Compatibility of poly(2,6-dimethyl-1,4-phenylene oxide)/poly(fluorostyrene-co-chlorostyrene) blends

The compatibility of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) with random copolymers of ortho- and para-fluorostyrene as well as with ortho- and para-chlorostyrene of various copolymer compositions was examined. The compatibility was studied by DSC and visual observation of film clarity. It was found that copolymers of ortho-fluorostyrene with para-chlorostyrene containing 15–74 mol % p-CIS are compatible with PPO in all proportions. Compatibility of the PPO/poly-(ortho-fluorostyrene-co-ortho-chlorostyrene) system was observed for copolymers containing between 15 and 36 mol % ortho-chlorostyrene. Copolymers of para-fluorostyrene with para-chlorostyrene, as well as copolymers of para-fluorostyrene with ortho-chlorostyrene appear to be incompatible with PPO at 210°C.     

Partial miscibility in the system poly(para-chlorostyrene-co-ortho-chlorostyrene)/poly(2,6-dimethyl-1,4-phenylene oxide)

The compatibility of random copolymers of para-chlorostyrene and ortho-chlorostyrene (PO copolymers) with poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) has been studied by differential scanning calorimetry (d.s.c.). Blends prepared by compression moulding of coprecipitated powders display either one or two glass transitions, dependent on the composition of the copolymer component of the blend. PO copolymers of para-chlorostyrene content from 23 to 64% are miscible with PPO in all proportions, using the customary criteria of a single calorimetric glass relaxation and optical clarity. Both homopolymers poly(para-chlorostyrene) (P_pClS) and poly(ortho-chlorostyrene) (P_oClS) are found to be incompatible with PPO; such blends exhibit two glass transitions at temperatures characteristic of the pure component phases. All compatible PO-PPO blends undergo phase separation upon annealing at elevated temperatures, indicating that a lower critical solution temperature (LCST) must exist. The phase separation is found to be reversible by annealing below the LCST, at temperatures which are still above the glass transitions of both blend components.     

Phase behavior of blends of poly(2,6-dimethyl-1,4-phenylene oxide)/polystyrene/poly(o-chlorostyrene-co-p-chlorostyrene) copolymer

The phase behavior of ternary blends of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO), polystyrene (PS) and a 50/50 mole % statistical copolymer of o-chlorostyrene and p-chlorostyrene [p(oClS-pClS)] has been investigated by differential scanning calorimetry (DSC) and analyzed in terms of a Flory-Huggins mean-field segmental interaction parameter treatment. Both PS/PPO and PPO/p(oClS-pClS) binary blends exhibit single glass transition temperatures over the full composition range whereas the PS/p(oClS-pClS) system displays a substantial immiscibilty window which extends into the ternary phase diagram. In principle, ternary systems provide enhanced opportunities relative to binary systems for evaluating segmental interaction parameters χ_ijs from experimental data because of the high sensitivity of phase boundary locations to these parameters and to component molecular weights. In this system the effect of these parameters on the phase boundary was studied experimentally and compared to calculated values.     

Effect of pressure on phase behavior in polymer blends of poly(2,6-dimethyl-1,4-phenylene oxide) and poly(o-fluorostyrene-co-p-fluorostyrene) copolymers

The effect of pressure on miscibility and phase separation in blends of random copolymers of ortho- and para-fluorostyrene, P(o-FS-co-p-FS) and poly(2,6-dimethyl-1,4-phenylene oxide), PPO, has been studied by differential thermal analysis (DTA) at pressures up to 300 MPa. At 200 MPa the copolymers containing from 10 to 38 mol% p-FS are miscible with PPO below 230°C using the customary criterion of a single calorimetric glass transition temperature (T_g). Each blend undergoes phase separation upon annealing at higher temperatures at both atmospheric and elevated pressures indicating the presence of a lower critical solution temperature (LCST). When the phase behaviors of the 50/50 wt% blends are examined as a function of temperature and copolymer composition, a symmetric miscibility “window” can be observed in the resulting temperature-composition diagram with a maximum at about 22 mol% p-FS. In a complementary set of experiments, the pressure dependence of the phase boundary for the blend of PPO and P(o-FS-co-p-FS) in which the copolymer contained 29 mol% p-FS was studied. The temperature minimum of the phase boundary is at about 50 wt% PPO and is independent of pressure. The consolute temperature, T_c, increases at about 0.1₀°C/MPa up to 200 MPa and then becomes independent of pressure to reach an asymptotic value at around 270°C. Similar behavior is also observed for blends in which the copolymer composition contains either 16 or 23 mol% p-FS. In these blends the decrease of dT_c/dP at higher pressures may indicate that the negative volume of mixing approaches zero above 200 MPa. This study shows therefore, that pressure no longer plays a role in increasing the miscibility above 200 MPa.     

Influence of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) on miscibility and properties of atactic poly(methyl methacrylate)

Miscibility and properties of two atactic poly(methyl methacrylate)‐based blends [containing 10 and 20% of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)] have been investigated as a function of thermal treatments. Differential scanning calorimetry and dynamic mechanical thermal analysis of blends quenched in liquid nitrogen or ice/water, after annealing at T > 190 °C, showed a single glass transition temperature, indicating miscibility of the components for the time‐temperature history. Two glass transition temperatures, equal to those of the pure components, are instead found for blends after annealing at T < 190 °C. Scanning electron microscopy confirmed the homogeneity for the former quenched blends and phase separation for the latter. These results indicate the presence of an upper critical solution temperature (UCST). Tensile experiments, performed on two series of samples annealed at temperatures above and below the UCST, showed that the copolyester induces a decrease of Young's modulus and stresses at yielding and break points, and a marked increase of elongation at break. Differences in tensile properties between the two series of annealed blends are accounted for by the physical state of the components at room temperature after annealing above or below the UCST. Copyright © 2004 Society of Chemical Industry     

Miscibility in blends of sulfonylated poly(2,6-dimethyl-1,4-phenylene oxide) and poly(p-bromostyrene-co-o-bromostyrene)

Miscibility in blends of random copolymers of p-bromostyrene (pBrSt) and o-bromostyrene (oBrSt) [P(pBrSt-co-oBrSt)] with partially sulfonylated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO) have been studied by differential scanning calorimetry (DSC). For an SPPO of given degree of sulfonylation, a miscibility window in terms of the isomeric composition of the brominated copolymer was seen; the location and width of the window was a function of sulfonylation. In general, copolymers with a higher content of pBrSt exhibit miscibility with SPPOs with higher degrees of sulfonylation. Upon annealing to temperatures of 280° and 320°C, only small changes in the miscibility regime were observed. The miscibility behavior was analyzed on the basis of the mean-field theory in terms of the individual segmental interaction parameters. © 1994 John Wiley & Sons, Inc.     

Compatibility of poly(p-fluorostyrene-co-o-fluorostyrene) with poly(2,6-dimethyl-1,4-phenylene oxide) and polystyrene

The compatibility of blends prepared from random copolymers of p-fluorostyrene and o-fluorostyrene with poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and blends of the copolymers with polystyrene (PS) has been examined using differential scanning calorimetry. It was found that compatibility in these systems depends on copolymer composition: copolymers containing from 10 to 38% of p-fluorostyrene are miscible with PPO in all proportions. The thermally induced phase separation in these systems was also studied and the existence of lower critical solution temperatures (LCST) was established for all compatible blends. The copolymers were found to be incompatible with PS regardless of composition.     

Miscibility of poly(styrene-co-acrylonitrile) and poly(α-methyl styrene-co-acrylonitrile) with copolymers of methyl methacrylate

Poly(α-methyl styrene-co-acrylonitrile) was found to be miscible with poly(methyl methacrylate-co-ethyl methacrylate) and with poly(methyl methacrylate-co-n-butyl methacrylate). All these blends exhibited lower critical solution temperatures. Poly(styrene-co-acrylonitrile) was also found to be miscible with poly(methyl methacrylate-co-ethyl methacrylate) and with poly(methyl methacrylate-co-n-butyl methacrylate). However, phase separation of these blends could not be induced by heating up to 300°C.     

Blends of poly(2,6-dimethyl-1,4-phenylene oxide)/ poly(styrene-co-methacrylic acid)/ poly(ethyl methacrylate-co-4-vinylpyridine)

Summary The miscibility of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) with poly(styrene-co-acrylic acid) (SAA) or poly(styrene-co-methacrylic acid) (SMA) containing respectively up to 22 mol % of acrylic or methacrylic acid was studied by Differential Scanning Calorimetry and viscosimetry. All PPO/SAA or PPO/SMA blends containing 60% or less by weight of PPO were miscible and showed only one glass transition temperature (Tg). Above 60% of PPO, two Tg's were however observed for the blends in which the acid content in the SAA or SMA reaches 20% or 12% by mole respectively; the higher Tg is slightly lower than the one of pure PPO, while the lower one corresponds to a miscible blend of lower content of PPO.A DSC study showed that depending on the blend ratio, two or three glass transition temperatures were observed when a copolymer of ethyl methacrylate containing 8 mol % of 4-vinylpyridine (EM4VP-8) was added to miscible PPO/SMA-12 blends. The PPO dissolution in the SMA-12 copolymer was affected by the specific interactions that occurred between this latter copolymer and the EM4VP-8.     

Miscible blends of poly(styrene-co-acrylonitrile) and poly(α-methyl styrene-co-acrylonitrile) with poly(methyl methacrylate) containing sterically hindered amine group

Poly(methyl methacrylate) containing a small amount of pendant 2,2,6,6-tetramethylpiperidinyl group was found to be miscible with poly(styrene-co-acrylonitrile) and with poly(α-methyl styrene-co-acrylonitrile). The poly(α-methyl styrene-co-acrylonitrile) blends exhibited lower critical solution temperatures. Phase separation of the poly(styrene-co-acrylonitrile) blends could not be induced by heating up to 270°C.     

Effect of poly(styrene‐co‐maleic anhydride) imidization on the miscibility and phase‐separation temperatures of poly(styrene‐co‐maleic anhydride)/poly(vinyl methyl ether) and poly(styrene‐co‐maleic anhydride)/ poly(methyl methacrylate) blends

The objective of this work was to study the miscibility and phase‐separation temperatures of poly(styrene‐co‐maleic anhydride) (SMA)/poly(vinyl methyl ether) (PVME) and SMA/poly(methyl methacrylate) (PMMA) blends with differential scanning calorimetry and small‐angle light scattering techniques. We focused on the effect of SMA partial imidization with aniline on the miscibility and phase‐separation temperatures of these blends. The SMA imidization reaction led to a partially imidized styrene N‐phenyl succinimide copolymer (SMI) with a degree of conversion of 49% and a decomposition temperature higher than that of SMA by about 20°C. We observed that both SMI/PVME and SMI/PMMA blends had lower critical solution temperature behavior. The imidization of SMA increased the phase‐separation temperature of the SMA/PVME blend and decreased that of the SMA/PMMA blend. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Miscibility and phase behavior in blends of poly(hydroxyether of bisphenol A) with poly(ethylene oxide-co-propylene oxide)

The miscibility of poly(hydroxyether of bisphenol A) (phenoxy) with a series of poly(ethylene oxide-co-propylene oxide) (EPO) has been studied. It was found that the critical copolymer composition for achieving miscibility with phenoxy around 60°C is about 22 mol % ethylene oxide (EO). Some blends undergo phase separation at elevated temperatures, but there is no maximum in the miscibility window. The mean-field approach has been used to describe this homopolymer/copolymer system. From the miscibility maps and the melting-point depression of the crystallizable component in the blends, the binary interaction energy densities, B_ij, have been calculated for all three pairs. The miscibility of phenoxy with EPO is considered to be caused mainly by the intermolecular hydrogen-bonding interactions between the hydroxyl groups of phenoxy and the ether oxygens of the EO units in the copolymers, while the intramolecular repulsion between EO and propylene oxide units in the copolymers contributes relatively little to the miscibility. © 1993 John Wiley & Sons, Inc.     

Miscibility in poly(vinyl chloride)/chlorinated poly(vinyl chloride) blends,and blends of different chlorinated poly(vinyl chlorides)

Blends of poly(vinyl chloride) with chlorinated poly(vinyl chloride) (PVC), and blends of different chlorinated poly(vinyl chlorides) (CPVC) provide an opportunity to examine systematically the effect that small changes in chemical structure have on polymer-polymer miscibility. Phase diagrams of PVC/CPVC blends have been determined for CPVC's containing 62 to 38 percent chlorine. The characteristics of binary blends of CPVC's of different chlorine contents have also been examined using differential calorimetry (DSC) and transmission electron microscopy. Their mutual solubility has been found to be very sensitive to their differences in mole percent CCl₂ groups and degree of chlorination. In metastable binary blends of CPVC's possessing single glass transition temperatures (T_g) the rate of phase separation, as followed by DSC, was found to be relatively slow at temperatures 45 to 65° above the T_g of the blend.     

Membranes based on poly(styrene-N-phenylmaleimide)/poly(2,6-dimethyl-1,4-phenylene oxide) blends

Blend membranes were prepared by casting chloroform solutions of mixtures of styrene-N-phenylmaleimide copolymer containing ca. 10 mol % imide units with poly(2,6-dimethyl-1,4-phenylene oxide) (PPO), and their phase behavior was evaluated. At a content of 20% PPO, the membranes were homogeneous; those having 40 or more % PPO exhibited phase separation. Membranes made of the parent polymers and their blends were tested in the pervaporation of aqueous ethanol solutions; permeabilities to oxygen, nitrogen, and carbon dioxide were also determined. The pervaporation characteristics and gas transport properties are discussed considering the interactions of polymer chains and the phase structure of the membranes. © 1995 John Wiley & Sons, Inc.     

Biodegradable polymer blends of poly(3-hydroxybutyrate) and poly(DL-lactide)-co-poly(ethylene glycol)

The melting and crystallization behavior and phase morphology of poly(3-hydroxybutyrate) (PHB) and poly(DL-lactide)-co-poly(ethylene glycol) (PELA) blends were studied by DSC, SEM, and polarizing optical microscopy. The melting temperatures of PHB in the blends showed a slight shift, and the melting enthalpy of the blends decreased linearly with the increase of PELA content. The glass transition temperatures of PHB/PELA (60/40), (40/60), and (20/80) blends were found at about 30°C, close to that of the pure PELA component, during DSC heating runs for the original samples and samples after cooling from the melt at a rate of 20°C/min. After a DSC cooling run at a rate of 100°C/min, the blends showed glass transitions in the range of 10–30°C. Uniform distribution of two phases in the blends was observed by SEM. The crystallization of PHB in the blends from both the melt and the glassy state was affected by the PELA component. When crystallized from the melt during the DSC nonisothermal crystallization run at a rate of 20°C/min, the temperatures of crystallization decreased with the increase of PELA content. Compared with pure PHB, the cold crystallization peaks of PHB in the blends shifted to higher temperatures. Well-defined spherulites of PHB were found in both pure PHB and the blends with PHB content of 80 or 60%. The growth of spherulites of PHB in the blends was affected significantly by 60% PELA content. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 1849–1856, 1997     

Blends of epoxy–amine resins with poly(phenylene oxide) as processing aids and toughening agents: I. Uncured systems

The effect of two different bisphenol‐A‐based diepoxides—nearly pure DGEBA340 and a DGEBA381 oligomer—and an aromatic diamine curative (MCDEA) on the solubility and processability of poly(phenylene oxide) (PPO) was studied. The solubility parameters of the diepoxies and the curative calculated from Fedors's method suggest miscibility of PPO with the components, and this was observed at the processing temperature; however, some of the blends were not transparent at room temperature, indicating phase immiscibility and/or partial PPO crystallization. The steady shear and dynamic viscosities of the systems agreed well with the Cox–Merz relationship and the logarithmic viscosities decreased approximately linearly with increasing amounts of DGEBA381, DGEBA340 or MCDEA, thus causing a processability enhancement of the PPO. The dynamic rheology of intermediate PPO:DGEBA compositions at 200 °C showed gel‐like behaviour. Dynamic mechanical analysis of blends with varying PPO:DGEBA ratios showed that the main glass transition temperature (T_g) of the blends decreased continuously with increasing epoxy content, with a slightly higher plasticizing efficiency being exhibited by DGEBA340 compared to DGEBA381. However, blends with 50 and 60 wt% PPO had almost identical T_g due to the phase separation of the former blends. The blends of MCDEA and PPO were miscible over the concentration range investigated and T_g of the blends decreased with increasing MCDEA concentration. © 2013 Society of Chemical Industry     

Nonisothermal crystallization kinetics of poly(ethylene terephthalate) and poly(methyl methacrylate) blends

The nonisothermal crystallization kinetics of poly(ethylene terephthalate) (PET) and poly(methyl methacrylate) (PMMA) blends were studied. Four compositions of the blends [PET 25/PMMA 75, PET 50/PMMA 50, PET 75/PMMA 25, and PET 90/PMMA 10 (w/w)] were melt‐blended for 1 h in a batch reactor at 275°C. Crystallization peaks of virgin PET and the four blends were obtained at cooling rates of 1°C, 2.5°C, 5°C, 10°C, 20°C, and 30°C/min, using a differential scanning calorimeter (DSC). A modified Avrami equation was used to analyze the nonisothermal data obtained. The Avrami parameters n, which denotes the nature of the crystal growth, and Z_t, which represents the rate of crystallization, were evaluated for the four blends. The crystallization half‐life (t_½) and maximum crystallization (t_max) times also were evaluated. The four blends and virgin polymers were characterized using a thermogravimetric analyzer (TGA), a wide‐angle X‐ray diffraction unit (WAXD), and a scanning electron microscope (SEM). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3565–3571, 2006     

Compatibility behavior in thermoplastic polymer blends containing poly(t-butylstyrene-co-acrylonitrile)

The phase behavior of a series of binary component polymer blends of poly(ε-caprolactone) (PCL) and poly(t-butylstyrene-co-acrylonitrile) (TBSAN) containing varying contents of acrylonitrile (AN) was examined to determine the influence of copolymer composition and PCL content on blend miscibility or immiscibility. Thermal measurements were extensively used to determine phase behavior, i.e., a single compositionally dependent glass transition temperature implies blend miscibility. Otherwise, immiscibility is assumed to dominant blend behavior. It was determined that TBSAN and PCL form miscible blends over a broad range of AN content, i.e., spanning from below 43.2 mol % (19.8 wt %) to about 66.4 mol % (39.6 wt %), a range considerably different from that found in poly(styrene-co-acrylonitrile) copolymers. TBSAN-containing blends were found to be immiscible when the AN content is less than about 43 mol % or greater than about 67 mol %. Small-angle light-scattering and polarized light microscopy was used to probe the substantial morphological changes in the miscible blends. Little change was observed in the immiscible blends. These results clarify the phase separation observed in these blend systems. © 1993 John Wiley & Sons, Inc.     

Thermal analysis of poly(acrylic acid)/poly(oxyethylene) blends

Blends between poly(acrylic acid) and two different poly(oxyethylenes), (1) polyethylene glycol (PEG-1000) and (2) poly(oxyethylene) (20) sorbitan monooleate (Tween-80), were studied by differential scanning calorimetry. The glass transition temperatures, T_g, of the various compositions of these blends were found to follow Fox's equation. At room temperature, blends containing no more than 60% PEG-1000 were amorphous and exhibited only a single glass transition. For these blends with PEG-1000, the glass transition temperatures for the annealed samples were higher than for the quenched samples due to the formation of a PEG crystalline phase. It was also found that addition of an amorphous polymer such as poly(acrylic acid) significantly reduced the degree of crystallinity of a semicrystalline polymer such as poly(oxyethylene). The Tween-80 systems did not show phase separation at room temperature. The compatibility between this poly(acrylic acid) and this poly(oxyethylene) was attributed to hydrogen bonding and to the lower crystalline lattice energy of this poly(oxyethylene) through its effect on its ideal solution solubility. © 1993 John Wiley & Sons, Inc.     

Thermal analyses of poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)

Thermal analyses of poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(HB–HV)], and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(HB–HHx)] were made with thermogravimetry and differential scanning calorimetry (DSC). In the thermal degradation of PHB, the onset of weight loss occurred at the temperature (°C) given by T_o = 0.75B + 311, where B represents the heating rate (°C/min). The temperature at which the weight-loss rate was at a maximum was T_p = 0.91B + 320, and the temperature at which degradation was completed was T_f = 1.00B + 325. In the thermal degradation of P(HB–HV) (70:30), T_o = 0.96B + 308, T_p = 0.99B + 320, and T_f = 1.09B + 325. In the thermal degradation of P(HB–HHx) (85:15), T_o = 1.11B + 305, T_p = 1.10B + 319, and T_f = 1.16B + 325. The derivative thermogravimetry curves of PHB, P(HB–HV), and P(HB–HHx) confirmed only one weight-loss step change. The incorporation of 30 mol % 3-hydroxyvalerate (HV) and 15 mol % 3-hydroxyhexanoate (HHx) components into the polyester increased the various thermal temperatures T_o, T_p, and T_f relative to those of PHB by 3–12°C (measured at B = 40°C/min). DSC measurements showed that the incorporation of HV and HHx decreased the melting temperature relative to that of PHB by 70°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 90–98, 2001