颜填料体积浓度对水性环氧导静电防腐蚀涂层性能的影响

考察了颜填料体积浓度（PVC）对水性环氧导静电防腐蚀涂料涂层导静电性能和防腐蚀性能的影响,运用X射线能谱（EDX）分析了导电填料的元素组成,采用电化学阻抗谱（EIS）、扫描电镜（SEM）等手段对不同颜填料体积浓度的涂层进行了性能测试及表征,根据不同颜填料体积浓度涂层的物理机械性能、盐水浸泡实验结果和电化学阻抗谱分析,确定该水性环氧导静电防腐蚀涂料的最佳颜填料体积浓度为35%。     

Glycerol-modified poly(vinyl alcohol)/poly(ethylene glycol) self-healing hydrogel for artificial cartilage

Poly(vinyl alcohol) (PVA) hydrogels have shown potential applications in bionic articular cartilage due to their tissue-like viscoelasticity, good biocompatibility and low friction. However, their lack of adequate mechanical properties is a key obstacle for PVA hydrogels to replace natural cartilage. In this study, poly(ethylene glycol) (PEG) and glycerol were introduced into PVA, and a PVA/PEG–glycerol composite hydrogel was synthesized using a mixing physical crosslinking method. The mechanical properties, hydrophilicity and tribological behavior of the PVA/PEG–glycerol hydrogel were investigated by changing the concentration of glycerol in PEG. The results showed that the tensile strength of the hydrogel reached 26.6 MPa at 270% elongation at break with 20 wt% of glycerol plasticizer, which satisfied the demand of natural cartilage. In addition, the excellent hydrophilicity of glycerol provides good lubricating properties for the composite gel under dry friction. Meanwhile, self-healing and cellular immunity assays demonstrated that the composite gel could have good self-healing ability and excellent biocompatibility even in the absence of external stimuli. This study provides a new candidate material for the design of articular cartilage, which has the potential to facilitate advances in artificial joint cartilage repair. © 2022 Society of Industrial Chemistry.     

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。     

PVA,PVA Blends,and Their Nanocomposites for Biodegradable Packaging Application

This review exclusively addresses material systems primarily based on poly(vinyl alcohol) (PVA), one of the most popular water-soluble biopolymers, for their use in packaging applications with the primary objective of reducing petrobased plastic waste. In addition, some typical PVA blends and nanocomposites are discussed as comparative studies for material packaging. Structural characteristics, mechanical, thermal, and barrier properties, in addition to biodegradation of these multiple material systems are summarized in a systematic manner. Finally, associated fabrication processing methods together with the most popular theoretical models used for the permeability of PVA nanocomposites are also reviewed in detail.     

Preparation,structure, and transport properties of ultrafiltration membranes of poly(vinyl chloride) (PVC), carboxylated poly(vinyl chloride) (CPVC), and PVC/CPVC blends

Ultrafiltration (UF) membranes were prepared from poly(vinyl chloride) (PVC), carboxylated poly(vinyl chloride) (CPVC), and PVC/CPVC blends by the phase-inversion method. The physical structure of the membranes was characterized by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The fouling characteristics of all the three membranes and acrylamide (AA)-grafted PVC membranes were characterized by ultrafiltration of bovine serum albumin (BSA) solution over a range of pH and of salt concentrations. Maximum adsorption of the protein on the membrane occurred near the isoelectric point of BSA and in the presence of the salts. The charge on BSA appears to be a dominant factor in determining the fouling. The UF results are explained in terms of nature of the membrane polymer, and effect of different ionic environments on the conformational changes of the protein. The ultrafiltration fluxes are correlated by a model based on the membrane resistance and the time-dependent resistance of the concentration polarization layer of the protein. The values of a mass transfer coefficient and concentration polarization were determined. Zeta potential of the membranes were also determined before and after the UF. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1117–1130, 1999     

Poly(vinyl alcohol) nanocomposites with sepiolite and heat‐treated sepiolites

Poly(vinyl alcohol) (PVA) nanocomposites with pristine sepiolite and heat‐treated (HT) sepiolites were prepared by the method of solution dispersion. The measurements of XRD, FTIR, TEM, and AFM were used for the characterization of the nanocomposites. Furthermore, thermal and optical properties were investigated by TG/DTG/DTA and UV‐visible transmission spectra, respectively. Both the effects of sepiolite/polymer ratio and the structural changes in sepiolite on heating were examined in terms of changes in the properties of the nanocomposites. The addition of sepiolite/HT sepiolites into the PVA matrix resulted in a decrease in the thermal decomposition temperatures of the nanocomposites because of the fact that sepiolite and HT sepiolites facilitated the elimination of the water and acetate groups from the PVA in the second step based on the TG/DTG studies. The HT sepiolites‐PVA nanocomposites had lower thermal stability and more influenced optical clarity than those of the sepiolite PVA, at the same filler levels. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Binary blends based on poly(N‐isopropylacrylamide): Miscibility studies with PVA,PVP, and PAA

Blends of poly(vinyl alcohol) (PVA), poly(acrylic acid), (PAA), and poly(vinyl pyrrolidone) (PVP), with poly(N‐isopropylacrylamide) (PNIPAM), were prepared by casting from aqueous solutions. Mechanical properties of PNIPAM/PVA blends were analyzed by stress–strain tests. Differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were employed to analyze the miscibility between the polymeric pairs. The results revealed that PNIPAM is not miscible with PVA and PVP in the whole range of composition. On the other hand, PNIPAM interacts strongly with PAA forming interpolymer complex due to the formation of cooperative hydrogen bonds. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 743–748, 2004     

Electrospun Poly(vinyl alcohol) Nanofibres with Biocidal Additives for Application in Filter Media, 2–Antimicrobial Activity,Regeneration, Leaching and Water Stability

Antimicrobial poly(vinyl alcohol) nanofibres are produced using AquaQure biocide as additive to the polymer solution. AquaQure is an aqueous antimicrobial agent containing mainly Cu²⁺ and Zn²⁺. Antimicrobial tests show that the fibres achieve up to a 5 log reductions in populations of E. coli, S. aureus, S. typhimurium, P. aeruginosa and K. pneumoniae bacteria. Reusability of the nanofibre membranes is investigated to establish if the nanofibres retain their morphology and antimicrobial effectiveness over six cycles of water filtration. Leaching of AquaQure constituents from the nanofibres into filtered water is assessed and found to be at acceptable levels.

     

Characterization of pigment-leached antifouling coatings using BET surface area measurements and mercury porosimetry

In this work BET surface area measurements and mercury porosimetry are used to characterize leached layers formed when seawater-soluble pigments (Cu₂O and ZnO) dissolve during accelerated leaching of simple antifouling coatings. Measurements on single-pigment coatings show that an increasing fraction of Cu₂O or ZnO pigment particles becomes unavailable for dissolution when the concentration of the pigment decreases in the coating and the interparticle distance in the binder matrix becomes larger. Experimental data for a coating initially containing a mixture of Cu₂O and TiO₂ pigments suggest that a substantial fraction of the smaller and inert TiO₂ particles may be lost from the coating upon dissolution of the larger Cu₂O particles. This inert particle translocation effect is important to take into account when interpreting polishing and leaching data and when developing mathematical models of antifouling coating behaviour because the active binder surface area and porosity of the leached layer are substantially increased. A similar effect was not observed for a coating with a mixture of ZnO and TiO₂ pigments. The two experimental methods are expected to be useful for practical analysis of leaching of seawater-soluble components from commercial antifouling coatings.     

Enhancement of Poly(Vinyl Alcohol)–Poly(Vinyl Pyrrolidone) Blend Properties using Modified Copper (II) Oxide and Ultrasonic Irradiation

Copper (II) oxide nanoparticles supported within poly(vinyl alcohol)/poly(vinyl pyrrolidone) films have been successfully prepared through ultrasonication method. It is discernible that before the preparation of blends, the surface of copper (II) oxide nanoparticles was modified with citric acid and vitamin C as biosafe capping agents. X-ray diffraction scans illustrated the semicrystalline nature of the obtained pure blend and exhibited a good combination between the blend and the modified copper (II) oxide nanoparticles. Also, thermal stability of blends was improved in comparison to the pure polymer blend with increasing modified copper (II) oxide nanoparticles.     

New aminated PVC compounds: Synthesis and characterization

Different compounds for the synthesis of poly(vinyl chloride) (PVC) with tertiary amino groups were tested, and the course of the modification reactions was followed under different conditions by nuclear magnetic resonance spectroscopy and elemental analysis. It is shown that PVC can be modified without side reactions with 2‐mercaptopyridine, 2‐mercaptopyrimidine, 4‐mercapto‐N,N‐dimethylaniline, and 4‐mercaptopyridine. The reactivity of the para‐substituted mercapto compounds is found to be considerably higher than that of the corresponding ortho products, and higher final degrees of modification are achieved. The availability of the amino group towards electrophilic attack in order to form quaternary ammonium salts was tested by reaction with methyl iodide. While this reaction takes place in good yields in the case of PVC modified with 4‐mercaptopyridine and 4‐mercapto‐N,N‐dimethylaniline, aminated PVC with the nitrogen atoms in ortho position do not react due to steric hindrance by the polymer chain. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1178–1185, 1999     

New chitin-based polymer hybrids, 4: soil burial degradation behavior of poly(vinyl alcohol)/chitin derivative miscible blends

Soil burial degradation behavior of miscible blend systems of poly(vinyl alcohol) (PVA)/partially deacetylated chitin (1), PVA/chitin-graft-poly(2-methyl-2-oxazoline) (2), and PVA/chitin-graft-poly(2-ethyl-2-oxazoline) (3) was investigated in comparison with the case of a pure PVA film. The degradation of the blend films was followed by the weight changes, scanning electron microscopic observation, Fourier transform infrared spectroscopy, ¹H-NMR, and size exclusion chromatography analyses. The rate of weight decrease in these PVA/chitin derivative hybrids was higher than that of control PVA in the soil burial test. Fourier transform infrared spectra of the recovered samples of the blends showed an apparent increase of the absorption intensity due to β-diketone structure in PVA, which reflects the progress of biodegradation of PVA by PVA-oxidizing enzymes. Scanning electron microscopic observation revealed that these blend films were degraded by bacteria and actinomycetes. The triad tacticity and number-average molecular weight of PVA in the hybrids after soil burial determined by ¹H-NMR and size exclusion chromatography, respectively, were almost the same as those before soil burial. These results suggested that enzymatic degradation of the hybrid films occurred mainly on the surface and that degradation of the PVA-based samples in the soil was accelerated by blending the chitin derivatives. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1171–1179, 1999     

Nanocomposites of poly(vinyl chloride) and nanometric calcium carbonate particles: Effects of chlorinated polyethylene on mechanical properties,morphology, and rheology

Nanocomposites of poly(vinyl chloride) (PVC) and nano‐calcium carbonate (CaCO₃) particles were prepared via melt blending, and chlorinated polyethylene (CPE) as an interfacial modifier was also introduced into the nanocomposites through preparing CPE/nano‐CaCO₃ master batch. The mechanical properties, morphology, and rheology were studied. A moderate toughening effect was observed for PVC/nano‐CaCO₃ binary nanocomposites. The elongation at break and Young's modulus also increased with increasing the nano‐CaCO₃ concentration. Transmission electron microscopy (TEM) study demonstrated that the nano‐CaCO₃ particles were dispersed in a PVC matrix uniformly, and a few nanoparticles agglomeration was found. The toughening effect of the nano‐CaCO₃ particles on PVC could be attributed to the cavitation of the matrix, which consumed tremendous fracture energy. The notched Izod impact strength achieved a significant improvement by incorporating CPE into the nanocomposites, and obtained the high value of 745 J/m. Morphology investigation indicated that the nano‐CaCO₃ particles in the PVC matrix was encapsulated with a CPE layer through preparing the CPE/nano‐CaCO₃ master batch. The evaluation of rheological properties revealed that the introduction of nano‐CaCO₃ particles into PVC resulted in a remarkable increase in the melt viscosity. However, the viscosity decreased with addition of CPE, especially at high shear rates; thus, the processability of the ternary nanocomposites was improved. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2714–2723, 2004     

Electron beam synthesis and characterization of poly(vinyl alcohol)/montmorillonite nanocomposites

Poly(vinyl alcohol) (PVA)/montmorillonite clay (MMT) nanocomposites in the form of films were prepared under the effect of electron beam irradiation. The PVA/MMT nanocomposites gels were characterized by X‐ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and mechanical measurements. The study showed that the appropriate dose of electron beam irradiation to achieve homogeneous nanocomposites films and highest gel formation was 20 kGy. The introduction of MMT (up to 4 wt %) results in improvement in tensile strength, elongation at break, and thermal stability of the PVA matrix. In addition, the intercalation of PVA with the MMT clay leads to an impressive improved water resistance, indicating that the clay is well dispersed within the polymer matrix. Meanwhile, it was proved that the intercalation has no effect on the metal uptake capability of PVA as determined by a method based on the color measurements. XRD patterns and SEM micrographs suggest the coexistence of exfoliated intercalated MMT layers over the studied MMT contents. The DSC thermograms showed clearly that the intercalation of PVA polymer with these levels of MMT has no influence on the melting transitions; however, the glass transition temperature (T_g) for PVA was completely disappeared, even at low levels of MMT clay. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1129–1138, 2006     

Thermal characteristics of poly(vinyl alcohol) and poly(vinylpyrrolidone) IPNs

Interpenetrating polymer network (IPN) hydrogels based on poly(vinyl alcohol) (PVA) and 1‐vinyl‐2‐pyrrolidone (VP) were prepared by radical polymerization using 2,2‐dimethyl‐2‐phenylacetophenone (DMPAP) and methylene bisacrylicamide (MBAAm) as initiator and crosslinker, respectively. The thermal characterization of the IPNs was investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dielectric analysis (DEA). Depressions of the melting temperatures of PVA segments in IPNs were observed with increasing VP content via the DSC. The DEA was employed to ascertain the glass transition temperature (T_g) of IPNs. From the result of DEA, IPNs exhibited two T_gs indicating the presence of phase separation in the IPN. The thermal decomposition of IPNs was investigated using TGA and appeared at near 270°C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1844–1847, 2002     

A honeymoon‐type adhesive for wood products based on acetoacetylated poly(vinyl alcohol) and diamines: Effect of diamines and degree of acetoacetylation

The honeymoon‐type adhesive for wood products based on acetoacetylated poly(vinyl alcohol) (AAPVA) was investigated focusing on the effect of acetoacetylation on performance, and that of amino compounds as a crosslinking agent. AAPVAs with different degrees of acetoacetylation were synthesized by the addition reaction of diketene in dimethylsulfoxide. Adhesive tests were carried out using aqueous solutions of AAPVA and six kinds of amino compounds, spread separately on test pieces of red meranti selected as the adherend. The mechanical strength of the bonded test pieces was then analyzed. It was found that the adhesive strength increased together with the degree of acetoacetylation at least until 3 h after the application of the adhesives. The degree of acetoacetylation had little effect on water resistance within the range 3.3–37.1%, and as a crosslinking agent, diamines containing primary amino groups were effective, although secondary amines and polyethyleneimine were not. It is assumed that the chemical structure of the amine influenced the crosslinking reaction at the adhesion interface. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2966–2972, 2004     

Preparation and characterization of conductive poly(vinyl alcohol)/polyaniline doped by dodecyl benzene sulfonic acid (PVA/PANDB) blend films

In this study a solution‐blend method is adopted to prepare conductive poly(vinyl alcohol)/polyaniline doped by dodecyl benzene sulfonic acid (PVA/PANDB) blend films. Emeraldine base (EB)‐type polyaniline (PANI) is dissolved in N‐methyl‐2‐pyrrolidinone (NMP) and then blended with PVA/dodecyl benzene sulfonic acid (DBSA) solution by various amounts. It is found that the electrical conductivity and the thermal degradation onset temperature of the PVA/PANDB blend film are increased as the amount of EB‐type PANI solution is increased. Fourier transform infrared (FTIR) spectra show that the intensity of the characteristic peak of the functional groups in the blend film is significantly changed as the amount of EB‐type PANI is changed. From optical microscopy examination, it indicates that the amount and size of green particles are increased with increasing the amount of EB‐type PANI solution. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3415–3422, 2007     

The influence of vanadium pentoxide on the structure and dielectric properties of poly(vinyl alcohol)

Polymers containing metal oxides of nanoscale dimensions have attracted attention because of their unique properties and new findings concerning technological applications. Polymers containing vanadium pentoxide (V₂O₅) have attracted our interest in respect of their potential applications in memory and switching devices. Poly(vinyl alcohol) (PVA) containing different concentrations of V₂O₅ ranging from 0 to 0.5 wt% were prepared. The synthesized PVA/V₂O₅ composites were cast as self‐standing flexible films. The composites were characterized using X‐ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. An attempt was made to study the relaxation characteristics of PVA/V₂O₅ samples. The permittivity and dielectric loss were determined as a function of V₂O₅ concentration. The results show that the optimum concentration is 0.3 wt%. The electrical conductivity and dielectric modulus in the temperature range 303–433 K at various frequencies (10–100 kHz) for the optimum concentration were investigated. XRD and FTIR results show that the addition of V₂O₅ reduces the crystallinity of PVA due to the interaction of vanadium ions with the OH groups of PVA. The application of the dielectric modulus formulism gives a simple method for evaluating the activation energy of the dielectric relaxation. The frequency dependence of the electrical conductivity follows the Jonscher universal dynamic law. The conductivity in the direct regime is described by the small polaron model. The electrical conductivity and dielectric properties show that Hunt's model is well adapted to PVA/V₂O₅ films. Copyright © 2010 Society of Chemical Industry     

Thermal and dynamic mechanical behavior of bionanocomposites: Fumed silica nanoparticles dispersed in poly(vinyl pyrrolidone), chitosan,and poly(vinyl alcohol)

Various bionanocomposites were prepared by dispersing fumed silica (SiO₂) nanoparticles in biocompatible polymers like poly(vinyl pyrrolidone) (PVP), chitosan (Chi), or poly(vinyl alcohol) (PVA). For the bionanocomposites preparation, a solvent evaporation method was followed. SEM micrographs verified fine dispersion of silica nanoparticles in all used polymer matrices of composites with low silica content. Sufficient interactions between the functional groups of the polymers and the surface hydroxyl groups of SiO₂ were revealed by FTIR measurements. These interactions favored fine dispersion of silica. Mechanical properties such as tensile strength and Young's modulus substantially increased with increasing the silica content in the bionanocomposites. Thermogravimetric analysis (TGA) showed that the polymer matrices were stabilized against thermal decomposition with the addition of fumed silica due to shielding effect, because for all bionanocomposites the temperature, corresponding to the maximum decomposition rate, progressively shifted to higher values with increasing the silica content. Finally, dynamic thermomechanical analysis (DMA) tests showed that for Chi/SiO₂ and PVA/SiO₂ nanocomposites the temperature of β‐relaxation observed in tanδ curves, corresponding to the glass transition temperature T_g, shifted to higher values with increasing the SiO₂ content. This fact indicates that because of the reported interactions, a nanoparticle/matrix interphase was formed in the surroundings of the filler, where the macromolecules showed limited segmental mobility. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008