Research on the Long Time Swelling Properties of Poly (vinyl alcohol)/Hydroxylapatite Composite Hydrogel

Poly(vinyl alcohol)/hydroxylapatite(PVA/HA)composite hydrogel was prepared by repeated freezing and thawing.The water loss properties of the resultant hydrogel were investigated by using optical microscope.Long time immersion tests of PVA/HA composite hydrogel were carried out in the diluted calf serum solution to study the change laws of swelling properties with the freezing-thawing cycles and HA content.The micro-morphologies of PVA/HA composite hydrogel after long time immersion were observed by means of the high-accuracy 3D profiler.The results show that the swelling process of PVA/HA composite hydrogel is the converse process of its water loss.Long time swelling ratio curves of PVA/HA composite hydrogel in the calf serum solution are manifested as four stages of quick increase,decrease,slow decrease and stable balance,and its equilibrium swelling ratio decreases with the increase of freezing-thawing cycles and HA content.It is revealed that the network structure of the composite hydrogel immersed for a long period is significantly improved with the increase of HA content. Perfect network structures of PVA/HA composite hydrogel as well as full and equilibrium tissues after swelling equilibrium are obtained when the HA content is 3% and the number of freezing-thawing cycles is 7.

Edible Coating for Shelf-Life Extension of Fresh Banana Fruit Based on Gamma Irradiated Plasticized Poly(vinyl alcohol)/Carboxymethyl Cellulose/Tannin Composites

The interest in the development of edible and biodegradable films has increased because it is every day more evident that non-degradable materials are doing much damage to the environment. Blends based on different ratios of plasticized poly(vinyl alcohol) (PVA), carboxymethyl cellulose (CMC) and Tannin compound were prepared by solution casting in the form of thin films. Then the blend films were exposed to different doses of gamma radiation. First, the effect of gamma irradiation and the Tannin compound, as an antimicrobial agent, on the thermal and mechanical properties was investigated. As an application in the field of the prolongation of food preservation lifetime, banana fruits were coated with solutions of gamma irradiated PVA/CMC blends in the presence of Tannin. The results showed that the gamma irradiation improved the thermal properties, which provides suitable materials based on natural biodegradable polymers for food preservation withstanding the temperature and stresses.

Compatibility and Properties of Biodegradable Blend Films with Gelatin and Poly(vinyl alcohol)

The blend films with gelatin and poly（vinyl alcohol） （PVA） were prepared by a solution casting method. The compatibility between gelatin and PVA in the blend films was investigated. The transmittance, Fourier-transform infrared spectroscopy （FTIR）, x-ray diffraction （XRD）, thermogravimetry analysis （TG）, and differential scanning calorimetry （DSC） were employed to characterize the resultant blend films. According to optic result, the opacity of the blend film at the ratio of 20/80 （w/w, Gel to PVA） was the lowest, indicating the best compatibility between Gel and PVA at the ratio. The results oflR, XRD, DSC, and TG revealed an intensive interaction and good compatibility between them in the blend film at the ratio. The mechanical properties and solubility showed that PVA content in the blend films obviously affected the elongation at break and solubility. The mechanical properties and water resistance of gelatin film may be improved by the introduetion of PVA.

Properties of PAn/PVA Conducting Composite Film by Electrochemical Polymerization

The polyaniline (PAn)/poly(vinyl alcohol) (PVA) conductive composite film is synthesized with perchloric acid (HClO 4) as the dopant and oxidant in reaction system by electrochemical polymerization. The result shows that this composite film has very high conductive properties, the maximum value of conductivity reaches 0.173 S/cm at the concentration 0.75 mol. The influences of HClO 4 on the conductivity of the composite film are investigated.In addition,the electrode reaction progress is discussed with the result that obtained from SEM and FTIR analyzing.

A Hybrid Membrane of Poly(vinyl alcohol) and Phosphotungstic Acid for Fuel Cells

Proton conducting membranes composed of phosphotungstic acid (PWA) and poly(vinyl alcohol) (PVA)were prepared. Conductivity and Fourier transform infrared spectrometer(FTIR) measurements show that most ofthe acid embedded are stable in the PVA matrix when the membrane is immerged in water or methanol solution atroom temperature. Conductivity of the composite membranes scatters around 10-3 S.cm-1 at room temperature.The methanol crossover through the membranes is about an order of magnitude lower than that through Nafion117 membrane.

Enhanced Electron Transfer for Hemoglobin in 2C_(12)N^+PVS-Composite Films Modified on Pyrolytic Graphite Electrodes

Stable thin films made from polyionic complex 2C12N+PVS- with incorporated Hb on PG electrodes were characterized by electrochemistry. The electron transfer between Hb and PG electrodes was greatly facilitated in microenvironment of 2C12N+PVS- films. The Hb-2C12N+PVS-films could be used to catalytically reduce trichloroacetic acid.

Research on the friction and wear mechanism of Poly(vinyl alcohol)/hydroxylapatite composite hydrogel

Poly(vinyl alcohol)/Hydroxylapatite(PVA/HA) composite hydrogel was prepared with poly(vinyl alcohol) and hydroxylapatite as raw materials, using the method of repeated freezing and thawing.The morphologies of PVA/HA composite hydrogel were observed by means of high-accuracy 3D profiler and scanning electron microscope(SEM).The compressive elastic modulus and the stress relaxation characteristics of PVA/HA composite hydrogel were measured using the flat-head cylinder indenter.The friction and wear tests between PVA/HA composite hydrogel and bovine knee articular cartilage were performed on the micro-tribometer.The worn morphologies of PVA/HA composite hydrogel were observed with environmental scanning electron microscope(ESEM).The results showed that PVA/HA composite hydrogel has the cross-link network microstructure which is similar to that of the natural bovine knee articular cartilages.With the increase of freezing-thawing cycles and the HA content, the degree of cross-link and the crystallization of PVA/HA composite hydrogel both increase, the elastic modulus increases evidently, the rate of stress relaxation is improved and the value of balance stress decreases.The friction coefficient decreases with the increase of the freezing-thawing cycles and the HA content.The more the freezing-thawing cycles are, the earlier the friction coefficient reaches the stable balance value.The friction deformation depth between PVA/HA composite hydrogel and bovine knee articular cartilage is inversely proportional to freezing-thawing cycles and the HA content.The main wear mechanisms of PVA/HA composite hydrogel are plastic flowing and adhesive flaking.The wear severity degree decreases with the increase of freezing-thawing cycles and the HA content.

聚丙烯腈对聚乙烯醇膜形貌和性能的改进

通过流延成膜的方法制备了聚乙烯醇/聚丙烯腈共混薄膜。通过扫描电镜分析了共混膜的形貌。通过差式扫描量热仪、热重分析、拉伸测试、表面接触角测试研究了共混膜的热力学性能、机械性能和化学性能。测试结果显示聚丙烯腈对聚乙烯醇膜的形貌和性能产生了显著的影响。

Preparation and Characterization of Poly(vinyl alcohol)/ZIF-8 Porous Composites by Ice-templating Method with High ZIF-8 Loading Amount

A bulk Poly(vinyl alcohol)/ZIF-8(PVA/ZIF-8)porous composite with aligned porous structure was prepared by ice-templating method.The microstructure of PVA/ZIF-8 porous composites was characterized by scanning electron microscopy(SEM).The results showed that the composites had regular pore structure and ZIF-8 nanoparticles were evenly distributed on the skeleton of PVA.X-ray diffraction(XRD)test results showed that the crystalline structure of ZIF-8 was well preserved in the composites.The specific surface area of the composite was characterized by nitrogen adsorption/desorption test.The specific surface area of the composite was up to 1160 m^2 g^1.PVA/ZIF-8 porous composites could also support a certain weight with almost no volume shrinkage.The carbon dioxide adsorption quantity of the composite was up to 11.3 cm^3 g^1,proving that PVA/ZIF-8 porous composite has a good application prospect in the field of carbon dioxide adsorption.

磺化聚乙烯醇/侧链磺化聚芳醚酮交联复合膜的制备与性能

通过溶液共混热处理方法,制备了磺化聚乙烯醇(SPVA)含量不同的SPVA/侧链磺化聚芳醚酮交联复合膜(Cr-SSPxx)。交联网络结构有效增强了交联复合膜的力学性能、热稳定性、氧化稳定性及尺寸稳定性,扫描电镜显示,交联复合膜呈现了更好的相容性和均一性。随交联度增加,交联复合膜的溶胀率呈现明显下降趋势,在25℃和80℃时,Cr-SSP30膜的溶胀率分别仅有3.7%和7.6%。由于SPVA对醇有阻碍作用,以及交联网络结构增加了膜的致密性,故该系列Cr-SSPxx膜展现出非常优秀的阻醇性能,交联复合膜的甲醇渗透率明显低于纯S-SPAEK膜和磺化聚乙烯醇/侧链型磺化聚芳醚酮复合膜,Cr-SSP30膜的甲醇渗透率仅为9.4×10^(-8) cm^(2)/s。虽然与磺化聚乙烯醇/侧链型磺化聚芳醚酮复合膜相比,交联复合膜的质子传导率有所降低,但由于独特的侧链磺化结构能够促进质子传导,质子传导率最低的Cr-SSP30膜的传导率在25℃和80℃时也都分别达到了0.034 S/cm和0.065 S/cm,同时表现出了更高的质子选择性,能够满足直接甲醇燃料电池(DMFC)的使用要求,有望在DMFC中得到应用。

EVOH-植酸复合活性包装膜对鲈鱼肉的保鲜效果

选用基膜材料乙烯-乙烯醇共聚物(EVOH),分别掺入0.05%、0.1%、0.2%(质量分数)的植酸,采用双螺杆挤出吹塑法制备得到安全保鲜薄膜,测定其透光率、水蒸气透过系数、雾度及抗拉强度来考察膜的基本性能。在冷藏(4±1)℃条件下使用聚乙烯(Polyethylene,PE)、EVOH及复合膜对鲈鱼肉进行保鲜,并以菌落总数(Total Viable Counts,TVC)、pH值、汁液流失率、挥发性盐基氮(Total Volatile Basic Nitrogen,TVB-N)、硫代巴比妥酸(Thiobarbituric Acid,TBA)以及感官评分作为鲜度指标评价其保鲜效果。与PE膜相比,添加0.2%植酸的复合膜雾度涨幅达到85.43%,透光率及抗拉强度显著下降(P<0.05)。贮藏期间,不同包装膜内样品的TVC、汁液流失率、TVB-N、TBA值均有不同程度的增加,其中PE膜与EVOH膜内样品的TVC值分别于第6、8 d达到不可接受的水平,而植酸的加入能有效的抑制各鲜度指标的增幅;与复合膜组相比,PE膜的鱼肉样品感官劣变更为显著(P<0.05)。综上所述,EVOH复合0.2%植酸制成的活性薄膜对鲈鱼肉具有最佳的保鲜效果,可使鲈鱼鱼肉保鲜期在(4±1)℃条件下延长至8 d。

聚乙烯醇纤维增强聚乳酸复合材料的制备及性能研究

以聚乳酸(PLA)和高强高模聚乙烯醇(PVA)纤维为原料,通过熔融共混热压成型工艺制备了不同PVA纤维含量的PLA/PVA复合材料,研究了复合材料的相形态、玻璃化转变、结晶和熔融行为以及力学性能。结果表明:低含量的PVA纤维能均匀地分散在PLA基体中,当纤维质量分数达到20%时,纤维发生团聚。差示扫描量热仪测试结果表明PVA纤维在PLA结晶过程中起到了成核作用。随PVA纤维含量增加,PLA的结晶度增加。此外,动态力学行为表明PVA纤维含量的增加有助于提高复合材料储能模量和刚性。复合材料的拉伸和弯曲模量随PVA纤维含量的增加而增加,当PVA纤维质量分数为20%时,拉伸和弯曲模量达到最大,与纯PLA相比,复合材料的拉伸和弯曲模量分别提高了43.5%和38.6%。但是,PVA纤维的加入并没有使复合材料的拉伸和弯曲强度得到较大改善。

聚乙烯醇/淀粉复合膜的制备及其对鲜花保鲜效果研究

以木薯淀粉和聚乙烯醇作为基本成膜物质,添加表面活性剂十二烷基磺酸钠,通过流延成膜法制备聚乙烯醇/淀粉复合膜。在单因素试验基础上,研究木薯淀粉、聚乙烯醇、表面活性剂十二烷基磺酸钠用量,成型加工温度和成型加工时间对聚乙烯醇/淀粉复合膜力学性能的影响,并通过正交试验对木薯淀粉、十二烷基磺酸钠用量和成型加工时间3个因素进行优化,确定聚乙烯醇/淀粉复合膜性能的较优工艺条件。同时,对新制备的复合膜土埋降解和鲜花保鲜性能进行了研究。结果表明:当聚乙烯醇用量为1 g,木薯淀粉用量为0.7 g,十二烷基磺酸钠用量为0.5 g,成型加工温度为80℃,成型加工时间为65 min时,制备的聚乙烯醇/淀粉复合膜力学性能较优,断裂伸长率高达262.58%、拉伸强度24.63 MPa。获得的新复合膜具有可降解性。聚乙烯醇/淀粉复合膜储藏80 h以后无霉菌生长迹象,对鲜花有一定保鲜效果。

Composite cathode and anode films for rechargeable lithium batteries

Recently the rechargeable Li and Li_ion polymer batteries have improved due to development of Li_ion conductive gel electrolytes and of high energe granting intercalation compounds. In our laboratory the composite cathodic film, the composite carbon anode film and PVC_based electralyte film were successfully prepared by casting procedures. Cycling experiments of the cells with Li or composite carbon anode in contact with PVC_based electrolyte and composite cathode were performed. Relatively good performance of the cell with Li anode, the composite cathode and LiPF-6_EC_DEC electrolyte was achieved in that over 50 cycles were possible with minimal capacity loss upon cycling. The same cell with PVC_based electrolyte was cycled over 20 cycles. Replacing Li anode by composite carbon anode, the cell behaved like the latter. It is found that appropriate amount of carbon content is helpful to improving specific capacity.

聚乙烯醇/纳米纤维素复合膜的渗透汽化性能及结构表征

将聚乙烯醇/纳米纤维素(PVA/NCC)复合膜应用于乙醇-水混合溶液的渗透汽化脱水过程,探讨了纳米纤维素对膜的溶胀性能、机械性能和渗透汽化性能的影响;利用原子力显微镜(AFM)探测了纳米纤维素的形貌特征;采用傅里叶变换红外光谱仪(FTIR)、扫描电镜(SEM)、差示扫描量热仪(DSC)和热重分析仪(TGA)对膜结构和热性能进行了表征.研究结果表明,棒状的纳米纤维素与PVA基体间形成了强烈的氢键作用且均匀分散在PVA基质中;纳米纤维素的加入提高了膜的熔融温度,增加了膜的热稳定性,有效地抑制了膜的溶胀,并提高了膜的机械性能;在PVA中添加纳米纤维素可以提高膜的渗透汽化分离性能,用纳米纤维素含量为2%的复合膜在80℃时分离体积分数为90%的乙醇水溶液,膜的分离因子达到347,比未加入纳米纤维素时提高24%;而渗透通量为288 g/(m2.h),比未加入纳米纤维素时下降11%.

聚乙烯醇/二氧化硅共混膜的制备及耐温、耐溶剂性能研究

以聚乙烯醇 (PVA)和正硅酸乙酯 (TEOS)为原料 ,通过溶胶 -凝胶 (Sol- Gel)方法 ,制备出不同二氧化硅含量的聚乙烯醇 /二氧化硅 (PVA/Si O2 )共混均质膜。通过热重分析 (TGA)、示差扫描量热法 (DSC)和动态力学分析 (DMA)研究了共混膜的热性能。结果表明 ,与 PVA膜相比 ,PVA/Si O2 共混膜具有更高的热稳定性 ,随 Si O2 含量的增大 ,共混膜的分解温度升高 ,玻璃化温度也略有提高。以水为溶剂 ,测定了共混膜的耐溶剂性能。与 PVA膜相比 ,PVA/Si O2

纳米SiO2对PVA基复合涂膜包装材料成膜透湿性能的影响

为改善聚乙烯醇(PVA)涂膜的阻湿保鲜效能特性,该文采用添加纳米SiO2对PVA基复合涂膜包装材料进行改性,应用响应曲面方法研究SiO2、硬脂酸、戊二醛对三元复合涂膜材料成膜效能特性的影响及交互作用。结果表明:加入纳米SiO2改性可有效提高PVA基复合涂膜包装材料的阻水、阻湿性能,优化组成膜透湿率8.18g/(m2.d)比对照组(不添加纳米SiO2的PVA复合膜)降低26.61%(p<0.05);硬脂酸、戊二醛对复合涂膜材料成膜透湿率的影响与纳米SiO2存在显著的交互作用,每100mL0.05g/mL的PVA溶液中纳米SiO2添加量在小于0.05g范围内随着SiO2含量增大,复合涂膜材料成膜透湿率随硬脂酸、戊二醛的比例增加而降低,阻湿性能提高。

交联PVA／SiO2复合膜的制备及性能

采用一种氮丙啶交联剂对聚乙烯醇(PVA)进行交联,通过红外等测试表征研究交联剂用量对交联膜化学结构、力学性能、溶胀性及耐水性的影响,从而确定薄膜性能最优时交联剂的用量。当交联剂用量质量分数为3%时,其拉伸强度和断裂伸长率分别提高25.9%和38.1%,力学性能得到明显改善。将性能最优交联膜与纳米SiO2复合,测试复合膜的力学性能,结果表明:其性能得到进一步提高。

聚乙烯醇基涂膜材料纳米SiO_2改性对其成膜包装效能特性的影响

采用纳米SiO2对聚乙烯醇(PVA)基复合涂膜包装材料进行改性,通过测定PVA基纳米复合涂膜材料的成膜透湿率、吸水率、透光率、透气性以及抑菌效果,研究纳米SiO2对其成膜包装效能特性的影响。结果表明:纳米SiO2改性PVA基复合膜的透湿率(18.78g/(m2.d))比未改性PVA基复合膜(27.39g/(m2.d))降低31.43%,吸水率(1.40%)降低了35.34%,透O2率(0.055g/(m2.d)和透CO2率(0.174g/(m2.d))分别降低了17.91%和18.31%,且复合膜的抑菌性能也得到提高。纳米SiO2改性可显著提高PVA基纳复合涂膜材料的阻隔性,尤其是阻湿阻水性等成膜包装效能特性,改善其食品保鲜包装的应用效果。

茶多酚改性对聚乙烯醇膜吸湿特性及抗氧化活性的影响

研究含不同质量分数茶多酚的聚乙烯醇膜的吸湿特性和抗氧化活性。通过等温吸湿实验研究了含不同质量分数茶多酚(0%、0.5%、1%、1.5%、2%)的聚乙烯醇膜的吸湿特性,并基于常用的等温吸湿模型对实验数据进行拟合表征;通过1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除实验分析了薄膜的抗氧化活性。结果表明:含不同质量分数茶多酚的聚乙烯醇膜均具有吸湿性,其等温吸湿曲线整体变化趋势相似,属于Ⅱ型等温吸湿曲线;薄膜的平衡含水率随水分活度的增加而显著增加(P<0.01),当水分活度大于0.6时,其平衡含水率增加幅度增大;茶多酚对聚乙烯醇膜的改性增加了其疏水性,在相同水分活度条件下,薄膜的吸湿性能随薄膜中茶多酚质量分数的增加而下降,但5种聚乙烯醇膜之间差异不显著(P>0.05);GAB等温吸湿模型对薄膜吸湿性能的拟合效果最好,R^2≥0.996;茶多酚对聚乙烯醇膜的改性使其具有抗氧化活性,DPPH自由基清除率随着薄膜中茶多酚质量分数的增加而显著提高(P<0.01),表明经茶多酚改性后的聚乙烯醇膜的抗氧化性能随薄膜中茶多酚质量分数的增加而增强。经茶多酚改性的聚乙烯醇膜具有吸湿和抗氧化功能,预示其作为塑料复合薄膜内层或中间层应用于湿度敏感型、含高脂肪等干燥易氧化食品包装具有较好的前景。