Effect of poly(vinyl pyrrolidone ) on the morph ology and physical properties of poly(vinyl alcohol) /sodium montmorill onite nanocompos ite films

Nanocomposites of poly(vinyl alcohol)(PVA),poly(vinyl pyrrolidone)(PVP) and sodium montmorillonite(Na~+MMT) were prepared by solution mixing and then cast into films.X-ray diffraction analysis and images of transmission electron microscopy establish the formation of PVA/Na~+MMT intercalated nanocomposite.Exfoliated and highly intercalated PVA/PVP/Na~+MMT nanocomposite formed in the presence of PVP.Inclusion of PVP in PVA/Na~+MMT matrix enhances the hydrogen bonding interactions between PVA and Na~+MMT and thus increases the mechanical properties and thermal stability of PVA/PVP/Na~+MMT nanocomposites compared to PVA/Na~+MMT nanocomposite.The interactions between PVA,PVP and Na~+MMT were established by the Fourier transform infrared spectroscopy.The moisture absorption tendency of both the PVA and PVA/PVP films reduced after the incorporation of Na~+MMT at 75%constant relative humidity.Differential scanning calorimetry studies show that the presence of PVP and Na~+MMT both are responsible for reducing the heat of fusion,and crystallinity of PVA.The flow behavior of the PVA,PVA/PVP and its nanocomposite solutions has been also studied.Water vapor permeability of PVA/PVP/Na~+MMT composite films decreased in the presence of nanoclay due to increasing tortuous paths for diffusion.     

聚乙烯醇-b-聚苯乙烯嵌段星形聚合物的制备

通过CCl₄调聚反应制备出了末端带有氯原子的聚醋酸乙烯酯(PVAc),进一步引发苯乙烯原子转移自由基聚合得到聚醋酸乙烯酯-b-聚苯乙烯嵌段共聚物(PVAc-b-PSt),此嵌段共聚物与偶联剂二乙烯基苯反应后醇解,得到了聚乙烯醇-b-聚苯乙烯星形嵌段共聚物(PVA-b-PSt)_n。分别以GPC,¹H-NMR及FT-IR对各步反应产物进行了表征,聚醋酸乙烯酯比较完全地引发苯乙烯进行原子转移自由基聚合(ATRP),聚合物相对分子质量与单体转化率呈线性关系,证明聚合过程为活性聚合;以二乙烯基苯偶联PVAc-b-PSt,得到了星形共聚物,并出现了星形共聚物之间的偶合;醇解过程进行比较完全,¹H-NMR及FT-IR谱图表明酯基团已较完全地转变成羟基。     

Flexible free-standing polyaniline/poly(vinyl alcohol) composite electrode with good capacitance performance and shape memory behavior

The increasing demand for portable and flexible energy storage devices drives the development of flexible electrodes and electrolytes. The aim of this work is to fabricate the flexible free-standing polyaniline/poly(vinyl alcohol)(PANI/PVA) composite electrode with good capacitance performance and shape memory behavior. The electrodes were fabricated by chemical oxidation polymerization of aniline in porous PVA(P-PVA) films. The morphology, electrochemical and mechanical properties of PANI/P-PVA...     

壳聚糖/聚乙烯醇温敏水凝胶的制备及性质研究

通过对壳聚糖的化学交联和聚乙烯醇(PVA)的物理交联作用来提高壳聚糖/甘油磷酸体系的凝胶密度和凝胶强度,形成互穿网络结构体系,并在甘油磷酸盐作用下形成具有温度敏感pH依赖型的水凝胶,在体温下能迅速成胶。通过交联剂进一步强化后的互穿网络体系结构更致密,机械强度好。Fourier红外光谱证明凝胶中存在交联剂和壳聚糖形成的Sch iff’s键。经PVA和化学交联后的温敏凝胶具有更紧密的结构,在原位温敏性可生物降解植入剂应用领域具有发展潜力。     

磷酸化环氧树脂/聚乙烯醇交联膜研究

以双酚A环氧树脂(DGEBA)与聚乙烯醇(PVA)为原料,按一定的配比共混成膜后热交联.探讨了交联对膜的溶解性、力学性能、热稳定性和抗氧化稳定性的影响.用多聚磷酸对交联膜进行磷酸化,引入质子传导基团,并表征了磷酸化膜的离子交换容量,抗氧化稳定性和导电率.通过溶解性测试和热重分析证明了交联反应的成功,通过拉伸测试和热重分析证实了交联在一定程度上改善了膜的力学性能,提高了热稳定性,且交联膜在Fenton's试剂中浸泡60h后其残余质量达70％以上;通过元素分析证实了磷酸化的成功,DGEBA/PVA交联膜中,30％DGEBA、磷酸化时间为50 min的膜在室温和100％湿度下的电导率最高达到了0.126 S/cm.     

壳聚糖/聚乙烯醇/氧氟沙星共混无纺布的制备及体外释放研究

以静电纺丝法制备了具有抗菌性能的壳聚糖/聚乙烯醇/氧氟沙星共混无纺布,测定了共混无纺布的力学性能,通过红外光谱(FT-IR) 、X-射线衍射(XRD)和扫描电子显微镜(SEM)对其结构性能进行了表征,选出了载药量较大、力学性能较好(壳聚糖/聚乙烯醇质量比为7,氧氟沙星质量分数为4%)的共混无纺布,在不同pH值的缓冲溶液中对其进行了体外药物释放实验。结果表明,所得的无纺布纤维直径均匀,平均为200nm。聚乙烯醇可以改善氧氟沙星/壳聚糖/聚乙烯醇共混无纺布的力学性能;氧氟沙星在壳聚糖/聚乙烯醇共混膜中有良好的相容性;氧氟沙星在pH为7.40的缓冲溶液中达到释放平衡时需要6h。     

聚亚甲基蓝变色膜的制备及其变色性能研究

用电化学沉积方法制备了1种电致变色膜——聚亚甲基蓝膜,探索了制备该膜的最佳条件并测试了薄膜的电致变色性能.结果表明：在含有2.00×10^-3mol/L硼砂和0.1 mol/L NaNO3的磷酸盐缓冲溶液中（pH 11.00）,保持60℃恒温,在＋0.80 V处恒电位电解40 min,可以使亚甲基蓝单体在ITO导电玻璃上聚合成聚亚甲蓝膜; 在±0.8 V电位范围内,膜颜色可在蓝色和无色间可逆变化,在618 nm处的透过率之差（ΔT）可达60%,薄膜具有很快的电变色速度,着色效率（CE）为182.6 cm2/C.     

Biodegradable starch/poly (vinyl alcohol) film reinforced with titanium dioxide nanoparticles

Biodegradable starch/poly (vinyl alcohol)/nano-titanium dioxide (ST/PVA/nano-TiO₂) nanocomposite films were prepared via a solution casting method. Their biodegradability, mechanical properties, and thermal properties were also studied in this paper. A general full factorial experimental approach was used to determine effective parameters on the mechanical properties of the prepared films. ST/PVA/TiO₂ nanocomposites were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results of mechanical analysis show that ST/PVA films with higher contents of PVA have much better mechanical properties. In thermal analysis, it is found that the addition of TiO₂ nanoparticles improves the thermal stability of the films. SEM micrographs, taken from the fracture surface of samples, illustrate that the addition of PVA makes the film softer and more flexible. The results of soil burial biodegradation indicate that the biodegradability of ST/PVA/TiO₂ films strongly depends on the starch proportion in the film matrix. The degradation rate is increased by the addition of starch in the films.     

Fabrication and characterization of poly(vinyl alcohol)/carbon nanotube melt-spinning composites fiber

A composite fiber based on carbon nanotube(CNT) and poly(vinyl alcohol)(PVA) was prepared by melt-spinning. Structural features and the mechanical performances of the PVA/CNT composite fiber were investigated as a function of draw condition. Initial moduli and tensile strengths of the drawn composite fibers are much higher than those of undrawn composite fiber. It is identified from XRD and 2D XRD that the composite fiber exhibits enhanced crystallinity and orientation degree with increasing the draw ratio. Accordingly, finger-like pores distributed along the axial direction homogeneous on the melt-spinning PVA fiber surface. After dry and hot-drawn, the hydrophobicity of PVA/CNT composites fiber decreased gradually.     

Influences of poly (vinyl alcohol) molecular weight and carbon nanotubes on radiation crosslinking shape memory polymers

Polyvinyl alcohol (PVA) of two molecular weights was used to prepare shape memory polymers based on chemical-crosslinking by glutaraldehyde. The chemical-crosslinking was done in the presence of 2-carboxyethyl acrylate oligomers (CEA) and nano-filler [multi-wall carbon nanotubes (MWCNT) and functionalized carbon nanotubes (MWCNT-NH2)] followed by radiation-induced crosslinking. The analysis of the material revealed an increase in the gel fraction and a significant reduction in swelling of the nanocomposite material that was crosslinked with both glutaraldehyde and ionizing radiation. The radiation crosslinked nanocomposites demonstrated approximately a 90% gelation over a range of 50–300 kGy irradiation doses. The scanning electron microscopy (SEM) analysis showed a homogeneous distribution of nanocomposites in the composite matrix. The thermal properties of radiation crosslinked (PVA/CEA) and (PVA-CEA)-nano-fillers were investigated by a thermogravimetric analysis (TGA). The mechanical properties were examined via dynamic mechanical analysis (DMA) which showed significant variation because of the addition of nanocomposites. This radiation crosslinked materials show good shape memory behavior that may be useful in many applications based on the range of temperatures at which Tan δ appears.     

Incorporation of hydroxyapatite in crosslinked gelatin/chitosan/poly(vinyl alcohol) hybrids utilizing as reinforced composite sponges,and their water absorption ability

The crosslinked gelatin/chitosan/poly(vinyl alcohol)/hydroxyapatite(GEL/CTS/PVA/HAp, GCPH) sponges were fabricated by a freeze-drying method to yield the reinforced composite sponges with proper features. The porosity value and pore size of the crosslinked GCPH sponges reached ～80% and 50–100 μm, respectively, which can be an appropriate range to allow cells to migrate into the reinforced composite sponges in the tissue engineering technology. Besides, the proper bonding presence between HAp par...     

Salt effects on formation of microcrystallites in poly(vinyl alcohol) gels prepared by cast-drying method

The preparation method of poly(vinyl alcohol)(PVA) gels by a simple cast-drying technique using salt solutions was reported in the present investigation.The effects of the salt concentration on the macro- and microscopic properties were examined in detail,and the relationships between macroscopic properties,such as swelling ratio,mechanical strength,and the network microstaicture were presented.It was found that the swelling ratio of PVA cast gel increased largely by adding a small amount of salt, and de...     

Compatibility of Soybean Protein and Poly (vinyl alcohol)

IntroductionTheuseofsoybean ,peanut,zeinandothervegetableproteinsasinexpensivefibermaterialstoreplacewoolandsilkcanbetracedbackto 1930s.Earlyin 1935 ,theItalianfirm ,SniaViscosa ,beganlarge scaleproductionofcaseinfibers[1] .Shortlyafterward ,ICIinEngland produced peanut proteinfibersknownasArdil.CoCornProductRefiningmanufacturedzeinproteinfiberin 1939.Theseusesofseedmealsintoindustryenhancethevalueoftheagriculturematerial.Thelargeintroductionofpetroleum basedfibersduring 194 0sand 195 0s…     

SrFe_(12)O_(19)/聚丙烯酸酯复合膜的制备及其电磁参量研究

以聚丙烯酸酯为基体,用不同质量百分比的锶铁氧体(SrFe12O19)粉末为吸收剂,用乳液共混法制备了一系列SrFe12O19/聚丙烯酸酯复合膜.用场发射扫描电镜(SEM)和X-射线衍射仪(XRD)对SrFe12O19粉末的形貌及结构进行了表征,对该复合膜的拉伸—应变进行了测试,研究了SrFe12O19粉体含量对复合膜的电磁性能的影响.结果表明:SrFe12O19/聚丙烯酸酯复合膜的割线模量随着SrFe12O19含量的增加而显著增加;断裂伸长率随SrFe12O19含量的增加而减少,并且,当SrFe12O19含量超过70%时出现了屈服应力.在1~2 000 kHz频段内,该复合膜的复介电常数和复磁导率随SrFe12O19在聚丙烯酸酯基体中含量的增加先增大后减小,当SrFe12O19填充量为70%时达到最大值,该现象与逾渗理论相符合.     

一种聚对亚苯基亚乙烯基类交替型发光共聚物的合成与性能

采用Wittig反应合成了一种分子主链由烷氧基取代的1,4二苯乙烯基苯(聚对亚苯基亚乙烯基(PPV)的三个单元的齐聚物)与柔性隔离链段五缩六乙二醇组成的交替型蓝绿色发光共聚物(DMDSB-SEO)。相对于苯环的2,5-位上没有甲氧基的聚合物DSB-SEO来说,DMDSB-SEO结构中甲氧基的引入,显著提高了聚合物的光量子效率,调整了其电子结构和光物理性能,同时大大改善了聚合物的溶解性和成膜加工性。该聚合物可溶于氯仿、四氢呋喃等有机溶剂,具有优良的溶解性和成膜加工性能。文中应用原子力显微镜(AFM)和相差显微镜等手段,研究了聚合物的相态结构以及聚合物对锂盐的溶解能力,并对此类材料的合理结构设计进行了讨论。     

聚含氟丙烯酸酯/蒙脱土复合乳液的制备及性能研究

以丙烯酸六氟丁酯(HFBM)为功能性单体,蒙脱土为改性剂,采用间歇式乳液聚合法合成了聚含氟丙烯酸酯/蒙脱土复合乳液,用红外光谱(FT-IR)、热重分析(TG)和X-射线衍射(XRD)对其结构进行了表征,并研究了复合乳化剂的配比、引发剂用量、含氟单体用量和蒙脱土含量对乳液聚合反应的影响,同时探讨含氟单体含量和有机蒙脱土含量对力学性能的影响.结果表明,季铵盐通过离子交换作用进入到蒙脱土层间,层间距由1.6 nm增加至2.2 nm;当m(十二烷基硫酸钠):m(曲拉通X-100)=3:2,引发剂用量为1wt%,含氟单体为9wt%时,具有较大的单体转化率(90.42%)和较小的凝胶率(0.72%);HFBM含量为9wt%,有机蒙脱土为2wt%时,乳胶膜有较大的拉伸强度为12.33 MPa.     

Preparation and characterization of poly(vinylidene fluoride) composite membranes blended with nano-crystalline cellulose

Poly(vinylidene fluoride) (PVDF) composite membranes blended with nano-crystalline cellulose (NCC) for ultrafiltration were prepared by a Loeb-Sourirajan (L-S) phase inversion process.The effects of NC...     

聚乙烯醇水凝胶的制备及应用进展

综述了PVA水凝胶的制备进展,详细介绍了PVA水凝胶的最新应用研究。     

温敏性聚乙烯醇/微凝胶复合水凝胶的制备与性质

 在聚乙烯胺大分子存在条件下,以特丁基过氧化氢(TBHP/-NH₂形成氧化还原对,通过接枝聚合方法引发N-异丙基丙烯酰胺聚合,合成了壳核微凝胶粒子,采用溶液共混和冷冻—恢复法制备了聚乙烯醇/微凝胶复合水凝胶膜。通过扫描电子显微镜(SEM)和透射电子显微镜(TEM)考察了微凝胶粒子的形貌和内部结构,并研究了微凝胶粒子以及聚乙烯醇/微凝胶复合水凝胶膜的温度响应性质。结果表明,微凝胶粒子为球形结构,具有壳核结构。微凝胶以及复合水凝胶膜均表现出相似的相转变温度,并且复合水凝胶膜具有快速响应性质。     

医用聚氯乙烯的表面磺酸化及抗凝血性能研究

利用SO2/O2混合气体等离子体处理医用聚氯乙烯(PVC)膜，在材料表面引入磺酸基，借助X射线光电子能谱和ATR-FTIR光谱对膜表面的组成及结构进行表征，通过动态凝血实验以及凝血酶原时间、部分凝血活酶时间、凝血酶时间的测定，对聚氯乙烯膜的抗凝血性能进行评价．实验结果表明，等离子体处理聚氯乙烯膜可以在材料表面有效地引入磺酸基，显著提高材料的抗凝血性能．