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     

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 studies on blends of poly(ethylene ortho-phthalate) and poly(vinyl acetate)

Blends of poly(ethylene ortho-phthalate) (PEOP), and poly(vinyl acetate) (PVAc), appear to be compatible at all compositions, from visual examination at room temperature and differential scanning calorimetry tests. Both low- (PEOP-1) and high-molecular weight (PEOP-2) alloys with PVAc show a single composition-dependent glass transition temperature (Tg). Some blends show Tg values that are below the Tg for either of the pure polymers. Couchman's equation, with a slight modification, can be used to model Tg behavior. All PEOP-2 blends with PVAc, phase separate at high temperatures, whereas PEOP-1–PVAc blends remain miscible under the same conditions. The composition dependence of the blends refractive index shows a deviation from simple additivity rules, and a similar trend is observed in density measurements. When comparing Flory's characteristic parameters for the polymers, compatibility is predicted for PVAc–PEOP blends. In contrast, blends of PEOP and poly(methyl methacrylate) (PMMA), which has a similar chemical structure to that of PVAc are predicted to be incompatible, in agreement with experimental evidence. It is suggested that compatibility is produced because of possible specific interactions between the aromatic group of PEOP and the ester carbonyl on PVAc, which is not sterically hindered as is the corresponding moiety on PMMA.     

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     

High-pressure sorption of carbon dioxide in solvent-cast poly(methyl methacrylate) and poly(ethyl methacrylate) films

Carbon dioxide sorption isotherms in poly(methyl methacrylate) (PMMA) and poly(ethyl methacrylate) (PEMA) are reported for pressures up to 20 atm. Temperatures between 35 and 80°C were studied for PMMA and temperatures between 30 and 55°C were studied for PEMA. Typical dual mode sorption isotherms concave to the pressure axis were observed in all cases. The measured Langmuir sorption capacities of both polymers extrapolated to zero at the glass transition (T_g) consistent with the behavior of other glassy polymer/gas systems. Sorption enthalpies for CO₂ in the Henry's law mode for PMMA and PEMA are in the same range (?2 to ?4 kcal/mole) as has been reported for a variety of other glassy polymers such as poly(ethylene terephthalate), polycarbonate, and polyacrylonitrile. Some of the data suggest that postcasting treatment of the PEMA films left a small amount of residual solvent in the film. the presence of the trace residual solvent during quenching from the rubbery to the glassy state after annealing appears to cause a dilation of the Langmuir capacity and an alteration in the apparent Langmuir affinity constant of the PEMA film. These results suggest the possibility of tailoring physical properties of glassy polymers such as sorptivity, permeability, impact strength, and craze resistance by doping small amounts of selected residuals into polymers prior to quenching to the glassy state from the rubbery state.     

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.     

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     

Miscibility of polymethyl methacrylate with poly(hydroxy ether) of bisphenol A

The miscibility of polymethyl methacrylate (PMMA) with the poly(hydroxy ether) of bisphenol A (phenoxy resin) was studied and PMMA has been found to be miscible with phenoxy resin. PMMA/phenoxy blends were found to be clear and showed a single, composition-dependent glass transition temperature. The k parameter of the Gordon-Taylor equation can be taken as a measure of the strength of the specific interaction between the two polymers, and a low value of k = 0.3 is found for the PMMA/Phenoxy blends. Fourier transform infrared (FTIR) showed the presence and nature of intermolecular interactions between the two polymers.     

Toughness enhancement of poly(lactic acid) by melt blending with natural rubber

Rubber toughened poly(lactic acid) (PLA) was prepared by blending with natural rubber (NR)‐based polymers. The blends contained 10 wt % of rubber and melt blended with a twin screw extruder. Enhancement of impact strength of PLA was primarily concernced. This study was focused on the effect of rubber polarity, rubber viscosity and molecular weight on mechanical properties of the blends. Three types of rubbers were used: NR, epoxidized natural rubber (ENR25 and ENR50), and natural rubber grafted with poly(methyl methacrylate) (NR‐g‐PMMA). Effect of viscosity and molecular weight of NR, rubber mastication with a two‐roll mill was investigated. It was found that all blends showed higher impact strength than PLA and NR became the best toughening agent. Viscosity and molecular weight of NR decreased with increasing number of mastication. Impact strength of PLA/NR blends increased after applying NR mastication due to appropriate particle size. DMTA and DSC characterization were determined as well. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Blends of poly[3,3-bis(chloromethyl)oxetane] with poly(vinyl acetate). I. Thermal and mechanical properties

Blends of poly[3,3-bis(chloromethyl)oxetane] (Penton) with poly(vinyl acetate) were prepared. Compatibility, morphology, thermal behavior, and mechanical properties of blends with various compositions were studied using differential scanning calorimetry (DSC), dynamic mechanical measurements (DMA), tensile tests, and scanning electron microscopy (SEM). DMA study showed that the blends have two glass transition temperatures (T_g). The T_g of the PVAc rich phase shifts significantly to lower temperatures with increasing Penton content, suggesting that a considerable amount of Penton dissolves in the PVAc rich phase, but that the Penton rich phase contains little PVAc. The Penton/PVAc blends are partially compatible. DSC results suggest that PVAc can act as a β-nucleator for Penton in the blend. Marked negative deviations from simple additivity were observed for the tensile strength at break over the entire composition range. The Young's modulus curve appeared to be S-shaped, implying that the blends are heterogeneous and have a two-phase structure. This was confirmed by SEM observations. © 1992 John Wiley & Sons, Inc.     

Viscoelastic properties,morphology, and thermal stability of rigid and plasticized poly(vinyl chloride)/poly(methyl methacrylate) blends

Viscoelastic properties, morphology, and thermal stability of rigid and plasticized poly(vinyl chloride)/poly (methyl methacrylate) (PVC/PMMA) blends were studied. For that purpose, blends of variable composition from 0 to 100 wt% were prepared in the presence (15, 30, and 50 wt%) and in the absence of di(2‐ethylhexyl) phthalate as plasticizer. Their miscibility was investigated by using dynamic mechanical thermal analysis (DMTA) and scanning electron microscopy (SEM). The DMTA and SEM results showed that the two polymers are miscible. Thermogravimetric studies on these blends were carried out in a flowing atmosphere of air from ambient temperature to 550°C. The results showed that the thermal degradation of rigid and plasticized PVC/PMMA in this broad range of temperature is a three‐step process and that PMMA exerted a stabilizing effect on the thermal degradation of PVC during the first step by reducing the rate of dehydrochlorination. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers     

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     

Thermal and mechanical properties of poly(methyl methacrylate) and ethylene vinyl acetate copolymer blends

A series of poly(methyl methacrylate) (PMMA) blends have been prepared with different compositions viz., 5, 10, 15, and 20 wt % ethylene vinyl acetate (EVA) copolymer by melt blending method in Haake Rheocord. The effect of different compositions of EVA on the physico‐mechanical and thermal properties of PMMA and EVA copolymer blends have been studied. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) has been employed to investigate the phase behavior of PMMA/EVA blends from the point of view of component specific interactions, molecular motions and morphology. The resulting morphologies of the various blends also studied by optical microscope. The DSC analysis indicates the phase separation between the PMMA matrix and EVA domains. The impact strength analysis revealed a substantial increase in impact strength from 19 to 32 J/m. The TGA analysis reveals the reduction in onset of thermal degradation temperature of PMMA with increase in EVA component of the blend. The optical microscope photographs have demonstrated the PMMA/EVA system had a microphase separated structure consisting of dispersed EVA domains within a continuous PMMA matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Investigation on thermoplastic co‐poly(ether‐ester) elastomer toughened poly(methylmethacrylate) blends

Blends of poly(methyl methacrylate) (PMMA) and copoly(ether‐ester) (COPE) elastomer have been prepared in different compositions namely, 95/5, 90/10, 85/15, and 80/20 wt % (PMMA/COPE), by melt mixing technique using twin screw extruder. The influence of COPE content on the mechanical properties especially impact strength, thermal behavior, and chemical resistance of PMMA have been investigated. The impact strength of the PMMA/COPE blends for all the compositions were found to be improved remarkably as compared to the virgin PMMA without affecting the other mechanical properties significantly. Various composite models, such as series model, parallel model, Halpin‐Tsai equation, and Kerner's model have been used to fit the experimental mechanical properties. The effect of chemical and thermal ageing on the performance of the PMMA/COPE blends was also studied. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

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.     

A nonradiative energy transfer fluorescence spectroscopy study of poly(vinyl chloride)/poly(methyl methacrylate) blends

The miscibility of poly(vinyl chloride)/atactic poly(methyl methacrylate (PVC/a-PMMA) blends was investigated by nonradiative energy transfer fluorescence spectroscopy using naphthalene-labeled PVC (PVC-N) with anthracene-labeled PMMA (PMMA-A), or anthracene-labeled PVC (PVC-A) with carbazole-labeled PMMA (PMMA-C). The two sets of results indicate an increase in energy transfer efficiency, corresponding to an increase in blend miscibility, as the PVC concentration increases and, more importantly, demonstrate that the same information about blend miscibility can be obtained using different donor-acceptor chromophore pairs and by changing the polymer to which the donor or the acceptor is attached. The effect of the tacticity of PMMA on its miscibility with PVC was also investigated using PMMA-C and PVC-A labeled polymers. The results confirm that PVC/a-PMMA blends are more miscible than PVC/i-PMMA blends over a large range of compositions.     

Epoxy modification with poly(vinyl acetate) and poly(vinyl butyral). I. Structure,thermal, and mechanical characteristics

Efficiency of the application of high strength heat resistant thermoplastics for improving fracture toughness and impact properties of epoxy resins motivated authors to try large‐scale production thermoplastics for the same purpose. Epoxy/anhydride systems were modified by up to 8 wt % poly(vinyl acetate) (PVAc) and up to 6 wt % poly(vinyl butyral) (PVB). In epoxy–PVAc blends it was possible to obtain morphologies with continuous thermoplastic phase. However, only sea‐island morphologies with a very small size of PVB‐rich phase were observed in epoxy–PVB matrices. The former type of morphology allowed a notable 2.4‐fold increase in the fracture toughness of epoxy resin and simultaneous up to 30% decrease in its' impact strength. The latter type of morphology caused a notably lower (45%) enhancement of the epoxy fracture toughness combined with a 50% increase in its' impact strength. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44081.     

Segregation morphology of poly(3-hydroxybutyrate)/poly(vinyl acetate) and poly(3-hydroxybutyrate-co-10% 3-hydroxyvalerate)/poly(vinyl acetate) blends as studied via small angle X-ray scattering

Segregation morphology of poly(3-hydroxybutyrate) (PHB)/poly(vinyl acetate) (PVAc) and poly(3-hydroxybutyrate-co-10% 3-hydroxyvalerate) (P(HB-co-10% HV)/PVAc blends crystallized at 70 °C have been investigated by means of small angle X-ray scattering (SAXS). Morphological parameters including the crystal thickness (l_c) and the amorphous layer thickness (l_a) were deduced from the one-dimensional correlation function (γ(z)). Blending with PVAc thickened the PHB crystals but not the P(HB-co-10% HV) crystals. On the basis of the composition variation of l_a, and the volume fraction of lamellar stacks (?_s) revealed that PHB/PVAc blends created the interlamellar segregation morphology when the weight fraction of PVAc (w_PVAc)≤0.2 and the interlamellar and interfibrillar segregation coexisted when w_PVAc>0.2, while P(HB-co-10% HV)/PVAc blends yielded the interfibrillar segregation morphology at all blend compositions. For both PHB/PVAc and P(HB-co-10% HV)/PVAc blends, the distance of PVAc segregation was promoted by increasing PVAc composition and the distance of PVAc segregation in P(HB-co-10% HV)/PVAc blends was greater than in PHB/PVAc at a given PVAc composition. The crystal growth rate played a key role in controlling the segregation of PVAc.     

Investigation of the structural,thermal, mechanical,and optical properties of poly(methyl methacrylate) and poly(vinylidene fluoride) blends

In this investigation, poly(methyl methacrylate) (PMMA) and poly(vinylidene fluoride) (PVDF) blends (w/w) were prepared in a Brabender (South Hackensack, NJ) plasticorder with a thermoplastic mixing chamber (type W60) preheated at 180°C. These blends were further converted into films by a conventional solution casting method and characterized with Fourier transform infrared spectroscopy, differential scanning calorimetry, X‐ray diffraction, mechanical property measurements, impact strength testing, ultraviolet–visible spectroscopy, refractive‐index measurements, and contact‐angle study. The Fourier transform infrared results indicated that the compatibility between these two systems resulted from hydrogen bonding between the carbonyl group of PMMA and the CH₂ group of PVDF. The thermal analysis showed depressions in the glass‐transition temperature, melting temperature, and crystallization temperature. The heat of crystallization increased with an increase in the PVDF content in the blend. An increase in the heat of crystallization meant an increase in the crystallinity. An increase in the cooling rate increased the crystallization rate. The improvement in the mechanical properties of the blend films indicated that the observed behavior was ascribable to a more coherent structure of the blends due to strong specific interactions between PMMA and PVDF chains. The impact strength analysis revealed a substantial increase in the impact strength from 21.64 to 38.52 J/m. Optical absorption spectra suggested the presence of an optical band gap energy that increased with an increase in the PVDF content in the blend. The contact angle against water increased with the PVDF content in the blend film, and this was caused by the hydrophobicity of PVDF due to the CF₂ group of PVDF. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009