New method of determining miscibility in binary polymer blends through hydrodynamic interaction: The free volume approach

A new method has been developed to determine the probability of miscibility in binary polymer blends through hydrodynamic interaction. This is achieved by the measurement of the free volume content in blends of carefully selected systems—styrene acrylonitrile (SAN)/poly(methyl methacrylate) (PMMA), PMMA/poly(vinyl chloride) (PVC), and PVC/polystyrene (PS)—with positron annihilation lifetime spectroscopy. The free volume content can predict the miscible/immiscible nature of the blends but provides no information on the extent of miscibility for different compositions of the blends. We have generalized a model used to understand the viscometric behavior of polymer/solvent systems to polymer/polymer systems through the free volume approach. This model provides two important parameters: a geometric factor (γ) and a hydrodynamic interaction parameter (α). γ depends on the molecular architecture, whereas α accounts for the excess friction at the interface between the constituents of the blend, and we propose that α can serve as a precursor to miscibility in a system and indicate which composition produces a high probability of miscibility. The efficacy of this proposition has been checked with measured free volume data for the three blend systems. The SAN/PMMA system produces a maximum α value of ?209 at 20% PMMA; PVC/PMMA produces a maximum α value of ?57 at 10% PMMA. Interestingly, for the PS/PVC system, α is close to zero throughout the entire concentration range. Therefore, we infer that α is perhaps an appropriate parameter for determining the composition‐dependent probability of miscibility in binary blend systems. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Characterization of interfaces in Poly (styrene-co-acrylonitrile) (SAN) based ternary polymer blends: A new approach from positron lifetime spectroscopy

Positron lifetime spectroscopy is used to develop a new approach to characterize the individual interfaces in ternary polymer blends and hence determine composition dependent miscibility level. This approach has its genesis in KSR and KRZ models for the evaluation of hydrodynamic interaction parameters (α_ij). The method successfully applied for binary blends (single interface) earlier is theoretically modified for ternary blends and experimentally verified by measuring free volume content in blends and their constituents. We have tested the efficacy of this method in two ternary blends namely SAN/PVC/PMMA and SAN/EVA/PVC at different compositions. The effective hydrodynamic parameter α_eff evaluated using individual α values turns out to be handy in predicting the overall miscibility level of a ternary blend. Results show that SAN/PVC/PMMA exhibits maximum α_eff of ?9.67 at composition 75/5/20 and SAN/EVA/PVC shows ?3.18 at 50/35/15 indicating that miscibility level is high at these compositions for these two blends. DSC and SEM studies have also been used to supplement positron results.     

Miscibility windows in ternary polymer blends of a polyester,polymethacrylate and poly(styrene‐co‐acrylonitrile)

Miscibility, phase diagrams and morphology of poly(ε‐caprolactone) (PCL)/poly(benzyl methacrylate) (PBzMA)/poly(styrene‐co‐acrylonitrile) (SAN) ternary blends were investigated by differential scanning calorimetry (DSC), optical microscopy (OM), and scanning electron microscopy (SEM). The miscibility window of PCL/PBzMA/SAN ternary blends is influenced by the acrylonitrile (AN) content in the SAN copolymers. At ambient temperature, the ternary polymer blend is completely miscible within a closed‐loop miscibility window. DSC showed only one glass transition temperature (T_g) for PCL/PBzMA/SAN‐17 and PCL/PBzMA/SAN‐25 ternary blends; furthermore, OM and SEM results showed that PCL/PBzMA/SAN‐17 and PCL/PBzMA/SAN‐25 were homogeneous for any composition of the ternary phase diagram. Hence, it demonstrated that miscibility exists for PCL/PBzMA/SAN‐17 and PCL/PBzMA/SAN‐25 ternary blends, but that the ternary system becomes phase‐separated outside these AN contents. Copyright © 2003 Society of Chemical Industry     

Effect of dehydrochlorination of PVC on miscibility and phase separation of binary and ternary blends of poly(vinyl chloride), poly(ethylene-co-vinyl acetate) and poly(styrene-co-acrylonitrile)

The enhancement of miscibility at the lower critical solution temperature (LCST) of the blends poly(vinyl chloride)/poly(ethylene-co-vinyl acetate) (PVC/EVA), poly(vinyl chloride)/poly(styrene-co-acrylonitrile) (PVC/SAN) and poly(vinyl chloride)/poly(ethylene-co-vinyl acetate)/poly(styrene-co-acrylonitrile) (PVC/EVA/SAN) was observed at the micron level. Such miscibility is attributed to the dehydrochlorination and formation of hydrogen bonds between blend components. However, macrolevel immiscibility of these blends heated to the LCST was observed. Such microdomain compatibility of these blends gives a synergistic character. Brittle-type failure observed for LCST samples testifies to the synergism in treated blends. ©1997 SCI     

Phase equilibrium in the binary and ternary blend system: Polycaprolactone-polyvinyl chloride-styrene acrylonitrile copolymer

An experimental study of binary and ternary phase equilibrium in the system polycaprolactone (PCL) poly(vi-nylchloride) (PVC)-77/23 styrene-acrylonitrile copolymer (SAN) is described. Miscibility is determined using differential scanning calorimetry (DSC) and turbidity. PCL/PVC and PCL/SAN are largely miscible systems but PVC/SAN is immiscible. The ternary system shows considerable miscibility. The blends are characterized by polarized light microscopy and wide-angle X-ray diffraction. The former measurement characterizes the structure of the spherulites. Additions of PVC, SAN, or PVC/SAN causes the spherulites observed in PCL to grow in size and become coarse. X-ray diffraction shows no movement of crystallographic peaks indicating the crystallographic unit cell is composed of PCL. Melting point depression measurements are used to calculate Flory χ interaction parameters for PCL/PVC and PCL/SAN. The melting point depression is also considered and used to investigate PVC/SAN interaction. An effort is made to compute the ternary phase diagram and tie lines.     

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 studies of polymer blends by viscometry methods

The intrinsic viscosities of blends of poly(vinyl chloride)/poly(ethylene-co-vinyl acetate) (PVC/EVA), poly(vinyl chloride)/poly(styrene-co-acrylonitrile) (PVC/SAN), and poly(ethylene-co-vinyl acetate)/poly(styrene-co-acrylonitrile) (EVA/SAN) have been studied in cyclohexanone as a function of blend composition. In order to predict the compatibility of polymer pairs in solution, the interaction parameter term, Δb, obtained from the modified Krigbaum and Wall theory, and the difference in the intrinsic viscosities of the polymer mixtures and the weight average intrinsic viscosities of the two polymer solutions taken separately are used. © 1994 John Wiley & Sons, Inc.     

A DSC investigation on the stabilizer distribution in PVC blends

The distribution of a liquid organotin stabilizer between the phases of heterogeneous poly(vinyl chloride) (PVC) blends has been studied by differential scanning calorimetry (DSC). This method can be used even at low stabilizer concentrations. At concentrations > 1 wt.-% the stabilizer can be detected in both phases of a PVC/SAN (poly(vinyl chloride)/poly(styrene-co-acrylonitrile)) blend. At lower concentrations no stabilizer could be found in the SAN phase. Determination of the induction period of thermal degradation at 180°C under nitrogen atmosphere showed no loss of thermal stability for blends containing the stabilizer partly in the SAN phase. Kinetic measurements with the DSC indicate a migration of the stabilizer out of the SAN phase, PVC/PMA (poly(vinyl chloride)/poly(methyl acrylate)) blends showed no solubility of the stabilizer in the soft PMA phase.     

Miscibility and rheological properties of poly(vinyl chloride)/styrene–acrylonitrile blends prepared by melt extrusion

Styrene–acrylonitrile (SAN) with acrylonitrile (AN) concentrations of 11.6–26 wt % and α‐methylstyrene acrylonitrile (αMSAN) with a wide range of AN concentrations are miscible with poly(vinyl chloride) (PVC) through solution blending. Here we examine the rheological properties and miscibility of PVC/SAN and PVC/αMSAN blends prepared by melt extrusion for commercial applications. We have investigated the rheological properties of the blends with a rheometer and a melt indexer. The PVC/SAN and PVC/αMSAN blends have a low melting torque, a long degradation time, and a high melt index, and this means that they have better processability than pure PVC. The miscibility of the blends has been characterized with differential scanning calorimetry, dynamic mechanical thermal analysis, and advanced rheometrics expansion system analysis. The miscibility of the blends has also been characterized with scanning electron microscopy. The SAN series with AN concentrations of 24–31 wt % is immiscible with PVC by melt extrusion, whereas αMSAN with 31 wt % AN is miscible with PVC, even when they are blended by melt extrusion, because of the strong interaction between PVC and αMSAN. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

DSC studies of poly(vinyl chloride)/poly(ε-caprolactone)/poly(ε-caprolactone)-b-poly(dimethylsiloxane) blends

Poly(vinyl chloride)/poly(ε-caprolactone)/poly(ε-caprolactone)-b-poly(dimethylsiloxane) [PVC/PCL/(PCL-b-PDMS)] blends were prepared by solvent casting from tetrahydrofuran. The content of PVC was kept constant (60 wt%); the PCL and PCL-b-PDMS contents were varied by replacing different amounts of PCL [0–20 wt% from the PVC/PCL (60/40) blend] with PCL-b-PDMS copolymer having different molecular weights of the PCL blocks. The thermal properties of prepared blends were investigated by differential scanning calorimetry in order to analyse miscibility (through glass transition temperature) and crystallinity. Differential scanning calorimetry analyses show that the PVC/PCL/PCL-b-PDMS blends are multi-phase materials which contain a PVC plasticized with PCL phase, a block copolymer PCL-b-PDMS phase (with crystalline and amorphous PCL and PDMS domains) and a PCL phase (preponderantly crystalline).     

The physical properties and morphology of poly-ϵ-caprolactone polymer blends

The compatibility, morphology, and mechanical properties of poly-?-caprolactone (PCL) blended with poly(vinyl chloride), nitrocellulose, and cellulose acetate butyrate are described in this study. Methods used in this investigation included differential scanning calorimetry, dynamic mechanical testing, small-angle light scattering, light microscopy and stress–strain testing. Blends of PCL with poly(vinyl chloride) (PVC) are shown to be compatible in all proportions. In the PCL concentration range 40–100%, the PCL crystallizes in the form of negative spherulites. The spherulites were found to be volume filling with as much as 35% PVC. The nitrocellulose blends with PCL exhibited the glass transition behavior of a compatible system over the composition range of 50–100% PCL. At lower PCL concentrations, phase separation was apparent. The PCL crystallinity was present only in the nitrocellulose blends with more than 50% PCL, and it was in the form of rod-like super-structures. Blends of PCL with cellulose acetate butyrate were shown to be phase separated, with one phase having nearly equal proportions of the two polymers. The PCL crystallinity was in the form of negative spherulites and was formed with PCL compositions as low as 50%. Stress–strain results show polycaprolactone to be an effective plasticizer for poly(vinyl chloride) and the cellulose derivatives studied.     

Free volume microprobe studies on poly(methyl methacrylate)/poly(vinyl chloride) and poly(vinyl chloride)/polystyrene blends

Blends of Poly(methyl methacrylate) (PMMA)/Poly(vinyl chloride) (PVC) and Poly(vinyl chloride) (PVC)/Polystyrene (PS) of different compositions were prepared by solution casting technique. The blends were characterized using Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), and Positron Lifetime Spectroscopy. DSC data were found to be inadequate to describe whether PMMA/PVC blends are miscible or not, possibly because of the small gap in their glass transition temperatures. On the other hand, PVC/PS blends were clearly found to be immiscible by DSC. FTIR results for PMMA/PVC indicate the possible interactions between the carbonyl group of PMMA and α‐hydrogen of PVC. Free volume data derived from Positron lifetime measurements showed that the PMMA/PVC blends to be miscible in low PVC concentration domain. For the first time, the authors have evaluated the hydrodynamic interaction parameter α, advocated by Wolf and Schnell, Polymer, 42, 8599 (2001), to take into account the friction between the component molecules using the free volume data. This parameter (α) has a high value (?57) at 10 wt% of PVC, which could be taken to read miscibility for PMMA/PVC blends to be high. In the case of PVC/PS blends, the positron results fully support the DSC data to conclude the blends to be immiscible throughout the range of concentration. As expected, the hydrodynamic interaction parameter α does not show any change throughout the concentration in PVC/PS blends, further supporting the idea that α is another suitable parameter in the miscibility study of polymer blends. POLYM. ENG. SCI., 46:1231–1241, 2006. © 2006 Society of Plastics Engineers     

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.     

Blends of imidized acrylic polymers with SAN copolymers and with PVC

A series of imidized acrylic polymers of varying structural composition generated by reaction of methylamine with poly(methyl methacrylate) were blended with a range of styrene/acrylonitrile or SAN copolymers (0–33% AN) and with poly(vinyl chloride). On the basis of glass transition behavior determined by differential scanning calorimetry, some but not all imidized acrylic structures were found to be miscible with PVC and with SAN copolymers within a limited window of AN levels. Acid functionality in the imidized acrylics appears to hinder their miscibility with SAN rather significantly and with PVC to a lesser extent. Miscible SAN blends showed lower critical solution temperature behavior whereas miscible blends with PVC did not up to the highest attainable temperatures. The composition factors that influence the phase behavior are described and interpreted in terms of possible mechanisms.     

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.     

Mechanical properties of oriented poly(vinyl chloride)–poly(caprolactone) blends

Blends of poly(vinyl chloride) (PVC) with polycaprolactone (PCL) of different compositions were prepared from solutions in tetrahydrofuran (THF). The dried blends were stretched at different temperatures above the glass transition, and the birefringence and mechanical properties were studied. It is shown that the birefringence of PVC and the 75/25 PVC/PCL blend follows an affine deformation scheme with a decreasing number of segments with deformation. The 50/50 PVC/PCL blend shows a complex orientation behavior because of the presence of crystallinity in the PCL phase. The mechanical properties of the blends are shown to increase with orientation, and the aggregate model is acceptably followed by the amorphous oriented blends.     

Synthesis of poly[(2‐oxo‐1,3‐dioxolan‐4‐yl)methyl vinyl ether‐co‐N‐phenylmaleimide] and its miscibility in blends with styrene‐acrylonitrile or poly(vinyl chloride)

The aim of the study was to investigate the synthesis of a copolymer bearing cyclic carbonate and its miscibility with styrene/acrylonitrile copolymer (SAN) or poly(vinyl chloride) (PVC). (2‐Oxo‐1,3‐dioxolan‐4‐yl)methyl vinyl ether (OVE) as a monomer was synthesized from glycidyl vinyl ether and CO₂ using quaternary ammonium chloride salts as catalysts. The highest reaction rate was observed when tetraoctylammonium chloride (TOAC) was used as a catalyst. Even at the atmospheric pressure of CO₂, the yield of OVE using TOAC was above 80% after 6 h of reaction at 80°C. The copolymer of OVE and N‐phenylmaleimide (NPM) was prepared by radical copolymerization and was characterized by FTIR and ¹H‐NMR spectroscopies and differential scanning calorimetry (DSC). The monomer reactivity ratios were given as r₁ (OVE) = 0.53–0.57 and r₂ (NPM) = 2.23–2.24 in the copolymerization of OVE and NPM. The films of poly(OVE‐co‐NPM)/SAN and poly(OVE‐co‐NPM)/PVC blends were cast from N‐dimethylformamide. An optical clarity test and DSC analysis showed that poly(OVE‐co‐NPM)/SAN and poly(OVE‐co‐NPM)/PVC blends were both miscible over the whole composition range. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1809–1815, 2000     

Thermal degradation of ternary blends of poly(ε‐caprolactone)/poly(vinyl acetate)/poly(vinyl chloride)

The thermal degradation of ternary blends of poly(ε‐caprolactone) (PCL), poly(vinyl acetate) (PVAC), and poly(vinyl chloride) (PVC) was studied using a thermogravimetry analyzer under dynamic heating in flowing nitrogen atmosphere. PCL degraded in a single stage, whereas the PVAC and PVC degraded in two stages during which acid is released in the first stage followed by backbone breakage in the second stage. The addition of PVC to either PCL or PVAC affected the thermal stability of the blend, whereas the addition of PVAC to PCL did not alter the thermal stability of the blend. In ternary blends, the addition of PVC affected the degradation of PVAC but did not influence the degradation of PCL in the range investigated. The increased addition of PCL to the binary blends of PVC/PVAC decreased the extent of thermal instability of PVAC because of the addition of PVC. The addition of even 10% PVAC to the PCL/PVC blend removed the thermal instability of PCL resulting from the addition of PVC and can be attributed to the ease of chlorine or hydrogen chloride capture of PVAC over PCL. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1378–1383, 2004     

Miscibility enhancement on the poly(vinylchloride)/poly(methylmethacrylate) blend and characterization by inverse gas chromatography: The corrected polymer–polymer interaction parameters from the probes dependency

The miscibility of poly(vinyl chloride)/poly(methylmethacrylate) (PVC/PMMA) system was improved by introducing some pyrrolidone units into the main chains of PMMA. For that purpose, we have synthesized two copolymers of poly(methylmethacrylate‐co‐vinylpyrrolidone) (MMVP) through a radical polymerization and carried out a comparative study of PVC/MMVP blends by inverse gas chromatography (IGC) and differential scanning calorimetry (DSC) methods. The adequacy of seven n‐alkane probes has been tested to determine the thermodynamic parameters. The miscibility of the two systems has been proved by a single T_g for each blend. This observation was also confirmed by DSC analysis. To highlight the presence of interaction and its intensity between PVC and MMVP in the blends, the polymer–polymer interaction parameters have been evaluated by IGC trough which the influence of the solute has been resolved. The Schneider approach confirmed the miscibility of these systems as the K deviates positively from unity. The miscibility has been appeared highlighted from the positive difference in surface energy between the pure polymers and their blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Miscibility phenomena in polyester/chlorinated polymer blends

Poly(caprolactone) (PCL)/poly(vinyl chloride) (PVC) blends are known to be miscible in the solid state. Recents measurements however indicate that a large number of polyesters are also miscible with PVC if the ratio CH₂/C?O of the polyester is between 4 and 10. At low CH₂/C?O ratios, polyesters are too rigid to interact specifically with PVC. At high CH₂/C?O ratios, the number of interacting groups becomes too small to give miscibility. Similarly, a large number of chlorinated polymers are shown to be miscible with PCL if their chlorine content is high enough. Surprisingly, polyesters are not in general miscible with chlorinated polymers if the mixture does not contain either PCL or PVC. The results presented in this paper suggest that a dipole-dipole interaction, between the carbonyl groups and the C-Cl groups, is responsible for the miscibility phenomena observed in polyester/chlorinated polymer blends.