Effect of tacticity of poly(methyl methacrylate) on the miscibility with poly(vinyl acetate)

The results of the miscibility between the chemically similar polymers poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc) published so far show inconsistent statements concerning miscibility. The problems may be due to differences in molecular weights, tacticity, and preparation methods of the polymers. This investigation was carried out by using either chloroform or tetrahydrofuran (THF) as solvent to prepare the blends, because to our knowledge, nobody has reported any tacticity effect of PMMA on the miscibility with PVAc. Therefore, in this article, different tactic PMMAs were used to mix with PVAc and their miscibility was studied calorimetrically. The results showed little effect of solvent and tacticity. PMMA and PVAc were determined to be almost completely immiscible because of the observation of two T_g's. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 35–39, 2004     

Polymer compatibility II. The system poly(methyl methacrylate)–poly(vinyl acetate). Preparation and impact behavior

Blends of poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc) were prepared by mixing the polymers in the melt and in the absence of a solvent. PMMA was the major constituent of the blend. Traces of gel permeation chromatograms showed that the starting materials retain their polymeric character after Brabender processing. Data obtained from notched Izod impact strength tests at 23°C showed that blends may exhibit values ranging from about 0.3 to 0.9 ft-lb/in. notch. Differences in mix conditions afford blends which, from a phenomenologic viewpoint, consist of a mixture of two glassy polymers or of a rubbery polymer dispersed in a glassy matrix. Micrographs of a crack pattern in companion blends consisting of PMMA/PVAc 85/15 are consistent with impact strength test results.     

Thermal decomposition behavior of γ‐irradiated poly(vinyl acetate)/poly(methyl methacrylate) miscible blends

Miscible polymer blends based on various ratios of poly(vinyl acetate) (PVAc) and poly(methyl methacrylate) (PMMA) were prepared in film form by the solution casting technique using benzene as a common solvent. The thermal decomposition behavior of these blends and their individual homopolymers before and after γ‐irradiation at various doses (50–250 kGy) was investigated. The thermogravimetric analysis technique was utilized to determine the temperatures at which the maximum value of the rate of reaction (T_max) occurs and the kinetic parameters of the thermal decomposition. The rate of reaction curves of the individual homopolymers or their blends before or after γ‐ irradiation displayed similar trends in which the T_max corresponding to all polymers was found to exist in the same position but with different values. These findings and the visual observations of the blend solutions and the transparency of the films gave support to the complete miscibility of these blends. Three transitions were observed along the reaction rate versus temperature curves; the first was around 100–200°C with no defined T_max, which may arise from the evaporation of the solvent. The second T_max was in the 340–380°C range, which depended on the polymer blend and the γ‐irradiation condition. A third transition was seen in the rate of reaction curves only for pure PVAc and its blends with PMMA with ratios up to 50%, regardless of γ‐ irradiation. We concluded that γ‐irradiation improved the thermal stability of PVAc/PMMA blends, even though the PMMA polymer was degradable by γ irradiation. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1773–1780, 2006     

Polymer compatibility III. The system poly(methyl methacrylate)–poly(vinyl acetate). Characterization studies

Blends of poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc) were prepared by mixing the polymers in the melt and in the absence of a solvent. PMMA was the major constituent of the blend. The polymer blends were tested, using various methods, to determine if they are compatible as solids. Data obtained from dynamic mechanical and DSC measurements show that, when they are mixed under given Brabender mix conditions, the blends exhibit properties characteristic of polymer pairs compatible as solids. If the mix conditions are altered, a two-phase system is evidenced. Using micrographs obtained by light microscopy in phase contrast as criteria, two companion blends containing PMMA/PVAc 80/20 would be classified as incompatible as solids because of the differences in refractive index of PMMA and PVAc. The micrographs also show that, in the system that would otherwise be listed as compatible, the PVAc domains appear to be relatively uniform in size and distribution through the PMMA matrix. In its companion blend, large, irregularly shaped particles of PVAc which are poorly dispersed in the PMMA matrix are evident.     

Compatibility and thermal properties of poly(acrylonitrile–butadiene–styrene) copolymer blends with poly(methyl methacrylate) and poly(styrene‐co‐acrylonitrile)

The mechanical and heat‐resistant properties of acrylonitrile–butadiene–styrene (ABS) binary and ternary blends were investigated. The relationship of compatibility and properties was discussed. The results show that poly(methyl methacrylate) (PMMA) and styrene–maleic anhydride (SMA) can improve the thermal properties of conventional ABS. The Izod impact property of ABS/PMMA blends increases significantly with the addition of PMMA, whereas that of ABS/SMA blends decreases significantly with the addition of SMA. Blends mixed with high‐viscosity PMMA are characterized by higher heat‐distortion temperature (HDT), and their heat resistance is similar to that of blends mixed with SMA. For high‐viscosity PMMA, from 10 to 20%, it is clear that blends appear at the brittle–ductile transition, which is related to the compatibility of the two phases. TEM micrographs show low‐content and high‐viscosity PMMA in large, abnormally shaped forms in the matrix. Compatibility between PMMA and ABS is dependent on both the amount and the viscosity of PMMA. When the amount of high‐viscosity PMMA varied from 10 to 20 wt %, the morphology of the ABS binary blends varied from poor to satisfactory compatibility. As the viscosity of PMMA decreases, the critical amount of PMMA needed for the compatibility of the two phases also decreases. SMA, as a compatibilizer, improved the interfacial adhesiveness of ABS and PMMA, which results in PMMA having good dispersion in the matrix. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2652–2660, 2002     

Phase behavior and properties of poly(methyl methacrylate)/poly(vinyl acetate) blends prepared via in situ polymerization

Polymer blends composed of poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc) were prepared via radical-initiated polymerization of methyl methacrylate (MMA) in the presence of PVAc. Differential scanning calorimetry and dynamic mechanical analysis were employed to investigate the miscibility and phase behavior of the blends. The PMMA/PVAc blends of in situ polymerization were found to be phase separated and exhibited a two-phase structure, although some chain transferring reaction between the components occurred. The phase separation resulted from the solvent effect of MMA during the in situ polymerization, which was confirmed by the investigation of phase behavior based on solution cast blending. Solubility analysis of the polymerized blends indicated that some chain transferring reaction between the components occurred during the polymerization. An abrupt increase in gel content from 21.2 to 72.4 wt % was observed when the inclusion of PVAc increased from 30 to 40 wt %, and the gel component consisted of the component polymers as shown by infrared spectroscopy studies. The thermogravimetric analysis study indicated that the inclusion of a small amount of PVAc gives rise to a marked stabilization effect on the thermal stability. The PMMA/PVAc blends exhibited increased notched impact properties with the inclusion of 5 wt % PVAc. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 675–684, 1998     

Phase behaviour and phase separation in polymer blends of poly(methyl methacrylate) with poly(vinyl acetate)

Summary Phase behaviour and phase separation in a binary polymer blends of poly(methyl methacryate) (PMMA) with poly(vinyl acetate) (PVAc) was invistigated by cloud method and light scattering. A lower critical solution temperature (LCST) type phase diagram was found. The mixture system of PMMA/PVAc is miscible. Kinetic study on demixing at the two-phase region above the LCST was carried out by light scattering.     

Study of miscibility of poly(vinyl acetate) and poly(vinyl alcohol) blends by fluorescence spectroscopy

Secondary relaxation of poly(vinyl alcohol) (PVA), poly(vinyl acetate) (PVAc), and their blends in different proportions (9 : 1, 1 : 1, and 1 : 9) were studied by photoluminescence of anthracene, fluorescein, and both probes dissolved in the polymer blends. The temperature of the glass transition in the homopolymers was determined by the radiationless deactivation of anthracene as T_g(PVAc) ? 304 K and the photobleaching of fluorescein as T_g(PVA) ? 350 K. The relaxation processes of the different phases of the polymer blends occur at temperatures close to the homopolymers, which may be explained by the localization of each molecular probe within the matrix. These deactivation curves, however, are not similar to those of the individual homopolymers, suggesting a partial miscibility between these polymers. © 1995 John Wiley & Sons, Inc.     

Enzymatic degradation of poly(D,L‐lactide) and its blends with poly(vinyl acetate)

The enzymatic degradation of poly(D ,L ‐lactide) (PLA) was investigated using two different lipases, Novozym 435 and Lipolase. The optimum temperature was 50°C for the enzymatic degradation of PLA. The effect of various solvents on the degradation of PLA was investigated at 50°C using Novozym 435, and toluene was found to be the best solvent among the solvents investigated. The enzymatic degradation of the blends of PLA and PVAc was investigated at 50°C in toluene. The enzymatic degradation of the blends of PLA and PVAc showed that there is an interaction between the polymers during degradation, which results in the reduction of degradation rate of both polymers in the blend. A continuous distribution model was used to determine the rate coefficients for polymer degradation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 657–680 2006     

Preparation of compatible blends of poly(methyl methacrylate) used in dentistry with a reactive terpolymer containing maleic anhydride and their thermomechanical characterization

This study focuses on the preparation of compatible blends with the poly(methyl methacrylate) (PMMA) using a reactive terpolymer maleic anhydride–styrene–vinyl acetate (MA–St–VA). In the first series of experiments, binary blends of the PMMA and the MA–St–VA terpolymer have been prepared in tetrahydrofurane. The PMMA and the MA–St–VA terpolymer formed the compatible blends. The effects on thermomechanical properties of MA–St–VA terpolymer ratio in the blends were studied. The glass transition temperatures (T_g), thermal expansion coefficient (α), and other thermomechanical parameters for the blends have been established by TMA method and the compatibility of two polymers has been evaluated by these TMA parameters. The addition of MA–St–VA terpolymer to PMMA made a plasticizing effect on PMMA. This effect regularly changed with the increasing of the terpolymer in the blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 363–367, 2006     

Radiational hardening of poly(vinylidene fluoride)–poly(methyl methacrylate)–polystyrene ternary blends

Specimens of poly(vinylidene fluoride) (PVDF)–poly(methyl methacrylate) (PMMA)–polystyrene (PS) polyblends with different weight percentage ratios of the three polymers were prepared with the solution cast technique. The effect of γ irradiation on the Vicker's microhardness was studied. Among the three pure polymers, PVDF, PMMA, and PS, the γ irradiation imparted crosslinking in PVDF, thereby causing radiational hardening. In the cases of PMMA and PS, the effect of irradiation exhibited a predominance of both the scissioning and crosslinking processes in different ranges of doses. Moreover, at a dose of 5 Mrad, in both PMMA and PS, maximum radiational crosslinking was observed. The effect of γ irradiation seemed to stabilize beyond 15 Mrad in PVDF and beyond 20 Mrad in PMMA and PS. Microhardness measurements on ternary blends of PVDF, PMMA, and PS revealed that the blend with low contents of PMMA, that is, up to 5 wt %, yielded softening, whereas increasing the content of PMMA beyond 5 wt % produced a hardened material because of radiational crosslinking, and a higher content of PMMA in the blend facilitated this crosslinking. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3107–3111, 2004     

Miscibility of biodegradable aliphatic polyester and poly(vinyl acetate) blends

We report miscibility behavior for synthetic biodegradable aliphatic polyester (BDP) and poly(vinyl acetate) (PVAc) blends by investigating their thermal, rheological, and mechanical properties. Two separate glass transition temperature peaks for the BDP/PVAc blends proved that these blend systems are immiscible. From the rheological measurement, the shear viscosity as a function of shear rate is observed to increase with increasing PVAc content in BDP/PVAc blends, since PVAc has a relatively high molecular weight compared to BDP. Moreover, BDP blends with 10 wt % PVAc have excellent mechanical properties. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1348–1352, 2000     

Probing the structure of polymer blends by vibrational spectroscopy: the case of poly(ethylene oxide) and poly(methyl methacrylate) blends

The blends of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) are prepared in the form of thin films from solution casting. The Fourier transform infrared spectra of the blends are recorded in the spectral range 400–4000 cm^?1. The spectra are analysed using various recent techniques of vibrational spectroscopy. It is concluded that upon blending PEO takes preferentially a planar zig-zag structure. Furthermore the intermolecular interactions between the molecules of PEO and PMMA in blends are very weak and their compatibility as blends is more ‘physical’ than ‘chemical’. Further, on the basis of the atomic charges transferred from model molecules it is seen that the blending is preferred with isotactic PMMA when compared to syndiotactic PMMA.     

Solution and solid state nuclear magnetic resonance investigation of poly(methylmethacrylate)/ poly(ethylene oxide) blends

It is well known that nuclear magnetic resonance spectroscopy (NMR) is a powerful method to characterize blends compatibility at the molecular level. In this work binary blends formed by poly(methylmethacrylate)/poly(ethylene oxide), PMMA/PEO, were investigated by different solution and solid state NMR techniques to obtain information on blends homogeneity and compatibility. It was characterized that the values of T₁^Hρ obtained by variable contact time and delayed contact time experiments, for each composition, were distinct and this fact suggests that regions with different molecular mobilities exist, as a consequence of blending interaction. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2955–2958, 2003     

Diffusion of benzene vapor in blends of poly(vinyl acetate) and poly(methyl acrylate)

Sorption and diffusion of benzene in miscible blends of poly(vinyl-acetate), PVAc, and poly(methyl acrylate), PMA, have been studied. The polymer-polymer interaction parameter values calculated from equilibrium vapor sorption data were all negative, indicating favorable interaction between the two polymers. The sorption of benzene vapor into these blends was measured at a temperature above the T_g's of the pure polymers and found to obey Fickian kinetics. The mutual diffusion coefficients were estimated from the initial slopes of the sorption curves. The concentration dependent diffusion coefficients were fitted to the empirical relation D = D_o exp(αC) which satisfactorily correlated the data. Values of the constant D_o were found to vary continuously with blend composition, while the α values did not. These experimental data were analyzed employing Fujita's free volume theory. It was found that the data was consistent with this theory. If the f_o values for the blends are assumed to be the weighted average of the component polymers, then the β parameter values for the blends also obey the additivity rule.     

Preparation and characterization of biodegradable polymer blends from poly(3‐hydroxybutyrate)/poly(vinyl acetate)‐modified corn starch

Biodegradable polymer blends prepared by blending poly(3‐hydroxybutyrate) (PHB) and corn starch do not form intact films due to their incompatibility and brittle behavior. For improving their compatibility and flexibility, poly(vinyl acetate) (PVAc) was grafted from the corn starch to prepare the PVAc‐modified corn starch (CSV). The resulting CSV consisted of 47.2 wt% starch‐g‐PVAc copolymer and 52.8 wt% PVAc homopolymer and its structure was verified by FT‐IR analysis. In comparison with 35°C of the neat PVAc, the glass transition temperature (T_g) of the grafted PVAc chains on starch‐g‐PVAc was higher at 44°C because of the hindered molecular mobility imposed from starch on the grafted PVAc. After blending PHB with the CSV, structure and thermal properties of the blends were investigated. Only a single T_g was found for all the PHB/CSV blends and increased with increasing the CSV content. The T_g‐composition dependence of the PHB/CSV blends was well‐fitted with the Gordon‐Taylor equation, indicating that the CSV was compatible with the PHB. In addition, the presence of the CSV could raise the thermal stability of the PHB component. It was also found that the presence of the PHB and PVAc components would not hinder the enzymatic degradation of the corn starch by α‐amylase. POLYM. ENG. SCI., 55:1321–1329, 2015. © 2015 Society of Plastics Engineers     

Enzymatic degradation of poly (ε-caprolactone), poly (vinyl acetate) and their blends by lipases

Poly (ε-caprolactone) (PCL) and poly (vinyl acetate) (PVAc) and their blends were degraded in toluene by two lipases (Novozym 435 and Candida Rugosa) at 60°C. The degradation of PCL and side-chain hydrolysis of PVAc yielded specific products of molecular weight ∼500 and ∼700, respectively. FTIR analysis of the polymer before and after enzyme treatment and the specific products show that there is large reduction of ester linkages and generation of -OH, -COO⁽⁻⁾, -COOH groups in the broken chains. The optimal temperature for the side-chain hydrolysis of PVAc was 60 and 65°C and the optimal temperature for the biodegradation of PCL was 55 and 60°C for Candida Rugosa and Novozym 435, respectively. Continuous distribution kinetics was proposed for determining the rate coefficients of the polymers and deactivation of the enzyme. Enzymatic degradation studies of PCL-PVAc blends showed that there is a drastic reduction in the degradation of PCL in the blends. This was modeled by the interaction between polymers.     

Phase separation,cure kinetics,and morphology of epoxy/poly(vinyl acetate) blends

Epoxy based on diglycidyl ether of bisphenol A + 4,4′diaminodiphenylsulfone blended with poly(vinyl acetate) (PVAc) was investigated through differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and environmental scanning electron microscopy (ESEM). The influence of PVAc content on reaction induced phase separation, cure kinetics, morphology and dynamic‐mechanical properties of cured blends at 180°C is reported. Epoxy/PVAc blends (5, 10 and 15 wt % of PVAc content) are initially miscible but phase separate upon curing. DMTA α‐relaxations of cured blends agree with T_g results by DSC. The conversion‐time data revealed the cure reaction was slower in the blends than in the neat system, although the autocatalytic cure mechanism was not affected by the addition of PVAc. ESEM showed the cured epoxy/PVAc blends had different morphologies as a function of PVAc content: an inversion in morphology took place for blends containing 15 wt % PVAc. The changes in the blend morphology with PVAc content had a clear effect on the DMTA behavior. Inverted morphology blends had low storage modulus values and a high capability to dissipate energy at temperatures higher than the PVAc glass‐transition temperature, in contrast to the behavior of neat epoxy and blends with a low PVAc content. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1507–1516, 2007     

Miscibility and the specific interaction of polyhydroxybutyrate blended with polyvinylacetate and poly(vinyl acetate‐co‐vinyl alcohol) with some biological applications

Bacterially produced polyhydroxybutyrate (PHB) polymer has a lot of potential as an application for environmentally degradable plastics. We aimed in this study to blend PHB with the semicrystalline polymers poly(vinyl acetate) (PVAc) and poly(vinyl acetate‐co‐vinyl alcohol) (PACA) to obtain material with better physical properties. We investigated compatibility over a wide composition range using different techniques. Viscosity measurements were used to study polymer–polymer miscibility in dilute solutions with chloroform as cosolvent. The data is discussed according to the viscosity interaction parameters, which are treated as excess properties by similarity with those of real solutions. Dielectric investigations were carried out at different frequencies ranging from 100 Hz to 50 kHz. The obtained data indicated that more than one relaxation mechanism was present, which were ascribed to the rotation of the main chain and its related motions. A glass‐transition temperature composition diagram, IR spectroscopy, and a morphological investigation were also used to give more information about the compatibility of such blends. The results of this study indicate that PHB/PVAc is semicompatible, whereas PHB/PACA is compatible at least in the assayed composition range of hydrolysis. We also extended the study to carry out some biological activity investigations, which were tested against the representative number of pathogenic organisms with the disk diffusion method. The different compositions of the investigated blend were biologically active when compared with the individual polymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2363–2374, 2002     

Solid‐state NMR and morphological studies of poly(ethylene‐co‐vinyl acetate)/poly(vinyl acetate) blends

To obtain a correlation among structure–morphology–mobility–compatibility properties of poly(ethylene‐co‐vinyl acetate) (EVA)/poly(vinyl acetate) (PVAc) blends, we have used scanning electron microscopy and solid‐state nuclear magnetic resonance in our investigations. The results are discussed in terms of blends, component dispersion, plasticization effect, and domain mobilities to acquire a response of the correlation between structural properties. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2990–2996, 1999