Miscibility Of Polycarbonate Research Articles

Properties of Polycarbonate (PC)/Multi-Wall Carbon Nanotube (MWCNT) Nanocomposites Prepared by Melt Blending

This investigation deals with an easy method to develop electrical conductivity in polycarbonate (PC)/multi-wall carbon nanotube (MWCNT) nanocomposites with low loading of MWCNT. This was achieved by melt-blending of in-situ bulk polymerized low molecular weight poly(methyl methacrylate) (PMMA)/MWCNT nanocomposites and PC in various compositions at 280 degrees C in internal mixer. Differential scanning calorimetry (DSC) study showed single Tg in (85/15 w/w) PC/PMMA blend, indicating miscibility of PC and PMMA in the blend. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies of the melt-blended PC/PMMA/MWCNT nanocomposites revealed homogeneous dispersion and distribution of MWCNTs in PC matrix. Finally, through optimizing the blending composition of PC and PMMA/MWCNT nanocomposites, electrical conductivity of 3.74 x 10(-7) S x cm(-1) was achieved in the (85/15 w/w) PC/PMMA/MWCNT nanocomposites with the MWCNTs loading as low as approximately 0.37 wt%. Storage modulus of PC was found to increase significantly in presence of small amount (0.37 wt%) of MWCNTs in the nanocomposites.

Transesterification effects on miscibility polycarbonate/poly(butylene adipate-co-terephthalate) blends

The effects of transesterification on the miscibility of polycarbonate (PC)/poly(butylenes adipate-co-terephthalate) (PBAT) blends were investigated. The PC/PBAT blends were prepared with a twin-screw extruder, and then annealed at 260 °C for 5 h to trigger the transesterification reaction. 1H NMR, FT-IR, and WAXD results indicated that transesterification in the annealed PC/PBAT blends took place and led to the formation of a random copolymer structure. Because the copolymer serves as a compatibilizer, the PC/PBAT blends showed improved miscibility, as confirmed by FE-SEM and DMA analyses. The compatible morphology achieved through transesterification ultimately increased the thermal stability of the PC/PBAT blends. We could thus conclude that transesterification in PC/PBAT blends forms a random copolymer which plays an important role as a compatibilizer and consequently improves the miscibility as well as the thermal properties of the blends.

Effects of AN-contents and shear flow on the miscibility of PC/SAN blends

The miscibility of polycarbonate (PC) with styrene- co-acrylonitrile random copolymer (SAN) has been systematically investigated as functions of acrylonitrile content and shear flow. Various AN-contents ranged from 11 to 74 wt% and different simple shear flow values up to 90 s −1 have been used to explore the effect of both material and proceeding parameters on the miscibility of PC and SAN blends. The finest phase dispersion of the SAN particles was observed at AN=25 wt% for PC/SAN=70/30 blends under the same processing condition using scanning electron microscope (SEM). The obtained morphologies indicated that PC and SAN could form a partial miscibility blend and the maximum miscibility occurred at AN=25 wt%. This observation was supported by considering the shifts in the glass processes of the two rich phases of the blend using the dynamical mechanical analysis (DMA) measurements. The optimum interaction of the two components at AN=25 wt% calculated from ellipsometric technique was found to be the only responsible parameter for the high miscibility of the blend. The viscoelastic properties of the pure polymer components were found to play a minor role in the obtained morphologies. The effect of simple shear flow on the morphology of PC/SAN-25=70/30 blend has been also investigated using a special shear apparatus of parallel plate geometry. It has been found that the dispersed phase of SAN was elongated and broken-up in the direction of flow with weaker contrast at high shear rates. The shear rate was found to enhance the miscibility of SAN (dispersed phase) in the PC matrix to a great extent as seen in the weak contrast of the two phases observed by transmission electron microscope (TEM).

Control of phase separation behavior of PC/PMMA blends and their application to the gas separation membranes

Gas transport and thermodynamic properties for the blends of polycarbonate (PC) and polymethylmethacrylate (PMMA) were studied. To explore glass transition temperatures of blends and their phase separation temperatures due to a lower critical solution temperature, LCST, a type of phase boundary, transparent blend films that are miscible and do not contain solvent-induced PC crystals were prepared by controlling molecular weights of each component. The average value of interaction energy densities between PC and PMMA obtained from the phase boundaries and the equation of a state theory based on the lattice fluid model was 0.04 cal/cm3. This result confirmed that miscibility of PC and PMMA blends at equilibrium depends upon the molecular weights of components. Gas transport properties of miscible blends and immiscible blends having the same chemical components and composition but a difference in morphology were examined at 35°C and 1 atm for the gases N2 and O2. Permeability and apparent diffusion coefficients were ranked in the order of the immiscible blend having a domain–matrix structure > the immiscible blend having an interconnected structure > the miscible blend. These results might be related to the differences in the local chain motions that depend on the intermolecular mixing level. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2950–2959, 1999

Modification of polycarbonate with miscible polyurethane elastomers

Polyurethane elastomers (PUEs) based on 4,4′-diphenylmethane diisocyanate and aliphatic polycarbonate diols and/or polytetramethylene glycols have been found to be miscible with polycarbonate (PC). Incorporation of 0–10% of PUEs in melt mixing decreases the glass transition temperature of PC (by 0–30°C), facilitates its processing, and improves its resistance to hydrothermal ageing. No phase separation in blends was detected by means of the absorption of the visible light and differential scanning calorimetry measurements. Dynamic mechanical and static bending measurements concurrently show a slight increase in the glassy state modulus, which can be viewed as an ‘antiplasticizing’ effect of PUEs in PC. This effect and the miscibility of PC with PUEs can be ascribed to their strong interaction, probably due to the formation of hydrogen bonds between urethane and carbonate groups.

Phase morphology of blends of polycarbonate with poly(methyl methacrylate‐co‐cyclohexyl methacrylate), and of polycarbonate with poly(methyl methacrylate) by solid state nuclear magnetic resonance, differential scanning calorimetry, and transmission electron microscopy

AbstractThe miscibility of polycarbonate (PC) with poly(methyl methacrylate‐co‐cyclohexyl methacrylate) (PMCHM) and with poly(methyl methacrylate) (PMMA) was studied by nuclear magnetic resonance (NMR) 1H spin‐lattice relaxation time in the rotating frame (1H T1p), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). A blend of PC/PMCHM (50/50 wt/wt) with the acrylic component PMCHM, a copolymer of PMMA and poly(cyclohexyl methacrylate) (80/20 wt/wt), shows only one T1p value, which indicates high miscibility in this blend. A blend of PC/PMMA (50/50 wt/wt) shows two 1H T1p values, which are similar to those of the homopolymers PC and PMMA. These results indicate high immiscibility. The “domain size” calculated from NMR results of the miscible blend PC/PMCHM is approximately 40 Å. The results of DSC and TEM are similar to the NMR results. However, TEM results show the presence of 3% PC domains in the PC/PMCHM blend, which are not seen by NMR or DSC. Those PC domains are approximately 500 Å. A strong intramolecular repulsion in the copolymer PMCHM and specific intermolecular interactions between PC and PMMA may explain the miscibility in the PC/PMCHM system. © 1994 John Wiley & Sons, Inc.

Thermal property and miscibility of polycarbonate/copolyester blends

The thermal property and the miscibility of polycarbonate (PC)/copolyester blends were investigated. For the study, different copolyesters were synthesized from terephthalic acid (TPA) and various mixtures of ethylene glycol (EG) and cyclohexane dimethanol (CHDM). Various blends of PC and copolyester were prepared by melt mixing and thermal properties of the blends were studied employing differential scanning calorimeter. It was found that the blends of the PC and the copolyesters were partially miscible when the glycol in the copolyester was composed of 10, 20, or 30 mole % CHDM. However, the blends of the PC and the copolyesters were miscible in all proportions when the glycol in the copolyester was composed of 50 or 70 mole % CHDM. Miscibilities of the PC/copolyester blends depending on the composition of the copolyester are discussed based on the thermal properties of the blends.

Miscibility of polycarbonate with methyl methacrylate-based copolymers

Poly(methyl methacrylate) and bisphenol-A polycarbonate having high molecular weights do not form homogeneous mixtures above the glass transition temperature at equilibrium. This paper outlines a strategy for developing melt-processible, homogeneous blends of polycarbonate with an acrylic polymer through copolymerization. Nine different comonomers were copolymerized with methyl methacrylate and these polymers were blended with polycarbonate. Copolymers based on cyclohexyl methacrylate and phenyl methacrylate gave homogeneous mixtures with polycarbonate having cloud points (lower critical solution temperature behaviour) near or above the temperature range needed for melt processing. The thermal stability of the acrylic polymers was examined and in some cases a third monomer was used to obtain improvements.

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

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.