聚乙烯醇/纳米氧化锌复合材料的性能

为了改善聚乙烯醇的性能,通过熔融挤出的方法制备了聚乙烯醇/纳米氧化锌复合材料.采用力学性能测试、热分析、X射线衍射和紫外光谱研究了纳米氧化锌对聚乙烯醇力学性能、热稳定性、结晶性能和紫外屏蔽性能的影响.结果表明:复合材料的拉伸强度和断裂伸长率分别在纳米氧化锌含量为1.0wt%和0.5wt%时达到最大值,拉伸强度比纯聚乙烯醇提高了20.27%,断裂伸长率略高于纯聚乙烯醇;当纳米氧化锌含量为2.0wt%时,复合材料失重10%的温度比纯聚乙烯醇提高20℃;纳米氧化锌显著提高了聚乙烯醇的耐光老化性能,同时使聚乙烯醇中产生了新的晶相.纳米氧化锌的加入有助于多种性能的改善.     

PVA/胶原共混溶液的流变性能

采用共轴圆筒旋转流变仪和锥-板型转子流变仪研究了聚乙烯醇(PVA)和胶原(COL)共混溶液的稳态和动态流变性能,讨论了温度、共混比、浓度对流动曲线的影响.结果表明:PVA/COL共混溶液为假塑性流体,其偏离牛顿流动行为的程度与共混物的组成和浓度有关.胶原对于体系流变性质的影响居于主要地位,共混溶液具有和胶原相似的流变行为,如弹性效应占主导(G′>G″)、相似的剪切变稀曲线、相近的动态变性温度等.当PVA含量增至80%时,PVA/COL共混溶液的动态变性温度比纯胶原的提高了约2 ℃,且流动性好.浓度对于PVA/COL共混体系粘弹性的贡献以弹性增加为主;浓度越高,流体弹性特征越显著且结构越稳定.     

海藻酸钠/聚乙烯醇/羟基磷灰石复合纤维制备工艺及其性能

以溶液纺丝法制备了海藻酸钠/聚乙烯醇/羟基磷灰石复合纤维,采用正交试验法和单因素分析法对复合纤维制备工艺与断裂强度和镉离子吸附量的关系进行研究。结果表明,SA与PVA质量分数为6%、SA与PVA质量比为4∶1、凝固浴CaCl2质量分数为2%、凝固浴温度为60℃、纺丝头牵伸比为2倍时纤维的吸附量最大。随着羟基磷灰石含量的增加,复合纤维对镉离子吸附量大幅度提高。     

Synthesis and properties of physically crosslinked poly (vinyl alcohol) hydrogels

The present study is an investigation of the properties of poly (vinyl alcohol), which would be a better contact lens material than conventional HEMA in some ways. A transparent PVA hydrogel was prepared from a PVA solution in a mixed solvent consisting of water and a water-miscible organic solvent, DMSO, by the freezing-thawing method. The water content, visible light transmittance, mechanical and swelling properties of the hydrogels were evaluated as a function of PVA concentration and number of freeze-thaw cycles. The results show that the properties of PVA hydrogels depend on the polymer concentration, the number of freeze-thaw cycles and the addition of the organic solvent.     

聚乙烯吡咯烷酮改善聚乙烯醇水溶液的电纺性研究

聚乙烯醇（PVA）水溶液中的高价金属离子与PVA大分子链上的羟基相互作用，形成了分子内和分子间的交联结构，降低了可纺性。添加具有羰基和亚氨基双官能团聚乙烯吡咯烷酮（PVP）后，由于PVP优先络合高价金属离子，这样，使PVA大分子链从交联结构中游离出来，提高了PVA的可纺性。当PVP过量时，PVP又与PVA形成交联作用，反而降低了PVA的可纺性。     

Thermal aging behavior of high performance poly(vinyl alcohol) hydrogel

The thermal aging behavior of poly(vinyl alcohol) (PVA) hydrogel was studied at four different temperatures of 40 ℃, 50 ℃, 60 ℃ and 70 ℃ in one year. The samples of PVA hydrogel were closely covered by plastic film. The changes of their chemical structures and physical properties during aging were measured through different measurable techniques including tensile testing, gel permeation chromatography (GPC), viscosity analysis, and Fourier transform infrared (FTIR) spectrum. The results showed that the molecular weight of PVA in hydrogel changed little with time and temperature. FTIR spectra of PVA in all the samples were similar to those of the original samples. The tensile strength of PVA hydrogel didn’t change until the 330th days.     

原位复合纳米羟基磷灰石／聚乙烯醇水凝胶的制备及性能研究

原位合成方法制备了n—HA／PVA复合水凝胶．通过调节聚乙烯醇、纳米羟基磷灰石和水的含量，制备了不同配比的复合水凝胶．用燃烧实验、TEM、IR和XRD等对材料的组成和结构进行了表征，并测定了水凝胶的力学性质．结果表明，PVA高分子空间三维结构对羟基磷灰石晶体的原位水热生长有一定影响，复合水凝胶中n-HA与PVA有一定键合，两相分布均匀，羟基磷灰石的含量对复合水凝胶的力学强度有很大影响．     

高分子量聚乙烯醇的合成及其分子量分布和立构规整性

采用醋酸乙烯的低温下以水为溶剂的紫外光引发乳液聚合方法，制得了高分子量的ＰＶＡ（ＤＰ为１３４００）并对所合成ＰＶＡ进行了分子量与分子量分布以及立构规整度的表征。     

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.     

具有光催化性能的温敏复合凝胶聚(N-异丙基丙烯酰胺)/纳米TiO_2的制备及表征

采用掺杂法制备具有光催化性能的聚(N-异丙基丙烯酰胺)/纳米TiO2温敏复合凝胶,利用凝胶的温敏性改善纳米TiO2的可回收性。研究TiO2负载率对复合凝胶的微观形貌、化学结构、吸水溶胀性及光催化性能的影响。结果表明:该复合凝胶具有均匀的微观多孔结构,纳米TiO2负载于复合凝胶孔结构内壁,未参与N-异丙基丙烯酰胺的聚合反应,对复合凝胶的化学结构和温敏性没有影响,各负载率复合凝胶的体积突变温度均为33℃,但复合凝胶的吸水溶胀性和光催化性能会随TiO2负载率的变化而变化。光催化实验证明:该复合凝胶的光催化性能随TiO2负载率的提高而增强;负载率50%的复合凝胶,在15W紫外灯作用下,4 h内对100 mg/L活性蓝X-BR的降解率达90%以上。最后对紫外光照射后的复合凝胶样品进行红外分析和热重分析,证明经反复紫外光照射后的复合凝胶不会发生明显降解,凝胶高分子化学结构没有显著变化。     

The Microstructure and Gelling Mechanism of Thermo-responsive Chitosan Hydrogel System

Thermo-respansive chitosan hydrogel system （TRCHS） was prepared and its mierostructure was investigated by scaning electron microscope （SEM） and mercury intrusion poremaster （MIP）. Based on analyzing the data, a special porosity property was reported at the first time. Its gelling mechanism was studied by a group of contrast experiments. Results may provide experimental and theoretical supports for how to apply it on tissue engineering scaffold and how to influeuee or control its essential properties.     

聚乳酸/纳米银负载二氧化硅复合材料的制备及性能

采用熔融共混的方法,在密炼机上制备了聚乳酸/纳米银负载二氧化硅(PLA/Ag-SiO2)纳米复合材料,并通过透射电镜、抑菌率和动态力学分析仪表征了复合材料的微观形态结构、抗菌性能和动态力学性能.研究结果表明,Ag-SiO2颗粒均匀地分散在在聚乳酸基体中,对金黄色葡萄球菌和大肠杆菌均体现出良好的抗菌作用,而纳米复合材料的储能模量尽管随着纳米粒子含量的增加而增加,但在纳米粒子含量低于10 000ppm时,纳米复合材料的储能模量均低于纯聚乳酸.     

Creep behaviour of wood flour/poly(vinyl chloride) composites

The experimental creep data were focused on wood-flour (WF) /poly vinyl chloride (PVC) composites with the variations in additive concentrations of wood flour, silane coupling agent, organomodified montmorillonite (OMMT) and nano-cacium carbonate (nano-CaCO₃). Their effects were analyzed using the Four-element Burger Model incorporating microscopic mechanisms. Total creep strain was low with increasing WF while elastic strain was high and plastic flow strain was low in modeling. Modification of WF with silane was beneficial to creep resistance, so did adding low ratio of OMMT (1.5 wt%) and nano-CaCO₃ in composites. Thus, it was effective in reducing creep either by stiffening the PVC matrix using rigid nano-particles or by improving their adhesion with resin. However, superfluous quantity of any additament did not benefit the improvement owing to either earlier destruction of their agglomerates or stress-concentrated cracks in the over-incrassated interface.     

Preparation and Swelling Behavior of Physically Crosslinked Hydrogels Composed of Poly（vinyl alcohol） and Chitosan

The physically crosslinked poly（vinyl alcohol）/chitosan （CS） composite hydrogels were prepared by cyclic freezing/thawing techniques, and the microstructure and swelling behavior of the hydrogels in the simulated gastric （pH 1.0） and intestinal （pH 7.4） media were investigated. The experimental results of infrared spectra （IR）, scanning electron microscope （SEM） and differential scanning calorimetry （DSC） demonstrated that poly（vinyl alcohol） and chitosan had good miscibility in the composite hydrogels, and the addition of chitosan perturbed the formation of poly（vinyl alcohol） crystallites. The swelling kinetics results indicated that the composite hydrogels had good pH sensitive properties to the acidic environments, and with the increase of chitosan content in the blend, the maximum swelling degreed and the swelling rate both increased, but it led to more dissolution at pH 1.0. And the composite hydrogels also exhibited good reversible swelling behavior with pH value of the swelling medium altering between 1.0 and 7.4. In addition, the higher freezing/thawing cycle times resulted in the lower swelling rate. Therefore, the swelling behavior of the composite hydrogels could be adjusted by changing the chitosan contents and the freezing/thawing cycle times.     

Effect of Polyvinyl Alcohol with a Thiol End Group on the Properties of Polyacrylic Dispersions and Spray-dried Powder

The emulsion polymerization of highly shear-stable copolymer dispersions of methyl methacrylate and butyl acrylate were carried out using poly （vinyl alcohol） with a thiol end group （PVA-SH） as protective colloid. The dispersions can be transformed into corresponding redispersible powder via a spray dryingcooling process. On-line FT-IR monitoring shows that grafting polymer of PVA-g-PMMA was formed mainly at the stage-1 of the emulsion polymerization. TEM images show, the PVA-SH shell was fragmentary when adding SDS at initial stage and integrated when adding at particle growing or final stage. The particle size turns to be smaller when delayed adding SDS surfactant. Triethanolamine, a co-regulator of PVA-SH, controlled the M to 50 000-70 000 and reduced the PDI to 1.5-1.7. The acrylic dispersions with 0.8wt%-1.5wt% PVA-SH1 can be spray-dried into super dispersible polymer powder （SDPP）, which can easily disperse in water and form recon- stituted dispersions with an average particle size smaller than 1 micron.     

羧酸酯稀土对聚氯乙烯的热氧稳定作用

用热烘法研究了羧酸酯稀土（ＣＥＲＥＳ）对聚氯乙烯（ＰＶＣ）的热氧稳定作用。借助于富里叶变换红外光谱（ＦＴＩＲ）分析．通过跟踪羰基基团在热老化过程中的变化，比较ＣＥＲＥＳ与有机锡及两者的复合稳定剂对ＰＶＣ的热氧稳定性能．     

Poly(N-isopropylacrylamide)-based vertically sandwichtyped hydrogel with fast temperature-response speed and its controlled-release characteristics

A novel poly(N-isopropylacrylamide)-based sandwich-typed hydrogel,which was featured with both ends of linear poly(N-isopropylacrylamide)(PNIPAM)chains being grafted onto cross-linked PNIPAM chains,was successfully prepared in a three-step process by a method of sequential synthesis.The proposed hydrogel displays faster and hydration/dehydration dynamic response to temperature cycling owing to linear PNIPAM chains to form big-pore structure.This work may lead to high attraction for targeting drug delivery systems,polymeric pump,sensors and so on.     

Antiplasticizing effect of MOCA on poly(vinyl chloride)

An obvious antiplasticizing effect has been observed in PVC with small amount of MOCA, 3,3’-dichloro-4,4’-diamino-diphenylmethane. PVC-MOCA interaction and crystallization behavior of PVC/MOCA blends were investigated in detail to explain the mechanism of antiplasticization on the basis of a series of techniques including DMA, FTIR, and DSC. The results of mechanical properties tests show that the tensile strength of PVC with 5 phr of MOCA reaches a maximum value, 69.5 Mpa, which is about 23 % higher than that of pure PVC. The rise in tensile strength was attributed to an antiplasticizing effect of MOCA on PVC as confirmed by DMA measurements. The evidences from FTIR reveal that a strong hydrogen-bonding interaction takes place between the nitrogen atom of –NH2 groups in MOCA and the methine proton of PVC repeat units. The results of DSC analysis indicate that crystallization behavior of MOCA is suppressed completely and the crystallinity of PVC decreases with the increase of MOCA amount.     

TiB2/Cu复合材料组织与性能的研究

以Ti、B和Cu的单质粉末为原料,经混粉-冷压成形-真空烧结,制备出原位自生TiB2陶瓷颗粒增强铜基复合材料.并借助热分析方法和X射线衍射对增强颗粒进行分析,同时通过扫描电子显微镜对复合材料组织进行观察,进一步测定复合材料的力学性能.结果表明,在Ti-B-Cu体系中,通过原位反应生成增强相是TiB2.随着B粉和Ti粉含...     

块状凝胶的制备及其协助溶菌酶复性的研究

利用水溶液聚合法合成温敏型聚N-异丙基丙烯酰胺(PNIPA)块状凝胶,对其性能进行了表征并将其应用到溶菌酶的复性研究中.制得的PNIPA凝胶的低临界溶解温度为33℃,最大溶胀倍率为27,凝胶达到溶胀及缩水平衡需24h.加入270 mg/mL凝胶时,溶菌酶复性后的比活力达到5 450.6 U/mg,与稀释复性相比提高了61.5%.对复性机理的分析表明:聚合物长链上的疏水基团与折叠中间体间的疏水相互作用是PNIPA凝胶协助复性的关键.