The phase behavior of ternary blends containing polycarbonate,phenoxy, and polycaprolactone

Ternary blends comprising bisphenol-A polycarbonate (PC), the polyhydroxyether of bisphenol-A (Phenoxy), and poly(ε-caprolactone) (PCL) were found to be generally miscible at PCL levels greater than 60% by weight and to show multiple amorphous phases at lower PCL levels. The melting point depression of PCL in the miscible region of the ternary and in the miscible binary blends with PC and Phenoxy was examined to obtain the enthalpic interaction parameters, B_ij, for each of the three binary interactions. The parameters associated with the miscible binary blends were negative, as expected, and indicated that PCL interacts more exothermically with Phenoxy than with PC. The parameter associated with Phenoxy/PC interaction was strongly positive as expected from the complete immiscibility shown by these materials. The interaction parameters were used to calculate the locus of compositions for which the heat of mixing is zero. The locus was found to agree well with the observed boundary between miscible and multiphase behavior in the ternary. This suggests that the phase behavior of ternary blends is largely determined by the same enthalpic considerations known to govern the phase behavior of binary blends.     

Phase stability of ternary blends

The phase behavior of ternary blends of tetramethyl polycarbonate (TMPC), polycarbonate (PC), and styrenic polymers has been examined by experiment and analyzed in terms of thermodynamic theories. The phase boundaries were predicted using both the modified Flory-Huggins theory and the lattice fluid theory. The boundaries predicted using the lattice fluid theory agree best with the experimental results. The experimental phase behavior of ternary blends was compared with binary blends having exactly the same chemical components and compositions except that the TMPC and PC units were present in the form of a copolycarbonate in the binary. The miscible region of these ternary blends is much narrower than that of the corresponding binary blends, even though the entropic and energetic terms of such ternary blends are more favorable than those of the binary blends. It is shown that a negative value of noncombinatorial free energy in multicomponent systems is not a sufficient condition for miscibility, because of asymmetries of mer-mer interactions. A comparison of the stability conditions for these binary and ternary blends shows that increasing the degrees of freedom tends to destabilize the mixture.     

Gas permeation in miscible homopolymer-copolymer blends: II. Tetramethyl bisphenol-A polycarbonate and a styrene/acrylonitrile copolymer

Gas sorption and transport properties for He, H₂, O₂, N₂, Ar, CH₄, and CO₂ at 35°C near atmospheric pressure have been obtained for miscible blends of tetramethyl bisphenol-A polycarbonate (TMPC) and a random copolymer of styrene with acrylonitrile (SAN) containing 9.5% by weight of acrylonitrile. All gas permeability, diffusion, and solubility coefficients obtained are lower than that calculated from the semilogarithmic additivity rule. These results are qualitatively interpreted by ternary solution theory and activated state theory which have been proposed to describe gas sorption and diffusion in miscible blends. The negative deviation of gas permeabilities for the blends from this rule can be explained semiquantitatively by free volume theory which takes volume contraction on mixing into account. The negative deviation increases with gas molecular size which results in larger ideal gas separation factors than that calculated from the additivity rule. For He/CH₄ and H₂/CH₄ pairs, the permselectivities for the blends are higher than that for either pure TMPC or SAN. The deviation from additivity for gas transport properties of TMPC/SAN blends is the opposite of that observed in the first paper of this series for PMMA/SAN blends. This can be attributed to the stronger interactions in TMPC/SAN blends than in PMMA/SAN blends.     

Miscibility study of polymer blends composed of semirigid thermotropic liquid crystalline polycarbonate,poly(vinyl alcohol), and chitosan

Miscibility of binary and ternary polymer blends composed of thermotropic liquid crystalline polycarbonate (LCPC), poly(vinyl alcohol) (PVA), and chitosan was investigated by viscosity method, FTIR spectrum, and scanning electron microscope techniques. Effect of addition of chitosan as a compatibilizer on miscibility and morphology of binary LCPC/chitosan and PVA/chitosan and ternary LCPC/PVA/chitosan polymer blends was discussed. These measurements indicated that addition of chitosan into the blends of LCPC with PVA leads to an increase of miscibility and a formation of clear fibril structures on fractured surfaces, which are due to intermolecular hydrogen‐bonding interaction between LCPC, PVA, and chitosan chains. It was suggested that side‐chain hydroxy group of PVA and amino and hydroxy groups of chitosan play an important role in the formation of miscible phase and improvement of morphology in binary and ternary blends composed of LCPC, PVA, and chitosan. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1616–1622, 2004     

Phase behavior of ternary blends containing dimethylpolycarbonate,tetramethylpolycarbonate and poly[styrene‐co‐(methyl methacrylate)] copolymers (or polystyrene)

The miscibility and phase behavior of ternary blends containing dimethylpolycarbonate (DMPC), tetramethylpolycarbonate (TMPC) and poly[styrene‐co‐(methyl methacrylate)] copolymer (SMMA) have been explored. Ternary blends containing polystyrene (PS) instead of SMMA were also examined. Blends of DMPC with SMMA copolymers (or PS) did not form miscible blends regardless of methyl methacrylate (MMA) content in copolymers. However, DMPC blends with SMMA (or PS) blends become miscible by adding TMPC. The miscible region of ternary blends is compared with the previously determined miscibility region of binary blends having the same chemical components and compositions. The region where the ternary blends are miscible is much narrower than that of binary blends. Based on lattice fluid theory, the observed phase behavior of ternary blends was analyzed. Even though the term representing the Gibbs free energy change of mixing for certain ternary blends had a negative value, blends were immiscible. It was revealed that a negative value of the Gibbs free energy change of mixing was not a sufficient condition for miscible ternary blends because of the asymmetry in the binary interactions involved in ternary blends. Copyright © 2004 Society of Chemical Industry     

Phase behavior of ternary polymer blends

The effect of varying interaction parameters on the phase diagrams of ternary polymer blends was explored by simulating spinodals through use of the Flory-Huggins lattice theory. Results indicate that miscibility is favored for the case of ternary mixtures of marginally miscible or marginally immiscible pairs where all pair interactions are nearly athermal. Miscibility is restricted for asymmetric ternary blends when one of the polymer pairs is either strongly miscible or strongly immiscible. For symmetric blends of partially immiscible pairs, both two-phase and three-phase miscibility gaps are predicted.     

Changes in the miscibility of binary and ternary blends having the same chemical components and compositions

The phase behavior of ternary blends of dimethylpolycarbonate (DMPC), tetramethyl polycarbonate (TMPC), styrene-acrylonitrile (SAN) copolymer has been explored. The experimental phase behavior of ternary blends was compared with that of binary blends having the same chemical components and compositions except that the DMPC and TMPC were present in the form of copolycarbonates (DMPC-TMPC). Miscible region of DMPC/TMPC/SAN ternary blends is narrower than that of DMPC-TMPC/SAN binary blends. In addition, phase separation temperature of binary blend was higher than that of corresponding ternary blend. However, the entropic and energetic terms of ternary blends were more favorable for miscibility than those of binary blends. To understand the phase behavior of blends, phase stability conditions of binary and ternary blends were analyzed. Some ternary blends that have negative interaction energy were not miscible because these blends do not satisfy stability conditions. It was revealed that the addition of component, accompanied by the asymmetry in the binary interactions, results in destabilization of blend.     

Miscibility of copolycarbonate blends with poly(styrene-co-acrylonitrile) copolymer and their interaction energies

The phase behavior of dimethyl polycarbonate-tetramethyl polycarbonate (DMPC-TMPC) blends with poly(styrene-co-acrylonitrile) copolymers (SAN) and the interaction energies of binary pairs involved in blend has been explored. DMPC-TMPC copolycarbonates containing 60 wt% TMPC or more were formed miscible blends with SAN containing limited amounts of AN. The miscibility of copolycarbonate with SAN decreases as the DMPC content increases. The miscible blends showed the LCST-type phase behavior or did not phase separate until thermal degradation. The binary interaction energies involved in the miscible blends were calculated from the phase boundaries using the lattice-fluid theory combined with binary interaction model. The phenyl ring substitution with methyl groups did not lead to interactions that are favorable for miscibility with polyacrylonitrile (PAN). The interaction energies of the polycarbonates blends with SAN copolymers as a function of AN content were obtained. It was revealed that the incline of the number of methyl groups on the phenyl rings of bisphenol-A unit acts favorably for the miscibility with SAN copolymer when SAN contains less than about 30 wt% AN and shifts the most favorable interaction to the low AN content.     

Mechanical properties and morphological changes of poly(lactic acid)/polycarbonate/poly(butylene adipate‐co‐terephthalate) blend through reactive processing

The mechanical properties and morphological changes of poly(lactic acid) (PLA), polycarbonate (PC), and poly(butylene adipate‐co‐terephthalate) (PBAT) polymer blends were investigated. Several types of blend samples were prepared by reactive processing (RP) with a twin‐screw extruder using dicumyl peroxide (DCP) as a radical initiator. Dynamic mechanical analyses (DMA) of binary polymer blends of PC/PBAT indicated that each component was miscible over a wide range of PC/PBAT mixing ratios. DMA of PLA/PBAT/PC ternary blends revealed that PBAT is miscible with PC even in the case of ternary blend system and the miscibility of PLA and PBAT can also be modified through RP. As a result, the tensile strain and impact strength of the ternary blends was increased considerably through RP, especially for PLA/PBAT/PC = 42/18/40 (wt/wt/wt) with DCP (0.3 phr). Scanning electron microscopy (SEM) analysis of the PLA/PBAT/PC blends revealed many small spherical island phases with a domain size of approximately 0.05–1 μm for RP, whereas it was approximately 10 μm without RP. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation of graded materials for miscible polycarbonate/poly(methyl methacrylate) blends by segregation under shear flow

Exposure to shear flow produced by a pressure-driven capillary rheometer provides a concentration gradient without phase separation in miscible polymer blends of bisphenol-A polycarbonate containing low-molecular-weight poly(methyl methacrylate) (PMMA). The strand surface extruded from the rheometer contains a large amount of PMMA. However, the strand is transparent because there is no light scattering due to phase separation. The segregation behavior, that is, enrichment of the PMMA content at the strand surface, is enhanced when the molecular weight of PMMA is low. Furthermore, the segregation is also enhanced at high temperatures and at high shear rates. By contrast, the die length barely affects the degree of segregation. The segregation phenomenon should be noted because it may facilitate the modification of the surface properties of various products.     

Melt viscosity reduction of polycarbonate with low molar mass liquid crystals

The phase behavior and rheological behavior of low molar mass liquid crystal (LLC) and polycarbonate blends is firstly reported. The results of small angle light scattering (SALS) indicate that the LLC is miscible in the mixture for weight fractions of LLC less than 6%. Mixtures of two different liquid crystals with two different molecular weight of polycarbonate were prepared inside the miscible regime of the blends. Both the complex and steady shear viscosities of the blends were found to be significantly decreased upon addition of small amounts of liquid crystal (1% by weight). At low shear rate, the steady state shear viscosity was similar to the pure polycarbonate, whilst, at higher shear rates, three further regimes of behavior, as has been described for liquid crystals and liquid crystal polymers, were found despite the low concentration of LLC; hence, the rheological properties of the blends can be significantly modified by small concentrations of LLC (as low as 1%). The decrease in melt viscosity of polycarbonate that we observe upon addition of LLC is not due to lubrication effects at the interfaces, as shown by reproducible oscillatory shear flow sweeps. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Morphology,dynamic mechanical,and electrical properties of bio‐based poly(trimethylene terephthalate) blends,part 2: Poly(trimethylene terephthalate)/poly(ether esteramide)/polycarbonate blends

Bio‐based poly(trimethylene terephthalate) (PTT) and poly(ether esteramide) (PEEA) blends were prepared by melt processing with varying weight ratios (0–20 wt %) of polycarbonate (PC). The blends were characterized by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), polarized light microscopy (PLM), and transmission electron microscopy (TEM). Electrostatic performance was also investigated for those PTT blends since PEEA is known as an ion conductive polymer. DMA suggests that PC is miscible with PEEA and selectively goes into PEEA phase in case of ternary blends of PTT/PEEA/PC. The glass transition temperature (T_g) for PC/PEEA is well predicted by Gordon Taylor equation. Addition of PC retards the electrostatic decay performance of PTT/PEEA blends by restricting the motion of ions in PEEA through increasing the T_g of PEEA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Boiling water aging of a miscible blend of polycarbonate and a copolyester

Extruded films and injection molded bars of a copolyester based on 1,4-cyclohexanedimethanol condensed with a mixture of isophthalic and terephthalic acids, of a bisphenol-A based polycarbonate, PC, and of the miscible blends of these compounds were exposed to boiling water for up to 15 days. The ductility and strengths of film specimens rich in PC were found to degrade as a result of PC hydrolysis. These properties of specimens rich in copolyester were found to decline as a result of crystallization of the copolyester. Best overall performance was obtained for 50/50 blends of PC and copolyester. All amorphous materials showed a transition from ductile to brittle behavior at the same weight average molecular weight as previously observed for pure PC. This feature plus the observation that PC hydrolyzes in the blend at the same rate as it does in the pure state allows most of the superior performance of the 50/50 blends to be explained in terms of blend molecular weight.     

Polyester–polycarbonate blends. V. Linear aliphatic polyesters

Polycarbonate blends with the linear aliphatic polyesters poly(ethylene succinate) (PES), poly(ethylene adipate) (PEA), poly(1,4-butylene adipate) (PBA), and poly(hexamethylene sebacate) (PHS) were prepared by solution casting. Blends containing PES, PEA, and PBA exhibited a single T_g by DSC and thus form a single, miscible amorphous phase with polycarbonate. However, blends containing PHS exhibited only partial miscibility. Crystallinity of the polyesters was reduced by mixing with polycarbonate; however, plasticization by the polyesters induced crystallization of the polycarbonate. Miscibility in these systems is the result of an exothermic heat of mixing stemming from an interaction of the carbonyl dipole of the ester group with the aromatic carbonate. The effect of polyester structure on miscibility with polycarbonate is interpreted by and correlated with heats of mixing obtained by direct calorimetry of low molecular weight liquid analogs of the polymers.     

Polyester–polycarbonate blends. VII. Ring-containing polyesters

Thermal analysis was used to show that blends of poly(1,4-cyclohexanedimethylene succinate) (PCDS) with polycarbonate (PC) are completely miscible in the amorphous phase. Blends of PC with poly(ethylene orthophthalate) (PEOP) were found to have a miscibility gap in the midconcentration range and are thus not miscible in all proportions. Similarly, a commercial copolyester formed from ethylene glycol, 1,4-cyclohexanedimethanol, terephthalic acid, and isophthalic acid is partially miscible with PC. These observations are discussed in terms of the structural features of the three polyesters.     

Miscibility behaviour of bisphenol-A polycarbonate and poly(para-chlorostyrene)

The miscibility behaviour of bisphenol-A polycarbonate (PC) and poly(para-chlorostyrene) (PpCIS) has been investigated. Special attention has been paid to the influence of the molar mass of PpCIS. Molar masses varying from 10 to > 1,000 kg/mol were used. The blends were studied by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and scanning and transmission electron microscopy (SEM and TEM). It was concluded that the blends of all three PpCIS grades and PC phase separate. In the low concentration region, some intermixing was found, especially for the blend with the low molar mass PpCIS. The most important effect of lowering the molar mass of PpCIS was an acceleration of the phase separation. The combination of SEM with electron probe X-ray microanalysis (EPMA) gave qualitative information on the miscibility behaviour and was found to be a useful extension of routine microscopy techniques used in blend studies.     

Miscibility of polycarbonate with poly(methyl methacrylate-co-cyclohexyl methacrylate)

Summary Miscibility of bisphenol-A polycarbonate, PC, with methyl methacrylate/cyclohexyl methacrylate, PMCHM, copolymers were examined by glass transition temperature and lower critical solution temperature, LCST, behavior. PMCHM copolymers were found to be miscible with PC at levels of below 4% or less of CHM in weight. Relatively small amount of the comonomer markedly raised phase separation temperature on heating. This result can be rationalized by intramolecular repulsion effect reported earlier.     

A miscibility study of ternary blends of polystyrene,tetramethylbisphenol-A polycarbonate,and poly(2,6-dimethyl-1,4-phenylene oxide)

Phase behaviorof ternary blends of polystyrene (PS), tetramethylbisphenol-A polycarbonate (TMPC), and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) at two different temperatures (i.e., 210 and 300 °C, respectively) was studied by means of differential scanning calorimetry. Miscibility of the ternary blends at either temperature was found restricted to limited compositions, in agreement with simulated spinodal curves based on published values of interaction parameters. The limited ability of PS, which is separately miscible with TMPC and PPO at 210 °C, to act as a common solvent for the immiscible TMPC/PPO pair at this temperature was explained in terms of the disparity in PS/TMPC and PS/PPO pair interactions (i.e., the 'X effect).     

Properties of ultrasound-assisted blends of poly(ethylene terephthalate) with polycarbonate

This study investigated the effect of ultrasound irradiation on blends of polyethylene terephtalate (PET) and polycarbonate (PC). The blends of PET/PC were prepared by a twin-screw extruder with an attached ultrasonic device. Thermal, rheological, and mechanical properties and morphology of the blends with and without sonication have been analyzed. The two distinct T_gs of the blends measured by DSC showed immiscibility over all compositions. The theoretical PET content that is miscible in PC-rich phase calculated using the Fox equation showed that ultrasonic waves made the blends more miscible. From mechanical test results, when sonication was not applied, the 20/80 blend was the most miscible composition. At that composition, the impact strength of sonicated blend was surprisingly high. It was believed to be due to the enhancement of compatibility by a reaction such as transesterification. The results from the morphology of the 20/80 sonicated blend were in agreement with DSC and impact test results.     

Time-resolved small-angle light scattering for the study of phase separation kinetics in bisphenol-a polycarbonate/poly(methy methacrylate) blends

An automated, solid-state small-angle light scattering apparatus has been constructed for the investigation of polymers; the main features of this system are a bidimensional CCD (charge coupled device) detector with 12-bit resolution and custom-made, user-friendly software for the acquisition and treatment of the scattering data. The miscibility and phase separation kinetics of several bisphenol-A polycarbonate/poly(methyl methacrylate) blends have been investigated using this apparatus. It was found that the rate of phase separation can be altered significantly by replacing part of the polydisperse poly(methyl methacrylate) (PMMA) in the blends by monodisperse PMMA.