聚乙烯醇／壳聚糖合金膜的相容性

本文通过 WAXD、DSC动态力学和应力一应变测量对 PVA/CS合金膜的聚集态结构进行了研究。发现,合金膜中的PVA结晶完善性变差,结晶度和结晶熔融峰温度随CS含量增加而降低。合金膜中的CS晶型发生了转化。动态力学损耗谱显示,合金膜中仍保持单组分的玻璃化松弛。当PVA含量大于50%％时,两个Tg峰中间产生一新的力学损耗峰。合金膜的模量和断裂强度高于单组分,而断裂伸长率低于单组分,这都表明,PVA与CS间存在强的相互作用,该共混体系为部分相容体系。     

聚乙烯醇/层状双金属氢氧化物复合膜的原位制备及其性能研究

采用一步水热法,原位制备了聚乙烯醇(PVA)/层状双金属氢氧化物(LDH)复合材料(PVA/LDH).与溶液共混法相比,原位生成法具有实验操作简单、制备周期短等优势.广角X射线衍射(WXRD)结果显示,利用该方法可在PVA溶液中原位生成晶型完整的LDH片状粒子.与溶液共混法制备所得复合体系的流变行为不同,原位合成体系在低剪切速率下的表观黏度随LDH含量的增加而下降.得益于LDH在PVA中的良好分散,填料含量为1.0 wt％时,复合膜的力学拉伸强度及弹性模量较纯PVA膜分别提高105.40％和133.20％.在保持复合材料高透光性基础上,薄膜的耐水性也有一定的提升,但其耐水蒸汽的提高仅当LDH含量达3.0 wt％才有所体现.     

两相聚合物共混体系的相逆转及其力学模型的研究——Ⅰ.模量与组成关系

本文从连续相变理论的角度,提出一个与共混组成相关的权重因子,应用对数加和规则,建立了能预测共混体系相逆转的力学模型,该模型对于描述共混体系的模量与组成关系具有良好的准确性和普适性。     

聚环氧乙烷(PEO)与聚醋酸乙烯酯(PVA)的共混研究

动态力学谱研究表明熔融共混PVA/PEO体系的无定形态中存在着纯PEO及PVA/PEO的相容或部分相容相。相容或部分相容相的T_g随共混物组成的变化远高于按照FOX方程的计算值。用结晶和分子间相互作用解释了这种对FOX方程的偏离。应用FTIR差示光谱技术对PVA/PEO共混物和PVA/DGDE浓溶液的研究证实了PVA分子链上酯基和PEO分子链存在着强的相互作用。     

PVA/HDPE/HDPE-g-MAH共混物的相形貌与动态流变性能

采用熔融共混法制备了聚乙烯醇(PVA)/高密度聚乙烯(HDPE)共混物,引入马来酸酐接枝高密度聚乙烯(HDPE-g-MAH)对体系进行增容。利用SEM、小振幅震荡剪切、溶剂提取、拉伸测试考察组成和增容剂含量对共混物相形貌、动态流变性质、相连续性和力学性能的影响。结果表明,当HDPE质量分数达到20%~30%时,PVA/HDPE/HDPE-g-MAH共混物呈现接近共连续的结构;储能模量-频率图中观察到较为明显的第二平台;PVA相的连续度达到98%;共混物的断裂伸长率由5%显著提高到25%左右。另外,当HDPE-g-MAH的含量增大时,共混物的相界面变得模糊,力学性能也随之提高。     

聚二甲基硅氧烷/聚氨酯共混体系的增容作用(Ⅰ)

采用二甲基硅氧烷-b-乙二醇嵌段共聚物(DMS-b-OE)对聚二甲基硅氧烷/聚氨酯(PDMS/PU)共混体系的增容,重点研究了增容共混体系的微观形态结构和力学性能之间的关系。扫描电子显微镜、动态力学分析和力学性能测试结果表明:DMS-b-OE对PDMS/PU具有优良的增容作用,改善了PDMS/PU共混体系的相容性,提高了该共混物的力学性能。其抗张强度由3.4MPa提高到7.6 MPa。     

两相聚合物共混体系的相逆转及其力学模型的研究——Ⅱ.动态粘弹响应

本文应用力学模型的方法,建立了能描述两相聚合物共混体系动态粘弹响应的理论方程。应用所建立的方程可以从理论上预测任一共混组成下的动态粘弹响应,从而为研究两相聚合物共混体系的动态力学性质以及分子松弛特征提供了有效的方法。     

聚乙烯醇/聚乙烯基吡咯烷酮共混体系相容性研究

用DSC、FTIR、SAXS和测定Flory-Huggins相互作用参数等方法对聚乙二醇(PVA1)/聚乙烯基吡咯烷酮(PVP)共混体系的研究。结果表明,该体系具有完全互容的性质。共混物只有一个玻璃化转变温度。用DMSO作溶剂浇铸的膜光学透明。PVA1的长周期和片晶厚度均随PVP含量增加而增大,但后者增大的幅度比前者小得多,表明PVP和PVA1的非晶部分形成均相并夹入到球晶内部。共混物中PVP羰基吸收峰和PVA1的羟基吸收峰与相应均聚物相比,在红外光谱图中皆向低频方向迁移,迁移波数随第二组分含量的增加而增大。表明二者间有氢键生成。用平衡熔点计算的Flory-Huggins相互作用参数为-0.88。     

聚氯乙烯与氯化聚乙烯共混改性的研究(Ⅱ)

本文用红外光谱法,差示扫描量热法(DSC)研究了氯化聚乙烯(CPE)的链结构性能及其对聚氯乙烯(PVC)改性的影响·用动态力学分析法(DMA)研究了PVC/CPE共混物的动态力学行为,表明CPE,PVC为部分相容两相体系。同时,用透射电子显微镜(TEM)观察了CPE在PVC/CPE共混物中的分布形态。当CPE在PVC/CPE共混物中形成比较完善的网络结构时,共混物具有更好的冲击性能。     

脂肪族聚碳酸酯(PPC)与聚乳酸(PLA)共混型生物降解材料的热学性能、力学性能和生物降解性研究

通过溶液浇铸法制备了脂肪族聚碳酸酯与聚乳酸的共混物(PPC/PLA).采用示差热分析(DSC)和热重分析(TG)研究了材料的热性能.采用拉伸力学试验研究了共混物的力学性能.通过土壤悬浊拟环境培养降解实验法和扫描电子显微镜分析(SEM)对共混材料的生物降解性能进行了研究.实验结果表明,随着PPC含量的增加,共混物的拉伸强度和杨氏模量降低,而生物降解速率却显著提高.但是,在一定的降解时间内,某些比例共混物的降解速率比100%PPC还要快.综合分析表明,PPC/PLA是力学性能和降解性能可以互补的共混体系.     

MECHANICAL MODEL FOR TWO-PHASE POLYMER BLEND SYSTEMS WITH THE CHARACTERISTICS OF PHASE INVERSION

For two-phase polymer blend systems, the phase inversion will take place as the blendcomposition is changed. In this paper a mechanical model has been proposed to describe themodulus-composition relation in the phase inversion region. The application of the mechanicalmodel to two polyurethane blend systems has been studied. It was found that the theoreticalprediction for the modulus-composition relation is quite consistent with the experimentalresults. Furthermore, the characteristics of the phase inversion can be determined uniquelyby the parameters involved in the mechanical model.     

In-situ Synthesis and Characterization of Poly(vinyl alcohol)/Hydroxyapatite Composite Hydrogel by Freezing-thawing Method

Poly(vinyl alcohol)/hydroxyapatite(PVA/HA) composite hydrogel was successfully in-situ synthesized via three cycles of freezing-thawing. The composition and structure of products were investigated by X-ray diffraction( XRD), Fourier transformed infrared spectroscopy(FTIR) and scanning electron microscopy(SEM). The influence of different preparation methods and contents of material on the mechanical properties of PVA/HA composite hydrogel was discussed through tensile and compressive tests. The template of PVA could avoid the agglomeration of HA particles, which improves the mechanical properties of the composite hydrogel effectively. The tensile strength, modulus and compressive performances of the PVA/HA composite hydrogel prepared by the in-situ synthesis method were better than those of hydrogel obtained by the simple blend metliod. In addition, the effect of the content of PVA, HA, and the pH value on tlie properties of tlie PVA/HA composite hydrogel has been discussed in detail.     

Investigation of Miscibility of Linseed Oil Epoxy with Poly(vinyl alcohol)

Blending of two polymers in solution is a simple and cost effective technique to improve upon the physical and mechanical properties of the component polymers. Maximum synergism in the properties of the two polymers occurs when they are thermodynamically miscible. Poly(vinyl alcohol) (PVA) yields tough, flexible and water sensitive films. Linseed oil epoxy(LOE), a product from sustainable resource, used as a plasticizer and corrosion resistant coating, does not produce free standing film. A blend of PVA with LOE may yield films of good toughness and flexibility, and low water absorption if the two components are miscible with each other. Blends of PVA with LOE were prepared in weight ratios 80/20, 60/40, 40/60 and 20/80 through solution method by mixing in dimethyl sulphoxide. In the first instance, the miscibility the two components were investigated using the techniques of viscosity and ultrasonic measurements. The study revealed that the two components showed miscibility up to below 60 wt% PVA in the blend as at the composition LOE: PVA 40/60, phase inversion occurs. Above this composition, immiscibility is indicated; differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) delineates the above behavior in the solid phase.     

六水合硝酸镁增塑改性淀粉-聚乙烯醇复合膜的合成与性能

以六水合硝酸镁[Mg(NO₃)₂·6H₂O]为增塑剂, 采用流延法制备了增塑改性的淀粉-聚乙烯醇(PVA)复合膜, 并研究了改性后淀粉-PVA复合膜的性能. 研究结果表明, Mg(NO₃)₂·6H₂O与淀粉和PVA发生一定的相互作用, 破坏了淀粉和PVA中的结晶结构. 因此, Mg(NO₃)₂·6H₂O的加入可提高淀粉与PVA间的相容性, 改变了淀粉-PVA复合膜的力学性能, 使其拉伸强度下降, 断裂伸长率提高.     

GO/PVA nanocomposites with significantly enhanced mechanical properties through metalion coordination

In this study, a simple and efficient way is demonstrated to create strong interfacial interaction between graphene oxide(GO) filler and poly(vinyl alcohol)(PVA) matrix through metal ion coordination. The coordination bonding provides efficient load transfer during the tensile process, and enhances the mechanical properties of the nanocomposites significantly. After being coordinated with Cu(Ⅱ) ions, GO/PVA composites show much higher Young's moduli and yield stresses than pure PVA and noncoordinated GO/PVA. UV–vis and FTIR spectra are performed to confirm the successful coordination between GO and PVA. Ethylene diamine tetraacetic acid disodium salt(EDTA-2 Na) is used to confirm the important role of coordination in enhancing the composites. This research provides a new approach to manufacture polymer-matrix nanocomposites with significantly improved mechanical performances.     

Thermal,mechanical and water barrier properties of graphene oxide/polyvinyl alcohol/polyol composite films

The novel polymer composite of polyvinyl alcohol (PVA), polyol(PO) and graphene oxide (GO) was used to prepare the PVA/PO and GO/PVA/PO with different weight percents of GO (0.5 and 1% denoted as (0.5 wt%)GO/PVA/PO and (1 wt%)GO/PVA/PO, respectively) through solution casting blend technique. The structure–properties of all used films were confirmed by scanning electron microscope (SEM), Transmission Electron Microscope (TEM), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and mechanical properties. The SEM results exhibited the uniform and homogeneous dispersion of GO in the PVA/PO blend matrix. The TEM and XRD analysis confirmed the structure and exfoliation of GO nanosheets, respectively. Thermal stability suggested that (0.5 wt%)GO/PVA/PO and (1 wt%) GO/PVA/PO films are more stable than PVA/PO. The tensile strength of (0.5 wt%)GO/PVA/PO and (1 wt%)GO/PVA/PO films reached 270.5% and 1349.6%, respectively, which are higher than that of the PVA/PO film. The decrease in the water absorption (WA) of GO/PVA/PO was found from 110.5 to 38.4%. The physico-mechanical properties of used films suggested that the prepared GO/PVA/PO blend composite films can be applied in food packaging areas.     

氯化镁/聚乙二醇复配增塑剂热塑加工聚乙烯醇

采用氯化镁和聚乙二醇对聚乙烯醇(PVA)进行增塑改性, 并利用熔融加工方法制备了PVA薄膜.采用傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)、差示扫描量热分析(DSC)和热重分析(TGA)方法研究了由氯化镁和聚乙二醇组成的复配增塑剂与PVA的相互作用及复配增塑剂对PVA结晶性能、热性能和力学性能的影响.结果表明, 由氯化镁和聚乙二醇组成的复配增塑剂能有效地破坏PVA自身的氢键, 降低PVA的结晶度和熔融温度, 提高PVA的热稳定性并扩展PVA的热塑加工温度窗口.由复配增塑剂通过热塑加工方法制得的PVA薄膜具有较好的力学性能, 拉伸强度为31 MPa, 断裂伸长率为466%.     

Effect of poly(ethylene oxide) on the structure and properties of poly(vinyl alcohol)

To improve the drawability of poly(vinyl alcohol) (PVA) thermal products, poly(ethylene oxide) (PEO), a special resin with good flexibility, excellent lubricity, and compatibility with many resins, was applied, and the Fourier transform infrared spectroscopy, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction (WXRD) were adopted to study the hydrogen bonds, water states, thermal properties, crystal structure, and nonisothermal crystallization of modified PVA. It was found that PEO formed strong hydrogen bonds with water and PVA, thus weakened the intra‐ and inter‐hydrogen bonds of PVA, changed the aggregation states of PVA chains, and decreased its melting point and crystallinity. Moreover, the interactions among PVA, water, and PEO retarded the water evaporation and made more water remain in the system to plasticize PVA. The existence of PEO also slowed down the melt crystallization process of PVA, however, increased the nucleation points of system, thus made more and smaller spherulites formed. The weakened crystallization capability of PVA and the lubrication of PEO made PVA chains to have more mobility under the outside force and obtain high mechanical properties. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1946–1954, 2010     

Modeling of tensile moduli in polystyrene/ polybutadiene blends

The tensile moduli of polystyrene/polybutadiene blends were studied with reference to the effect of the blend ratio. A comparison between the experimental results and the theoretical predictions of the tensile properties was also made. The models selected were the parallel, series, Halpin–Tsai, Takayanagi, Kerner, and Kunori models. Various theoretical models were applied to predict the location of the phase inversion region in these blends. Different equations were also applied for the prediction of the tensile modulus of cocontinuous structures for comparison. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 755–764, 2002     

聚醚砜/纤维素晶体共混膜材料及其超滤性能

聚醚砜与纤维素晶体等共混成铸膜液,采用浸没沉淀相转化法制备聚醚砜/纤维素晶体共混膜材料.通过超滤装置检测复合膜的水通量、截留率、平均孔径、孔隙率、抗污染性等超滤性能,从而讨论了纤维素晶体含量对共混膜超滤性能的影响.采用抗张测试机、热重分析仪(TGA)、原子力显微镜(AFM)对共混膜的力学性能、热稳定性能、形貌结构进行表征.结果表明,随着纤维素晶体的含量的增加,共混膜的纯水通量先升高后有所降低,截留率均保持在91%～95%,抗张强度、断裂伸长率先增大后有所下降,抗污染性较纯聚醚砜膜显著提高.当纤维素晶体质量分数为1%时,纯水通量达到最大为813.3L·m-2·h-1,孔隙率为88.8%,平均孔径达为70.9nm,抗张强度为7.25MPa,断裂伸长率为11.6%,平均污染度FR值为22.0%,衰减系数m值为35.8%.共混膜具有由纤维素晶体、聚醚砜热降解分别引起的两个失重阶段.共混膜为典型非对称膜结构,表皮层较为致密,多孔支撑层孔径较大.