Miscibility and morphology of poly(vinylidene fluoride)/poly[(vinylidene fluoride)‐ran‐trifluorethylene] blends

This study presents an investigation of the effect of the different crystalline phases of each blend component on miscibility when blending poly(vinylidene fluoride) (PVDF) and its copolymer poly[(vinylidene fluoride)‐ran‐trifluorethylene] [P(VDF–TrFE)] containing 72 mol % of VDF. It was found that, when both components crystallized in their ferroelectric phase, the PVDF showed a strong effect on the crystallinity and phase‐transition temperature of the copolymer, indicating partial miscibility in the crystalline state. On the other hand, immiscibility was observed when both components, after melting, were crystallized in their paraelectric phase. In this case, however, a decrease in crystallization temperatures suggested a strong interaction between monomers in the liquid state. Blend morphologies indicated that, in spite of the lack of miscibility in the crystalline state, there is at least miscibility between PVDF and P(VDF–TrFE) in the liquid state, and that a very intimate mixture of the two phases on the lamellar level can be maintained upon crystallization. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1362–1369, 2002     

Miscibility,phase behavior,and mechanical properties of ternary blends of poly(vinyl chloride)/polystyrene/chlorinated polyethylene-graft-polystyrene

The effectiveness of chlorinated polyethylene-graft-polystyrene (CPE-g-PS) as a polymeric compatibilizer for immiscible poly(vinyl chloride)/polystyrene (PVC/PS) blends was investigated. The miscibility, phase behavior, and mechanical properties were studied using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), Izod impact tests, tensile tests, and scanning electron microscopy (SEM). DSC and DMA studies showed that PVC is immiscible with chlorinated polyethylene (CPE) in CPE-g-PS, whereas the PS homopolymer is miscible with PS in CPE-g-PS. The PVC/PS/CPE-g-PS ternary blends exhibit a three-phase structure: PVC phase, CPE phase, and PS phase that consisted of a PS homopolymer and PS in CPE-g-PS. The mechanical properties showed that CPE-g-PS interacts well with both PVC and PS and can be used as a polymeric compatibilizer for PVC/PS blends. CPE-g-PS can also be used as an impact modifier for both PVC and PS. SEM observations confirmed, after the addition of CPE-g-PS, improvement of the interfacial adhesion between the phases of the PVC/PS blends. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 995–1003, 1998     

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     

Behavior of flexible poly(vinyl chloride)/poly(hydroxybutyrate valerate) blends

Blends of flexible poly(vinyl chloride) (PVC) and a poly(hydroxybutyrate valerate) (PHBV) copolymer were prepared and characterized with different techniques. The tensile strength of PVC did not show a marked reduction at PHBV concentrations up to 50 phr, despite a lack of miscibility between the two polymers. The crystallization of the PHBV copolymer was markedly hindered by the presence of PVC, as calorimetric results revealed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Miscibility and thermal behavior of poly(vinyl chloride)/feather keratin blends

Various poly(vinyl chloride) (PVC)/feather keratin (FK) blends were prepared via a solution blending method in the presence of N,N‐dimethylformamide as a solvent. The miscibility of the blends was studied with different analytical methods, such as dilute solution viscometry, differential scanning calorimetry, refractometry, and atomic force microscopy. According to the results obtained from these techniques, it was concluded that the PVC/FK blend was miscible in all the studied compositions. Specific interactions between carbonyl groups of the FK structure and hydrogen from the chlorine‐containing carbon of the PVC were found to be responsible for the observed miscibility on the basis of Fourier transform infrared spectroscopy. Furthermore, increasing the FK content in the blends resulted in their miscibility enhancement. The thermal stability of the samples, as an important characteristic of biobased polymer blends, was finally examined in terms of their FK weight percentage and application temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Compatibility study of recycled poly(vinyl chloride)/styrene‐acrylonitrile blends

The aim of the present study is to analyze the compatibility between recycled Poly(vinyl chloride) (PVC) and styrene‐acrylonitrile copolymer (SAN). With this objective recycled PVC coming from credit cards have been blended with both virgin and recycled SAN with the aim of increase the benefits of recycled PVC. The compatibility of the components will be crucial for the final properties of the material. Furthermore, the recycled nature of some of the components will determine the compatibilization capability of the blend. The degradation level in the recycled materials was determined using Fourier transform infrared spectroscopy (FTIR). The compatibility between the PVC and the SAN was studied using differential scanning calorimetry and dynamic mechanical analysis. A greater compatibility was observed in mixtures of PVC and virgin SAN than in mixtures of PVC and recycled SAN. Finally, a morphological study of the fracture surface under cryogenic conditions was carried out using scanning electron microscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Morphology and properties of poly(vinylidene fluoride)/silicone rubber blends

Blends of poly(vinylidene fluoride) (PVDF) and silicone rubber (SR) were prepared through melt mixing. The morphology, rheology, crystallization behavior, mechanical properties, dynamic mechanical properties and thermal properties of the PVDF/SR blends were investigated. The blend with 9 wt % of SR showed spherical shape of disperse phase whereas the blend with 27 wt % of SR resulted in irregular shape of rubber phase. The rheology showed that the complex viscosity and storage modulus of the blends decreased with increasing the SR content. The mechanical properties of the blends were decreased with increasing the SR content but that were significantly improved after dynamical vulcanization. The crystallization temperature of PVDF phase in PVDF/SR blends was increased. The incorporation of SR improved the thermal stability of PVDF/SR blends, and the temperature at 10% mass loss of the blends increased to about 489°C compared with 478°C of the pure PVDF. The mass of residual char in experiment of the blends was lower than that obtained in theory. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39945.     

Compatibility of poly(vinylidene fluoride) (PVDF)/polyamide 12 (PA12) blends

Poly(vinylidene fluoride) (PVDF)/polyamide 12 (PA12) blends showed new peaks in XRD profile with increasing PA12 and the crystallinity of PA12 significantly decreased with the addition of PVDF. PVDF showed three relaxation regions at about −40, 40, and 100°C, respectively, and glass transition temperature (T_g ) of PA12 increased in blends (10.8→30.14°C) and α‐relaxation of PVDF decreased from 100.26 to 86.46°C. Complex viscosities (η*) vs. composition curve showed a great positive deviation in PVDF‐rich and a small negative deviation in PA12‐rich blends. The N—H and C=O stretching band of PA12 shifted slightly toward higher wavelength, and from curve‐fitted data the area of hydrogen‐bonded C=O stretching bands of PA12 decreased with the addition of PVDF, especially in the 30/70 blend, implying the existence of interactions between the β‐hydrogen atom of PVDF and amide carbonyl group of PA12 in the blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1374–1380, 2000     

Counterion dependent crystallization kinetics in blends of a perfluorosulfonate ionomer with poly(vinylidene fluoride)

Blends of poly(vinylidene fluoride) (PVDF) with a perfluorosulfonate ionomer, Nafion^®, have been prepared and examined in terms of the crystallization kinetics of the PVDF component. In blends of PVDF with Na⁺-form Nafion^®, the rates of bulk crystallization, as observed by DSC, and the spherulitic growth rates of the PVDF component, as observed using optical microscopy, were found to be very similar to that of pure PVDF. This behavior was attributed to the course phase separation of Na⁺-form Nafion^® from PVDF and melt incompatibility of the physically cross-linked ionomer with the crystallizable component. In this segregated state, the PVDF component of the blend is allowed to crystallize in pure phases that are isolated under the influence of Nafion^®. In contrast, when the ionomer was exchanged with more weakly interacting quaternary alkylammonium counterions, a decrease in both the rate of bulk crystallization and spherulitic growth was observed. Furthermore, the crystallization kinetics of PVDF in these blends was found to be dependent on the counterion size; as the size of counterions associated with the Nafion^® component increased, the rate of crystallization decreased. This behavior was attributed to a weakening of the electrostatic interactions in the ionomer phase and thus an increase in the extent of phase mixing with the larger ions.     

Compatibilization of regenerated low density polyethylene/poly(vinyl chloride) blends

The aim of this work is to study the valorization of regenerated low density polyethylene (rLDPE) by blending with PVC in the presence of chlorinated polyethylene (CPE) as compatibilizer. For this purpose, four rLDPE samples coming from neat or dirty wastes were used. They were obtained after milling, washing, and extrusion in a conventional recycling plant. They were first characterized in terms of physicochemical (density, melt flow index, water absorption, and level of oxidation by Fourier transform infrared spectroscopy) and mechanical (tensile and shore D hardness) properties. The effect of the ratio of PVC on these physical and mechanical properties was then investigated. These binary blends exhibited lower properties than those of the separated polymers. The addition of CPE to the binary blend with weight proportion of 50/50 leads to a substantial improvement of the considered properties which is due to a better interfacial adhesion between rLDPE and PVC as evidenced by the analysis of the morphology of the blends by scanning electron microscopy. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermal properties of graphite‐loaded nitrile rubber/poly(vinyl chloride) blends

The thermal properties (thermal conductivity, thermal diffusivity, and specific heat capacity) of nitrile rubber (NBR)/poly(vinyl chloride) (PVC) blends were measured in the temperature range of 300–425 K. The incorporation of graphite into the NBR/PVC (30/70) matrix improved its thermal properties. Moreover, these properties slightly changed with the temperature. The thermal conductivity values of the prepared samples were compared with values modeled according to the Maxwell–Eucken, Cheng–Vachon, Lewis–Nielsen, geometric mean, and Agari–Uno models. The Agari–Uno model best predicted the effective thermal conductivity for the whole range of blend ratios and for the whole range of graphite contents in NBR/PVC (30/70)/graphite composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Study of crystal structure and properties of poly(vinylidene fluoride)/graphene composite fibers

Poly(vinylidene fluoride) (PVDF) nascent composite fibers were prepared through the melt-spinning method with different graphene (GE) contents, following which post-stretched composite fibers were obtained using a post-stretching process under thermal treatment condition. The effects of GE content and post-stretching ratio on the crystal structure and properties of the fibers were investigated in order to obtain PVDF composite fibers with high β crystal content and high hydrophobicity and oleophilicity. The results indicated that the addition of GE led to some extent to an improvement in the content of β crystals and the orientation of crystals. Furthermore, the addition of GE obviously improved the mechanical properties, hydrophobicity and oleophilicity of nascent composite fibers. The post-stretching ratio had a significant influence on the transition of the crystal phase from α to β and the orientation of crystals. In addition, the post-stretching played a positive role in enhancement of mechanical properties and hydrophobicity. When 5 wt% GE was added and the post-stretching ratio was 6, PVDF composite fibers with high β crystal content, super-oleophilicity and high hydrophobicity could be obtained. The β crystal content of PVDF composite fibers could reach 62.8%, oil contact angle was 0° and water contact angle was 116.0°. © 2021 Society of Industrial Chemistry.     

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     

Evaluation of compatibility of poly(vinyl chloride)/starch acetate blends using simple techniques

Solution blending of poly(vinyl chloride) (PVC) and starch acetate (d.s. 2.5) synthesized in our laboratory was carried out in 1,4‐dioxane. The compatibility of these blends based on the heat of mixing and the free‐energy concept was examined theoretically. Experimental evidence for the compatibility of these blends was derived from viscometric and ultrasonic studies and density measurements. Interaction parameters suggest that polymer–polymer interaction is greater than polymer–solvent interaction in the blends under study. All the experimental and theoretical evidence show that the blends are incompatible at the compositions studied. Morphological studies showed a uniform dispersion of starch acetate in PVC. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1851–1861, 1999     

Evolution of morphology,ferroelectric, and mechanical properties in poly(vinylidene fluoride)–poly(vinylidene fluoride‐trifluoroethylene) blends

Considering the complementary properties of poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride‐trifluoroethylene) [P(VDF‐TrFE)], it appears that their blends have the potential to be promising candidates for device applications. We report the evolution of morphology, ferroelectric, and mechanical properties (modulus and hardness) and their dependence on preparation temperature for PVDF–P(VDF‐TrFE) blends. From ferroelectric hysteresis measurements it was found that P(VDF‐TrFE) rich blends treated at higher temperature show significant values of remanent polarization. Remanent polarization values show a fourfold increase in these P(VDF‐TrFE) rich blends treated at higher temperature. Interestingly, blends prepared from high temperature showed greater value of remanent polarization even though they were found to consist of smaller amount of electroactive phase as compared to their low temperature treated counterpart. Nanoindentation experiments revealed that high temperature treatment improves the modulus of blends by at least 100%. This report attempts to tie these findings to the morphology and crystallinity of these blends. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45955.     

Compatibility,steady and dynamic rheological behaviors of polylactide/poly(ethylene glycol) blends

Understanding the rheological behavior of plasticized polylactide (PLA) contributed to the optimization of processing conditions and revealed the microstructure–property relationships. In this study, the morphological, thermal, steady and dynamic rheological properties of the PLA/poly(ethylene glycol) (PEG) blends were investigated by scanning electron microscope, differential scanning calorimeter, and capillary and dynamic rheometers, respectively. The results illuminated that the melt shear flow basically fitted the power law, whereas the temperature dependence of the apparent shear viscosity (η_a) or complex viscosity (η*) followed the Arrhenius equation. Both the neat PLA and PLA/PEG blends exhibited shear‐thinning behavior. Because the incorporation of PEG reduced the intermolecular forces and improved the mobility of the PLA chains, the η_a, η*, and storage and loss moduli of the PLA/PEG blends decreased. The PEG content (W_PEG) ranged from 0 to 10 wt %, both η_a and η* decreased significantly. However, the decrements of η_a and η* became unremarkable when W_PEG exceeded 10 wt %. The reason was attributed to the occurrence of phase separation, which resulted in the decrease in the plasticization and lubrication efficiencies. This study demonstrated that the addition of the right amount of PEG obviously improved the flow properties of PLA. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42919.     

Influence of fluorine interface to the crystallization of poly (vinylidene fluoride)/silicone rubber/fluororubber elastomeric tertiary blends via dynamical curing

ABSTRACT

We demonstrate the influence of fluorine interface to the crystallization of poly(vinylidene fluoride) (PVDF)/silicone rubber (SR)/fluororubber (FKM) tertiary dynamic curing blends. In contrast to PVDF/SR binary blend, the average size of PVDF spherulites turns smaller and the crystallization rate is lower in PVDF/SR/FKM tertiary blend when more fluororubber component was added into the blends at the same crystallization temperature. Incorporation of FKM does not change the crystalline form of PVDF in the blends. The resulting mechanical properties of tensile strength, flexural strength, Izod impact strength and elongation at break for PVDF/SR/FKM tertiary blends are enhanced compared with PVDF/SR binary blend.     

Spherulitic morphology and growth of poly(vinylidene fluoride)/poly(3-hydroxybutyrate-co-hydroxyvalerate) blends by optical microscopy

Poly(vinylidene fluoride) (PVDF) and poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV), both semicrystalline polymers, are miscible as shown by the single glass transition temperature over the entire composition range. Morphology of PVDF/PHBV blends was investigated by optical microscopy under two different crystallization conditions. PVDF showed the spherulitic morphology at 150 °C in the PVDF/PHBV blends, where PHBV acted as the noncrystallizing component. PHBV also showed the spherulitic morphology within the matrix of the pre-existing PVDF crystals when PVDF/PHBV blends were quenched from the melt to the crystallization temperature below the melting point of PHBV. The spherulitic growth of PHBV was investigated as the function of both blend composition and crystallization temperature.     

Viscoelastic and pressure–volume–temperature properties of poly(vinylidene fluoride) and poly(vinylidene fluoride)–hexafluoropropylene copolymers

The relationship between the pressure, volume, and temperature (PVT) of poly(vinylidene fluoride) homopolymers (PVDF) and poly(vinylidene fluoride)–hexafluoropropylene (PVDF–HFP) copolymers was determined in the pressure range of 200–1200 bar and in the temperature range of 40°C–230°C. The specific volume was measured for two homopolymers having a molecular weight (M_w) of 160,000–400,000 Da and three copolymers containing between 3 and 11 wt % HFP with a molecular weight range of 320,000–480,000 Da. Differential scanning calorimetry (DSC) was used to simulate the cooling process of the PVT experiments and to determine the crystallization temperature at atmospheric pressure. The obtained results were compared to the transitions observed during the PVT measurements, which were found to be pressure dependent. The results showed that the specific volume of PVDF varies between 0.57 and 0.69 cm³/g at atmospheric pressure, while at high pressure (1200 bar) it varies between 0.55 and 0.64 cm³/g. For the copolymers, the addition of HFP lowered its melting point, while the specific volume did not show a significant change. The TAIT state equation describing the dependence of specific volume on the zero‐pressure volume (V₀,T), pressure, and temperature has been used to predict the specific volume of PVDF and PVDF–HFP copolymers. The experimental data was fitted with the state equation by varying the parameters in the equation. The use of the universal constant, C (0.0894), and as a variable did not affect the predictions significantly. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 230–241, 2001