Blends of bisphenol-A polycarbonate and acrylic polymers: III. Effect of imide concentration on compatibility

Imide units copolymerized with MMA units have been selected in order to improve compatibility between PC and acrylics through specific interaction or internal repulsion. Good dispersion of acrylic inside a PC matrix has been observed upon melt mixing, which can be partially explained by the good rheological agreement between these two polymers. Transmission electron microscopy has shown that the system remains phase separated from 5 to 95 wt % of PC. Phase diagrams for three different imide concentrations have been drawn. Results obtained by DSC (conventional and with enthalpy relaxation) are similar to those obtained by optical cloud point detection. The phase diagrams show the raise of the PC/PMMA demixtion curve (LCST type) when percentage of imide increases in the acrylic phase. Theoretical calculations on binary interaction energy density show a slight improvement of the interaction between acrylic and PC when imide percentage increases. Cloud point measurements on 50/50 PC/acrylic blends varying the imide concentration show that the improvement of compatibility deduced from the raise of the demixtion curve (LCST type) is more related to a kinetic effect (the high T_g of imidized samples is reducing macromolecule mobility) than specific interactions. The calculated favorable interactions are probably too weak to be detected with cloud point measurements. The microstructures obtained after crystallization of the PC phase under solvent vapors in phase separated PC/acrylics blends can also be explained by T_g effects. Moreover, solvent vapor exposure could be a powerful tool to determine the real thermodynamic behavior of the blends at room temperature. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 749–761, 1997     

Blends of polycarbonate and poly(ϵ‐caprolactone) and the determination of the polymer–polymer interaction parameter of the two polymers

The thermal properties of blends of polycarbonate (PC) and poly(ε‐caprolactone) (PCL) were investigated by differential scanning calorimetry (DSC). From the thermal analysis of PC‐PCL blends, a single glass‐transition temperature (T_g) was observed for all the blend compositions. These results indicate that there is miscibility between the two components. From the modified Lu and Weiss equation, the polymer–polymer interaction parameter (χ₁₂) of the PC‐PCL blends was calculated and found to range from −0.012 to −0.040 with the compositions. The χ₁₂ values calculated from the T_g method decreased with the increase of PC weight fraction. By taking PC‐PCL blend as a model system, the values of χ₁₂ were compared with two different methods, the T_g method and melting point depression method. The two methods are in reasonably good agreement for the χ₁₂ values of the PC‐PCL blends. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2072–2076, 2000     

Compatibility studies of blends of polycarbonate and poly(ethylene terephthalate)

Blends of bisphenol-A polyarbonate (PC) and poly(ethylene terephthalate) (PET) has been investigated by differential scanning calorimetry and scanning electron microscopy. Blends were prepared by screw extrusion and solution casting with weight fractions of PC in the blends varying from 0.90 to 0.10. From the measured glass transition temperature (T_g) and apparent weight fractions of PC and PET dissolved in each phase, it appears that PET dissolves more in the PC-rich phase than does the PC in the PET-rich phase. The composition-dependent values of the Flory–Huggins polymer–polymer–interaction parameter were determined and found to be from 0.054 to 0.037 for extruded blends at 275°C and from 0.058 to 0.040 for solution casting at 25°C. The interaction parameter decreases with increasing PET concentration. This result is consistent with the values of the T_gs, the microscopy study, and the measured extrudate swell ratios which show that compatibility increases more in the PET-rich compositions than in the PC-rich compositions. The PC–PET blends are not microscopically miscible for all the blend compositions.     

Thermal characterization of polycarbonate/polycaprolactone blends

In this work, we prepared blends of bisphenol A polycarbonate (PC) and poly(ϵ‐caprolactone) (PCL) in a wide composition range by melt mixing and solution mixing. Two different molecular weights of PCL were used (nominally, 10.000 g/mol, PCL10, and 80.000 g/mol, PCL80). The thermal behavior of both systems was studied via differential scanning calorimetry under dynamic and isothermal conditions. The blends were miscible in the entire composition range in the liquid and amorphous states, as indicated by the single glass‐transition temperature (T_g) exhibited by both the PC/PCL10 and PC/PCL80 blends. The compositional variation of the T_g was accurately described by the Fox equation for the PC/PCL80 blends, whereas slight deviations from this equation were exhibited by the PC/PCL10 blends. For blend compositions containing 40% or more PCL, either one or both blend components crystallized. Crystallization occurred during cooling from the melt or during subsequent heating in the form of cold crystallization. Although PCL crystallization was reduced and its crystallization rate decreased with the addition of PC, PCL was a very effective macromolecular plasticizer for PC, to the extent that crystallization during the scan was detected for some blend compositions. Isothermal crystallization experiments allowed the determination of equilibrium melting points (T) by the Hoffman–Weeks extrapolation method. A T depression was found for both PCL and PC components as the content of the other blend component was increased. The Avrami equation was closely obeyed by both blend components during the isothermal overall crystallization kinetics up to crystalline conversion degrees of 60–70% and with values of Avrami indices ranging from 3 to 4, depending on the crystallization temperature employed. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 771–785, 2001     

Effect of aging time on properties of acrylic impact modifier modified bisphenol A polycarbonate

Polycarbonate (PC) was blended with acrylic impact modifiers (AIMs). The effects of modifiers weight fraction on the Izod impact strength and yield strength of PC/AIM blends were investigated. The samples with 4% modifiers were aged under the T_g of PC in an air‐circulating oven, and the effects of aging time on impact strength, yield strength, modulus, elongation at break, post yield stress drop (PYSD) values, and morphology of fracture surface were investigated. The effects of aging time on the shape of stress–strain curve were also investigated. The aged samples were heat‐treated over the T_g of PC to erase the effects of physical aging. It was found that the drop of impact strength caused by physical aging can be recovered, the increment of yield strength and PYSD value caused by physical aging can only be partly recovered, and the heat‐treatment over the T_g of PC caused further increment of modulus. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2715–2724, 2005     

Intimate blending of binary polymer systems from their common cyclodextrin inclusion compounds

A procedure for the formation of intimate blends of three binary polymer systems polycarbonate (PC)/poly(methyl methacrylate) (PMMA), PC/poly(vinyl acetate) (PVAc) and PMMA/PVAc is described. PC/PMMA, PC/PVAc, and PMMA/PVAc pairs were included in γ‐cyclodextrin (γ‐CD) channels and were then simultaneously coalesced from their common γ‐CD inclusion compounds (ICs) to obtain intimately mixed blends. The formation of ICs between polymer pairs and γ‐CD were confirmed by wide‐angle X‐ray diffraction (WAXD), fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). It was observed [solution ¹H nuclear magnetic resonance (NMR)] that the ratios of polymers in coalesced PC/PMMA and PC/PVAc binary blends are significantly different than the starting ratios, and PC was found to be preferentially included in γ‐CD channels when compared with PMMA or PVAc. Physical mixtures of polymer pairs were also prepared by coprecipitation and solution casting methods for comparison. DSC, solid‐state ¹H NMR, thermogravimetric analysis (TGA), and direct insertion probe pyrolysis mass spectrometry (DIP‐MS) data indicated that the PC/PMMA, PC/PVAc, and PMMA/PVAc binary polymer blends were homogeneously mixed when they were coalesced from their ICs. A single, common glass transition temperature (T_g) recorded by DSC heating scans strongly suggested the presence of a homogeneous amorphous phase in the coalesced binary polymer blends, which is retained after thermal cycling to 270 °C. The physical mixture samples showed two distinct T_gs and ¹H T_1ρ values for the polymer components, which indicated phase‐separated blends with domain sizes above 5 nm, while the coalesced blends exhibited uniform ¹H spin‐lattice relaxation values, indicating intimate blending in the coalesced samples. The TGA results of coalesced and physical binary blends of PC/PMMA and PC/PVAc reveal that in the presence of PC, the thermal stability of both PMMA and PVAc increases. Yet, the presence of PMMA and PVAc decreases the thermal stability of PC itself. DIP‐MS observations suggested that the degradation mechanisms of the polymers changed in the coalesced blends, which was attributed to the presence of molecular interactions between the well‐mixed polymer components in the coalesced samples. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2578–2593, 2005     

An intimate polycarbonate/poly(methyl methacrylate)/poly(vinyl acetate) ternary blend via coalescence from their common inclusion compound with γ‐cyclodextrin

In this study, we successfully report an intimate ternary blend system of polycarbonate (PC)/poly(methyl methacrylate) (PMMA)/poly(vinyl acetate) (PVAc) obtained by the simultaneous coalescence of the three guest polymers from their common γ‐cyclodextrin (γ‐CD) inclusion compound (IC). The thermal transitions and the homogeneity of the coalesced ternary blend were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The observation of a single, common glass transition strongly suggests the presence of a homogeneous amorphous phase in the coalesced ternary polymer blend. This was further substantiated by solid‐state ¹³C NMR observation of the T_1ρ(¹H)s for each of the blend components. For comparison, ternary blends of PC/PMMA/PVAc were also prepared by traditional coprecipitation and solution casting methods. TGA data showed a thermal stability for the coalesced ternary blend that was improved over the coprecipitated blend, which was phase‐segregated. The presence of possible interactions between the three polymer components was investigated by infrared spectroscopy (FTIR). The analysis indicates that the ternary blend of these polymers achieved by coalescence from their common γ‐CD–IC results in a homogeneous polymer blend, possibly with improved properties, whereas coprecipitation and solution cast methods produced phase separated polymer blends. It was also found that control of the component polymer molar ratios plays a key role in the miscibility of their coalesced ternary blends. Coalescence of two or more normally immiscible polymers from their common CD–ICs appears to be a general method for obtaining well‐mixed, intimate blends. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4182–4194, 2004     

The epoxy–polycarbonate blends cured with aliphatic amine—I. Mechanism and kinetics

Reaction mechanism of the PC–epoxy blends cured by aliphatic amine has been investigated by varying PC contents in the blends. The transamidation reaction tends to convert nearly all the carbonates into N-aliphatic aromatic carbamates even at ambient temperature before normal curing. The remaining amine proceeds the normal curing with epoxy at a higher temperature (80°C). For the PC–epoxy/aliphatic amine blend containing 6 wt % PC, the yielded N-aliphatic aromatic carbamate further reacts with amine to produce the urea structure. The urea undergoes substitution reaction with the hydroxyl formed from the normal curing to give the N-aliphatic aliphatic carbamate. For the blend containing 12 wt % PC, the N-aliphatic aromatic carbamate converts into the N-aliphatic aliphatic carbamate via two different routes. For the blend containing lower molecular weight of the aliphatic amine, the N-aliphatic aromatic carbamate reacts with hydroxyl to form the N-aliphatic aliphatic carbamate directly. For the blend containing higher molecular weight of aliphatic amine, the N-aliphatic aromatic carbamate decomposes into the aliphatic isocyanate accelerated by the presence of the residual oxirane. The isocyanate formed then reacts with hydroxyl to yield the N-aliphatic aliphatic carbamate. The activation energy (E_a) and preexponential factor (A) of the PC–epoxy/POPDA blends decrease with the increase of the PC content. Kinetic study by thermal analysis by the method of autocatalyzed model is able to correctly predict oxirane conversion vs. time relationship for the neat epoxy/aliphatic amine and the PC–epoxy/aromatic amine systems because the dominant reaction is the normal curing reaction between amine and oxirane. The model fails to predict the PC–epoxy/aliphatic amine system because the system is complicated by several other reactions besides the normal curing reaction. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2169–2181, 1997     

Reaction-induced miscibility in blends comprised of bisphenol-A polycarbonate and poly(trimethylene terephthalate)

The inherent miscibility and effects of reaction-induced changes on the phase behaviour of blends of poly(trimethylene terephthalate) (PTT) with bisphenol-A polycarbonate (PC) were studied. The as-prepared (solution-cast) blends exhibited two well-spaced and separated glass transition temperatures (T_gs) and a heterogeneous phase-separated morphology, indicating an immiscible system. However, after annealing at high temperature (at 260 °C), the blends original two T_gs merged into one single T_g, and the annealed blends exhibited a homogeneous morphology, and turned from having a semicrystalline into having an amorphous nature upon extended annealing. The annealing-induced changes of phase behaviour in the blends were analyzed. The homogenization process of the blends upon heating is attributed to chemical transreactions between the PTT and PC chain segments, as evidenced with FT-IR characterization. The IR result showed a new aryl C-O vibration peak at 1,070 cm^–1 for the annealed blends, which is characteristic of an aromatic polyester structure formed from exchange reactions between PTT and PC. The transreactions between PTT and PC led to a random copolymer comprised of PC/PTT segments, which is believed to serve as a compatibilizer at the beginning stage of transreactions, but at later stage, the random copolymer became the main species of blends and turned to a homogeneous and amorphous phase.     

Melting behavior,miscibility, and hydrogen-bonded interactions of poly(ε-caprolactone)/poly(4-hydroxystyrene-co-methoxystyrene) blends

The miscibility of poly(4-hydroxystyrene-co-methoxystyrene) (HSMS) and poly(ε-caprolactone) (PCL) was investigated by differential scanning calorimetry and Fourier transform infrared spectroscopy (FTIR). HSMS/PCL blends were found to be miscible in the whole composition range by detecting only a glass transition temperature (T_g), for each composition, which could be closely described by the Fox rule. The crystallinity of PCL in the blends was dependent on the T_g of the amorphous phase. The greater the HSMS content in the blends, the lower the crystallinity. The polymer–polymer interaction parameter, χ₃₂, was calculated from melting point depression of PCL using the Nishi-Wang equation. The negative value of χ₃₂ obtained for HSMS/PCL blends has been compared with the value of χ₃₂ for poly(4-hydroxystyrene) (P4HS)/PCL blends. The specific nature, quantitative analysis, and average strength of the intermolecular interactions in HSMS/PCL and P4HS/PCL blends have been determined at room temperature and in the molten state by means of Fourier transform infrared spectroscopy (FTIR) measurements. The FTIR results have been in good correlation with the thermal behavior of the blends. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36 : 95–104, 1998     

Acrylic polymer/silica hybrid for electron‐beam resists

An acrylic polymer/silica hybrid resist film was investigated for fabricating a microstructure by electron‐beam (EB) lithography. EB lithography on the hybrid thin film afforded a positive pattern whose depth corresponded to the EB exposure dose; this indicated that the hybrid was an analog resist and could fabricate a three‐dimensional microstructure. The resist film had high heat resistance and compatibility with the underlying quartz plate, probably because of the silica component. The acrylic polymer/(RSiO_1.5)_n hybrid film showed higher EB sensitivity than a film of the crosslinked acrylic polymer and an acrylic polymer/(SiO₂)_n hybrid. Atomic force microscopy observation of the hybrid film surface showed the homogeneous dispersion of the acrylic polymer and the silica components in the hybrid film. The acrylic polymer component was EB‐sensitive, whereas dispersing the acrylic polymer and silica components homogeneously also played an important role in increasing the EB sensitivity. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2107–2116, 2006     

Pyrolysis mass spectrometry analysis of polycarbonate/poly(methyl methacrylate)/poly(vinyl acetate) ternary blends

Direct insertion probe pyrolysis mass spectrometry (DIP-MS) analyses of polycarbonate/poly(methyl methacrylate)/poly(vinyl acetate), (PC/PMMA/PVAc), ternary blends have been performed. The PC/PMMA/PVAc ternary blends were obtained by coalescing from their common γ-cyclodextrin-inclusion compounds (CD-ICs), through the removal of the γ-CD host (coalesced blend), and by a co-precipitation method (physical blend). The coalesced ternary blend showed different thermal behaviors compared to the co-precipitated physical blend. The stability of PC chains decreased due to the reactions of CH₃COOH formed by deacetylation of PVAc above 300 °C, for both coalesced and physical blends. This process was more effective for the physical blend most likely due to the enhanced diffusion of CH₃COOH into the amorphous PC domains, where it can further react producing low molecular weight PC fragments bearing methyl carbonate chain ends. The decrease in thermal stability of PC chains was less significant for the coalesced ternary blend indicating that the diffusion of CH₃COOH was either somewhat limited or competed with intermolecular reactions between PMMA and PC and between PMMA and PVAc, which were detected and were associated with their close proximity in the intimately mixed coalesced PC/PMMA/PVAc ternary blend.     

A study of the blending of ethylene–styrene copolymers differing in the copolymer styrene content: Miscibility considerations

Blends of two or more ethylene–styrene (ES) copolymers that differed primarily in the comonomer composition of the copolymers were studied. Available thermodynamic models for copolymer–copolymer blends were utilized to determine the criteria for miscibility between two ES copolymers differing in styrene content and also between ES copolymers and the respective homopolymers, polystyrene and linear polyethylene. Model estimations were compared with experimental observations based primarily on melt‐blended ES/ES systems, particularly via the analysis of the glass‐transition (T_g ) behavior from differential scanning calorimetry (DSC) and solid‐state dynamic mechanical spectroscopy. The critical comonomer difference in the styrene content at which phase separation occurred was estimated to be about 10 wt % for ES copolymers with a molecular weight of about 10⁵ and was in general agreement with the experimental observations. The range of ES copolymers that could be produced by the variation of the comonomer content allowed the study of blends with amorphous and semicrystalline components. Crystallinity differences for the blends, as determined by DSC, appeared to be related to the overlapping of the T_g of the amorphous component with the melting range of the semicrystalline component and/or the reduction in the mobility of the amorphous phase due to the presence of the higher T_g of the amorphous blend component. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2976–2987, 2000     

Complete miscibility of ternary aryl polyesters demonstrating a new criterion and horizon for miscibility characterization

A ternary miscible blend system comprising only crystallizable aryl polyesters [poly(ethylene terephthalate), poly(trimethylene terephthalate), and poly(butylene terephthalate)] was characterized with the criteria of thermal analyses, microscopy, and X‐ray characterizations. The reported ternary miscibility (in the quenched amorphous state of blends of the three aryl polyesters) was truly physical and under the condition of no chemical transesterifications; this justified that transesterification was not a necessary condition for miscibility in polyester blends in this case. This study further proposed and tested a novel concept of a new criterion for miscibility characterization for polymer blends of only crystallizable polymers. A single composition‐dependent cold‐crystallization‐temperature (T_cc) peak in blends of only semicrystalline polymers was taken as an indication of an intimate mixing state of miscibility. The theoretical background for establishing the single composition‐dependent T_cc peak as a valid miscibility criterion for crystallizable polymer blends was examined. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2394–2404, 2003     

Compositionally symmetric diblock copolymer blends of moderate polydispersity

Recent experimental evidence and theoretical predictions indicate that binary blends of relatively monodisperse diblock copolymers remain miscible if the molecular weight disparity of the constituent copolymers is not too great. In this work, we examine the effect of moderate copolymer polydispersity on both the microstructural characteristics and phase behavior of blends prepared from four compositionally symmetric poly(styrene-b-isoprene) (SI) diblock copolymers ranging in polydispersity (M̄_w/M̄_n) from 1.02 to 1.30. Blend periodicities, measured by small-angle X-ray scattering, compare favorably with predictions from a strong segregation theory proposed for lamellar diblock copolymer blends composed of monomolecular copolymers. Transmission electron microscopy, employed to ascertain the real-space morphological characteristics of these blends, reveals that a lamellar → cylindrical transition occurs in macrophase-separated blends. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2653–2658, 1997     

Synthesis of polycarbonate from dimethyl carbonate and bisphenol-a through a non-phosgene process

A novel nonphosgene process for producing bisphenol-A polycarbonate (PC) was developed through a transesterification between bisphenol-A (BPA) and dimethyl carbonate (DMC) and a melt-polycondensation of the resulting bisphenol-A bismethylcarbonate (1). The transesterification was carried out by heating bisphenol A in dimethylcarbonate in the presence of Lewis acid catalysts, removing the by-producing methanol using molecular shieves 4A. Among various catalysts, a combination of (Bu₂SnCl)₂O and dimethylaminopyridine gave the best results to produce 1 in 22% yield for 48 h. Using a larger amount of the molecular sieves further improved the yield to 80% in 120 h. The resulting 1 was heated under reduced pressure in the presence of titanium catalysts to produce PC in good yields. The resulting PC had high weight average molecular weight (M_w) of 75,000. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2087–2093, 1999     

Fast FTIR imaging: A new tool for the study of semicrystalline polymer morphology

The distribution of chemical species and the degree of orientation in semicrystalline polymer systems have been studied using fast Fourier transform infrared (FTIR) imaging. A variety of poly(ethylene glycol) systems, including pure polymer, high and low molecular weight blends, and blends with amorphous polymers, were studied. It is shown that fast FTIR imaging can be used to determine the distribution of species with different molecular weights and can be used to determine the degree of segregation of different components in blends with amorphous polymers. Additionally, by employing an infrared polarizer, the degree of orientation was determined in these systems by the generation of spatially‐resolved dichroic ratio images. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2353–2359, 1999     

Poly(silylenemethylene)‐based polymer blends. III. Synthesis and properties of polymer blends containing siloxane‐crosslinked poly(silylenemethylene)s

Soft–hard binary polymer blends consisting of amorphous poly(silylene methylene)s (PSMs) and crystalline poly(diphenylsilylenemethylene) were prepared by both melt processing at 360 °C and in situ polymerization at 300 °C. Linear and siloxane‐crosslinked PSMs were used as amorphous components for the purpose of determining how the crosslinks affected the interactions between the component polymers. Differential scanning calorimetry and dynamic mechanical analysis indirectly suggested that discernable differences between the blends containing linear and crosslinked PSMs were attributable to the degree of interactions between the amorphous and crystalline components. The morphological differences between these blends were studied with transmission electron microscopy. The dispersion phase was smaller in the blends containing crosslinked PSM than that in the blends containing linear PSM. This directly indicated that a larger interaction between the amorphous and crystalline phases was obtained by the introduction of crosslinks because of the smaller viscosity difference between the phases and a larger degree of polymer chain entanglement. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 257–263, 2003     

Miscibility of semirigid thermotropic liquid crystalline polycarbonate with poly(vinyl chloride)

Miscibility and morphology of polymer blends of semirigid thermotropic liquid crystalline (LC) polycarbonate (LCPC) with three commercial amorphous poly(vinyl chloride)s (PVC) having various molecular weights were investigated by means of differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). No phase separation was observed in the LCPC/PVC polymer blends. LCPC forms miscible polymer blends with the PVCs independent of molecular weight. The dynamic storage modulus of the LCPC/PVC polymer blends changes systematically with blend composition.     

Blends of bisphenol-A polycarbonate and acrylic polymers: II. PC/acrylic copolymers as a new route for compatibilization

An acrylic polymer containing acid and anhydride units, referred to as reactive polyglutarimide (RPGI), has been used to react with PC. The reaction has been previously determined as an acidolysis of the carbonate bond which breaks the PC chain in two parts. One of those two parts remains free while the other one is grafted on the acrylic backbone. We have found that the anhydride units could also react with the carbonate bonds. In this case the PC macromolecule would also be broken in two parts, which would, however, both be grafted on the acrylic backbone. The reaction has been performed in solution in order to keep good contact between the reacting units. The influence of temperature and concentration on the grafting ratio has been studied. The best experimental conditions were determined in order to obtain a grafted copolymer where the acrylic backbone only supports, on the average, one PC side chain through acid reaction or two PC chains through anhydride reaction. Indeed, these two types of reactions could not be isolated. The efficiency of this copolymer as emulsifier has been studied in solution cast blends as well as in melt mixed blends. The copolymer strongly affects the microstructure in solution cast blends where films containing 30 wt % of PC have become transparent. However, the dispersed phase size of solvent cast blends could be highly influenced by the casting conditions related to solvent trapping. In melt mixed samples, the copolymer also reduces significantly the dispersed phase size, but no transparent blends have been observed so far. These results were compared with those given in the literature describing the efficiency of a synthesized copolymer which has a more complicated structure. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 735–747, 1997