Thermally induced phase separation in homogeneous blends of poly(2,6-dimethyl-1,4-phenylene oxide) with poly(o-fluorostyrene-co-p-chlorostyrene) and with poly(o-fluorostyrene-co-o-chlorostyrene)

The phase separation behavior of initially compatible blends of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) with poly(o-fluorostyrene-co-p-chlorostyrene) [poly(oFS-co-pCIS)] and with poly(o-fluorostyrene-co-o-chlorostyrene) [poly(oFS-co-oCIS)] was studied by DSC. It was found that copolymers of poly(oFS-co-pCIS) containing between 15 and 62 mol % pCIS have shown no phase separation after annealing at temperatures up to 320°C. It was also observed that blends containing this copolymer with 74 mol % pCIS show phase separation at 250°C, which depended on blend composition. Additionally, all PPO/poly(oFS-co-oCIS) blends exhibit phase separation after annealing to a temperature of 230°C. Thermal degradation of the polymer blends was not observed at the temperatures studied.     

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.     

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 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.     

Polymer blends of polyamide-6 and poly(phenylene oxide) compatibilized by styrene-co-glycidyl methacrylate

Incompatible polymer blends between polyamide-6 (PA6) and poly(phenylene oxide) (PPO) have been compatibilized in situ by the styrene-glycidyl methacrylate (SG) reactive copolymers. The epoxy functional groups in SG copolymers can react with the PA6 amine and carboxylic endgroups at interface to form various SG-g-PA6 copolymers. These in situ-formed grafted copolymers tend to anchor along interface to function as compatibilizer of the blends. The styrene and the SG segments of the grafted copolymers are miscible (or near miscible) with PPO; whereas the PA6 segments are structurally identical with PA6 phase. The compatibilized blend, depending on quantity of the compatibilizer addition and the glycidyl methacrylate (GMA) content in the SG copolymer, results in smaller phase domain, higher viscosity, and improved mechanical properties. About 5% GMA is the optimum content in SG copolymer that produces the best compatibilization of the blends. This study demonstrates that SG reactive copolymers can be used effectively in compatibilizing polymer blends of PA6 and PPO. © 1996 John Wiley & Sons, Inc.     

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.     

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     

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 transesterification in ternary blends of poly(ethylene naphthalate)/poly(pentamethylene terephthalate)/poly(ether imide)

Miscibility and morphology of poly(ethylene 2,6‐naphthalate)/poly(pentamethylene terephthalate)/poly(ether imide) (PEN/PPT/PEI) blends were studied by differential scanning calorimetry (DSC), optical microscopy (OM), proton nuclear magnetic resonance imaging (¹H‐NMR), and wide‐angle X‐ray diffraction (WAXD). OM and DSC results from ternary blends revealed the immiscibility of PEN/PPT/PEI blends, but ternary blends of all compositions were phase‐homogeneous following heat treatment at 300°C for over 60 min. Annealing samples at 300°C yielded an amorphous blend with a clear and single T_g at the final state. Experimental data from ¹H‐NMR revealed that PEN/PPT copolymers (ENPT) were formed by the so‐called transesterification. The effect of transesterification on glass transition and crystallization was discussed in detail. The sequence structures of the copolyester were identified by triad analysis, which showed that the mean sequence lengths became shorter and the randomness increased with heating time. The results reveal that a random copolymer improved the miscibility of the ternary blends, in which, the length of the homo segments in the polymer chain decreased and the crystal formation was disturbed because of the irregularity of the structure, as the exchange reaction proceeded. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3840–3849, 2006     

Blends of poly(2,6‐dimethyl‐1,4‐phenylene oxide)/polyamide 6 toughened by maleated polystyrene‐based copolymers: Mechanical properties,morphology, and rheology

Poly(2,6‐dimethyl‐1,4‐phenylene oxide)/polyamide 6 (PPO/PA6 30/70) blends were impact modified by addition of three kinds of maleated polystyrene‐based copolymers, i.e., maleated styrene‐ethylene‐butylene‐styrene copolymer (SEBS‐g‐MA), maleated methyl methacrylate‐butadiene‐styrene copolymer (MBS‐g‐MA), and maleated acrylonitrile‐butadiene‐styrene copolymer (ABS‐g‐MA). The mechanical properties, morphology and rheological behavior of the impact modified PPO/PA6 blends were investigated. The selective location of the maleated copolymers in one phase or at interface accounted for the different toughening effects of the maleated copolymer, which is closely related to their molecular structure and composition. SEBS‐g‐MA was uniformly dispersed in PPO phase and greatly toughened PPO/PA6 blends even at low temperature. MBS‐g‐MA particles were mainly dispersed in the PA6 phase and around the PPO phase, resulting in a significant enhancement of the notched Izod impact strength of PPO/PA6 blends from 45 J/m to 281 J/m at the MBS‐g‐MA content of 20 phr. In comparison, the ABS‐g‐MA was mainly dispersed in PA6 phase without much influencing the original mechanical properties of the PPO/PA6 blend. The different molecule structure and selective location of the maleated copolymers in the blends were reflected by the change of rheological behavior as well. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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.     

Preparation and characterization of poly(methyl methacrylate) beads

The phase behavior of Poly(ethylene terephthalate)/Poly(ethylene‐2,6‐naphthalate)/Poly(ethylene terephthalate‐co‐ethylene‐2,6‐naphthalate) (PET/PEN/P(ET‐co‐EN)) ternary blends in molten state was evaluated from differential scanning calorimetry (DSC) and NMR results as well as optical microscopic observations. Copolymer of ethylene terephthalate and ethylene‐2,6‐naphthalate was prepared by a condensation polymerization, which was a random copolymer with an intrinsic viscosity (IV) of 0.3 dL/g. The phase diagram of the ternary blends revealed that the miscibility of ternary blends in molten state was dependent on the fraction of P(ET‐co‐EN) in the blends and holding time of the blends at high temperatures above 280°C. With increase in the holding time, the fraction of copolymer in the blends necessary to induce the immiscible to miscible transition decreased. For the blends with longer holding time at 280°C, the phase diagram in molten state was irreversible against the temperature, although a reversibility was found for the blends with short holding time of 1 min at 280°C. The irreversibility of phase behavior was not explained simply by the increase of copolymer content produced during heat treatment. Complex irreversible physical and chemical interactions between components and change of phase structure of the blend in the molten state might influence on the irreversibility. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Phase behavior for blends of styrene containing triblock copolymers with poly(2,6-dimethyl-1,4-phenylene oxide)

The extent to which the styrene end-blocks of three commercially available triblock copolymers can mix with a particular poly(2,6-dimethyl-1,4-phenylene oxide) (M_n = 22,600 and M_w = 34,000) or PPO has been examined by investigation of the glass transition behavior of the PPO and polystyrene (PS) portions of the blends using differential scanning calorimetry. Each block copolymer has a butadiene-based mid-block which was hydrogenated for two of these materials, but not the third. The three copolymers differ substantially in overall molecular weight and in molecula weight of the blocks. However, in analogy with the literature on blends of homopolymer polystyrene with styrene-based block copolymers, the molecular weight of the PS block should be the principal factor affecting the phase behavior in the present blends. Mixtures of the PPO with the block copolymers having PS blocks with M = 14,500 (nonhydrogenated midblock) and with M = 29,000 (hydrogenated mid-block) exhibited single composition-dependent T_gs for the hard phase, indicating complete mixing of PS segments with the PPO, for all proportions. On the other hand, the block copolymer having a PS block with M = 7,500 and a hydrogenated mid-block exhibited two separate hard phase T_gs corresponding to an essentially pure PPO phase and a PS-rich phase. For blends of homopolymer PS with styrene-based block copolymers, the similar two-phase behavior of the glassy portion can be readily explained by entropic considerations. For the present case, the favorable enthalpic contribution for mixing PPO and PS is an additional factor which seems to influence the restrictions on molecular weight for complete mixing; however, additional work is needed to develop a more quantitative assessment of this new issue.     

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.     

Blends of SBS triblock copolymer with poly(2,6‐dimethyl‐1,4‐phenylene oxide)/polystyrene mixture

Blends of styrene–butadiene–styrene (SBS) or styrene–ethylene/1‐butene–styrene (SEBS) triblock copolymers with a commercial mixture of polystyrene (PS) and poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) were prepared in the melt at different temperatures according to the chemical kind of the copolymer. Although solution‐cast SBS/PPO and SBS/PS blends were already known in the literature, a general and systematic study of the miscibility of the PS/PPO blend with a styrene‐based triblock copolymer in the melt was still missing. The thermal and mechanical behavior of SBS/(PPO/PS) blends was investigated by means of DSC and dynamic thermomechanical analysis (DMTA). The results were then compared to analogous SEBS/(PPO/PS) blends, for which the presence of a saturated olefinic block allowed processing at higher temperatures (220°C instead of 180°C). All the blends were further characterized by SEM and TGA to tentatively relate the observed properties with the blends' morphology and degradation temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2698–2705, 2003     

Reactively formed ENPT copolymers as compatibilizers in ternary blends of poly(ethylene naphthalate)/poly(pentamethylene terephthalate)/poly(ether imide)

The compatibility of ternary blends of poly(ethylene naphthalate)/poly(pentamethylene terephthalate)/poly(ether imide) (PEN/PPT/PEI) was studied by examining the transesterification of PEN and PPT. ENPT copolymers were formed in situ as compatibilizers between PPT and PEI components in ternary blends. Differential scanning calorimetric (DSC) results for ternary blends showed the immiscibility of PEN/PPT/PEI, but ternary blends of all compositions were phase‐homogeneous after heat treatment at 300°C for more than 60 min. Annealing samples at 300°C yielded amorphous blends with a clear, single glass transition temperature (T_g), as the final state. Additionally, ENPT copolymer improved the compatibility of ENPT/PPT/PEI blends, yielding a homogeneous phase in the ENPT‐rich compositions. The morphology of the ENPT/PPT/PEI blends was altered from heterogeneous to homogeneous by controlling the concentration of PPT in the ENPT copolymers as well as the concentration of the ENPT copolymers. Moreover, a homogeneous phase with a clear T_g was observed when the concentration of PPT in the ENPT copolymer fell to 70 wt% in the ENPT/PEI = 50/50 blends. Experimental results indicate how the concentration of PPT in the ENPT copolymer affects miscibility in the ENPT/PEI blends. POLYM. ENG. SCI. 46:337–343, 2006. © 2006 Society of Plastics Engineers     

Effect of bisphenol A on the miscibility,phase morphology,and specific interaction in immiscible biodegradable poly(ε‐caprolactone)/poly(L‐lactide) blends

We have investigated the enhancement in miscibility, upon addition of bisphenol A (BPA) of immiscible binary biodegradable blends of poly(ε‐caprolactone) (PCL) and poly(L ‐lactide) (PLLA). That BPA is miscible with both PCL and PLLA was proven by the single value of T_g observed by differential scanning calorimetry (DSC) analyses over the entire range of compositions. At various compositions and temperatures, Fourier transform infrared spectroscopy confirmed that intermolecular hydrogen bonding existed between the hydroxyl group of BPA and the carbonyl groups of PCL and PLLA. The addition of BPA enhances the miscibility of the immiscible PCL/PLLA binary blend and transforms it into a miscible blend at room temperature when a sufficient quantity of the BPA is present. In addition, optical microscopy (OM) measurements of the phase morphologies of ternary BPA/PCL/PLLA blends at different temperatures indicated an upper critical solution temperature (UCST) phase diagram, since the ΔK effect became smaller at higher temperature (200°C) than at room temperature. An analysis of infrared spectra recorded at different temperatures correlated well with the OM analyses. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1146–1161, 2006     

Behavior of aqueous solutions of poly(ethylene oxide-b-propylene oxide) copolymers containing a hydrotropic agent

The effect of the hydrotropic agent, sodium p-toluenesulfonate (NaPTS), was evaluated on the micelle formation process and on phase behavior of aqueous solutions containing poly(ethylene oxide-b-propylene oxide) (PEO–PPO) copolymers. We have studied monofunctional diblock copolymers coupled with hydrocarbons groups (R—PEO—PPO—OH and R—PPO—PEO—OH, where R length is linear C₄ and C_12–14). The critical micelle concentration (CMC) and critical micelle temperature (CMT) values of the aqueous copolymers solutions were obtained from both surface tension versus concentration plots and the dye solubilization method. The influence of the hydrocarbons groups length and PPO segment position in the structure of the copolymers were also analyzed. The same measures were obtained for the aqueous solutions of hydrotropic agent which, in turn, also presented molecular aggregation. The presence of the hydrotropic agent in the aqueous copolymers solutions altered the surface tension of these solutions and the occupied molecular area per copolymer molecule at air–water interface and CMC and CMT values of the copolymers. On the other hand, the aggregation points and the surface tension of the NaPTS solutions were dependent on the copolymer structure and composition. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2459–2468, 1998     

Synthesis of poly(chloroprene-co-isobutyl methacrylate) and its compatibilizing effect in polychloroprene/poly(isobutyl methacrylate) blends

A copolymer of chloroprene (CP) and isobutyl methacrylate (iBMA) [poly(CP-co-iBMA)] was prepared in benzene by radical copolymerization. For comparison, the graft copolymer of iBMA onto polychloroprene (CR) [poly(CR-g-iBMA)] was also prepared. The glass transition temperature of the poly(CP-co-iBMA) was about ?32.4°C. The monomer reactivity ratios determined by the Finneman-Ross method were given as r₁ (CP) = 1.80 and r₂ (iBMA) = 0.74 in the copolymerization of CP and iBMA, respectively. Miscibility of blends of CR and poly(isobutyl methacrylate) (PiBMA), prepared by casting from tetrahydrofuran (THF) solution, was investigated by their glass transition temperature behaviors and morphologies. Although the blends of CR and PiBMA were incompatible, the addition of poly(CP-co-iBMA) or poly(CR-g-iBMA) enhanced miscibility between the two base polymers. It was found that the extent of partial miscibility becomes larger when adding poly(CP-co-iBMA) than poly(CR-g-iBMA) as a third component to the CR/PiBMA blend of 50/50 wt % composition. © 1993 John Wiley & Sons, Inc.