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     

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

It can be concluded from the work of Schurer et al.¹⁰ that poly(vinyl chloride) (PVC) is more miscible with syndiotactic than with isotactic poly(methyl methacrylate) (PMMA). By choosing different molar masses for the various tactic forms of PMMA it is possible to obtain blends with PVC with similar phase behaviour, i.e. in all cases a cloud-point curve with a minimum in the vicinity of 190°C. In this way a more quantitative statement about the influence of the tacticity of PMMA on its miscibility with PVC can be made. One of the principal differences between syndiotactic or atactic PMMA and isotactic PMMA is the higher flexibility of the latter. Using Flory's equation of state theory it will be shown that the effect of this difference is large enough to explain the difference in phase behaviour observed. Heats of mixing of low molar mass analogues were also measured and found to be negative.     

Effect of tacticity of poly(methyl methacrylate) on the miscibility with poly(styrene‐co‐acrylonitrile)

Isotactic, atactic, and syndiotactic poly(methyl methacrylates) (PMMAs) (designated as iPMMA, aPMMA, and sPMMA) with approximately the same molecular weight were mixed separately with poly(styrene‐co‐acrylonitrile) (abbreviated as PSAN) containing 25 wt % of acrylonitrile in tetrahydrofuran to make three polymer blend systems. Differential scanning calorimetry (DSC) was used to study the miscibility of these blends. The results showed that the tacticity of PMMA has a definite impact on its miscibility with PSAN. The aPMMA/PSAN and sPMMA/PSAN blends were found to be miscible because all the prepared films were transparent and showed composition dependent glass transition temperatures (T_gs). The glass transition temperatures of the two miscible blends were fitted well by the Fox equation, and no broadening of the glass transition regions was observed. The iPMMA/PSAN blends were found to be immiscible, because most of the cast films were translucent and had two glass transition temperatures. Through the use of a simple binary interaction model, the following comments can be drawn. The isotactic MMA segments seemed to interact differently with styrene and with acrylonitrile segments from atactic or syndiotactic MMA segments. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2894–2899, 1999     

Study of the solvent effect on miscibility between poly(vinyl chloride) and poly(methyl methacrylate) in the solution state – viscometric measurements

In this work, the solvent effect on the miscibility between poly(vinyl chloride) (PVC) and poly(methyl methacrylate) (PMMA) in ternary polymer solutions was examined by the viscometric method. In these systems, we could understand that the used solvents, tetrahydrofuran (THF) or N,N‐dimethylformamide (DMF), mainly affect the interaction between PVC and PMMA, while prompting various miscible properties. In PVC/PMMA/THF solution, THF is a near θ‐solvent and a poor solvent for PVC and PMMA, respectively. The mixing of the tighter PMMA coils and more extended PVC coils in THF may cause the sea–island heterogeneous structure below the weight fraction of PMMA in the polymer mixture w_PMMA = 0.7, resulting in immiscible PVC/PMMA mixtures. At w_PMMA ≥ 0.7, the PVC/PMMA mixtures are relatively miscible, giving homogeneous polymer solutions. It means that the miscibility between PVC and PMMA depends on the composition of polymer mixture. However, due to the similar affinity of DMF to PVC and PMMA, PVC/PMMA/DMF solutions exhibit high miscibility between PVC and PMMA at about w_PMMA = 0.5. © 2000 Society of Chemical Industry     

Effect of tacticity on the transition behaviour of poly(methyl methacrylate)/poly(vinyl chloride) blends. Thermally stimulated depolarization study

The transition behaviour of blends of poly(vinyl chloride) (PVC) and poly(methyl methacrylate) isotactic (i-PMMA) and syndiotactic (s-PMMA) was determined in the temperature range ?150°C to +130°C by the thermally stimulated depolarization currents method (TSDC). The evolution of the current spectra was analysed as a function of blend composition. From the variation of properties of the peaks (presence or not of two T_g peaks, shifting or not of their positions, existence or not of interfacial components, regular or complex variation of the peak amplitudes ...), it was concluded that i-PMMA and PVC form an incompatible system over the entire concentration range while in s-PMMA/PVC blends, some compatibility probably exists but only for concentrations in s-PMMA not higher than 10 wt%. By referring to literature data, this value is much smaller than the compatibility range found from d.s.c. and mechanical measurements but is close to that determined from optical and electronic spectroscopy methods. These results emphasize the important role played by the type of method used to find out compatibility of a given polymer pair and show that the TSDC technique may be particularly useful for studying the interfacial phenomena associated with phase separation owing to its exceptional ability for easily detecting Maxwell-Wagner-Sillars polarization generated by the trapping of charge carriers at phase boundaries.     

Effect of the tacticity of poly(methyl methacrylate) on the phase diagram of its ternary blends

Previously, isotactic and atactic poly(methyl methacrylates) (PMMAs) were found to be miscible with poly(vinyl phenol) (PVPh) and poly(hydroxy ether of bisphenol‐A) (phenoxy) because all the prepared films were transparent and showed composition‐dependent glass transition temperatures (T_g's). However, syndiotactic PMMA was immiscible with PVPh because most of the cast films had two T_g's. On the contrary, syndiotactic PMMA was still miscible with phenoxy. According to our preliminary results, PVPh and phenoxy are not miscible. Also to our knowledge, nobody has reported any results concerning the effect of the tacticity of PMMA on its ternary blend containing PVPh and phenoxy. The miscibility of a ternary blend consisting of PVPh, phenoxy, and tactic PMMA was thus investigated and reported in this article. Calorimetry was used as the principal tool to study miscibility. An approximate phase diagram of the ternary blends containing different tactic PMMA was established, probably for the first time, based on differential scanning calorimetry data. Immiscibility was found in most of the studied ternaries but a slight difference due to the effect of tacticity of PMMA was definitely observed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2720–2726, 2002     

Crystallization behavior and hydrophilicity of poly(vinylidene fluoride)/poly(methyl methacrylate)/poly(vinyl pyrrolidone) ternary blends

Ternary blends composed of matrix polymer poly(vinylidene fluoride) (PVDF) with different proportions of poly(methyl methacrylate) (PMMA)/poly(vinyl pyrrolidone) (PVP) blends were prepared by melt mixing. The miscibility, crystallization behavior, mechanical properties and hydrophilicity of the ternary blends have been investigated. The high compatibility of PVDF/PMMA/PVP ternary blends is induced by strong interactions between the carbonyl groups of the PMMA/PVP blend and the CF₂ or CH₂ group of PVDF. According to the Fourier transform infrared and wide‐angle X‐ray difffraction analyses, the introduction of PMMA does not change the crystalline state (i.e. α phase) of PVDF. By contrast, the addition of PVP in the blends favors the transformation of the crystalline state of PVDF from non‐polar α to polar β phase. Moreover, the crystallinity of the PVDF/PMMA/PVP ternary blends also decreases compared with neat PVDF. Through mechanical analysis, the elongation at break of the blends significantly increases to more than six times that of neat PVDF. This confirms that the addition of the PMMA/PVP blend enhances the toughness of PVDF. Besides, the hydrophilicity of PVDF is remarkably improved by blending with PMMA/PVP; in particular when the content of PVP reaches 30 wt%, the water contact angle displays its lowest value which decreased from 91.4° to 51.0°. Copyright © 2011 Society of Chemical Industry     

Investigation on crystallization behavior and hydrophilicity of poly(vinylidene fluoride)/poly(methyl methacrylate)/poly(vinyl pyrrolidone) ternary blends by solution casting

Ternary blends composed of matrix polymer poly(vinylidene fluoride) (PVDF) with different proportions of poly(methyl methacrylate) (PMMA)/poly(vinyl pyrrolidone) (PVP) blends were prepared by solution casting. The crystallization behavior and hydrophilicity of ternary blends were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), wide angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), and contact angle test. According to morphological analysis, the surface was full of typical spherulitic structure of PVDF and the average diameter was in the order of 3 μm. The samples presented predominantly β phase of PVDF by solution casting. It indicated that the size of surface spherulites and crystalline phase had little change with the PMMA or PVP addition. Moreover, FTIR demonstrated special interactions among the ternary polymers, which led to the shift of the carbonyl stretching absorption band of PVP. On the other hand, the melting, crystallization temperature, and crystallinity of the blends had a little change compared with the neat PVDF in the first heating process. Except for the content of PVP containing 30 wt %, the crystallinity of PVDF decreased remarkably from 64% to 33% and the value of t_1/2 was not obtained. Besides, the hydrophilicity of PVDF was remarkably improved by blending with PMMA/PVP, especially when the content of PVP reached 30 wt %, the water contact angle displayed the lowest value which decreased from 98.8° to 51.0°. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

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     

Solvent effects on the miscibility of poly(methyl methacrylate)/poly(bisphenol a carbonate) blends

Blends of atactic or syndiotactic poly(methyl methacrylate) (designated as aPMMA or sPMMA) and poly(bisphenol A carbonate) (PC) were prepared from solution casting. Tetrahydrofuran (THF) and chloroform were used as solvent. Experimental results indicated that the as‐cast blends from THF were quite different from the chloroform‐cast ones. After film preparation, THF‐cast blends did not show any visible phase separation. However, chloroform‐cast blends formed a phase‐separated structure. The as‐cast PC from either solvent was not completely amorphous, and had a melting point at 239–242°C, indicating a certain degree of crystallinity. In contrast, the quenched samples of aPMMA/PC blends prepared from the two solvents behaved virtually the same. They both showed aPMMA dissolves better in PC, but PC solubility in aPMMA is very little. Using sPMMA instead of aPMMA to blend with PC, different results were obtained. The quenched sPMMA/PC blends cast from THF showed only one T_g. However, immiscibility (i.e., two T_gs) was found in the same blend system when cast from chloroform. THF was believed to cause the observation of single T_g due to the following kinetic reason. sPMMA and PC were still trapped together even after THF removal in a homogeneous, but nonequilibrium state below the glass transition. Therefore, the quenched sPMMA/PC blends were not truly thermodynamically miscible. From the results of aPMMA or sPMMA with PC, increasing syndiotacticity seemed to improve the miscibility between PMMA and PC. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2842–2850, 2001     

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     

Miscibility studies of hydroxypropyl cellulose/poly(vinyl pyrrolidone) in dilute solutions and solid state

The miscibility of hydroxypropyl cellulose (HPC) and poly(vinyl pyrrolidone) (PVP) blends in aqueous solutions was studied using viscosity, ultrasonic velocity, and refractive index techniques at 30°C. The interaction parameters ΔB, μ, and α calculated from viscosity using Sun and Chee methods indicated the miscibility of this blend. This was further confirmed by ultrasonic and refractive index results. The HPC/PVP blend films are prepared by solution casting method and are analyzed by differential scanning calorimetry, X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopic techniques that confirmed the complete miscibility. This miscibility is due to the strong intermolecular H-bonding interactions between  OH groups of HPC and CO groups of PVP. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

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     

Effect of thermal treatments on the miscibility of poly(vinyl cinnamate) binary blends

Poly(vinyl cinnamate) (PVCN) could undergo thermal or photo crosslinking. PVCN was previously found to be miscible with poly(vinyl phenol) (PVPh) [also named poly(hydroxystyrene)]. In this article, the miscibility between PVCN with or without thermal crosslinking and poly(styrene‐co‐hydrostyrene) (designated as MPS) was investigated. PVCN was determined to be miscible with MPS with 15% of hydroxystyrene (MPS‐15) at two compositions but partially miscible or immiscible at PVCN/MPS‐15(50/50) composition. For MPS with 5% of hydroxystyrene (MPS‐5), two T_g values were detected indicating mostly immiscibility. However, PVCN after thermal crosslinking was determined to be miscible with both MPS‐5 and MPS‐15. Immiscibility was found between thermally crosslinked PVCN and PVPh different from miscibility in the original PVCN/PVPh blends. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Concerning the miscibility of poly(vinyl phenol) blends — FTi.r. study

The results of a Fourier transform infrared study of poly(vinyl phenol) (PVPh) blends containing a number of chemically and structurally dissimilar polymers are presented. These polymers include the polyesters poly(ε-caprolactone) and poly(?-propiolactone); poly(vinyl alkyl ethers) where the alkyl groups are methyl, ethyl and isobutyl respectively; poly(ethylene oxide) and poly(vinyl pyrrolidone). All of these PVPh blends, with the exception of that containing poly(vinyl isobutyl ether), exhibit infrared spectral features consistent with a significant degree of mixing. Intermolecular hydrogen bonding interactions involving the PVPh hydroxyl group and either the carbonyl or ether oxygen moieties of the other polymers in the blend are identified. The relative strengths of these intermolecular interactions are discussed together with ramifications pertinent to the overall subject of polymer miscibility.     

Dynamical study on the late stage of demixing in poly(methyl methacrylate) and poly(vinyl acetate) blends

A dynamical study was made on demixing of an immiscible polymer blend, whose specimens were prepared by solvent casting and had very finely phase separated structures in the initial stage of the demixing. Light scattering experiments showed the applicability of a scaling rule to the later stage of the growth of phase separation structures. The demixing can be described by a scaling theory proposed by Furukawa.     

The effect of layered double hydroxides dispersion on thermal and mechanical properties of poly(vinyl chloride)/poly(methyl methacrylate) blends

Poly(vinyl chloride) (PVC)/layered double hydroxide (LDH) composites and PVC/poly(methyl methacrylate) (PMMA)/LDH composites were prepared via solution intercalation into PVC using both unmodified and organo‐modified LDHs and variable‐molecular‐weight PMMA as additional components. The LDH dispersion was investigated using X‐ray diffraction analysis and electron microscopy in scanning and transmission modes. Spotlight fourier transform infrared (FTIR) chemical imaging analysis was also used to obtain a deeper insight into the dispersion of polymer phases and LDH segregation. Thermal properties were determined using thermogravimetric analysis and differential scanning calorimetry; moreover, a preliminary investigation of mechanical properties in tensile mode and evaluation of the Vicat softening temperature were carried out. The morphological analysis of PVC/LDH and PVC/PMMA/LDH composites evidenced in both cases the presence of disordered micro‐aggregates with loss of the LDH crystallographic symmetry depending on the amount and molecular weight of PMMA. In particular, in the case of PVC/PMMA/LDH composites, the FTIR imaging analysis showed that PMMA mostly segregated in the LDH phase. However, even if the degree of LDH dispersion was not elevated (micro‐aggregates with disordered structures and size ranging from 0.5 up to 11 µm were evidenced), thermal stability and mechanical properties of the composites were improved with a synergic effect of PMMA and LDH. © 2013 Society of Chemical Industry     

Thermal and spectroscopic studies of poly(N‐vinyl pyrrolidone)/poly(vinyl alcohol) blend films

Poly(N‐vinyl pyrrolidone) (PVP) and poly (vinyl alcohol) (PVA) homopolymers and their blended samples with different compositions were prepared using cast technique and subjected to X‐ray diffraction (XRD) measurements, infrared (IR) spectroscopy, ultraviolet/visible spectroscopy, and thermogravimetric analysis (TGA). XRD patterns of homopolymers and their blended samples indicated that blending amorphous materials, such as PVP, with semicrystalline polymer, such as PVA, gives rise to an amorphous structure with two halo peaks at positions identical to those found in pure PVP. Identification of structure and assignments of the most evident IR ‐ absorption bands of PVP and PVA as well as their blends in the range 400–2000 cm^?1 were studied. UV–vis spectra were used to study absorption spectra and estimate the values of absorption edge, E_g, and band tail, E_e, for all samples. Making use of Coats‐Redfern relation, thermogravimetric (TG) data allowed the calculation of the values of some thermodynamic parameters, such as activation energy E, entropy ΔS^#, enthalpy ΔH, and free energy of activation ΔG^# for different decomposition steps in the samples under investigation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Casting solvent effect on crystallization behavior and morphology of poly(ethylene oxide)/poly(methyl methacrylate)

Poly(ethylene oxide) (PEO)/poly(methyl methacrylate) (PMMA) blends were prepared by casting from either chloroform or benzene solvents. After casting from solvents, all samples used in this study were preheated to 100°C and held for 10 min. Then, the solvent effect on the crystallization behavior and thermodynamic properties were studied by differential scanning calorimeter (DSC). Also, the morphology of spherulite of casting film was studied by polarized optical microscope. From the DSC and polarizing optical microscopy (POM) results, it was found that PEO/PMMA was miscible in the molten state no matter which casting solvent was used. However, the crystallization of PEO in the chloroform‐cast blend was more easily suppressed than it was in the benzene‐cast blend. Relatively, the chloroform‐cast blend showed the greater melting‐point depressing of PEO crystals. Also, the spherulite of chloroform‐cast film showed a coarser birefringence. It was supposed that the chloroform‐cast blend had more homogeneous morphology. It is fair to say that polymer blends, cast from solvent, are not necessarily in equilibrium. However, the benzene‐cast blends still were not in equilibrium even after preheating at 100°C for 10 min. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1627–1636, 2000     

Effect of tacticity of poly(methyl methacrylate) on interfacial region with silica in polymer nanocomposite

The effect of tacticity on the interfacial region between poly(methyl methacrylate) (PMMA) and silica in a PMMA/silica nanocomposite was investigated by differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The glass transition temperature (T_g) values of the syndiotactic (st-) and atactic (at-) PMMA/silica nanocomposites are higher than those of the neat PMMA. Conversely, the T_g of the isotactic (it-) PMMA/silica nanocomposite is slightly higher than that of the neat it-PMMA. DSC and XRD results suggest that the restriction of the PMMA chain mobility in the silica nanoparticle interfacial region heightens as the syndiotactic content increases. FT-IR results show that this phenomenon is caused by the interaction between the carbonyl group of PMMA and the silanol group on the silicon dioxide surface. Therefore, it can be concluded that the syndiotactic-rich PMMA has a significantly different molecular mobility from that of the neat PMMA in the interfacial region with silica nanoparticle surface than isotactic-rich PMMA.