PVA Component Research Articles

Characterization of polyvinyl alcohol-nanocellulose composite film and its release effect on tetracycline hydrochloride

Desmodium intortum(Mill.) Urb. is an important source of organic fertilizers, but its utilization value has not been developed favorably. The utilization of polyvinyl alcohol is optimized, combined with the film-forming properties of polyvinyl alcohol, to prepare a high-quality composite film. When the nanocellulose content reached 0.8 %, the tensile stress reaches the maximum value, and the composite film is not easily torn. The addition of NCC reduces the crystallinity of the PVA component and increases the initial decomposition temperature of the alcohol-nanocellulose composite film. The thermal decomposition rate of the PVA/NCC composite film is slightly lower than that of the pure PVA film, indicating that the addition of NCC improves the heat resistance of the PVA film. The electron microscope results show that PVA has good compatibility with NCC. The release results of tetracycline hydrochloride showed that when the nanocellulose content reached 0.8 %, the loading rate reached 83.07 %. R2 value of the two materials is 0.99 under the zero-order model fitting, which suggest the release process is transported by Supercase-II transport kinetics. Through the inhibition zone and cytotoxicity, it is proved that this material has a certain bacteriostatic effect and good cytocompatibility.

Optimization of thermo - physiological properties of structurally modified wool/polyester blended fabrics using desirability function

The thermo-physiological properties of handloom fabrics produced with or without modified wool/polyester yarns in the weft has been studied. Yarn samples at different blend compositions are prepared according to mixture design at a different percentage of fibres using design expert software. The effect of percentage of different fibres, namely polyester, wool and PVA, on different thermo-physiological properties along with fabric properties obtained for different fibres after the dissolution of PVA component at yarn stage or fabric stage have also been studied. This paper also reports the potential of different fibres optimization to achieve maximum desirability for different thermo-physiological properties of treated (at yarn stage and fabric stage) and untreated fabrics with the help of desirability function. Treated fabrics at both stages show better thermo-physiological comfort properties as compared to untreated fabrics. In general, after dissolution of the PVA component both at the yarn stage or at the fabric stage, the treated fabric gives a higher value of thermal resistance, compressibility, drying capacity and water vapour permeability, while a lower value of air permeability and bending rigidity in comparison with untreated fabrics. Results of optimization for treated (at yarn stage and fabric stage) fabrics show higher overall desirability that can be achieved by using less percentage of wool fibres in case of treated fabrics (either at yarn stage or fabric stage).

Characterization of dual nano-size effects of ACC-cellulose nanofibrils on crystallization behavior of hydrophilic poly(vinyl alcohol)

This study attempts to clarify thermodynamic quantification on interaction between poly(vinyl alcohol) (PVA) and wood-derived cellulose nanofibrils (CNFs) obtained by aqueous counter collision (ACC) method. Aqueous mixtures of PVA/ACC-CNFs with various fiber widths were cast as the target materials. The interfacial interactions between the two components were characterized through thermodynamic evaluation of the crystalline PVA component as a probe in the cast mixture. As the result, surface properties of the ACC-CNFs found to reflect on the crystallization behavior of the interacted PVA component, resulting in dual nano-size effects of either diluent or nucleating agent. Melting point depression behaviors of the PVA component indicated that ACC-CNFs with thinner widths induced nucleation effects on PVA crystallization, whereas ACC-CNFs with ca. 100 nm in width encouraged diluent effects on PVA components. It is noted that this trend found to be reverse to the case for PVA/ACC-CNFs of bacterial nanocellulose previously reported.

Fabrication of flexible SiO2 nanofibrous yarn via a conjugate electrospinning process

Abstract Nowadays, different kinds of polymers, including ceramics, are electrospun into fibrous materials with different structures by electrospinning. Generally, the as-spun ceramic fibers are randomly oriented membranes and brittle without flexibility. Here, we report the fabrication of flexible SiO2 electrospun yarns using poly(vinyl alcohol) (PVA) as a template through a conjugate electrospinning process and calcination. It was found that the calcined as-spun fibers and yarns are obviously thinned with PVA component removal. Fourier transform infrared spectroscopy and energy-dispersive spectroscopy examinations suggested that the obtained yarn after calcination was SiO2 yarn. The SiO2 yarn showed good flexibility without cracking after 180° bending. The flexible ceramic yarn may have potential application in functional textiles.

Characterization of newly developed void raw silk fabrics in comparision with raw silk fabrics

CSTRI has developed new technology for the production of void raw silk in reeling process. In this technology, the cocoons were reeled along with PVA yarn as core, which is termed as void silk, since PVA component would be dissolved subsequently. Three types of raw silk yarns were produced by maintaining 10, 20, 30 cocoons per end and with same cocoons with PVA yarn as core. These yarns were utilized for the production of fabrics in power looms with bivoltine silk as warp and raw silk/void silk as weft. After weaving the fabrics, the fabric samples were degummed and dyed using reactive dyes in HTHP dyeing machine, wherein, the PVA component as well as sericin were dissolved so as to create hollowness in the fabrics and showed an improvement in various fabric properties viz., fabric thickness, cover factor, crimp, crease recovery, drape, tensile properties etc. The void silk fabrics has unique appearance on the surface compared to regular silk fabrics and can be utilized for children wear and ladies dress materials for niche market.

Optimization of Structurally Modified Wool/Polyester Blended Yarns Using Desirability Function

Fibers are structural unit of a staple yarn, and its properties influence the properties of yarn. Structural modification through selective removal of component opens further scope of application. Yarns were prepared according to the mixture design for different fibers using design expert software. The effect of composition and selective removal of PVA on yarn properties has been reported. The potential of different fibers optimization to achieve maximum desirability for different properties of yarn for treated and untreated yarns with the help of desirability function has also been reported. It has been observed that dissolution of PVA component led to an increase in compressibility and reduction in packing fraction. Results of optimization for treated and untreated yarns show that almost same overall desirability can be achieved by using lower percentage of wool fiber in the case of treated yarn.

Fabricating ternary hydrogels of P(AM-co-DMAEMA)/PVA/β-CD based on multiple physical crosslinkage

Ternary hydrogels composed of poly[acrylamide-co-2-(dimethylamino)ethyl methacrylate] [P(AM-co-DMAEMA)], poly(vinyl alcohol) (PVA) and β-cyclodextrin (β-CD) were fabricated based on the multiple physical interactions such as inclusion complexation, hydrogen bonding and polymer crystallinity, and exhibited high storage modulus. To illustrate the individual role of each physical interaction, symmetrical investigation has been performed. P(AM-co-DMAEMA)s with two compositions, prepared by radical polymerization at −20 °C below the freezing point of reaction medium of water, were served as the inclusion guest for the inclusion host of β-CD. The inclusion complex between dimethylaminoethyl group of DMAEMA and β-CD was identified through 2D NOESY NMR spectroscopy. Hydrogen bonding between each pairs of hydrogel components was confirmed with FTIR analysis and contributed the second form of crosslinkage. Under freezing polymerization and further freezing-thawing treatment, PVA component tended to crystallize to serve as the third type of physical crosslinkage, which was recognized with X-ray diffraction. Rheological and thermo-gravimetrical analysis was used to inspect the modulus and thermal stability of the hydrogels, respectively. Three hydrogels of P(AM-co-DMAEMA)/PVA-g-β-CD, P(AM-co-DMAEMA)/PVA/β-CD and P(AM-co-DMAEMA)/PVA were synthesized under the same condition to make the comparison. The whole results disclosed the strong dependence of hydrogel properties on the hydrogel components, reflecting the synergistic effects of different physical crosslinkages for the formation of those physical hydrogels.

Facile fabrication of PVA composite fibers with high fraction of multiwalled carbon nanotubes by gel spinning

Poly(vinyl alcohol) (PVA) composite fibers with high fraction of multiwalled carbon nanotubes (MWCNTs) were prepared by gel spinning process. Here, a modified process was introduced to prepare concentrated PVA/MWCNTs/DMSO spinning dope, and to attain good dispersion of MWCNTs in the fibers. The final composite fibers were studied by thermogravimetric analyzer (TGA), Fourier transform infrared spectrometer (FTIR), Raman spectroscopy, differential scanning calorimetry (DSC), and WAXD analysis. The total content of MWCNTs in PVA composite fibers, from 5 to 30 wt%, was confirmed by TGA analysis. FTIR and Raman measurements demonstrated the existence of strong hydrogen interaction between MWCNTs and PVA matrix. SEM images of composite fibers showed smooth surface, regular cross‐section shape and good dispersion of MWCNTs in the fibers. DSC analysis showed that the crystallinity first increased and then decreased with the increase of MWCNTs contents. It can be concluded that low concentration of MWNCTs can act as nucleation sites for crystallization of PVA component, and large amount of MWCNTs may impede the crystallization of PVA component. The WAXD analysis results indicated that the crystal orientation of the PVA component in PVA composite fibers is almost identical at the same drawn ratio. Polarized Raman analysis indicated a small increase in MWCNTs orientation for the composite fibers. The mechanical properties tests showed that the composite fibers exhibit significant improvement in tensile strength and modulus as compared to the neat PVA fibers. The composite fibers also showed sustained growth in electrical conductivity. POLYM. ENG. SCI., 58:37–45, 2018. © 2017 Society of Plastics Engineers

Fabrication and properties of polyvinyl alcohol/starch blend films: Effect of composition and humidity

In this work, starch/polyvinyl alcohol (PVA) blend films with different compositions were prepared by melt processing. The effect of the composition and relative humidity (RH) on the structure and properties of the resulting blends were investigated. OH groups on starch and PVA formed hydrogen bonding interactions, which could improve the compatibility of the two components. With the increase of starch, the degree of crystallinity of PVA component decreased. The fracture surface of the blend films exhibited rough surface, suggesting the tough fracture. With the increase of starch, the water uptake at equilibrium decreased. With the increase of RH, the water uptake at equilibrium of the resulting blends increased. The tensile strength, elongation at break and Young’s modulus decreased with increasing content of starch. However, at 50% starch content, the flexibility of the blend films was still high, with the elongation at break more than 1000% and tensile strength of 9MPa, which was superior to the commonly LDPE package films. The tensile strength and Young’s modulus decreased with the increase of RH, while the elongation at break was enhanced dramatically, indicating the improved flexibility. Therefore, these kinds of blend films exhibited wide application potentials as packaging materials.

Estimation of pore size and porosity of modified polyester/PVA blended spun yarn

The performance of a textile material depends on the arrangement of its constituent fibres. For good mechanical behaviour strong inter fibre cohesion is necessary. In order to impart comfort characteristics, a permeable structure is desired. Staple fibre, by virtue of its limited length and other constraints, cannot produce fully compacted structure. For an optimum performance, a balance between the permeable and cohesive characteristics is necessary. An estimation of the openness of the structure may help in designing product for specific requirement. The degree of openness, however, may be varied through necessary modifications during and post manufacturing stage. In the present study empirical relations have been developed to calculate the equivalent pore diameter and porosity for three different modes of packing in yarns. Theoretical calculation was done for all three possible modes of packing while the experimental evaluations were made using the cross sectional images. The change in pore size and porosity were also estimated for a polyester/PVA blended yarn on removal of PVA component. A comparison of experimentally measured porosity was made with the results obtained theoretically. Hexagonal close packing resulted lowest porosity and experimentally measured values were in close association with the theoretically measured porosity.

Effect of urea and formamide plasticizers on starch/PVA bioblend sheets

ABSTRACTThe starch/polyvinyl alcohol (PVA) bioblend sheets containing urea and formamide as plasticizers were prepared through melt processing in presence of water. The experiments indicated that urea and formamide plasticizers could form strong hydrogen bonds with starch/PVA molecules. Urea exhibited better plasticizing effect than formamide. Urea also could greatly destroy the crystal structures of PVA component in the blends, leading to the decreased crystallinity of the blends. Formamide was a good solvent for urea and could prevent urea separating from the blends, resulting in the improved stability of plasticizing systems. The blends exhibited good flexibility. Therefore, the incorporation of both urea and formamide into starch/PVA blends could exhibit synergistic effects to ensure the blends with both good plasticizing effect and the stability of the plasticizing systems. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42311.

Formation of a tunable starch‐based network by in situ incorporation of mercapto groups and a subsequent thiol‐ene click reaction

AbstractA tunable starch‐based hydrogel was prepared by crosslinking unsaturated macromonomers in the presence of H2S. First, well‐defined poly(vinyl alcohol) (PVA) was prepared by alcoholysis of poly(vinyl acetate) obtained by reversible addition‐fragmentation chain transfer (RAFT) polymerization of vinyl acetate. Subsequently, carbon‐carbon double bonds were incorporated onto PVA through esterification with maleic anhydride. Finally, the hydrogel was formed via concurrent electrophilic addition and thiol‐ene reaction between starch maleic half‐ester, unsaturated PVA and H2S using potassium persulfate as initiator at 60 °C. Elemental analysis showed the percentage of sulfur in the gel ranged from 0.86% to 1.73%, depending on the chain length of PVA. The storage modulus, loss modulus and glass transition temperature of the networks varied from 12.7 to 50.9 MPa, from 3.7 to 15.7 MPa and from 57.0 to 71.8 °C, respectively. Both the swelling and release behavior of the gels were also modulated by changing the unsaturated PVA component. © 2012 Society of Chemical Industry

Interfacial interaction and mechanical properties of chitin whisker–poly(vinyl alcohol) gel‐spun nanocomposite fibers

AbstractNanocomposite fibers were prepared from chitin whiskers (ChWs) as the reinforcing phase and poly(vinyl alcohol) (PVA) as the matrix. Colloidal suspensions of ChWs, obtained by acid hydrolysis of chitin from crab shell, were thoroughly mixed with aqueous PVA. The homogeneous PVA–ChW suspensions were gel‐spun into a methanol coagulating bath. Wide‐angle X‐ray diffraction patterns evidenced the orientation of ChWs along the fiber axis. From differential scanning calorimetry, the crystallinity of the PVA component was found to increase with ChW loading due to the possible dragging of PVA chains adhering to ChWs during vertical extrusion. The non‐isothermal crystallization peak of PVA was observed to shift to lower temperature with ChW loading indicating interfacial interactions between PVA and ChW. Further interaction between PVA and ChW was evidenced by the shifting of the Fourier transform infrared bands of PVA to lower wavenumber and the dynamic tan δ peak, corresponding to α‐relaxation of PVA, shifting to higher temperature. The interaction of ChWs with the matrix PVA yielded a significant enhancement in the mechanical properties of the nanocomposites. Copyright © 2012 Society of Chemical Industry

Electrical Sensitivity and Mechanical Properties of Fast Responsive PAMPS–PAA‐PVA T–IPN Hydrogels

AbstractMacroporous ternary‐interpenetrating polymer network (M‐T‐IPN) hydrogels composed of poly(acrylic acid) (PAA), poly(2‐acrylamido‐2‐methyl propyl sulfonic acid) (PAMPS), and poly(vinyl acohol) (PVA) were synthesized by two steps of polymerization using PEG6000 as a pore‐forming agent. By selectively washing away the PVA component, a macroporous structure was formed homogeneously in the hydrogels. The M‐T‐IPN hydrogels exhibited excellent compressive strength, and the maximum compressive strength was about 12.0 MPa. The bending behaviors of the M‐T‐IPN hydrogels in an electric field were investigated. When deionized water swollen samples were placed between a pair of electrodes in NaCl solutions, the M‐T‐IPN hydrogels showed a significant bending behavior upon the application of an electric field. The hydrogels bend toward the cathode when the concentration of polyanions in interior hydrogels is higher than the concentration of NaCl in exterior solutions. In contrast, the hydrogels bend toward the anode when the concentration of polyanions in interior hydrogels is lower than the concentration of NaCl in exterior solutions. © 2011 Wiley Periodicals, Inc. Adv Polym Techn 32: E20–E31, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.20266

Structural changes of starch/polyvinyl alcohol biocomposite films reinforced with microcrystalline cellulose due to biodegradation in simulated aerobic compost environment

AbstractStarch/Polyvinyl alcohol (PVA) based biocomposite films reinforced with micro crystalline cellulose (MCC) (10 wt %) particles were prepared by solution casting method, incorporating glycerol as plasticizer. These biocomposite films were subjected to biodegradation at ambient temperature in a simulated aerobic compost pit. The extent of biodegradation of these films was studied in terms of weight loss. The corresponding changes in the structure of the films were observed using scanning electron microscopy, X‐Ray diffraction study, and differential scanning calorimetry. The melting point of PVA component of the biocomposite film shifted from 204 to 223°C with increase in biodegradation time and a remarkable difference was observed in their melt crystallization behavior. The unreinforced films also showed a similar trend, but the increase in the crystallinity of PVA was more pronounced in MCC reinforced films than that observed in the unreinforced ones. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.

Surface-coated fly ash reinforced biodegradable poly(vinyl alcohol) composite films: part 2-analysis and characterization

Composite films of poly(vinyl alcohol) (PVA) reinforced with 5, 10, 15, 20 and 25 wt.% surface-coated fly ash by surfactant, sodium lauryl sulphate (SLS-FA) along with 1 wt.% cross-linking agent, glutaraldehyde (GLA) were prepared by aqueous casting method. The tensile strengths of the composite films were increased proportionally with the addition of SLS-FA. The maximum 75% higher strength of the composite with 20 wt.% was achieved compared to that of neat PVA. The modulus of the composites was also increased proportionally with SLS-FA and the maximum 218% reached in composite with 20 wt.%, but the strain at break was decreased with addition of SLS-FA. Changes in FTIR spectra reflect the chemical and/or physical bonding in the ternary PVA, SLS-FA and GLA component systems. In the study of surface morphology, the connectivity was visualized in SEM images along with interstitial voids. The films with SLS-FA show 53% smoother surface calculated with AFM compared to unmodified FA composite films.

Nanoporous ultra-high specific surface inorganic fibres

Nanoporous inorganic (silica) nanofibres with ultra-high specific surface have beenfabricated by electrospinning the blend solutions of poly(vinyl alcohol) (PVA) and colloidalsilica nanoparticles, followed by selective removal of the PVA component. Theconfigurations of the composite and inorganic nanofibres were investigated by changing theaverage silica particle diameters and the concentrations of colloidal silica particles inpolymer solutions. After the removal of PVA by calcination, the fibre shape of pure silicaparticle assembly was maintained. The nanoporous silica fibres were assembled as a porousmembrane with a high surface roughness. From the results of Brunauer–Emmett–Teller(BET) measurements, the BET surface area of inorganic silica nanofibrous membranes wasincreased with the decrease of the particle diameters. The membrane composed ofsilica particles with diameters of 15 nm showed the largest BET surface area of270.3 m2 g−1 and total porevolume of 0.66 cm3 g−1. The physical absorption of methylene blue dye molecules by nanoporous silica membraneswas examined using UV–vis spectrometry. Additionally, the porous silica membranesmodified with fluoroalkylsilane showed super-hydrophobicity due to their porous structures.

Chitosan bicomponent nanofibers and nanoporous fibers

Nanofibers with average diameters between 20 and 100 nm have been prepared by electrospinning of 82.5% deacetylated chitosan ( M v = 1600 kDa) mixed with poly(vinyl alcohol) (PVA, M w = 124–186 kDa) in 2% (v/v) aqueous acetic acid. The formation of bicomponent fibers was feasible with 3% concentration of solution containing up to an equal mass of chitosan. Finer fibers, fewer beaded structures and more efficient fiber formation were observed with increasing PVA contents. Nanoporous fibers could be generated by removing the PVA component in the 17/83 chitosan/PVA bicomponent fibers with 1 M NaOH (12 h). Fiber formation efficiency and composition uniformity improved significantly when the molecular weight of chitosan was halved by alkaline hydrolysis (50 wt % aqueous NaOH, 95 °C, 48 h). The improved uniform distribution of chitosan and PVA in the bicomponent fibers was attributed to better mixing mostly due to the reduced molecular weight and to the increased deacetylation of the chitosan.

An improved hydrophilicity via electrospinning for enhanced cell attachment and proliferation

The wettability of electrospun poly(epsilon-caprolactone) (PCL) mats was improved by co-electrospinning with poly(vinyl alcohol) (PVA), by double-spinneret electrospinning method. The improved hydrophilicity of the hybrid PCL/PVA mats was confirmed by water contact angle measurement. The in vitro cell attachment on the hydrophobic PCL and hydrophilically modified PCL/PVA mats was compared by culture studies using human prostate epithelial cells (HPECs). The stability of water-soluble PVA component in the electrospun PCL/PVA mats was checked by thermogravimetric analysis and intensity of fluorescence material after immersion in water for 7 days. The images from scanning electron microscopy, field emission scanning electron microscopy, and optical microscopy showed that the attachment and proliferation rate of HPECs were improved by introducing PVA into the electrospun PCL mats.

Structural properties of γ‐irradiated poly(vinyl alcohol)/poly(ethylene glycol) polymer blends

AbstractThe effect of various doses of γ radiation on the structural properties of water‐soluble polymer blends based on poly(vinyl alcohol) (PVA) and poly(ethylene glycol) (PEG) has been investigated. Although the aqueous solutions of individual PVA and PEG homopolymers were homogeneous and clear, films transparent to visual observation were only formed by solution casting of pure PVA and those blends containing low ratios of PEG up to 30%. The structure‐property behavior of this range of blends before and after γ irradiation was investigated by light reflectance and UV absorbance, differential scanning calorimetry (DSC), IR spectroscopy, and tensile mechanical testing. The DSC thermograms of PVA/PEG blends, before or after γ irradiation, showed a solely endothermic peak over the temperature range 40–140°C, which may have arisen from the melting of the PEG component or from the glass transition of PVA/PEG as a miscible blend in accordance with those calculated on the basis of the theoretical Fox equation. Also, these thermograms did not clearly show any transition that arised from the pure PVA component. However, the improvement in tensile mechanical properties of PVA/PEG blends, the reflectance, and the optical absorption measurements support the idea of improved miscibility after γ irradiation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 167–176, 2004