Poly Vinyl Acetate Blends Research Articles

Spatial Variations in Hydrogen Bonding Interaction within Polymer Blends Revealed by Infrared Nanoimaging.

Hydrogen bonding plays a crucial role in enhancing the miscibility of polymer blends, allowing for the tailoring of their physicochemical properties to meet diverse application demands. However, nanoscale imaging of its impact on the phase-separation behavior of multicomponent polymeric materials remains largely unexplored. In this work, we introduce scattering-type scanning near-field optical microscopy (s-SNOM) equipped with a broadly tunable quantum cascade laser as a tool for investigating spatial variations in hydrogen-bonding interactions within blends of polyvinyl acetate (PVAc) and polyvinylphenol (PVPh), spin-coated from tetrahydrofuran solution. Our multiwavelength s-SNOM imaging approach reveals distinct features, namely, the hydrogen bonding mediated miscible PVAc/PVPh blend and the phase-separated PVAc domain. These results provide a more detailed understanding, indicating that hydrogen bonding may not lead to a completely uniform blend throughout the film, as previously believed, based on far-field spectroscopy. Furthermore, through comparisons between topography and near-field images, we find that the PVAc/PVPh hydrogen-bonded domain exhibits a strong affinity for the Si surface with its native oxide, while the free (non-hydrogen-bonded) PVAc film is vertically phase-separated atop the blend. Overall, our work demonstrates that s-SNOM is an effective and efficient tool for studying intermolecular interactions relevant to various chemical and biological phenomena.

Preparation and Characterization of New Phase Change Materials Based on PTLA / PVAc Blends

The role of phase change materials in energy storage and heat regulation has attracted more and more attention in recent years. PTLA, as a new biodegradable polyester polymer material obtained by the copolymerization of lactic acid and propylene carbonate showed us an appropriate phase transition temperature around 10 °C and the large phase transition enthalpy of about 50 J/g. In this manuscript, PTLA and traditional polymer of polyvinyl acetate (PVAc) were used to prepare novel phase transition materials by physical blending. And the blending compounds showed us the phase transition temperature in the range from 0 °C to 30 °C and the phase transition enthalpy in the range from 50 J/g to 78 J/g. Else, the thermal stability and blending compatibility were also studied in details, by Thermogravimetric analysis and scanning electron microscopy respectively.

CHARACTERIZATION OF SYNTHESIZED POLYMERIC BLEND MEMBRANES ENHANCED BY METHYL DIETHANOLAMINE FOR EFFICIENT CO2 SEPARATION

The limited performance of pure glassy and rubbery polymeric membranes for natural gas purification are due to their intrinsic properties. Optimizing their properties by blending both polymers are expected to address the shortage. The foremost objective of this research is to synthesis enhance polymer blend membranes (EPBM) using glassy polysulfone (PSU) and rubbery polyvinyl acetate (PVAc) with the addition of amine for carbon dioxide (CO2) removal from methane (CH4). The EPBM were developed by varying the composition of PVAc ranging from 5 to 20 wt. % with 95 to 80 wt. % base PSU in dimethylacetamide (DMAc) solvent. The amines composition was added to the blend and kept at 10 wt. % over solvent. The findings showed good miscibility between PSU and PVAc blends and the original functional groups of polymers and amines were shown by FTIR with very few spectral peak shifts. The synthesized EPBM were found to have homogenous surfaces and a packed bed sphere structure as shown by FESEM images. Increasing the composition of PVAc from 5 to 20 wt. % has significantly reduced the glass transition temperature (Tg) of PSU from 185.09oC to 155.75oC.

Antimicrobial property and water-triggered release characteristics of zinc sulphate-polyvinyl acetate adhesive blend

Water-triggered antimicrobial blends are beneficial in inhibiting the growth of microorganisms in moist environment. In this study, zinc sulfate polyvinyl acetate blend was fabricated by mixing polyvinyl acetate adhesive to zinc sulfate solution. Zinc sulfate served as the antimicrobial component while polyvinyl acetate adhesive served as the binder and water soluble component. White and translucent blends are produced in the study. The results of Disc Diffusion method showed that the zinc sulfate polyvinyl acetate blend has an antimicrobial property against Escherichia coli. Conductivity measurements show that the conductivity increases through time due to the release of zinc ions in water. Results show that the sample with higher amount of zinc sulfate solution has higher saturation conductivity and longer saturation time. Lastly, color analysis shows that the transmittance of the samples decreases as the amount of ZnSO4 solution added in the blend increases.

Polymer bilayers with enhanced dielectric permittivity and low dielectric losses by Maxwell–Wagner–Sillars interfacial polarization: Characteristic frequencies and scaling laws

ABSTRACTAn efficient approach to obtain polymeric materials with high permittivity values and low dielectric losses is presented in the current study. For this purpose, dielectric measurements by means of broadband dielectric spectroscopy, numerical simulations, and analytical calculations have been carried out for bilayer structures consisting in an insulating and a conductive polymer layer. Polyethyleneterephtalate and polytetrafluoroethylene have been used as insulating layers while, as conductive materials, blends of polyvinyl acetate with an ionic liquid, 1‐butyl‐3‐methylimidazolium tetrafluoroborate. The dielectric properties of the samples have been investigated in a broad frequency (from 10−1 to 107 Hz) and temperature range in order to determine, through the analysis of the scaling laws governing the interfacial polarization effects, the characteristic frequency ranges and the amplitude of the enhanced permittivity. An excellent agreement is found between the experimental results, the numerical simulations, and the analytical calculations. Finally, we show that bilayer polymeric materials with permittivity values as high as ε′ = 556 and with low dielectric losses (tan(δ) = 0.001) can be readily obtained by the current approach. This could have multiple applications, especially in the field of organic electronics. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47551.

Thermal and structural analysis of silk–polyvinyl acetate blends

Bombyx Mori silk and polyvinyl acetate (PVAc) were combined in different ratios to form protein–synthetic polymer blend films. The effect of silk content on PVAc blends was investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). SEM images revealed that silk and PVAc in different ratios can form a homogeneous morphology. FTIR spectra suggested structural changes in the films such as the formation of beta-sheet crystals with the increase of PVAc content in the blends. A single glass transition temperature for each blend was found in DSC curves, indicating that a good miscibility existed in the blends. These protein–polymer blend films may be useful for a variety of applications in materials and biomedical fields.

The effect of nano-TiO2 and SiO2 on bonding strength and structural properties of poly (vinyl acetate) composites

Abstract Polyvinyl acetate (PVAc) is a thermoplastic polymer widely used in the furniture industry. It has many advantages such as easy processing, cheap, biodegradable; but, resistance to water and hot medium is not enough to the application area. In this study, the effect of nano-TiO 2 and nano-SiO 2 on bonding performance and structural properties of PVAc were investigated. Bonding strength with block shear test and structural properties with thermogravimetric analysis-TGA, X-ray diffraction-XRD, and transmission electron microscopy-TEM of PVAc were determined. The obtained results showed that bonding strength with cooperating both TiO 2 and SiO 2 for 1% and 2% were improved. XRD and TEM results proved to be the homogenously interactions for 1% and 2% between nano fillers and matrix. TGA results showed that thermal stability of PVAc blends was largely improved.

Tanshinone IIA – loaded pellets developed for angina chronotherapy: Deconvolution-based formulation design and optimization, pharmacokinetic and pharmacodynamic evaluation

This paper put forward a deconvolution-based method for designing and optimizing tanshinone IIA sustained-release pellets (TA-SRPs) with improved efficacy in the treatment of variant angina. TA-SRPs were prepared by coating TA ternary solid dispersion immediate-release pellets (TA-tSD-IRPs) with the blends of polyvinyl acetate (PVAc) and polyvinyl alcohol–polyethylene glycol (PVA–PEG) using fluidized bed technology. The plasma concentration–time curve of TA-tSD-IRPs following oral administration as a weight function was investigated in New Zealand white rabbits. The predicted/expected plasma concentration–time curve of TA-SRPs as a response function was simulated according to the circadian rhythm of variant angina during 24h based on chronotherapy theory. The desired drug release profile of TA-SRPs was obtained via the point-area deconvolution procedure using the weight function and response function, and used for formulation optimization of TA-SRPs. The coating formulation of TA-SRPs was optimized as 70:30 (w/w) PVAc/PVA–PEG with 5% (w/w) coating weight due to in vitro drug release profile of these TA-SRPs was similar to the desired release profile (similarity factor f2=64.90). Pharmacokinetic studies of these optimized TA-SRPs validated that their actual plasma concentration–time curve possessed a basically consistent trend with the predicted plasma concentration–time curve and the absolute percent errors (%PE) of concentrations in 8–12h were less than 10%. Pharmacodynamic studies further demonstrated that these TA-SRPs had stable and improved efficacy with almost simultaneous drug concentration–efficacy. In conclusion, deconvolution could be employed in the development of TA-SRPs for angina chronotherapy with simultaneous drug efficacy and reduced design blindness and complexity.

Rheological and thermal behavior of PVAc/starch blends modified by acrylic acid

A novel plastic of polyvinyl acetate (PVAc) blended with starch was prepared in our research. Acrylic acid (AA) was added adequately in step of PVAc preparation as modifier, with emulsifier and initiator each occupied with 2.5 and 0.7 wt% of monomer. We used a capillary rheometer to evaluate rheological properties of PVAc and starch blends. The rheological behavior of the blends shows pseudoplastic and shear thinning. In this article, we also studied effects of AA content and temperature on viscosity. The results show that the viscosity of blends increased gradually as AA content increasing and it shows decreased as temperature increasing. The thermal behaviors of these materials were evaluated by differential scanning calorimetry and thermogravimetric analysis. The starch and AA content were considered to be the main influence factors. From the diagrams we concluded that the addition of adequate AA content could improve the compatibility and stability of the blends; however, the starch content was limited properly otherwise the stability of blends would be weakened. POLYM. ENG. SCI., 54:2449–2454, 2014. © 2013 Society of Plastics Engineers

Flow behaviour of polyvinyl alcohol (PVOH) modified blends of polyvinyl acetate (PVAc)/natural rubber (NR) latexes

During compounding processes, polymer latexes are mixed with various colloidal systems (in particular, PVOH) or surface-active agents to modify the flow behaviour in order to suit the manufacturing process. In this study, the flow behaviour of aqueous dispersed PVAc, NR and different mixed dispersions were investigated both in the absence and presence of PVOH as flow modifier, using an Ostwald glass capillary viscometer. The results show an almost linear decrease in the relative viscosity of the NR/PVAc dispersion mixtures in the absence of a modifier, but the presence of different amounts of PVOH gave rise to significant deviations from this behaviour. It was found that these changes in the relative viscosities are governed by a balance between the following four effects: (i) the higher mobility of the NR chains compared to those of PVAc, which generally caused a decrease in the viscosities of the dispersion mixtures; (ii) the physical adsorption of PVOH on the NR chains that slowed down the movement of these chains and caused an increase in relative viscosity; (iii) the chemical interaction between the functional groups on PVAc and PVOH that gave rise to latex thickening and increased the relative viscosity; (iv) a dilution effect which reduced the viscosity, unless counterbalanced by one or more of the other effects. Key words: Dispersion flow behaviour, viscosity, rubber latex, polyvinyl alcohol, polyvinyl acetate.

Release Behavior of Tanshinone IIA Sustained-Release Pellets Based on Crack Formation Theory

The objective of this study was to investigate the drug release mechanism and in vivo performance of Tanshinone IIA sustained-release pellets, coated with blends of polyvinyl acetate (PVAc) and poly(vinyl alcohol)-poly(ethylene glycol) (PVA-PEG) graft copolymer. A formulation screening study showed that pellets coated with PVAc-PVA-PEG at a ratio of 70:30 (w/w) succeeded in achieving a 24 h sustained release, irrespective of the coating weight (from 2% to 10%). Both the microscopic observation and mathematical model gave further insight into the underlying release mechanism, indicating that diffusion through water-filled cracks was dominant for the control of drug release. In vivo test showed that the maximum plasma concentration of sustained-release pellets was decreased from 82.13 ± 17.05 to 40.50 ± 11.72 ng mL as that of quick-release pellets. The time of maximum concentration, half time, and mean residence time were all prolonged from 3.80 ± 0.40 to 8.02 ± 0.81 h, 4.28 ± 1.21 to 8.18 ± 2.06 h, and 8.60 ± 1.59 to 17.50 ± 2.78 h, compared with uncoated preparations. A good in vitro-in vivo correlation was characterized by a high coefficient of determination (r = 0.9772). In conclusion, pellets coated with PVAc-PVA-PEG could achieve a satisfactory sustained-release behavior based on crack formation theory.

Characterization and gas permeability of polyurethane and polyvinyl acetate blend membranes with polyethylene oxide–polypropylene oxide block copolymer

Blend membranes of polyurethane (PU) and polyvinyl acetate (PVAc) were prepared in the presence of various polyethylene oxide–polypropylene oxide–polyethylene oxide triblock copolymer (Pluronic) contents by solution casting technique with N,N-dimethylformamide as solvent. The blends with 5% (wt) PVAc showed higher CO2 permeability (≈73Barrer) compared to the PU membrane. The domain size of the dispersed PVAc phase of PU/PVAc blend membranes was controlled by adding the Pluronic. When the Pluronic was added at 0.5–2parts per hundred of PU/PVAc blend (phr) in PU/PVAc membranes in the range of the PVAc content of 5–15% (wt), the domain size of the dispersed phase was reduced markedly and its permeability was consequently increased. In the blend membranes with 2–4phr Pluronic contents an enhancement of CO2/CH4 (α≈33) and CO2/N2 (α≈97) selectivities was observed. According to thermal analysis, these results were attributed to the presence of ethylene oxide–propylene oxide units which increase CO2 permeability and to a decrease of crystallinity in PU/PVAc blends. The experimental permeabilities of the blends were compared with the calculated permeabilities based on modified additive logarithmic model.

Combined XPS and contact angle studies of ethylene vinyl acetate and polyvinyl acetate blends

In this study, we prepared thin films by blending ethylene vinyl acetate copolymers (EVA) containing 12–33 (wt.%) vinyl acetate (VA) with polyvinyl acetate (PVAc) and high density polyethylene homopolymers. Large area micropatterns having controlled protrusion sizes were obtained by phase-separation especially for the PVAc/EVA-33 blends using dip coating. These surfaces were characterized by XPS and contact angle measurements. A reasonably linear relation was found between the VA content on the surface (wt.%) obtained from XPS analysis and the VA content in bulk especially for PVAc/EVA-33 blend surfaces. PE segments were more enriched on the surface than that of the bulk for pure EVA copolymer surfaces similar to previous reports and VA enrichment was found on the EVA/HDPE blend surfaces due to high molecular weight of HDPE. Water θ e decreased with the increase in the VA content on the blend surface due to the polarity of VA. A good agreement was obtained between γ s − and atomic oxygen surface concentration with the increase of VA content. The applicability of Cassie–Baxter equation was tested and found that it gave consistent results with the experimental water contact angles for the case where VA content was lower than 55 wt.% in the bulk composition.

Improving performance of polyvinyl acetate (PVA) as a binder for wood by combination with melamine based adhesives

In this study blending PVA with MUF and MF was evaluated as an approach to enhance the performance of PVA towards water and elevated temperatures. MF and MUF were added to PVA at different proportions: 15%, 30%, 50%, 70% and 100%. Blends of PVA with MF and MUF were used as adhesives to bond wood joints. The shear strength of wood joints was measured at dry and wet states, and elevated temperatures. Thermogravimetric analysis was used to study thermal stability of PVA and its blends with MF and MUF. The structural changes caused by the inclusions were characterized by Fourier transforms infrared spectroscopy (FT-IR). The results showed that shear strength of wood joints were improved by the addition of MF and MUF to PVA in all conditions. Adding small amounts of MUF or MF (as low as 15%) enhanced the performance of wood joints towards water and elevated temperatures. The extent of improvement was sometimes so high that the strength of glue line surpassed strength of wood in wet conditions leading to wood failure rather than glue failure. MF had more effectiveness in improving shear strength of wood joints than MUF in all conditions. Thermal stability of PVA was increased by MF but the effect of MUF on thermal stability of PVA was dependent on MUF proportions and temperatures. FT-IR analyses showed that there are some chemical bonds between PVA and MF. Considering costs, effectiveness and formaldehyde emission, adding 15% MF to PVA seems the optimal proportion of MF in the PVA blends.

TVOC and formaldehyde emission behaviors from flooring materials bonded with environmental-friendly MF/PVAc hybrid resins

Polyvinyl acetate (PVAc) was added as a replacement for melamine-formaldehyde (MF) resin in the formaldehyde-based resin system to reduce formaldehyde and volatile organic compound (VOC) emissions from the adhesives used between plywoods and fancy veneers. A variety of techniques, including 20-l chamber, field and laboratory emission cell (FLEC), VOC analyzer and standard formaldehyde emission test (desiccator method), were used to determine the formaldehyde and VOC emissions from engineered flooring bonded with five different MF resin and PVAc blends at MF/PVAc ratios of 100:0, 70:30, 50:50, 30:70 and 0:100. Although urea-formaldehyde (UF) resin had the highest formaldehyde emission, the emission as determined by desiccator method was reduced by exchanging with MF resin. Furthermore, the formaldehyde emission level was decreased with increasing addition of PVAc as the replacement for MF resin. UF resin in the case of beech was over 5.0 mg/l, which exceeded E2 (1.5-5.0 mg/l) grade. However, MF30:PVAc70 was <or=E1 (below 1.5 mg/l) grade. Because formaldehyde emission is caused by formaldehyde-based resin, the engineered floorings bonded with PVAc only had emissions of just 0.25 mg/l. The results of formaldehyde emission by the 20-l small-chamber and FLEC methods showed a similar tendency with those from the desiccator method. After the replacement of UF resin by MF resin, PVAc addition further reduced formaldehyde emission. With increasing installation time, formaldehyde emission factors (EFs) were decreased. Furthermore, the results of the desiccator method correlated with those of the 20-l chamber and FLEC methods. VOC emission results by 20-l small-chamber and FLEC methods were similar to the formaldehyde and aldehyde emission results. VOCs were calculated between C6 and C16 as total VOC (TVOC). The TVOC EF results by 20-l small-chamber and FLEC methods were comparable with that of formaldehyde emission by FLEC. Although the major emitted harmful gas from wood-based composites was formaldehyde, it was followed by VOC emission. Although it was hard to compare directly the 20-l chamber and FLEC results because the data were based on the sum of only four VOC compounds, the VOC analyzer can be applied as a pre-test method for TVOC emission test. The TVOC emission results were also similar to the FLEC results. Due to its good correlation with the TVOC emission levels obtained from the standard desiccator, FLEC and 20-l chamber methods, the VOC analyzer can be successfully applied to the measurement of TVOC emissions from adhesives used in building materials. This paper presents TVOC and formaldehyde emission behaviors from the engineered floorings that used in Korean housing recently. To reduce emissions, MF/PVAc hybrid resins were used as bonding material. Normally, TVOC and formaldehyde emissions in indoor conditions are caused by interior materials. The results explained 'materials control' of interior materials are the first way to improve indoor air quality. There is a need to study about environmental-friendly materials for solving indoor air quality problem.

Investigation into new materials for optical devices: the miscibility and solvent effects of azobenzene derivative blends

AbstractWith the increasing demand for novel devices with optical applications the search for new materials to data store and process becomes a priority. By introducing blends, tailor made properties and low cost give added advantage. Miscibility is an essential requirement for a new material, this research thus involves miscibility studies of poly(4‐(N‐(2‐methacryloyloxyethyl)‐N‐ethylamino)‐4′‐nitroazobenzene)90‐co‐(methyl methacrylate)10, (azobenzene derivative) with polymethyl‐methacrylate (PMMA), polyvinylacetate (PVAc) and polyvinylchloride (PVC) prepared in tetrahydrofuran (THF), and/or dimethylformamide (DMF) and/or dichloromethane (CH2Cl2). The glass transitions, solvent and varying molecular weight effect were investigated, since these all primarily influence the miscibility. THF was found to encourage miscibility at specific compositions of PVAc and PVC blends. However, with CH2Cl2 and DMF immiscibility is encouraged. The Fox–Flory equation was applied to the blends analyzing the PVC blends in DMF as deviations from ideality. Different molecular weights of PMMA were identified as immiscible regardless of solvent. PMMA's lower solubility in THF and CH2Cl2 compared to the azobenzene derivative, displayed the existence of PMMA islands. In all blends the favorable and unfavorable interactions between polymer–solvent–polymer systems are considered. Furthermore, the miscibility effect on increasing the MMA content of the azobenzene derivative was also investigated. Copyright © 2002 John Wiley &amp; Sons, Ltd.

The shrinkage compensation of unsaturated polyester resins — polyvinyl acetate blends polymerization proceeds through fractal morphologies: characterization and simulation

Blends of unsaturated polyester, styrene and polyvinyl acetate are hot cured either between glass plates or under pressure in a molding simulator. The morphologies of the products are observed using microscopy and show their usual aspects. They are characterized according to fractal concepts by image processing; the influence of mixture composition, pressure and temperature is investigated. Based on the hypothesis that phase separation governs the shrinkage compensation, a computer simulation of the fissuration phenomenon is performed using the diffusion limited agregation (DLA) model. This fractal model gives realistic results, and is used to show the effect of network parameters on the fissures fractal dimensions.

Compatibility studies on solution of polystyrene and polyvinyl acetate blend by density and viscometric methods

Density and viscometric studies were conducted on solutions of blends of polystyrene (PS) and polyvinyl acetate (PVAc) at 30 °C in toluene, methyl ethyl ketone (MEK) and tetrahydrofuran (THF) at 2% total solid content. Experimental densities of the blends were found to be lower than the calculated values assuming additivity of volumes of polymers and solvent. The plots of relative viscosity ( η rel) with compositions are of the S-type, indicating two-phase formation with reversal of phases at intermediate compositions. Comparison of the calculated (using the Krigbaum-Wall equation for both solvents) and observed intrinsic viscosities shows higher calculated values. Data obtained using all solvents are similar, implying that polymer-polymer interactions are dominant over polymer-solvent interactions. The three solvents were chosen based on their ability to dissolve the two polymers and because they differ in both structure and properties. Results obtained show that the versatility of viscometric techniques and density measurements is not affected by the choice of solvent. The results suggest that PS and PVAc are incompatible.

Transient currents in discharge mode in cellulose acetate: polyvinyl acetate blend films

The transient currents measured in discharge mode with cellulose acetate (CA): polyvinyl acetate (PVAc) blend films (≈ 20µm thick) as a function of charging field [(1.5–4.5)×104 V/cm], temperatures (323–373 K) and polymer weight ratio (90:10 and 75:25) have been found to follow Curie-von Schweidler law, characterized with two slopes in short and long time regions. Isochronals characteristics (i.e. current/temperature plots at constant times) constructed from these data seemed to reveal a broad peak observed at 363 K. Values of activation energy increase with PAVc content and also with time of observation. Space charge due to trapping of injected charge carriers in energetically distributed traps and induced dipoles created because of the piling up of charge carriers at the phase boundary of heterogeneous structure of blend are considered to account for the observed currents.