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.     

A study of aromatic polyester/chlorinated polymer blends

A large number of studies have been devoted in recent years to the miscibility behavior of linear polyesters with chlorinated polymers, including poly(vinyl chloride) (PVC), chlorinated PVC, chlorinated poly(ethylenes), and copolymers of vinylidene chloride (Saran). However, similar studies with aromatic polyesters are lacking. It is the purpose of this paper to compare the properties of blends made of poly(ethylene terephthalate), poly(butylene terephthalate) or poly(hexamethylene terephthalate) and of various chlorinated polymers. It is shown that a high concentration of chlorine atoms is required to achieve miscibility. Moreover, there is a “miscibility window” in terms of the carbonyl concentration of polyesters, immiscibility being found for carbonyl concentrations outside this window, A similar behavior was observed before for linear polyester/chlorinated polymer blends and for polyester/polycarbonate blends. Solid state small-angle light scattering experiments were also conducted to follow the morphology of the blends as a function of composition. Spherulites were found but their size vary with composition.     

Inter- and intrachain elastic interactions in polymers and polymer blends

The damped Debye lattice or damped torsional oscillator model for viscoelastic relaxation in the primary transition region takes into account elastic interchain interactions as well as the more usually invoked intrachain interactions. To test the importance of these interchain interactions, we have applied this model to compatible blends formed from atactic polystyrene (PS) and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO). Qualitative predictions of the variation of stress relaxation behavior of the blends as a function of PPO concentration have been made. Also, predictions concerning properties of these blends upon dilution suggest very distinctive behaviors. We have measured stress relaxation master curves in the primary transition region of PS-PPO blends of various concentrations and have found that the predicted behavior is indeed observed. Furthermore, the unusual effects of dilution on the properties of these blends have been observed with dioctyl phthalate used as diluent. These results show that inter- as well as the more familiar intramolecular elastic interactions are important factors in determining viscoelastic behavior of bulk polymers in this transition region.     

Phase behavior of ternary polymer blends with favorable interactions

Atactic poly(methyl methacrylate) (aPMMA) and poly(vinyl pyrrolidone) (PVP) with a weight‐average molecular weight of 360,000 g/mol were found to be immiscible on the basis of preliminary studies. Poly(styrene‐co‐vinyl phenol) (MPS) with a certain concentration of vinyl phenol groups is known to be miscible with both aPMMA and PVP. Is it possible to homogenize an immiscible aPMMA/PVP pair by the addition of MPS? For this question to be answered, a ternary blend consisting of aPMMA, PVP, and MPS was prepared and measured calorimetrically. The role of MPS between aPMMA and PVP and the effects of different concentrations of vinyl phenol groups on the miscibility of the ternary blends were investigated. According to experimental results, increasing the vinyl phenol contents of MPS has an adverse effect on the miscibility of the ternary blends. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2064–2070, 2005     

DNA-like interactions enhance the miscibility of supramolecular polymer blends

We have investigated the miscibility behavior, specific interactions, and supramolecular structures of blends of the DNA-like copolymers poly(vinylbenzylthymine-co-butyl methacrylate) (T-PBMA) and poly(vinylbenzyladenine-co-styrene) (A-PS) with respect to their vinylbenzylthymine (VBT) and vinylbenzyladenine (VBA) contents. ¹H nuclear magnetic resonance spectroscopy and one- and two-dimensional Fourier transform infrared spectroscopy revealed that hydrogen bonding occurred exclusively between the VBA and VBT units. In addition, size exclusion chromatography, dynamic light scattering, and viscosity analyses provided evidence for the formation of supramolecular network structures in these binary blend systems. A miscibility window existed in the A-PS/T-PBMA blend system when the VBT and VBA fractions in the copolymers were greater than 11 mol%, as predicted using the Painter-Coleman association model.     

Intermolecular interactions and phase transition behavior of miscible polymer blends

A linear equation is proposed to quantify the glass transition behavior of miscible polymer blends in terms of the polymer-polymer interaction density parameter whose values are obtainable from the melting point depression method. This practical model is successfully applied to four series of binary polyblends containing poly(hydroxy ether) of biphenol A, poly(vinyl chloride), poly(vinylidene fluoride), and poly(2,4-dimethyl-1,4-phenylene oxide) as the common components. Each of these groups of polymer systems exhibits a distinct type of intermolecular interaction that can be characterized by the two coefficients of the model equation. In connection with the present analysis, three novel expressions are introduced for describing the glass transition temperature—composition relations of the polymer systems of interest.     

Functionalized elastomeric compatibilizer in PA 6/PP blends and binary interactions between compatibilizer and polymer

Superior impact properties were obtained when maleic anhydride grafted styrene ethylene/butylene styrene block copolymer (SEBS-g-MAH) was used as a compatibilizer in blends of polyamide 6 (PA 6) and isotactic polypropylene (PP), where polyamide was the majority phase and polypropylene the minority phase. The optimum impact properties were achieved when the weight relation PA:PP was 80:20 and 10 wt% SEBS-g-MAH was added. The blend morphology was systematically investigated. Transmission electron microscopy (TEM) indicated that the compatibilizer forms a cellular structure in the PA phase in addition to acting as an interfacial agent between the two polymer phases. In this cellular-like morphology the compatibilizer appears to form the continuous phase, while polyamide and polypropylene form separate dispersions. In microscopy, PA appeared as a fine dispersion and PP as a coarse dispersion. The mechanical properties indicated that in fact PA, too, is continuous, and the blend can be interpreted as possessing a modified semi-interpenetrating network (IPN) structure with separate secondary dispersion of PP. The coarser PP dispersion plays an essential role in impact modification. Binary blends of the compatibilizer and one blend component were also investigated separately. The same cellular structure was observed in the binary PA/SEBS-g-MAH blends, and SEBS-g-MAH again appeared to form the continuous phase when the elastomer concentration was at least 10 to 20 wt%. By contrast, in PP/SEBS-g-MAH only conventional dispersion of elastomeric SEBS-g-MAH was observed up to 40 wt% elastomer. Impact strength was improved and the elastic modulus was lowered in both PA/SEBS-g-MAH and PP/SEBS-g-MAH blends when the elastomer content was increased. The changes in modulus indicate that the semi-IPN-like structure is formed in the binary PA/SEBS-g-MAH blends as well as in the ternary structure.     

Speciality polymer blends of polyurethane elastomers and chlorinated polyethylene rubber (peroxide cure)

Two elastomers having polar reactive functional groups may react with each other upon heating. Considering this view, blends of polyurethane (AU) and chlorinated polyethylene (CPE) elastomer have been prepared where better performance properties can be obtained through interchain crosslinking reaction. The entire study was carried out using dicumyl peroxide (DCP) as a curing agent where both the phases were vulcanized to form new materials. The state of cure gradually increased with the addition of CPE. Hardness, modulus and tensile strength were also increased with increase of CPE content. The elongation at break decreased with higher amount of CPE. After ageing, hardness increased but the modulus and tensile strength decreased. There was drastic change in elongation at break on ageing. IR spectra suggested that interchain crosslinking occurred between AU and CPE elastomers. High temperature DSC studies also revealed the improvement of thermal stability with the addition of CPE. SEM study also suggested interphase crosslinking. © 2000 Society of Chemical Industry     

Studies on polymer blends with moderate specific interactions. 2. phase structure of blends SAN/TPU and SAN/TPU/EVA

This paper deals with morphological studies of binary and ternary blends composed of poly(styrene-co-acrylonitrile) (SAN), polyurethane elastomer (TPU) and poly(ethylene-co-vinyl acetate) (EVA). Selective etching was found necessary to expose the morphologies of the blends. Chloroform or hot acetone, hexane/toluene (2/1v/v) and NaOH/CH₃OH (1wt%) were found to be selective etching agents for SAN, EVA and TPU, respectively. SAN and TPU form blends with fine dispersion structure, while SAN and EVA lead to rough phase structure with poor phase adhesion. These results are in accordance with the difference in the mechanical properties of SAN/TPU and SAN/EVA. In addition, for SAN/TPU/EVA blends, if TPU is only a minor component, it is preferentially located at the interphase, playing the role of a compatibilizer. As the amount of TPU increases, the compatibility is gradually improved. ©1997 SCI     

Effect of polymer-filler surface interactions on the phase separation in polymer blends

For the blends of chlorinated polyethylene and copolymer of ethylene with vinyl acetate, the effect of the introducing filler (fumed silica) on the phase behavior of the blends was investigated. It was found that introducing filler in polymer blends depending on its amount lead either to the increase or to the decrease in the temperature of phase separation. At the filler concentration where both components transit into the state of a border layers, the phase separation temperature increases. This effect was explained by the change of the total thermodynamic interaction parameter in the ternary system polymer-polymer-filler. At lower concentration of a filler, the possible effect is the redistribution of the blend components according to their molecular masses between filler surface (in the border layer) and in the bulk that may diminish the phase separation temperature.Effect of the filler on the phase behavior was explained by the simultaneous action of two mechanisms: by changing the thermodynamics of interaction near the surface due to selective adsorption of one of the components and by the redistribution of components according to their molecular masses between the boundary region (near the surface) and in the matrix.The measurements of the kinetics of phase separation and calculation of the parameters of the activation energy are in agreement with proposed mechanisms.     

Miscible chitosan/tertiary amide polymer blends

The miscibility of five chitosan/tertiary amide polymer blend systems was studied. Based on the optical transparency of the blend and the existence of a single glass transition temperature, chitosan was found to be miscible with poly(N‐vinyl‐2‐pyrrolidone), poly(N‐methyl‐N‐vinylacetamide), poly(N,N‐dimethylacrylamide), poly(2‐methyl‐2‐oxazoline), and poly(2‐ethyl‐2‐oxazoline). Fourier transform infrared spectroscopy showed the existence of hydrogen‐bonding interactions between chitosan and the tertiary amide polymers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1785–1790, 2000     

Reptation in polymer blends

Forward recoil spectrometry (FRES) was used to measure the tracer diffusion coefficients D*_PS and D*_PXE of deuterated polystyrene (d-PS) and deuterated poly(xylenyl ether) (d-PXE) chains in high molecular weight protonated blends of these polymers. The D*s were shown to be independent of matrix molecular weights and to decrease as M⁻², where M is the tracer molecular weight, suggesting that the tracer diffusion of both species occurs by reptation. These D*s were used to determine the monomeric friction coefficients ζ_0,PS and ζ_0,PXE of the individual PS and PXE macromolecules as a function of ф, the volume fraction of PS in the PS:PXE blend. Since ζ_0,PSζ_0,PXE at each ф, the rate at which a PS molecule reptates is much greater than that of a PXE molecule, even though both chains are diffusing in identical surroundings. Part of this difference may be due to the difficulty of backbone bond rotation of the PXE molecule. However, even when measured at a constant temperature increment above the glass transition temperature, ζ_0,PS and ζ_0,PXE were observed to be markedly composition dependent. In addition the ratio ζ_0,PS/ζ_0,PXE varied from a maximum of 4 × 10⁻² near ф=0.85 to a minimum of 5 × 10⁻⁵ for ф=0.0. These results show that intramolecular barriers do not solely determine the ζ₀s of the components in this blend. Clearly, the interactions between the diffusing chains and the matrix chains also influence ζ₀.     

Hydrogen-bonding in polymer blends

Hydrogen bonding in polymer blends is a topic of great interest to polymer scientists because such systems have many potential applications. Introducing functional groups to one component to make it capable of forming hydrogen bonds to another, thereby enhancing the miscibility of otherwise immiscible blends, is one of the major achievements during the past 20 years of polymer science. The Painter–Coleman association model generally describes these interactions accurately. This Review discusses in detail the effects of hydrogen bonding on the miscibility and thermal properties of polymer blend systems.     

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.     

Rheology-morphology relationships in nylon 6/liquid-crystalline polymer blends

Extrusion measurements have been carried out on blends of nylon 6 and a liquid-crystalline copolyesteramide (LCP). The flow curves at low temperature show a behavior similar to that of pure LCP with a rapid rise of the viscosity at low shear rates. At high shear rates the viscosity is lower than that for each of the two components. This minimum has been attributed to the lack of interactions between the two phases and to the formation of fibrils of the LCP phase. The SEM analysis shows, indeed, that fibrils of the LCP phase are produced in the convergent flow at the inlet of the capillary at high shear rates. These fibrils are lost during the flow in the long capillary.     

Development of hydroxyapatite nanoparticles reinforced chlorinated acrylonitrile butadiene rubber/chlorinated ethylene propylene diene monomer rubber blends

Hydroxyapatite nanoparticles (HA) reinforced polymer blend based on chlorinated nitrile rubber (Cl-NBR) and chlorinated ethylene propylene diene monomer rubber (Cl-EPDM) were prepared. Resulting blend composites were analyzed with regard to their rheometric processing, crystallinity, glass transition temperature (T_g), mechanical properties, oil resistance, AC conductivity, and transport behavior. The decrease in optimum cure time with the addition of HA is more advantageous for the development of products from these blend nanocomposites. The XRD, FTIR, and SEM confirmed the attachment and uniform dispersion of HA nanoparticles in the Cl-NBR/Cl-EPDM blend. The good compatibility between polymer blend and nanoparticles was also deduced by the formation of spherically shaped HA particles in the blend matrix determined by TEM analysis. DSC analysis showed an increase in T_g of the blend with the filler loading. The addition of HA particles to the blend produced a remarkable increase in tensile and tear strength, hardness, AC conductivity, abrasion, and oil resistance. The diffusion of blend composites was decreased with an increase in penetrant size. The diffusion mechanism was found to follow an anomalous trend. Among the blend composites, the sample with 7 phr of HA not only showed good oil and solvent resistance but also a remarkable increase in AC conductivity and mechanical properties.     

Miscibility enhancement of supramolecular polymer blends through complementary multiple hydrogen bonding interactions

We have investigated the miscibility behavior and specific interactions of supramolecular poly[vinylbenzylthymine‐co‐(butyl methacrylate)] (T‐PBMA) and poly[(2‐vinyl‐4,6‐diamino‐1,3,5‐triazine)‐co‐styrene] (VDAT‐PS) blends with respect to their vinylbenzylthymine (VBT) and 2‐vinyl‐4,6‐diamino‐1,3,5‐triazine (VDAT) contents. Fourier transform infrared spectroscopy revealed that multiple hydrogen bonding interactions occurred exclusively between the VDAT and VBT units, which were stronger than adenine and thymine interactions. A miscibility window occurred in the VDAT‐PS/T‐PBMA blend system when the VBT and VDAT fractions in the copolymers were greater than 7 mol%, as predicted using the Painter–Coleman association model. Copyright © 2010 Society of Chemical Industry     

Electroactive polymer blends

The rapid development of two new classes of electrically active polymer materials, electronically conducting and electroactive polymers and ion-conducting polymers respectively, offers new possibilities for application of both classes of material, especially in combination with each other. While some of these combinations have been attempted before, they all met serious problems due to poor interpenetration of the two polymers. The recent availability of solubilized and soluble electroactive and conductive polymers has greatly advanced the possibilities of reducing the interpenetration problem. Some experimental studies using the combination of solubilized electroactive polypyrrole with poly(ethylene oxide) in an electroactive polymer blend electrode for solid-state polymer batteries are discussed. The opportunities for using polymer blends for solid-state electrochemical polymeric devices, and avenues for the development of materials for such devices, are also reviewed.     

Surface characteristics of polymer/small molecule blends

Inverse gas chromatographic data have been obtained for polystyrene, polycarbonate, and two substituted amines used as additives in the polymers. Surface energies have been determined and evaluations made of acid/base interaction parameters and Flory–Huggins χ values for the surface bounded interphase. It was shown that acid/base considerations are implicated in the miscibility of these polymer/additive systems. Surface energy analyses showed that surface and bulk compositions in blends differed whether or not the blend components were miscible. Composition differences were the result of thermodynamic drives to minimize surface free energy. © 1994 John Wiley & Sons, Inc.