添加不同物质的聚乙烯醇/海藻酸钠静电纺丝研究

分别添加少量NaCl、乙酸、表面活性剂十二烷基硫酸钠(SDS),研究少量添加物对海藻酸钠/聚乙烯醇(PVA)溶液性质和静电纺纤维的影响,并初步探讨了溶液静电纺丝机制。结果表明:NaCl改变了溶液的电导率和黏度,乙酸降低了溶液的黏度、提高了溶剂挥发性,SDS降低了溶液的表面张力;适量的添加物可使纤维形貌得到改善;添加物对电纺纤维化学结构无本质影响;无机盐离子加剧了纤维拉伸作用,结晶性有所提高;处于泰勒锥处液滴表面受到静电排斥力、表面张力、同种聚合物分子间的氢键作用力、不同聚合物分子间的氢键作用力以及聚合物同水等溶剂形成的氢键作用力。     

海藻酸钠/聚乙烯醇/银复合纤维的静电纺丝

采用静电纺丝方法,在不同海藻酸钠/聚乙烯醇质量比、含银量、纺丝电压、纺丝液流速、接收距离条件下,制备了海藻酸钠/聚乙烯醇/银复合纤维,利用扫描电镜分析了纤维直径分布及形态。结果表明:海藻酸钠与聚乙烯醇的质量比和含银量对复合纤维成纤性和纤维形态的影响较为显著。海藻酸钠与聚乙烯醇质量比为2∶8、银占溶质质量分数的0.1%、纺丝电压为20 kV、纺丝液流速为0.1 mL/h、接收距离为8 cm时,纺丝效果最佳,纤维形态最好。     

增塑剂甘油对以淀粉为填料的聚乙烯醇泡沫塑料性能的影响研究

研究了在不同增塑剂甘油用量情况下,材料的密度、孔隙率、吸水率、拉伸强度和回弹率的关系,得出了甘油增塑对材料性能的影响规律。实验结果表明：当甘油质量浓度为30g／L时,材料的密度和吸水率最小值分别为0．075g／cm^3和1581．5％。当甘油质量浓度为25g／L时,材料的拉伸强度最大值为1．477MPa。回弹率随甘油含量增加而增加,应根据材料的应用领域选定最佳用量。     

Poly(vinyl alcohol)/Clay‐Based Nanocomposite Hydrogels: Swelling Behavior and Characterization

Polymer/clay composite hydrogels were prepared based on PVA hydrogels containing 3–10 wt.‐% MOM. Their microstructure and morphology were studied by FT‐IR, WAXS and SEM, whereas the interactions between MOM and PVA were evaluated by thermal analyses. The swelling ratios for the PVA/MOM hydrogels decrease with increasing MOM content. WAXS results indicate that MOM was intercalates, and DSC results show a strong interaction between PVA and MOM. This interaction results in a stable network, which is confirmed by the elastic modulus and the thermal decomposition behavior of the hydrogels. Therefore, MOM acts as a co‐crosslinker, improving the stability of the network.

     

Poly(vinyl alcohol) and poly(vinyl amine) blend membranes for isopropanol dehydration

Blended membranes of hydrophilic polymers poly(vinyl alcohol) (PVA) and poly(vinyl amine) (PVAm) were prepared and crosslinked with glutaraldehyde. The prepared membranes were characterized using infrared (attenuated total reflection mode) spectroscopy, differential scanning calorimetry, X‐ray diffractometry, and scanning electron microscopy measurements. Pervaporation performances of the membranes were evaluated for the separation of water‐isopropanol (IPA) mixtures. As the PVAm content increased from PVAm0 to PVAm1.5, the flux through a 70 μm film increased from 0.023 to 0.10 kg/m² h at an IPA/water feed ratio of 85/15 at 30 °C. The driving force for permeation of water increased due to the temperature but it has no effect on IPA permeation. Activation energies for the permeation of IPA and water were calculated to be 17.11 and 12.46 kJ/mol, respectively. Controlling the thickness of the blend membrane could improve the permeation flux with only a marginal reduction in the separation factor. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45572.     

Hybrid Hydrogels Based on Poly(vinyl alcohol) (PVA)/Agar/Poly(ethylene glycol) (PEG) Prepared by High Energy Electron Beam Irradiation: Investigation of Physico‐Mechanical and Rheological Properties

A series of hybrid hydrogels based on poly(vinyl alcohol) (PVA)/agar/poly(ethylene glycol) (PEG) prepared by a solution casting method using e‐beam irradiation are investigated to determine the effect of agar and PEG content (1, 2, and 4 wt%) on their physicomechanical and rheological properties. The gel content of the hydrogels decreases with increasing agar and PEG contents. The equilibrium swelling of PVA hydrogel decreases on blending with agar while adding PEG to PVA/agar increases the swelling by about 400%. No obvious change in the dehydration behavior of the hybrid hydrogels is observed on changing agar and PEG contents. The solid‐like rheological behavior of the hydrogels is not significantly affected by agar content, while it approaches a liquid‐like behavior at high PEG loading. The tensile strength of the hybrid hydrogels is improved by increasing agar content, while its elongation‐at‐break is decreased. On the other hand, the opposite results are found regarding the influence of PEG and its content on the mechanical properties of the hybrid hydrogels.

     

Novel Thermoreversible Injectable Hydrogel Formulations Based on Sodium Alginate and Poly(N-Isopropylacrylamide)

Novel injectable thermoreversible hydrogel compositions with semi-interpenetrating network structure were prepared through the addition of sodium alginate (SA) to poly(N-isopropylacrylamide) (PNIPAM) aqueous solutions. The addition of the hydrophilic alginate strongly improved the stability against syneresis of the 15 wt% PNIPAM hydrogels formed at 37°C from less than 15 min in the absence of alginate to more than 7 days in the presence of 4 wt% SA. Besides the SA concentration, the hydrogel stability depended on the molecular weight and polydispersity of PNIPAM, being lower when a high molecular weight fraction was present. The phase transition temperature (T_ph) of the PNIPAM aqueous solutions decreased with alginate concentration, while the dynamic viscosity and elastic modulus of the hydrogels increased. By decreasing the PNIPAM molecular weight and polydispersity, the dynamic viscosity and elastic modulus of the PNIPAM–alginate hydrogels formed above T_ph diminished, while their viscoelastic behavior changed from predominantly elastic to predominantly viscous.     

卤化聚乙烯醇的研究

通过将聚乙烯醇（PVA）直接卤化取代,筛选出Cl,Br等卤化剂,催化剂,并优选出合适的体系,使其既保持PVA的高阻氧性,又能保证加工性时的热稳定性。     

Poly(vinyl alcohol) Based pH Responsive Semi-IPN Hydrogels: A Comparative Swelling Investigation

The semi-interpenetrating polymer network (IPN) hydrogels composed of poly(vinyl alcohol) (PVA) and random copolymers of poly(acrylamide-co-sodium methacrylate), poly(AAm-co-NMA); poly(acrylamide-co-potassium methacrylate), poly(AAm-co-KMA); poly(acrylamide-co-maleic acid), poly(AAm-co-MA) were prepared by conventional co-polymerization employing ammonium persulphate (APS)/N,N,N¹,N¹-tetraethylmethylenediamine (TMEDA) as redox initiating system in presence of N,N¹-methylenebisacrylamide (MBA) as a crosslinker. The swelling behavior of these semi-IPN hydrogels were compared in detail in various swelling media, including different pH, salt, and biological fluids.     

Surface Modification of Poly(vinyl alcohol) Fibers

The surfaces of PVA fibers prepared by in situ fibrillation were modified by first crosslinking using glyoxal and then attaching cationic and anionic groups by grafting. Crosslinking prior to modification was beneficial in minimizing the solubility of the fibers in the aqueous medium in which they were modified. Heterogeneous modification techniques were employed so that fiber properties could be preserved. PAA and PDMC were grafted from the PVA microfibrils using the KPS/NaS₂O₃ redox initiating system. Grafting was confirmed by FTIR and NMR spectroscopy. The modified PVA fibers were also analyzed by DSC, TGA, and SEM.

     

乙酰乙酰化聚乙烯醇的合成

通过酯交换反应将乙酰乙酰基引入聚乙烯醇(PVA),并采用红外光谱对产物进行了表征。重点讨论了反应温度、反应时间、乙酰乙酸酯用量等因素对酯交换反应的影响。试验发现:随乙酰乙酸酯用量的增加,乙酰乙酰化程度逐渐增大;随反应温度的升高,乙酰乙酰化程度先逐渐提高,后趋于稳定;随反应时间的延长,乙酰乙酰化程度提高,2.5h后趋于平衡。     

Nanostarch Reinforced with Chitosan/Poly (vinyl pyrrolidone) Blend for In Vitro Wound Healing Application

Nanostarch, which is inexpensive and environmentally abundant, has been used as filler to prepare biocompatible films. The bio-nanocomposites were synthesized by solution casting method. TEM analysis proves that the average particle size of the nanostarch is in the range of 20–40?nm. Thermal stability and cell viability of CS/PVP matrix were best enhanced at 1% of nanostarch loading. The antibacterial activity exhibited by CPS bio-nanocomposite against Staphylococcus aureus and Pseudomonas aeruginosa and synergistic effects of CPS such as barrier properties, swelling properties, and better blood compatibility make it a suitable material for in vitro wound healing application.     

Hydrogels from glycidyl derivatives of poly(vinyl alcohol)

Poly(vinyl alcohol) (PVA) was modified with phthalic anhydride to obtain half esters with carboxylic acid groups, which made the reaction with epichlorohydrin easier. The oxirane ring underwent a further crosslinking that led to crosslinked polymers with polar groups capable of interacting strongly with water and therefore with properties of hydrogels. The curing kinetics of the crosslinking were studied by differential scanning calorimetry, and the dependence of the activation energy on conversion degree was studied by isoconversional kinetic analysis. Water absorption was determined gravimetrically as a function of time at room temperature. The swelling behavior of these hydrogels was related to the degree of crosslinking. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 693–698, 2003     

肝素化聚乙烯醇性能研究

用聚乙烯醇(PVA)缩醛化方法,共价键结合肝素。用Schiff试剂染色法、红外光谱分析、X射线光电子能谱法(ESCA)、元素分析等测试方法证明醛基和肝素的存在。力学性能测定表明,肝素化聚乙烯醇的拉伸强度达到12 25MPa,断裂伸长率为400%。生物学指标说明,在全血凝固时间实验(CT)中,肝素化聚乙烯醇的抗凝时间达3h,在活性部分凝血时间实验(APTT)中,缩醛化聚乙烯醇共价键结合肝素非常牢固,没有肝素脱落到血液中,证明肝素化聚乙烯醇具有显著的抗凝血性。     

聚乙烯醇薄膜的共混改性

从聚合物结构方面分析了聚乙烯醇（PVA）薄膜的水溶性,提出用共混改性方法提高PVA薄膜的溶解性能。研究了聚丙烯酸不同中和度,不同共混组分组成对薄膜水溶性和力学性能的影响,并利用差示扫描量热法（DSC）、傅立叶红外光谱（FTIR）、广角X射线衍射（WXRD）等手段对共混改性机理进行了分析。     

拉伸对熔纺聚乙烯醇纤维结构形态的影响

采用含水的复合改性剂增塑聚乙烯醇(PVA),制备熔纺PVA纤维原丝。经冷拉伸3倍后,分别在160、220℃下进行热拉伸。研究了拉伸对纤维结构和表面、截面形貌的影响。结果表明:拉伸使纤维分子取向,结晶度升高;熔纺PVA纤维截面为圆形,拉伸后在纤维表面产生沿轴向的微孔,增加了纤维表面的粗糙度。     

Study of electrospinning of sodium alginate,blended solutions of sodium alginate/poly(vinyl alcohol) and sodium alginate/poly(ethylene oxide)

Alginate is an interesting natural biopolymer for many of its merits and good biological properties. This paper investigates the electrospinning of sodium alginate (NaAlg), NaAlg/PVA‐ and NaAlg/PEO‐ blended systems. It was found in this research that although NaAlg can easily be dissolved in water, the aqueous NaAlg solution could not be electrospun into ultrafine nanofibers. To overcome the poor electrospinnability of NaAlg solution, synthetic polymers such as PEO and PVA solutions were blended with NaAlg solution to improve its spinnability. The SEM images of electrospun nanofibers showed that the alginate (2%, w/v)–PVA (8%, w/v) blended system in the volume ratio of 70 : 30 and the alginate (2%, w/v)–PEO (8% w/v) blended system in the volume ratio of 50 : 50 could be electrospun into finest and uniform nanofibers with average diameters of 118.3 nm (diameter distribution, 75.8–204 nm) and 99.1 nm (diameter distribution, 71–122 nm), respectively. Rheological studies showed a strong dependence of spinnability and fiber morphology on solution viscosity and thus on the alginate‐to‐synthetic polymer (PVA or PEO) blend ratios. FTIR studies indicate that there are the hydrogen bonding interactions due to the ether oxygen of PEO (or the hydroxyl groups of PVA) and the hydroxyl groups of NaAlg. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Nanofiltration membranes based on poly(vinyl alcohol) and ionic polymers

Nanofiltration membranes based on poly(vinyl alcohol) (PVA) and ionic polymers, such as sodium alginate (SA) and chitosan, were prepared by casting the respective polymer solutions. The membranes prepared from PVA or PVA–ionic polymer blend were crosslinked in a isopropanol solution using glutaraldehyde as a crosslinking agent. The membranes were characterized with Fourier transform infrared spectroscopy and X‐ray diffractometry and swelling test. The membranes crosslinked through the acetal linkage formation between the  OH groups of PVA and the ionomer and glutaraldehyde appeared to be semicrystalline. To study the permeation properties, the membranes were tested with various feed solutions [sodium sulfate, sodium chloride, poly(ethylene glycol) with 600 g/mol of molecular weight (PEG 600), and isopropyl alcohol]. For example, the permeance and the solute rejection of the 1000 ppm sodium sulfate at 600 psi of upstream pressure through the PVA membrane were 0.55 m³/m² day and over 99%, respectively. The effects of the ionomers on the permeation properties of the PVA membranes were studied using the PVA–SA and PVA–chitosan blend membranes. The addition of small amount of ionic polymers (5 wt %) made the PVA membranes more effective for the organic solute rejection without decrease in their fluxes. The rejection ratios of the PEG 600 and isopropanol were increased substantially. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1755–1762, 1999     

聚乙烯醇/纳米二氧化硅复合偏光膜的制备及结构与性能研究

采用溶液成膜法制备了聚乙烯醇(PVA)/纳米二氧化硅(SiO2)碘系复合偏光膜,并研究了复合偏光膜的结构、偏光性能和热性能。紫外分析表明,随Si场含量的增加,偏光膜的透过率先增加后减小,而偏光率先减小后增加。红外分析表明,纳米SiO2加人后与PVA分子中的-OH发生了相互作用。XRD分析表明,加人纳米SiO2后PVA偏光膜的结晶度下降。TG分析表明,加人纳米SiO2后PVA偏光膜高温热稳定性有所提高。     

高相对分子质量聚乙烯醇的研究进展

综述了高相对分子质量聚乙烯醇的发展及其用途。从聚合方法和引发方式两方面介绍了国内外合成高相对分子质量聚乙烯醇研究进展。简述了高强高模PVA的使用场合及其应用前景,并对今后我国高相对分子质量聚乙烯醇工业的发展提出了建议。