Properties Of Polyvinyl Alcohol Research Articles

Preparation and properties of polyvinyl alcohol (PVA) and hydroxylapatite (HA) hydrogels for cartilage tissue engineering.

A novel bioactive hydrogel for cartilage tissue based on polyvinyl alcohol (PVA) and hydroxylapatite (HA) were prepared, the effects of its component contents on the mechanical properties and microstructure of the hydrogel were investigated. The important properties of the scaffold composites, such as density, porosity, compressive modulus and microstructure were studied and analyzed through various measurements and methods. The biodegradability of hydrogel was evaluated by soaking the samples into artificial degradation solution at body temperature (36 - 37 oC) in vitro. Experimental results showed that the PVA/HA hydrogels had a density of 0.572 - 0.683 g/cm3, a porosity of 63.25 - 96.14% and a compressive modulus of 5.62 - 8.24 MP. The HA compound in the hydrogels enhanced the biodegradation significantly and linearly increased the rate of biodegradation by 2.3 - 8.5 %. The compressive modulus of PVA/HA exhibited a linear reduce to 0.86 - 1.53 MP with the time of degradation. The scaffold composites PVA/HA possess a high porosity, decent compressive modulus and good biodegradability. After further optimizing the structure and properties, this composite might be considered as novel hydrogel biomaterials to be applied in the field of cartilage tissue engineering.

Synergistic effect of cellulose nanowhiskers reinforcement and dicarboxylic acids crosslinking towards polyvinyl alcohol properties

ABSTRACTIn the presented work, a significant increase in the tensile strength of the PVA composite material is reported. The obtained best value of 122 MPa and 14.6% swelling shows the excellent synergistic effect of both crosslinker and reinforcement material. The composite films were prepared by simple mechanical dispersion of reinforcement material, bacterial cellulose nanowhiskers (BCNW) into PVA solution followed by crosslinking with diacids, succinic acid (SuA), and adipic acid (AdA). The effect of aliphatic carbon chain length of crosslinker on thermal, mechanical, and water uptake properties is evaluated and discussed in detail. Neat PVA had the strength of 37.3 MPa. With 5% reinforcement of BCNW, that is, without crosslinking, it exhibited 97% increase, that is, 74.5 MPa. With crosslinking of 15 mmol of SuA and AdA PVA films for 2 h had excellent thermal properties with swelling percentage of 19 and 26.6% and tensile strength of 103 and 67 MPa, respectively. The best result obtained was for 5% BCNW–PVA films crosslinked with 15 mmol SuA. These results were explained on the basis of synergetic crosslinking and extended hydrogen bonding between PVA and reinforcement material. The composite films can be used as biological implants, a membrane for pervaporation and filtration system, etc. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2515–2525

Study of Electrical Conduction of Polyvinylalcohol Films Doped by 4-Dimethylaminobenzonitrile Molecule

ABSTRACTFilms of pure and doped polyvinylalcohol (PVA) with 4-dimethylaminobenzonitrile (DMABN) molecule are prepared during the development of these films. The effect of UV irradiation and doping on electrical properties of PVA is investigated. We show that the system polymer-molecule has a certain photostability following UV irradiation. The variation of electrical current with temperature show two regions corresponding to different values of activation energy. The activation energies are changed from 0.22 to 0.47 eV, from 0.11 to 0.37 eV and from 0.13 to 0.29 eV for respectively undoped, doped and doped irradiated films. The analysis of I–V characteristics suggests that Schottky emission is the dominant charge transfer mechanism governed by complex of hydrogen bonding.

X-ray irradiation-induced changes in (PVA–PEG–Ag) polymer nanocomposites films

ABSTRACTThe effects of X-ray irradiation on the structural, thermal and optical properties of polyvinyl alcohol–polyethylene glycol–silver (PVA–PEG–Ag) nanocomposites have been investigated. The samples of nanocomposites were prepared by adding Ag nanoparticles with 5 wt% to the (PVA–PEG) blend. The films of 0.05 mm thickness were prepared by the casting method. These films were irradiated with X-ray doses ranging from 20 to 200 kGy. The resultant effect of X-ray irradiation on the structural properties of PVA–PEG–Ag has been investigated using X-ray diffraction and Fourier transform infrared spectroscopy. Also, thermal property studies were carried out using thermogravimetric analysis. Further, the transmission of the PVA–PEG–Ag samples and any color changes were studied. Fourier transform infrared spectroscopy measurements showed that the crosslinking is the dominant mechanism at the dose range 50–200 kGy. This led to a more compact structure of PVA–PEG–Ag samples, which resulted in an improvement in its thermal stability with an increase in the activation energy of thermal decomposition. Moreover, the color intensity ΔE was greatly increased with an increase in the dose, and was accompanied by a significant increase in the yellow color component.

Study of electrical conduction of polyvinylalcohol films doped by 4-dimethylaminobenzonitrile molecule

Films of pure and doped polyvinylalcohol (PVA) with 4-dimethylaminobenzonitrile molecule are prepared during the development of these films. The effect of UV irradiation and doping on electrical properties of PVA is investigated. We show that the system polymer-molecule has a certain photostability following UV irradiation. The variation of electrical current with temperature shows two regions corresponding to different values of activation energy. The activation energies are changed from 0.22 to 0.47 eV, from 0.11 to 0.37 eV and from 0.13 to 0.29 eV for respectively undoped, doped and doped irradiated films. The analysis of I–V characteristics suggests that Schottky emission is the dominant charge transfer mechanism, governed by hydrogen bonding complex.

Optimization and spectroscopic studies on carbon nanotubes/PVA nanocomposites

Nanocomposite films of polyvinyl alcohol (PVA) containing constant ratio of both single and multi-wall carbon nanotubes had been obtained by dispersion techniques and were investigated by different techniques. The infrared spectrum confirmed that SWNTs and MWNTs have been covalently related OH and CC bonds within PVA. The X-ray diffraction indicated lower crystallinity after the addition of carbon nanotubes (CNTs) due to interaction between CNTs and PVA. Transmission electron microscope (TEM) illustrated that SWNTs and MWNTs have been dispersed into PVA polymeric matrix and it wrapped with PVA. The properties of PVA were enhanced by the presence of CNTs. TEM images show uniform distribution of CNTs within PVA and a few broken revealing that CNTs broke aside as opposed to being pulled out from fracture surface which suggests an interfacial bonding between CNTs and PVA. Maximum value of AC conductivity was recorded at higher frequencies. The behavior of both dielectric constant (ɛ′) and dielectric loss (ɛ″) were decreased when frequency increased related to dipole direction within PVA films to orient toward the applied field. At higher frequencies, the decreasing trend seems nearly stable as compared with lower frequencies related to difficulty of dipole rotation.

ポリビニルアルコールの微結晶を自己核剤とした結晶化度の向上と力学物性

ポリビニルアルコールの微結晶を自己核剤とした結晶化度の向上と力学物性

The molecular simulation of the miscibility, mechanical properties and physical cross-linking behavior of the poly(vinyl alcohol)/poly(acrylic acid) composited membranes

The miscibility and mechanical properties of poly vinyl alcohol (PVA) and poly acrylic acid (PAA)-composited membranes were studied with molecular simulation. The Flory–Huggins parameters (δ) were calculated to prove the good miscibility of PVA and PAA. The radial distribution functions of hydroxyl and carboxyl atoms and the average number of H-bonds were observed to indicate the degree of physical cross-linking between PVA and PAA. The influences of intermolecular physical cross-linking on the glass transition temperature and mechanical properties were estimated. The results revealed that the PVA/PAA membrane with a composition of 2:3 has the best plastic properties, which exhibits a good application value. All of the simulated results showed good agreement with the experimental data. It indicates that the method presented in this work has a promising application prospect.

Thermal and morphological characterization of poly(vinyl alcohol) based phenylboronic acid hybrid nanofibers: the effect of experimental parameters on the nanofiber diameter

The aim of this study was to prepare and characterize phenylboronic acid/poly(vinyl alcohol) composite nanofibers. The effects of solution properties and processing parameters on the structure and morphology of the nanofibers were thoroughly investigated. The structure and morphology of nanofibers were examined by SEM, DSC, and FTIR spectroscopy. The nanofiber diameter and the nanostructured morphology depended on solution viscosity, applied electric voltage and tip-to-collector distance. The combination of different materials and processing parameters could be used to fabricate bead-free composite nanofibers. It was found that the solution viscosity have relatively larger effects on the fiber diameter than the other parameters. The thermal properties of polyvinyl alcohol and polymer composite nanofibers were investigated. The analysis revealed that composite containing nanofibers gave higher char yield compared to poly(vinyl alcohol) nanofiber.

Optimization of parameters through Taguchi method for enhanced corrosion inhibition of poly (vinyl alcohol-serine)

Parametric optimization was carried out for the mixture of polyvinyl alcohol (PVA) and l-serine using Taguchi statistical approach. L9 orthogonal array of experiments were designed and the results were analyzed with Qualitek software. Synergistic effect of the mixture was enhanced at the Qualitek predicted optimized conditions. The graft polymer, poly(vinyl alcohol-serine) (PVAS), was synthesized using free radical-initiated reactions of l-serine with PVA in order to achieve effective inhibition. PVAS was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, and powder X-ray diffraction analysis. The thermal properties of PVAS were studied by thermogravimetry, differential thermal analysis, and differential scanning calorimetry. The corrosion inhibition property of PVAS on mild steel corrosion was continuously monitored using electrochemical techniques. Temperature effect on the inhibition properties of PVAS was studied using electrochemical and gravimetric measurements. AFM studies confirmed the formation of polymeric film on mild steel surface which inhibits the rate of corrosion. Theoretical calculations using Hyperchem 7.0 proved the better corrosion mitigation properties of PVAS compared to PVA. The experimental results and surface analysis confirmed the effective inhibition process of the graft polymer which was also supported by the theoretical calculations. A good correlation was obtained between the results of the electrochemical measurements, conventional gravimetric measurement, surface analysis, and theoretical calculations. All the studies proved the enhanced corrosion inhibition properties of PVA through grafting of polyserine.

Erratum to “Characterization and electrical properties of polyvinyl alcohol based polymer electrolyte films doped with ammonium thiocyanate” [Mater. Sci. Eng. B 184 (2014) 49–57

Erratum to “Characterization and electrical properties of polyvinyl alcohol based polymer electrolyte films doped with ammonium thiocyanate” [Mater. Sci. Eng. B 184 (2014) 49–57

Effect of trifluoroacetic acid on the properties of polyvinyl alcohol and polyvinyl alcohol–cellulose composites

Highly stretchable polyvinyl alcohol (PVA) films with a strain at break of around 700% were obtained from solutions in trifluoroacetic acid (TFA). Structural and chemical analysis by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (ATR–FTIR) showed that TFA is retained by PVA via hydrogen bonds between the carboxylic acid groups and the hydroxyl groups of the polymers causing a strong plasticizing effect. Additionally, composites of PVA with cellulose could be developed using TFA as common solvent. The morphological and mechanical properties of the polymer composites could be accurately tuned by modifying the relative concentrations of the two polymers. Data from water adsorption isotherms and wetting measurements indicated that the presence of trifluoromethyl groups in PVA render the composite films relatively hydrophobic.

Optical and electrical properties of polyvinyl alcohol doped CdS nanoparticles prepared by sol–gel method

In-situ technique is used to generate cadmium sulfide nanoparticles in PVA matrix. The as-prepared films are characterized by X-ray diffraction, transmission electron microscopy, ultraviolet–visible absorption, Fourier transform infrared spectroscopy and photoluminescence measurements. Temperature dependence dark conductivity measurements are made on as-deposited PVA:n-CdS nanocomposites films in order to identify the conduction mechanism. The conduction in PVA:n-CdS nanocomposites films is temperature activated process having single activation energy. Steady state photo-conductivity and transient photoconductivity measurements with intensity are done in different temperature range. The measurement shows that PVA doped CdS is good candidate for photovoltaic devices.

Morphology and properties of poly vinyl alcohol (PVA) scaffolds: Impact of process variables

Successful engineering of functional biological substitutes requires scaffolds with three-dimensional interconnected porous structure, controllable rate of biodegradation, and ideal mechanical strength. In this study, we report the development and characterization of micro-porous PVA scaffolds fabricated by freeze drying method. The impact of molecular weight of PVA, surfactant concentration, foaming time, and stirring speed on pore characteristics, mechanical properties, swelling ratio, and rate of degradation of the scaffolds was characterized. Results show that a foaming time of 60s, a stirring speed of 1000rpm, and a surfactant concentration of 5% yielded scaffolds with rigid structure but with interconnected pores. Study also demonstrated that increased foaming time increased porosity and swelling ratio and reduced the rigidity of the samples.

Preparation and Property Evaluations of Polyvinyl Alcohol (PVA)/Graphene Nanosheets (GNs) Composite Nanofibrous Mats by Using Electrospinning

This study aims to examine the influence of graphene nanosheets (GNs) on the morphology and electrical property of polyvinyl alcohol (PVA) nanofiberous mats. GNs (0.03 %, 0.05 %, 0.1 %, and 0.3 %) are added to PVA solution, and then electrospun into PVA/GNs nanofiberous mats. A viscosity measurement and electrical conductivity measurement are performed on the samples to determine their properties. The experiment results show that when the content of GNs increases from 0.1 % to 0.3 %, the fiber diameter of PVA/GNs nanofiberous mats increases from 166 nm to 239 nm, the conductivity slightly increases, but the viscosity greatly increases. An increment in viscosity causes the beads to form complete fibers, which is in line with the outcome of scanning electron microscopic (SEM) observation.

Synthesis and photoluminescence enhancement of PVA capped Mn2+ doped ZnS nanoparticles and observation of tunable dual emission: A new approach

This paper reports the enhanced photoluminescence (PL) property of polyvinyl alcohol (PVA) capped Mn2+ doped ZnS nanocrystals prepared by chemical precipitation method. The surface-modified Mn2+ doped ZnS nanocrystals resulted in the multi-color property. The morphology and crystallite size were characterized by field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) techniques. The crystallite size was estimated to be 5nm from HRTEM and calculated as 2–4nm from peak broadening of the X-ray diffraction (XRD) pattern with cubic zincblende structure. Increase in the band gap with decrease in the crystallite size was observed from the UV–visible absorption spectrum, which confirms the quantum confinement effect. The room temperature photoluminescence (PL) emission measurements revealed the presence of blue (427nm) and near IR reddish–orange (752nm) emission bands in addition to the typical yellow–orange (585nm) bands in all the Mn2+ doped samples, which were attributed due to transition within the 3ds configuration of Mn2+ ions incorporation in ZnS host under UV excitation at 320nm. As far as we know, the reddish–orange bands at 752nm near IR region along with the blue and yellow–orange colored PL are reported for the first time. In this way, the PL color from these ZnS nanocrystals can be tuned from UV to near infrared region (IR). The synthesized ZnS:Mn NPs can be further functionalized for using them as biolabels.

Dissolution behavior of poly vinyl alcohol in water and its effect on the physical morphologies of PLGA scaffolds

Presented are data from a study of the aqueous properties of Poly Vinyl Alcohol (PVA), a well studied emulsifying agent, used in the preparation of biodegradeable Poly (DL-Lactide-Co-Glycolide) (PLGA) scaffolds/microparticles in water. How these properties affect the physical morphologies of PLGA scaffolds/microparticles produced from the various PVA solutions at different concentrations via the water emulsion synthetic method were also evaluated. UV-Visible absorbance measurements showed a quantitative correlation between the estimated concentrations of PVA used in solution preparations and the actual concentrations in solution. The physical appearance/morphologies of the PLGA scaffolds produced from the different PVA solutions were the same irrespective of the concentration used.

Effect of sodium alginate modification of graphene (by ‘anion-π’ type of interaction) on the mechanical and thermal properties of polyvinyl alcohol (PVA) nanocomposites

Layered aligned dispersion of graphene in graphene/polyvinyl alcohol (PVA) nanocomposites is prepared in the form of films through simple solution processing route. The results indicate that there exist an interfacial interaction between PVA and graphene because of hydrogen bonding. This is responsible for the change in structure of PVA (such as decrease in the level of crystallization) and exhibiting ductile PVA nanocomposite film with improved tensile modulus, tensile strength, and thermal stability. Moreover, to improve the mechanical properties of PVA nanocomposites, graphene is successfully modified using a non-covalent modifier, sodium alginate (SA) and there exist an ‘anion-π’ type of interaction in between SA and graphene. The modification results in finer dispersion of the graphene in PVA/SA-m-graphene nanocomposites. In addition, there exist a hydrogen bonding in between PVA and SA. This has resulted in the remarkable improvement in mechanical properties of PVA/SA-m-graphene nanocomposites as compared to pure PVA and PVA/graphene nanocomposites. The increase in mechanical properties of PVA/SA-m-graphene nanocomposites is achieved through better load transfer from graphene to polymer matrix, despite decrease in crystallinity of PVA. Improvement in tensile modulus and tensile strength is highest at 0.5 wt.% of SA-modified graphene in PVA/SA-m-graphene nanocomposites because of finer dispersion of graphene and is 62 and 40% higher than that of pure PVA. Addition of SA-modified graphene also improves the thermal stability of PVA/SA-m-graphene nanocomposites remarkably as compared to unmodified graphene PVA nanocomposites.

Investigation of nanolevel molecular packing and its role in thermo-mechanical properties of PVA–fMWCNT composites: positron annihilation and small angle X-ray scattering studies

Carbon based nanofillers have shown phenomenal improvements in thermo-mechanical properties of poly vinyl alcohol (PVA) based nanocomposites depending on their interaction with PVA molecules and dispersion in the polymer matrix. In the present study, PVA based nanocomposites with amino-functionalized multi-wall carbon nanotubes (fMWCNTs, 0.2, 0.4, 0.8 and 1.0 wt%) were prepared by a simple casting method from aqueous solution. The relative increase in Young's modulus with 0.4% fMWCNTs was observed to be comparable with that for PVA-nanodiamond composite films which have been shown to have higher strength compared to nanotube and graphene oxide based nanocomposites. In order to investigate the nanolevel molecular packing (sub-nano level free volumes and nano level lamellar structure) and its role in thermal and mechanical properties, positron annihilation spectroscopy and small angle scattering have been used. The crystallinity and morphology of the samples were characterized using X-ray diffraction and scanning electron microscopy. The studies showed that interfacial interaction between PVA molecules and functionalities on the surface of fMWCNTs results in the formation of an ordered structure of PVA molecules which enhances load transfer between the PVA matrix and fMWCNTs leading to improved mechanical properties. The thermal properties of the composites were observed to be unaffected at the studied filler concentration.

Research on Miniature Thermoplastic Processing of Polyvinyl Alcohol Based Nanocomposites

This paper discusses the synthesis and preparation of polyvinyl alcohol based nanocomposites through the use of miniature thermoplastics processing technology. It studies the influence of different process conditions, the amount of raw materials and water on the processing performance, tensile strength and elongation at break of polyvinyl alcohol based nanocomposites. Studies have shown that using two miniature thermoplastic processes does not have much influence on the mechanical properties of polyvinyl alcohol based nanocomposites, different amount of polyvinyl alcohol will lead to enhancement of the tensile strength of the polyvinyl alcohol based nanocomposites system by the increasing amount of glycerin, and the water content has a great influence on the performance of polyvinyl alcohol based nanocomposites. To this end, according to the analysis of experimental results, it can obtain preparation conditions and influencing factors of polyvinyl alcohol based nanocomposites with the miniature thermoplastic processing conditions, and provide a new theoretical method and means for nanocomposites.