Polymer blends containing poly(vinylidene fluoride). Part III: Polymers containing ester,ketone, or ether groups

To further investigate the nature of the specific interaction leading to the miscibility of poly(vinylidene fluoride), PVF₂, with certain oxygen containing polymers, blends of PVF₂ with poly(ε-caprolactone), PCL, with poly(vinyl methyl ether), PVME, and with poly(vinyl methyl ketone), PVMK, were prepared. PVMK/PVF₂ blends were found to be miscible while blends of PVME/PVF₂ and PCL/PVF₂ were found not to be miscible. These results show that the specific interaction with PVF₂ involves mainly the carbonyl group rather than the entire ester group. The relative effectiveness of having this group in the chain or pendant to it is not yet resolved.     

Polymer blends containing poly(vinylidene fluoride). Part IV: Thermodynamic interpretations

A summary of the transitional behavior of blends containing poly(vinylidene fluoride), PVF₂, and various oxygen-containing polymers is presented. These data are used to establish the presence of a single miscible amorphous phase. The depression of the PVF₂ melting point in those blends judged to be miscible is analyzed using standard thermodynamic arguments to determine the heats of mixing between the amorphous diluents and the PVF₂. These heats of mixing are exothermic indicating the presence of strong interactions between the binary pairs. A comparison between the observed interaction strengths and the dipole moments of the various diluents suggests that the exothermic heats of mixing are the result of strong dipole-dipole interactions. Nearly all the miscible blends with PVF₂ show Lower Critical Solution Temperature (LCST) behavior. The direct correlation between the temperature location of this phase instability and the observed interaction strength suggests that the instability is more the result of enthalpic considerations than entropic ones.     

New vinyl ester copolymers as stabilisers for dispersion polymerisation in scCO2

In this paper we demonstrate new poly vinyl alkylate homopolymers and copolymers with excellent solubility in scCO₂ that can be used as stabilisers for dispersion polymerisation in scCO₂. Poly (vinyl acetate) (PVAc) was combined in various ratios with poly (vinyl butyrate) (PVBu) and poly (vinyl octanoate) (PVOc) to both tune the scCO₂-solubility and provide adequate steric stabilisation. The polymer cloud points observed were found to be dependent on the ratio of the different blocks and the molecular weights and polydispersities (PDI) of the polymers. The effectiveness of these new polymeric stabilisers for dispersion polymerisation of N-vinyl pyrrolidone (N-VP) in scCO₂ is presented.     

A Viscometric Study of the Miscibility Behaviour of Poly(N-Vinyl Pyrrolidone) Blends

The miscibility behaviour of blends of poly(N-vinyl pyrrolidone) (PVP) with poly(vinyl chloride) (PVC), poly(vinyl acetate) (PVAc) and vinyl chloride–vinyl acetate (VCVAc) copolymer has been investigated on the basis of a viscometric approach. PVP is found to be miscible with PVC over the entire composition range, as is evident from the high values observed for the intrinsic viscosity of transfer. This is further supported by the single glass transition temperature observed in differential scanning calorimetry studies of the blend films. Blends of PVP with VCVAc copolymer exhibit microphase separation which is shown clearly in the scanning electron micrographs of the films. PVAc/PVP blends show interaction only at low PVAc contents, but in general are immiscible. © of SCI.     

Miscibility enhancement on the immiscible binary blend of poly(vinyl acetate) and poly(vinyl pyrrolidone) with bisphenol A

The miscibility behavior and hydrogen bonding of ternary blends of bisphenol A (BPA)/poly(vinyl acetate) (PVAc)/poly(vinyl pyrrolidone) (PVP) were investigated by using differential scanning calorimetry and Fourier transform infrared spectroscopy (FTIR). The BPA is miscible with both PVAc and PVP based on the observed single T_g over the entire composition range. FTIR was used to study the hydrogen-bonding interaction between the hydroxyl group of BPA and the carbonyl group of PVAc and PVP at various compositions. Furthermore, the addition of BPA is able to enhance the miscibility of the immiscible PVAc/PVP binary blend and eventually transforms into miscible blend with single T_g, when a sufficiently quantity of the BPA is present due to the significant Δχ and the ΔK effect.     

CO2-solubility of oligomers and polymers that contain the carbonyl group

Poly(vinyl acetate) (PVAc) is miscible with CO₂ over a broad range of molecular weights at 298 K. The cloud-point pressures needed to dissolve ∼5 wt% poly(methyl acrylate) (PMA) at 298 K are significantly greater than those needed to dissolve PVAc, even though a PMA repeat group has the same number of carbon, hydrogen, and oxygen atoms as in PVAc. This large difference in dissolution pressures is attributed to the lack of accessibility of the carbon dioxide to the carbonyl group in PMA. In addition, experimental data for poly(dimethyl siloxane) (PDMS) copolymers with readily accessible side groups suggest that an acetate group is slightly more CO₂-philic than an acrylate group. PVAc is more CO₂-soluble than other hydrocarbon homopolymers, including poly(propylene oxide) (PPO) and poly(lactide) (PLA). However, PVAc is significantly less miscible with CO₂ than PDMS and poly(fluoroalkyl acrylate) (PFA).     

Sorption and transport of inert gases in PVF2/PMMA blends

Sorption and transport of several inert gases (He, Ar, N₂, and CH₄) in miscible blends of PMMA and PVF₂ are reported as a function of pressure at 35°C. For each gas, the permeabilities are independent of pressure for all blend compositions. Sorption isotherms are linear for rubbery compositions (PVF₂-rich) and nonlinear for glassy compositions (PMMA-rich) as expected. In contrast to CO₂, these gases do not plasticize any of these materials. The data are analyzed using appropriate models for sorption and transport, and the parameters are correlated in terms of blend composition and molecular characteristics of the gases. Effects of crystallinity are discussed. Sorption behavior is compared with poly(methyl acrylate) and poly(vinyl acetate).     

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     

Studies on the miscibility and phase structure in blends of poly(epichlorohydrin) and poly(vinyl acetate)

The miscibility of atactic poly(epichlorohydrin) (aPECH) with poly(vinyl acetate) (PVAc) was examined under two different conditions: (i) in dilute solution, using vicometeric measurements and (ii) as cast films, using differential scanning calorimetric (DSC) and FT-infrared spectroscopy. Phase separation on heating, i.e. lower critical solution temperature (LCST) behavior of the aPECH/PVAc blends was examined by the measurement of transmitted light intensity against temperature. From viscosity measurements, the Krigbaum-Wall polymer-polymer interaction (ΔB) was evaluated. The DSC results show that the aPECH/PVAc blends are miscible as evidenced by the observation of a single composition-dependent glass-transition temperature (T_g) which is well described by the Couchman and Gordon Taylor models. The Flory-Huggins interaction parameter (χ₁₂) calculated from the T_g-method was negative and equal to −0.01, indicating a relatively low interaction strength. The FT-IR results match very well with those of DSC. The cloud point phenomenon is thermodynamically driven but phase separation, once taken place, is diffusion controlled in normal accessible time.     

Polymer blends containing poly(vinylidene fluoride). Part I: Poly(alkyl acrylates)

The transitional behavior of poly(vinylidene fluoride) (PVF₂) blends with poly(methyl acrylate) and with poly(ethyl acrylate) was examined by differential thermal analysis and dynamic mechanical testing. Both blend systems were judged to be miscible on the bases of the presence of single, composition dependent glass transitions and of the strong melting point depression of the PVF₂ component, Blends of poly(isopropyl acrylate) with poly(vinylidene fluoride) were found to be immiscible. These results suggest that miscibility of the acrylate series depends on a specific attractive interaction between the PVF₂ and oxygen within the acrylate and the effect of this interaction is diminished as the hydrocarbon content of the ester is increased.     

Studies of polyester/chlorinated poly(vinyl chloride) blends

Chlorinated poly(vinyl chloride) (CPVC) was solution blended with poly(caprolactone) (PCL), poly(hexamethylene sebacate) (PHMS), poly(α-methyl-α-n-propyl-β-propiolactone) (PMPPL), poly(valerolactone) (PVL), poly(ethylene adipate), poly(ethylene succinate) and poly(β-propiolactone). From calorimetric glass transition temperature (T_g) measurements, it is concluded that CPVC is miscible with polyesters having a CH₂/COO ratio larger than three (PCL, PHMS, PMPPL and PVL). The Gordon-Taylor k parameter was also calculated and found equal to 1.0 and 0.56 for PCL/CPVC and PHMS/CPVC blends, respectively. From these values, it is concluded that CPVC gives a stronger interaction with polyesters than poly(vinyl chloride) due to its larger chlorine content.     

Structures and gas permeabilities of poly(vinyl chloride)/oligo(dimethylsiloxane) blend membranes

A series of polymer blend membranes with several weight ratios of poly(vinyl chloride) (PVC) and oligo(dimethylsiloxane) (ODMS) were prepared and the permeation behaviors of O₂ and N₂ were studied. These components are only partially miscible to each other, leading to a phase separation. In order to improve the compatibility of these polymer blends, the use of a graft copolymer PVC-g-ODMS was explored. The gas permeation studies, the thermal analyses, and the microscopic observations were made on PVC-g-ODMS/ODMS blend membranes, and the results indicate that these blend membranes have rather high gas permeabilities together with good mechanical properties.     

Miscibility of linear low density polyethylene (LLDPE)-graft-poly(methyl methacrylate) with poly(vinylidene fluoride) (PVF2) and its application as compatibilizer LLDPE/PVF2 blends

Differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) were used to study the miscibility of blends of a graft copolymer of poly(methyl methacrylate) on linear low density polyethylene (LLDPE-g-PMMA, G-3) with poly(vinylidene fluoride)

1 Systematic name: poly(1,1-difluoroethylene).

(PVF₂) and the compatibilization of blends of LLDPE/PVF₂. The specific interaction between PMMA side chains and PVF₂ in G-3/PVF₂ binary blends is weaker than that between the homopolymers PMMA and PVF₂. There are two states of PVF₂ in the melt of a G-3/PVF₂ (60/40, w/w) blend, one as pure PVF₂ and the other interacting with PMMA side chains. The miscibility between PMMA side chains and PVF₂ affects the crystallization of PVF₂. LLDPE-g-PMMA was demonstrated to be a good compatibilizer in LLDPE/PVF₂ blends, improving the interfacial adhesion and dispersion in the latter. Diffusion of PMMA side chains into PVF₂ in the interfacial region reduces the crystallization rate and lowers the melting point (T_m) and the crystallization temperature (T_c) of PVF₂ in the blends.     

Miscibility and hydrogen bonding in blends of poly(vinyl acetate) with phenolic resin

The miscibility of phenolic resin and poly(vinyl acetate) (PVAc) blends was investigated by differential scanning calorimeter (DSC), Fourier transform infrared spectroscopy (FT-IR) and solid state ¹³C nuclear magnetic resonance (NMR). This blend displays single glass transition temperature (T_g) over entire compositions indicating that this blend system is miscible in the amorphous phase due to the formation of hydrogen bonding between hydroxyl groups of phenolic resin and carbonyl groups of PVAc. Quantitative measurements on fraction of hydrogen-bonded carbonyl group using both ¹³C solid-state NMR and FT-IR analyses result in good agreement between these two spectroscopic techniques. According to the proton spin-lattice relaxation time in the rotating frame (T_1ρ^H), the phenolic/PVAc blend is intimately mixed on a scale less than 2-3 nm. Furthermore, the inter-association equilibrium constant and its related enthalpy of phenolic/PVAc blends were determined as a function of temperatures by infrared spectra based on the Painter-Coleman association model.     

Transition behavior of poly(vinylidene fluoride)/poly(ethyl methacrylate) blends

Previous work has shown evidence that PMMA and PEMA are miscible with PVF₂. The present paper examines in detail the behavior of PEMA/PVF₂ blends by thermal analysis and dynamic mechanical testing. All transitions and relaxations are affected by blond composition but in a complex manner owing to the crystallization of PVF₂ from blends rich in this component. Inadequacies of the simple two-phase picture of semi-crystalline polymers is believed responsible for some of the transitional behavior observed here. The melting point depression observed for PVF₂ was found to be consistent with an exothermic heat of mixing for this pair comparable in value to that found for PPMA/PVF₂/All evidence here are consistent with the previous conclusion of miscibility for these systems.     

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.     

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.     

Compatibility of nylon 6 with poly(vinyl alcohol), hydroxylated poly(vinyl acetate) and poly(vinyl acetate)

Summary The compatibility of nylon 6 with poly(vinyl acetate)(PVAc) and poly(vinyl alcohol)(PVA) was investigated in terms of the melting-temperature depression. In order to vary the compatibility systematically, a hydroxylated poly(vinyl actate)(m-PVAc) was prepared by hydrolyzing PVAc with KOH in CH₃OH. It was found that the compatibility with nylon 6 is better in the systematic order PVA> m-PVAc> PVAc.     

Preparation of poly(vinyl butyral) with high acetalization rate

Poly(vinyl alcohol) (PVA) can be dissolved in a nonaqueous medium in the presence of catalytic concentration of ethyl nitrate dimethyl sulfoxide, C₂H₅ONO₂ · DMSO (EN · DMSO). From the PVA solution, poly(vinyl butyral) (PVBu) was prepared by acid‐catalyzed homogeneous acetalization of PVA with butyraldehyde. The formation of PVBu was confirmed by IR and ¹H‐NMR spectra. The degree of acetalization of PVBu was found to be 95 mol %, which was verified by ¹H‐NMR data and acetylation method. The molecular mass of the polymer was determined by GPC method. The glass transition temperature, T_g, was measured from differential scanning calorimetric (DSC) thermograms. Thermal stabilities were checked by thermogravimetric analysis (TGA) and differential thermogravimetry (DTG). The acetal decomposed in three stages. The corresponding initial decomposition temperatures were found to be 285, 390, and above 500°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1182–1186, 2001