Miscibility studies of sodium alginate/poly(vinyl alcohol) blend in water by viscosity,ultrasonic, and refractive index methods

The miscibility of a sodium alginate/poly(vinyl alcohol) blend in water was studied by viscosity, ultrasonic velocity, and refractive index techniques at 30, 40, and 50°C. Using the viscosity data, interaction parameters μ and α were computed. These values revealed that the blend is miscible when the sodium alginate content is more than 50% in the blend. This was further confirmed by ultrasonic and refractive index methods. It was further observed that the temperature has only a marginal effect on the miscibility of this blend. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 33–39, 2003     

Miscibility studies of epoxy/unsaturated polyester resin blend in chloroform by viscosity,ultrasonic velocity,and refractive index methods

Miscibility studies of blends of epoxy with unsaturated polyester resin in chloroform were carried out by viscosity, ultrasonic velocity, and refractive methods at 30°C. By using viscosity data, the interaction parameters were computed, which indicated that epoxy/unsaturated polyester resin blends were miscible. The miscibility was further confirmed by the ultrasonic velocity and refractive index methods. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2970–2972, 2003     

Synthesis and characterization of konjac glucomannan/poly(vinyl alcohol) interpenetrating polymer networks

Novel interpenetrating polymer networks (IPNs) coded as KP were synthesized successfully from poly(vinyl alcohol) (PVA) and konjac glucomannan (KGM) in the presence of glutaraldehyde as a crosslink agent. The transparent IPN films that were 40 μm thick were prepared by means of conventional solvent‐casting technique and dried at room temperature for 2 days. The structure and miscibility of the KP films were studied by Fourier transformed infrared spectra, scanning electron microscopy, differential scanning calorimetry, wide‐angle X‐ray diffraction, and ultraviolet visible spectroscopy (UV–Vis). The results indicated that strong intermolecular interaction caused by crosslink bonding between PVA and KGM occurred in the IPN films, resulting in wonderful miscibility when the reaction time is 4 h. The tensile strength, elongation at break, and moisture uptake was much higher than that of the pure PVA film, KGM film, and uncrosslinked blend films. In other words, the structure of IPN endowed the films with excellent performance, so the new material has promising applications to food package film and agricultural film because of its biodegradability. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2775–2780, 2004     

Synthetic absorbent for dyestuffs based on gamma crosslinked poly(vinyl alcohol) (PVA)

This work reports on the characterization and uses of gamma radiation‐crosslinked poly(vinyl alcohol) (PVA) films as absorbents for different classes of dyestuffs normally released from textile factors. Dyestuffs were selected from different producers. These dyestuffs were Remacryl Blue (basic dye), Remazol Golden Orange (reactive dye), Solar Orange (direct dye), and Sandolan (acid dye). The percentage dye sorption by PVA was determined by spectroscopic analysis and color‐strength measurements of the PVA films after absorbing the different dyestuffs. The results showed that the concentration of dimethylbisacrylamide as a crosslinking agent has a great effect on the gel fraction and percentage swelling in water of the PVA polymer. In general, crosslinked PVA showed a low tendency to absorb the different dyestuffs under investigation at room temperature. This tendency was shown to increase with an increasing temperature of the dye solution from room temperature to 70°C. Meanwhile, the highest percentage of dye sorption was found in the case of the basic dye and the lowest one in the case of the reactive dye depending on the active groups on the dyes. Moreover, the percentage dye sorption by PVA was slightly higher in the acid medium rather than in the alkaline one. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 349–354, 2003     

Molecular modeling simulations and thermodynamic approaches to investigate compatibility/incompatibility of poly(l-lactide) and poly(vinyl alcohol) blends

This paper investigates the molecular modeling simulation approaches for understanding the blend compatibility/incompatibility of poly(l-lactide), PLL and poly(vinyl alcohol), PVA. Blends of PLL/PVA have been widely used in biotechnology as well as membranes in separation science. Realizing their importance, we thought of investigating to verify experimental observations on their compatibility/incompatibility aspects by calculating thermodynamic interactions between PLL and PVA over the entire range of blend compositions. In doing so, Flory-Huggins interaction parameter, χ, was computed for different blends using atomistic simulations to predict blend miscibility. It was found that at 1:9 blend composition of PLL/PVA, miscibility was observed, but increasing immiscibility was prevalent at higher compositions of PLL component. Computed results confirmed the literature findings on differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) and mechanical property studies, suggesting the validity of modeling strategies. Plots of Hildebrand solubility parameter, δ, and cohesive energy density, CED, supported these findings. Miscibility of PLL and PVA polymers is attributed to hydrogen-bonding effect. Literature findings have been validated to understand the nature of interactions between different groups of the polymers by computing radial distribution function, RDF, for groups that are tentatively involved in such interactions, leading to miscibility or immiscibility. RDF plot was constructed to identify the exact contribution of particular atoms of polymers to confirm miscibility/immiscibility of blends. Results of this study are correlated well with the reported data. Kinetics of phase separation was examined using density profiles calculated from the MesoDyn approach to examine miscibility/immiscibility aspects of the blends. Computed free energy from the mesoscopic simulation of blends reached equilibrium, particularly when simulation was performed at higher time step, indicating the stability of the blend at certain compositions. X-ray diffraction profiles have been constructed for individual polymers as well as for their blends, which agreed well with the reported data.     

Viscosimetric study of poly(vinyl alcohol)/poly(styrenesulfonic acid) miscibility in dilute aqueous solution

The miscibility of poly(vinyl alcohol) (PVA) and poly(styrenesulfonic acid) (PSSA) in dilute aqueous solutions was studied by a viscosimetric method. At a constant molecular weight of PSSA, it was found that the miscibility of both polymers increases with the molecular weight and the number of acetate groups of the PVA samples (1 and 12% unhydrolyzed sites). Moreover, this miscibility increases slightly with the total mixture concentration in the interval 1–2 g/dL. By comparison of the results of reduced viscosity of PVA/PSSA and PVA/poly(sodium styrenesulfonate) (PSSNa) mixtures, it has been deduced that the miscibility of two polymers is due mainly to intermolecular interactions between the hydroxyl and sulfonic groups of PVA and PSSA, respectively. These groups act as acceptors and donors of hydrogen bonds which are the responsible for polymers' miscibility. © 1996 John Wiley & Sons, Inc.     

Preparation of glucose oxidase immobilized in different carriers using radiation polymerization

Glucose oxidase (EC 1.1.3.4) was immobilized on different polymeric materials using different immobilization techniques (entrapping by γ‐irradiation, and covalent binding using epichlorohydrin). Studies were carried out to increase the thermal stability of glucose oxidase (GOD) for different applications. The activity and stability of the resulting biopolymers have been compared with those of free GOD. The effect of different polyvinyl alcohol/polyacrylamide (PVA/PAAm) compositions of the copolymer carrier on the enzymatic activity of the immobilized GOD was studied. The maximum enzymatic activity was obtained with the composition ratio of PVA/PAAm of 60:40. The behaviour of the free and immobilized enzyme was analysed as a function of pH. A broadening in the pH profile (5.5–8) was observed for immobilized preparations. The activity and stability of the resulting biopolymers produced by immobilization of GOD onto different carriers have been compared, in both aqueous and organic media, with those of the free GOD. The enzyme's tolerance toward both heat and organic solvent was enhanced by immobilization onto polymers. The addition of different concentrations of organic solvents (10–50%, v/v) to the enzyme at higher temperature (60 °C) was found to stabilize the enzyme molecule. The strongest stabilizing effect on the enzymatic activity was achieved at a concentration of 10%. Copyright © 2005 Society of Chemical Industry     

Effect of different types of carbon black on the mechanical and acoustic properties of ethylene–propylene–diene rubber

The effects of the incorporation of different types of carbon black as fillers on some selected physical and mechanical properties of ethylene–propylene–diene rubber (EPDM) based compounds were studied with the results of density, ultrasonic wave velocity, and tensile measurements. Ultrasonic wave velocities (both longitudinal and shear) were measured at frequencies up to 4 MHz at room temperature. The density, ultrasonic attenuation coefficient, and tensile strength results showed that rubber mixes containing general‐purpose furnace (GPF) black at a concentration of 25 phr had the best physical and mechanical properties. These results were interpreted to be due to the better compatibility of GPF black, which, because of its particle size and structure, filled the interstitial spaces in EPDM and provided better reinforcement of the elastomer. The use of a nondestructive technique such as ultrasonic measurement presents a new possibility for testing rubber and plastic products more efficiently. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Dynamic–Mechanical Properties of Bioartificial Polymeric Materials

Bioartificial polymeric materials represent a new class of polymeric materials based on blends of synthetic and natural polymers, designed with the purpose of producing new materials with enhanced properties with respect to the single components. The mechanical properties of bioartificial materials prepared using poly(vinyl alcohol) (PVA), poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA) as synthetic components, and collagen (SC), gelatin, starch, hyaluronic acid (HA) and dextran as biological components, were investigated by dynamic mechanical thermal analysis. The materials were prepared in the form of films or hydrogels and treated by glutaraldehyde (GTA) vapour or thermal dehydration in order to reduce their solubility in water. The results indicate that SC/PVA, gelatin/PVA and starch/PVA films behave as biphasic systems, showing good mechanical properties over a wide range of temperature. It was observed that the GTA procedure affects only the biological component of the SC/PVA and gelatin/PVA blends, whilst the thermal treatment influences mainly the synthetic polymer. In the case of HA/PVA hydrogels, a modulus variation was found with the HA content related to the organization degree and perfection of the PVA network structure. It seems evident that, in the experimental conditions used, dextran/PAA mixtures behave as miscible blends showing a glass transition intermediate between those of the pure components. With both untreated and GTA-treated gelatin/PMAA blends, it was not possible to evaluate the miscibility of the systems; it could only be affirmed that these materials show good mechanical properties over a wide range of temperature. © 1997 SCI.     

Miscibility studies on chitosan/hydroxypropylmethyl cellulose blend in solution by viscosity,ultrasonic velocity,density, and refractive index methods

The miscibility studies of chitosan (CHI)/hydroxypropylmethyl cellulose (HPMC) blend in buffer solution (0.1M acetic acid + 0.2M sodium acetate) were carried out by viscosity, ultrasonic velocity, density, and refractive index methods at 30, 40, and 50°C, respectively. Using viscosity data, the interaction parameter μ and α were computed. These values revealed that the blend is miscible when the CHI content is more than 50% in the blend. The obtained results were further confirmed by ultrasonic velocity, density, and refractive index study. And also the result revealed that the change in temperature has no significant effect on the miscibility of CHI/HPMC polymer blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2738–2742, 2006     

Miscibility and phase structure of binary blends of poly(L‐lactide) and poly(vinyl alcohol)

Blend films of poly(L ‐lactide) (PLLA) and poly(vinyl alcohol) (PVA) were obtained by evaporation of hexafluoroisopropanol solutions of both components. The component interaction, crystallization behavior, and miscibility of these blends were studied by solid‐state NMR and other conventional methods, such as Fourier transform infrared (FTIR) spectra, differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction (WAXD). The existence of two series of isolated and constant glass‐transition temperatures (T_g's) independent of the blend composition indicates that PLLA and PVA are immiscible in the amorphous region. However, the DSC data still demonstrates that some degree of compatibility related to blend composition exists in both PLLA/atactic‐PVA (a‐PVA) and PLLA/syndiotactic‐PVA (s‐PVA) blend systems. Furthermore, the formation of interpolymer hydrogen bonding in the amorphous region, which is regarded as the driving force leading to some degree of component compatibility in these immiscible systems, is confirmed by FTIR and further analyzed by ¹³C solid‐state NMR analyses, especially for the blends with low PLLA contents. Although the crystallization kinetics of one component (especially PVA) were affected by another component, WAXD measurement shows that these blends still possess two isolated crystalline PLLA and PVA phases other than the so‐called cocrystalline phase. ¹³C solid‐state NMR analysis excludes the interpolymer hydrogen bonding in the crystalline region. The mechanical properties (tensile strength and elongation at break) of blend films are consistent with the immiscible but somewhat compatible nature of these blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 762–772, 2001     

A dynamic mechanical and thermal analysis of unplasticized and plasticized poly(vinyl alcohol)/methylcellulose blends

The miscibility of poly(vinyl alcohol) (PVA)/methylcellulose (MC) blends was investigated over the entire composition range using the dynamic mechanical analyzer (DMA) and the differential scanning calorimeter (DSC). On the basis of the glass transition temperature, determined by DMA, one could conclude that the blends exhibited some miscibility below 80 wt % of MC and a good miscibility above 80 wt % of MC. The highest depressions of the melting and crystallization temperatures of the blends compared to those of PVA, determined via DSC analysis, were observed for MC contents greater than 80 wt %. The miscibility between PVA and MC can be attributed to the hydrogen bonds formed between the two components. The DMA studies showed that water is a good plasticizer for PVA and poly(ethylene glycol) 400 (PEG 400), a good plasticizer for MC. The inclusion of both water and PEG 400 in the blends revealed a synergistic plasticizing effect, which resulted in an increased miscibility between PVA and MC over a greater range of MC compositions (>60 wt %). The elongations of PVA, MC, and their blends were found to increase with the addition of PEG 400, but the tensile strengths to decrease. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1825–1834, 2001     

Miscibility of polymethylmethacrylate and polyethyleneglycol blends in tetrahydrofuran

The miscibility of polymethylmethacrylate (PMMA) and polyethyleneglycol (PEG) blends in tetrahydrofuran (THF) has been investigated by viscosity, density, refractive index, and ultrasonic velocity studies. Various interaction parameters such as polymer–solvent and blend–solvent interaction parameters and heat of mixing have been calculated using the viscosity, density, and ultrasonic velocity data. The results indicated the existence of positive interactions in the blend polymer solutions and that they are miscible in THF in the entire composition range. The study also revealed that variation in the temperature does not affect the miscibility of PMMA and PEG blends in THF significantly. The presence of hydrogen bonding in the blends in the solid state has also been indicated by FTIR studies. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Dextran/poly(acrylic acid) mixtures as miscible blends

Bioartificial polymeric materials based on blends of dextran and poly(acrylic acid) were prepared in form of films and characterized in order to evaluate the miscibility of the natural component with the synthetic one. Films with different composition ratios were prepared by solution casting and analyzed by dynamic mechanical-thermal analysis, differential scanning calorimetry, and scanning electron microscopy. The obtained results indicate that dextran is miscible with poly(acrylic acid). The miscibility was mainly ascertained on the bases of the occurrence of a single composition-dependent glass transition temperature in each blend and also on the bases of the transparency and homogeneity of the films. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2089–2094, 1997     

Ultrasonic Velocity Studies and Allied Parameters of Polyacrylamide/Polyethyleneglycol (600) and Polyacrylamide/Polyvinylalcohol Blend Solution at Low Concentrations

Viscosity, adiabatic compressibility, intermolecular free length, and acoustic impedance of polyacrylamide in polyethylene glycol (600) and polyvinyl alcohol polymer blended solutions at 303 K have been evaluated from ultrasonic (2 MHz) measurements of their density. The results have been interpreted in light of polymer–solvent and polymer–polymer interactions. Variations in the compatibility of the blends caused by increases of PEG (600) and polyvinyl alcohol are also ultrasonically studied. Structural changes have been found in the PVA and PEG (600) systems.     

Network characterization and swelling behavior of chemical hydrogels based on acid‐containing poly(vinyl alcohol)

Poly(vinyl alcohol) (PVA) was modified with phthalic and succinic anhydrides to give vinyl alcohol–vinyl ester copolymers that contain carboxylate groups. These half‐esters were then crosslinked by using the poly‐ (ethylene glycol) (PEG) 400 diglycidylether. Low crosslinker/carboxylate ratios were used to obtain low degrees of crosslinking, so the capacity of the resulting hydrogel to absorb water was high. Water absorption was determined gravimetrically as a function of time at room temperature. The equilibrium swelling ratio and compressive modulus were characterized for all the resulting PVA hydrogels and related to the network structure. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3026–3031, 2003     

Interpolymer associations between poly(vinyl alcohol) and poly(diallyldimethylammonium chloride) in aqueous dilute solution

This article studied the compatibility of poly(vinyl alcohol) (PVA) with poly(diallyldimethylammonium chloride) (PDADMACl) in a dilute aqueous solution. At a total mixture concentration and a constant molecular weight of PDADMACl, it was found that interpolymer associations increase with the molecular weight and decrease with the degree of hydrolysis of the PVA sample (87–89 and 98–99%). From these results, it can be deduced that the compatibility of PVA and PDADMACl is due to specific intermolecular interactions that could be assigned mainly to electrostatic interactions between hydroxyl groups within PVA chains and ion atoms within PDADMACl. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 433–435, 2002     

PA6/PVA共混物的相容性与力学性能研究

制备了聚酰胺6/聚乙烯醇(PA6/PVA)共混物,通过DMA、FTIR、DSC和力学性能测试等方法对共混物进行了表征,利用Hoffman-Weeks方程和Flory熔点下降方程求得了PA6的平衡熔点和两种聚合物的相互作用参数,研究了共混物的相容性和力学性能。结果表明:在氢键的作用下,PA6/PVA共混物具有良好的相容性;PA6与PVA相互作用参数为-0.085,进一步证明了PA6/PVA共混物是热力学相容体系;当PVA含量为50%时,PA6/PVA共混物的相容性和力学性能最佳。     

Preparation and characterization of CMCS/PVA blend membranes and its sorption and pervaporation performance (I)

Novel pervaporation (PV) membranes for ethanol dehydration were prepared by blend poly(vinyl alcohol) (PVA) and carboxymethyl chitosan (CMCS), followed by the crosslinking reaction with glutaraldehyde; the structure and miscibility of the blend membranes were characterized by Fourier transform infrared, X‐ray diffraction, and differential scanning calorimetry; the results indicated that the blends were miscible. The effect of feed concentration, operation temperature, crosslinking agent content, etc. on sorption performance and PV performance of the blend membrane is investigated. The membrane of CMCS/PVA blend ratio of 8 : 2 exhibited a high separation factor of 2959 with a reasonably high water flux value of 0.14 kg m^?2h^?1 at the azeotropic feed composition (95 wt % of ethanol) at a temperature of 45°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Characterization of associating hydrogels of poly(vinyl alcohol) and poly(vinyl pyrrolidone)

In this study, hydrogels were prepared from blends of poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP). The miscibility of the polymers was confirmed with differential scanning calorimetry with the appearance of a single glass‐transition temperature. Additionally, a negative Flory–Huggins interaction parameter further verified the interaction between PVA and PVP. We evaluated the stability of the hydrogels by swelling the gels in phosphate‐buffered saline solutions at pH 7.4. With attenuated total reflectance‐Fourier transform infrared spectroscopy, it was determined that, during swelling, PVP dissolved out of the gel over time and the equilibrium gel content of PVP was nearly identical in all of the samples investigated. After the dissolution of PVP, the equilibrium water content of the gels ranged from 64 to 76 wt %. Additionally, rubber elasticity studies were performed to elucidate information about the physically crosslinked network structure. As determined from rubber elasticity experiments, the mesh size of the physically crosslinked hydrogels ranged from 90 to 230 Å. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009