temperature.This investigation provides a convenient route to tune the crystallization behavior of PBS and PLA.     

Synthesis, crystallization and hydrolysis of aromatic-aliphatic copolyester: Poly(trimethylene terephthalate)-co-poly(l-lactic acid)

In this study, poly(trimethylene terephthalate)-co-poly(l-lactic acid) (PTT-co-PLLA) copolyesters with different compositions were synthesized by melt polycondensation. The crystal morphologies of PTT-co-PLLA copolyesters were investigated with polarized light microscope (PLM). It was found that PTT-co-PLLA copolyesters exhibited banded spherulites with smaller band spacing at the same degree of super-cooling compared with PTT homopolymer. The PLLA segments in those copolyesters ranged from 0 to 28.4 mol% and did not form crystals during crystallization. Hydrolysis study on PTT homopolymer and PTT-co-PLLA copolyesters was carried out in buffer solutions. PTT-co-PLLA copolyesters represented pronounced hydrolytic degradation, which increased with the content of lactyl units. And it was concluded that degradation of PTT-co-PLLA was mainly attributed to the scission of PLLA segments.     

Selective localization of graphene oxide in electrospun polylactic acid/poly(ε-caprolactone) blended nanofibers

Despite their immiscibility, blending polylactic acid (PLA) with poly(ε-caprolactone) (PCL) provides an efficient strategy for obtaining a biopolymer blend with tailored properties due to their complementary physical properties. In this study, graphene oxide (GO) was employed as a 2-D nanofiller and nucleating agent to improve the properties of the immiscible PLA/PCL blends at 70/30, 50/50, and 30/70 wt ratios. Nanofibers of PLA/PCL blends and PLA/PCL/GO composites were investigated. It was interesting to find that the GO selectively localized in the minor phase resulting from the phase separation. The selective localization of the GO as the nucleating agent had an influence on the degree of crystallinity and crystalline morphology in the blended composites. This study also demonstrated that the molecular chains in the PLA phase oriented along the fiber axes, while in the PCL phase, the partial crystallites changed their orientation direction to be perpendicular to the fiber axes with the addition of GO.     

结晶性芳香聚酯高压结晶行为研究进展

运用高压极限手段研究聚合物的结构、形态和性能是20世纪60年代以来兴起的一项聚合物前沿课题。本文主要结合作者自己的研究工作，重点叙述聚对苯二甲酸乙二醇酯(PET)的高压结晶行为研究，包括温度、压力、时间及分子量对PET高压结晶行为的影响，高压结晶PET的形态。以及对PET伸直链晶体结晶机理的探讨，同时简要介绍了对其它结晶性芳香聚酯诸如聚对苯二甲酸丁二醇酯(PBT)及聚对萘二甲酸乙二醇酯(PEN)的高压结晶行为研究，反映了该领域的研究概况和最新进展。并对今后的研究提出了展望。