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.     

The supermolecular structure of poly(vinyl chloride)–poly(methyl methacrylate) blends

Investigations of the supermolecular structure of PVC/PMMA blends, covering a wide range of composition, are presented. It was found that a transition layer exists between PVC and PMMA phases. The thickness of the transition layer is independent of blend composition. The scattering intensity distribution function for blends is characteristic of isotropic, amorphous systems with a completely random distribution of phases. It was shown that scattering intensity distribution function may be used for calculation of a distribution, which corresponds a two-phase system with sharp phase boundaries. Values of correlation lengths, inhomogeneity lengths, and specific surfaces were then calculated. A model of the supermolecular structure of PVC/PMMA blend was finally proposed.     

Synthesis and luminescence studies of poly(vinyl acetate)–Eu (III) coordination compound

In this research, the polymeric coordination compound of PVAc–Eu (III) was synthesized, and the formation of coordination bonding between Eu (III) and the carbonyl oxygen in PVAc was investigated by Fourier transform infrared (FT‐IR) spectroscopy, Raman spectroscopy (RS), and X‐ray photoelectron spectroscopy (XPS). The luminescent characteristics/properties of the prepared PVAc–Eu (III) were studied using fluorescence spectroscopy (FS). The results indicated that (1) the interaction/association between PVAc and Eu (III) in the prepared PVAc–Eu (III) was coordination bonding instead of weak physical adsorption, and (2) the photoluminescence intensity of PVAc–Eu (III) was approximately three times that of EuCl₃. This research provided a theoretical foundation for the potential use of PVAc–Eu (III) as an innovative polymeric luminescent material, particularly for the applications in areas such as adhesives, coatings, textiles and others, the areas in which PVAc is an important raw material. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3617–3622, 2007     

Refractive index of solutions containing poly(vinyl acetate) and poly(methyl methacrylate)

Refractive index measurements can be used successfully for on-line evaluation of extent of reaction in solution polymerization reactors. For this reason, the refractive index of solutions containing tert-butanol (TBOH), methyl methacrylate (MMA), vinyl acetate (VA), poly(methyl methacrylate) (PMMA), and poly(vinyl acetate) (PVA) were measured and a mathematical correlation was developed to fit the experimental data. The correlation can be extended to fit published data obtained with different solvents.     

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     

Solution and solid‐state blend compatibility of poly(vinyl alcohol) and poly(methyl methacrylate)

The blend miscibility of poly(vinyl alcohol) and poly(methyl methacrylate) in N,N′‐dimethylformamide solution was investigated by viscosity, density, ultrasonic velocity, refractive index, and UV and fluorescence spectra studies. Differential scanning calorimetry and scanning electron microscopy were used to confirm the blend miscibility in the solid state. Blends were compatible when the concentration of poly(vinyl alcohol) was greater than 60 wt %. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2415–2421, 2006     

Influence of tacticity of poly(methyl methacrylate) on the compatibility with poly(vinyl phenol)

Isotactic, atactic, and syndiotactic poly(methyl methacrylate) (PMMA) were mixed with poly(vinyl phenol) (PVPh) separately in tetrahydrofuran to make three polymer blend systems. Differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy were used to study the miscibility of these blends. Isotactic PMMA was found to be more miscible with PVPh than atactic or syndiotactic PMMA. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1773–1780, 1997     

Influence of tacticity of poly(methyl methacrylate) on the compatibility with poly(vinyl chloride)

Blends of conventional poly(vinyl chloride) (PVC) and poly(methyl methacrylate) (PMMA) with different tacticities were obtained both from the bulk and from solution. The glass transition temperatures (T_g) of the blends were determined with a differential scanning calorimeter and by dynamic mechanical measurements. Some turbidity measurements on films and viscosity measurements on mixed solutions supplied additional information about the state of mixing. From the results it appeared that isotactic (i-)PMMA and PVC form an incompatible system over the entire composition range (two T_g's), whereas blends of syndiotactic (s-)PMMA and PVC form a compatible system up to a composition corresponding with a monomer unit ratio of about 1:1. For higher s-PMMA contents phase separation is observed; one phase corresponding with the 1:1 s-PMMA—PVC associate and the other phase representing the excess of pure s-PMMA. This effect of tacticity is discussed in terms of the differences in chain conformation of i- and s-PMMA.     

Study of dynamic mechanical properties of poly(vinyl chloride)–ethylene vinyl acetate copolymer and poly(vinyl chloride)–chlorinated ethylene vinyl acetate copolymer mixtures

The compatibility of the mixtures poly(vinyl chloride)—ethylene vinyl acetate copolymer and poly(vinyl chloride)—chlorinated ethylene vinyl acetate copolymer was studied by the method of dynamic mechanical testing. The character of G′ and G″ was confronted with the Takayanagi model. In all cases a limited compatibility of the components was observed.     

Permeation characteristics of poly(vinyl alcohol)–poly(vinyl acetate) composite porous membranes

Poly(vinyl alcohol) (PVAc) composite porous membrane has been prepared from PVAc latex film by extraction with acetone. The PVAc latex was prepared by emulsion polymerization of vinyl acetate in the presence of PVA, employing the hydrogen peroxide–tartaric acid systemm as an initiator. The extraction degree of PVAc could be controlled in a wide range by changing the addition method of the initiator, and, acoordingly, PVA–PVAc omposite porous membranes which had variosu void volumes were obtained. The maximum void volume attained was ca. 90%. Permation characteristics of organic solvents wre investigated on the membranes whose extraction degrees were 95.6% and 80.7%. Thge feeds were benzene, n-hexane, cyclohexane, and their mixtures. neither swelling nor shrinkage in tje appearance size of the while benzene hardly permeated even at 20 kg/cm². The grafted PVAc in the mebrane was removed or converted into grafted PVA by treatment with sodium methylate, and then the depression of benzene permeation was lost. The grafted PVAc was suggested to be localizd on the cell wall and was found to function as a valve which closes with nenzene or a good solvent for PVAc and opens with n-haxane or a poor solvent for PVAc.     

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     

Comparison of the phase behaviour of the liquid-crystalline polymer/poly(methyl methacrylate) and poly(vinyl acetate)/poly(methyl methacrylate) blends

The phase behaviour of blends of a liquid-crystalline polymer (LCP) and poly(methyl methacrylate) (PMMA), as well as the phase state of blends of PMMA and poly(vinyl acetate) (PVA) has been investigated using light scattering and phase-contrast optical microscopy. The blends of LCP and PMMA have been obtained by coagulation from ternary solutions. The cloud point curves were determined. It was established that both pairs demix upon heating, ie have an LCST. In the region of intermediate composition, the phase separation proceeds according to a spinodal mechanism; however for LCP/PMMA blends, the decomposition proceeds according to a non-linear regime from the very onset. In the region of small amounts of LCP, the phase separation follows a mechanism of nucleation and growth. For PMMA/PVA blends, the spinodal decomposition proceeds according to a linear regime, in spite of the molecular mobility that PVA chains develop at lower temperatures. Only after prolonged heat treatment does the process transit to a non-linear regime. The data show a similarity between the phase behaviour of blends of liquid-crystalline and of flexible amorphous polymers. The distinction consists of the absence of a linear regime of decomposition for LCP-PMMA blends. © 1999 Society of Chemical Industry     

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     

Preparation and structure of poly(vinyl alcohol)–poly(vinyl acetate) composite porous membrane

The preparation of poly(vinyl alcohol) (PVA)–poly(vinyl acetate) (PVAc) composite porous membrane was investigated by extracting PVAc with solvent from films of PVAc lattices which were obtained by the emulsion polymerization of vinyl acetate (VAc) in the presence of PVA. The formation of the porous membrane depended upon whether or not PVAc in the latex film was easily extracted with solvent. In the case of using hydrogen peroxide (HPO)–tartaric acid (TA) as an initiator, in the film of the latex which was produced from the batch method in which all ingredients of the batch were put into the reaction vessel before starting polymerization, PVAc could be extracted over 90% of total PVAc with common organic solvents. In the film of the latex which was produced from the dropwise addition method of VAc and initiator, the PVAc extraction was about 20-30%. On the other hand, in the case of using ammonium persulfate as an initiator, the desired porous membrane was not obtained. The structure of the porous membrane obtained from the latex of the batch method by using HPO—TA consisted of spherical cells which were made up of PVA and grafted PVAc or insoluble PVAc like microgels, which were not extracted with organic solvent and were connected by small pores. The PVA—PVAc composite porous membrane is permeated by n-hexane with 5.58 × 10² mL/cm²·s at 0.5 kg/cm², by benzene with only 1.33 × 10^?3mL/cm²·s even at 60 kg/cm².     

The compatibility of poly(methyl methacrylate) and chlorinated polyethylene

The compatibility of poly(methyl methacrylate) with chlorinated polyethylene was studied using differential thermal analysis and dynamic mechanical measurements. For around 50% chlorination of polyethylene they were found to be compatible and show an LCST, but not at 27% chlorination as had previously been thought. The previous results were explained as due to a matching of refractive indices over some temperatures. The compatibility was explained by the heat of mixing which becomes favourable at chlorination levels above approximately 46%.     

Polyurethane–poly(methyl methacrylate) interpenetrating polymer networks. I. Synthesis,characterization, and preliminary blood compatibility studies

Simultaneous polyurethane–poly(methyl methacrylate) (PU–PMMA) interpenetrating polymer networks (IPNs) were synthesized with the PMMA polymerization initiated at room temperature. Transparent IPNs with better miscibility and synergism of mechanical properties were obtained. Dynamic mechanical analysis data indicated that up to 30% PMMA can be incorporated into PU networks without substantial phase separation. The PU–PMMA 90/10 IPNs elicit less than 2% hemolysis, suggesting that these materials could be used as blood contacting materials. © 1996 John Wiley & Sons, Inc.     

Cellulose nitrate–poly(vinyl chloride-co-vinyl acetate)–polyurethane ternary IPNs: FT-IR and morphological studies

Ternary semi-IPNs of nitrocellulose, poly(vinyl chloride-co-vinyl acetate), and polyurethanes have been synthesized and characterized by FT-IR, SEM, and differential scanning calorimetry. Semi-IPNs of nitrocellulose-polyurethanes are found to be incompatible whereas the ternary system consisting of nitrocellulose-poly(vinyl chloride-co-vinyl acetate) and polyurethanes is partially compatible. Hydrogen bonding interactions are discussed based on the FT-IR analysis. The tensile strength and percent elongation are interpreted on the basis of the NCO/OH ratio and composition.     

Automated microscopic technique for evaluating poly(vinyl chloride)–plasticizer compatibility

An automated microtechnique has been developed that permits a rapid, reproducible determination of the Flory–Huggins χ interaction parameters for poly(vinyl choloride)–plasticizer systems. It is a modification of the Anagnostopoulos method of determining an apparent melting temperature of a poly(vinyl chloride) (PVC) particle in excess plasticizer. A microscope equipped with a photodiode sensor is used to measure changes in the light transmitted through a plasticizer sample containing a PVC particle as the temperature is increased at a fixed rate, either 0.2 or 1.0°C/min. Data acquisition is done by computer so that minimal operator assistance is required. The apparent melting region is characterized by a sigmoidal change in the light transmitted through a fixed sample area. This curve allows an accurate, reproducible definition of the apparent melting temperature from which the χ parameter is easily derived. The values obtained for the interaction parameter of PVC with four plasticizers chosen from the phthalate and phosphate families are in good agreement with general trends of solvent quality. Separate experiments demonstrated that the overall transmittance profile reflects changes in both the size and the optical clarity of the PVC particle during heating. This leads to added features in the profile that reflect important diffusion and swelling characteristics for a given system. © 1994 John Wiley & Sons, Inc.     

Polymer compatibility and interpolymer association in the poly(acrylic acid)–polyacrylamide–water ternary system

Polyacrylamide and poly(acrylic acid) form a water-insoluble phase when solutions of the two having concentrations that are not too low are mixed. The insoluble complex contains nearly stoichiometric 1 : 1 ratios of acrylamide and acrylic acid. The phase behavior of the ternary system was studied as a function of the degree of neutralization, α, of poly(acrylic acid). The complex is not formed when α is high. The formation of the complex was studied by measurement of pH increases observed when poly(acrylic acid) was titrated with polyacrylamide to infer a degree of linkage, θ, between the two polymers. A Hill plot of the data showed that the association was cooperative when the molecular weight was high.     

Dielectric studies on the miscibility in poly(vinyl acetate)/ poly(ethyl methacrylate) blends

The glass transition relaxation of different blends of poly(vinyl acetate) and poly(ethyl methacrylate) have been investigated by dielectric relaxation spectroscopy in the frequency range from 20 Hz to 1 MHz. The obtained results suggest that the poly(vinyl acetate)-rich blends show immiscibility between the two components, whereas the poly(ethyl methacrylate)-rich blends show partial miscibility. The results obtained by differential scanning calorimetry and the analysis of the Maxwell–Wagner–Sillars effect seem to confirm the dielectric relaxation results. © 1996 John Wiley & Sons, Inc.