Structure and mechanical properties of uniaxially oriented films of syndiotactic polystyrene and poly(2,6‐dimethyl‐1,4‐phenylene oxide) blends

The structure and mechanical properties of highly oriented films of a miscible blend of syndiotactic polystyrene and poly(2,6‐dimethylphenylene‐1,4‐oxide) (sPS/PPO) were studied in the composition range of sPS/PPO = 10/0 to 5/5. The oriented films were prepared by stretching the amorphous films of the blends. Wide‐angle X‐ray diffraction and polarized FTIR spectroscopy were used to analyze the amount of mesophase and molecular orientation. Drawing of the amorphous films of sPS and sPS/PPO blend induced a highly oriented mesophase. The mesophase content increases with increasing draw ratio and becomes nearly constant above a draw ratio of 3. Under the same draw ratio, the mesophase content decreases with increasing PPO content. The orientation function in the mesophase is as high as 0.95–0.99 irrespective of the composition and draw ratio. On the other hand, the orientation of molecular chains in the amorphous phase and mesophase increases with increasing draw ratio, and it decreases with increasing PPO content. The drawn films of pure sPS show high strength and high modulus in the drawing direction, but exhibit low strength in the direction perpendicular to the drawing. In the case of sPS/PPO = 7/3 blend, however, the ultimate strength in the perpendicular direction was dramatically improved compared with that of pure sPS and the ultimate strength in the parallel direction was similar to that for the oriented pure sPS. The improved mechanical properties in the sPS/PPO blends were discussed in relation to the structural characteristics of the sPS/PPO blend system. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91:2789–2797, 2004     

Thermal,mechanical, and morphological characterization studies of poly(2,6‐dimethyl‐1,4‐phenylene oxide) blends with polystyrene and brominated polystyrene

The miscibility of the binary and ternary blends of poly(2,6‐dimethyl‐1,4‐phenylene oxide), brominated polystyrene, and polystyrene was investigated using a differential scanning calorimeter. The morphology of these blends was characterized by scanning electron microscopy. These studies revealed a close relation between the blend structure and its mechanical properties. The compatibilizing effect of poly(2,6‐dimethyl‐1,4‐phenylene oxide) on the miscibility of the polystyrene/brominated polystyrene blends was examined. It was found that poly(2,6‐dimethyl‐1,4‐phenylene oxide), which was miscible with polystyrene and partially miscible with brominated polystyrene, compatibilizes these two immiscible polymers if its contention exceeds 33 wt %. Upon the addition of poly(2,6‐dimethyl‐1,4‐phenylene oxide) to the immiscible blends of polystyrene/brominated polystyrene, we observed a change in the morphology of the mixtures. An improvement in the mechanical properties was noticed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 225–231, 2000     

Blends of head-to-head polystyrene with poly(2,6-dimethyl-1,4-phenylene oxide)

Blends of head-to-head polystyrene and poly(2,6-dimethyl-1,4-phenylene oxide) were prepared and found to be miscible as judged by a single T_g. The measurements were carried out by d.s.c. and dilatometry. At high concentrations of PPO (> 80%) the mixture is on the threshold of incompatibility as indicated by the increase of the width of the transition step increase by d.s.c. and the increase of the free volume as calculated from dilatometric data. The thermal stability studies of head-to-head polystyrene-(HH-PS)-poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) blends by thermal volatilization analysis show two decomposition processes in the temperature range characteristic for both homopolymers. The temperature of the maximum rate of decomposition for PPO in the blend is slightly shifted towards lower temperatures as compared with pure PPO. This can be explained by assuming that the PPO degradation is induced by radicals formed during the decomposition of HH-PS.     

Synthesis of block copolymers with thermodynamically compatible chain segments: di‐ and triblock copolymers of polystyrene and poly(2,6‐dimethyl‐1,4‐phenylene oxide)

Mono‐ and bifunctional poly(phenylene oxide) (PPO) macroinitiators for atom transfer radical polymerization (ATRP) were prepared by esterification of mono‐ and bishydroxy telechelic PPO with 2‐bromoisobutyryl bromide. The macroinitiators were used for ATRP of styrene to give block copolymers with PPO and polystyrene (PS) segments, namely PPO‐block‐PS and PS‐block‐PPO‐block‐PS. Various ligands were studied in combination with CuBr as ATRP catalysts. Kinetic investigations revealed controlled polymerization processes for certain ligands and temperature ranges. Thermal analysis of the block copolymers by means of DSC revealed only one glass transition temperature as a result of the compatibility of the PS and PPO chain segments and the formation of a single phase; this glass transition temperature can be adjusted over a wide temperature range (ca 100–199 °C), depending on the composition of the block copolymer. Copyright © 2005 Society of Chemical Industry     

Study on poly(2,6-dimethyl-1,4-phenylene oxide)/SBS triblock copolymer blends

The relationship between the miscibility and the physical properties of polymer blends of poly(2,6-dimethyl-1,4-phenylene oxide) and polystyrene (PS), high-impact polystyrene (IPS) and poly(styrene-block-butadiene-block-styrene) (SBS), which are blended in different compositions by a twin-screw extruder is discussed. The three types of SBS that were used are SBS1, SBS2 and SBS3 having different styrene/butadiene ratios. Dynamic mechanical analysis and differential scanning calorimetry were used to study the miscibility. The morphology was examined by SEM. The miscibility of the blends decreases with decreasing PS content. The notch sensitivity is improved by blending. Finally, the micelle model was used to explain the testing phenomena.     

Ion‐exchange membranes prepared by blending sulfonated poly(2,6‐dimethyl‐1,4‐phenylene oxide) with polybenzimidazole

New ion‐exchange acid/base‐blend (SPPO/PBI) membranes were prepared by mixing N,N‐dimethylacetamide (DMA) solutions of sulfonated poly(2,6‐dimethyl‐1,4‐phenylene oxide) (SPPO) in the ammonium form and of polybenzimidazole (PBI), casting the solution as a thin film, evaporating the solvent, and treating the membrane with aqueous hydrochloric acid. The resulting membranes were found insoluble in DMA. The preliminary tests of the membranes were carried out in an H₂/O₂ fuel cell at room temperature. Their performance in the fuel cell increased with the increase in the concentration of SPPO sulfonic acid groups in the blend, but the membranes formed with the highly sulfonated SPPO alone or predominanting, which swelled excessively in water, did not give reproducible results, and their performance was usually inferior to that of the membranes having an optimum ratio of both components. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1118–1127, 2002     

High‐resolution thermogravimetry of poly(2,6‐dimethyl‐1,4‐phenylene oxide)

The thermal degradation and kinetics of poly(2,6‐dimethylphenylene oxide) (PPO) were studied by high‐resolution thermogravimetry. The thermogravimetry measurements were conducted at an initial heating rate of 50°C min⁻¹, resolution 4.0, and sensitivity 1.0 in both nitrogen and air from room temperature to 900°C. A two‐step degradation process was clearly revealed in air at the temperatures of 430°C and 521°C. The thermal degradation temperatures and kinetic parameters of the PPO appear to be higher in air than in nitrogen, indicative of a higher thermostability in air. The temperature, activation energy, order, and frequency factor of the thermal degradation of the PPO in nitrogen are 419°C, 100–120 kJ mol⁻¹, 0.5, and 13–17 min⁻¹, respectively. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1887–1892, 1999     

Synthesis and characterization of a poly(ether–ester) copolymer from poly(2,6 dimethyl‐1,4‐phenylene oxide) and poly(ethylene terephthalate)

A series of poly(ether–ester) copolymers were synthesized from poly(2,6 dimethyl‐1,4‐phenylene oxide) (PPO) and poly(ethylene terephthalate) (PET). The synthesis was carried out by two‐step solution polymerization process. PET oligomers were synthesized via glycolysis and subsequently used in the copolymerization reaction. FTIR spectroscopy analysis shows the coexistence of spectral contributions of PPO and PET on the spectra of their ether–ester copolymers. The composition of the poly(ether–ester)s was calculated via ¹H NMR spectroscopy. A single glass transition temperature was detected for all synthesized poly(ether–ester)s. T_g behavior as a function of poly(ether–ester) composition is well represented by the Gordon‐Taylor equation. The molar masses of the copolymers synthesized were calculated by viscosimetry. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

The preparation of microporous membranes from blends of poly(2,6‐dimethyl‐1,4‐phenylene oxide) and sulfonated poly(2,6‐dimethyl‐1,4‐phenylene oxide)

Poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) is a chemically resistant polymer and, therefore, an attractive material for the formation of membranes. However, membranes of unmodified PPO prepared by an immersion precipitation possess very low hydraulic permeabilities at the filtration processes. The membranes with higher hydraulic permeabilities can be prepared from sulfonated PPO and/or from blends of unsulfonated PPO and sulfonated PPO. In conclusion, the mechanism of the formation of membranes from blends of unsulfonated PPO and sulfonated PPO is suggested. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 161–167, 1999     

Self‐condensing atom transfer radical polymerization of inimers of different reactivity ratios with styrene and the thermal properties of poly(2,6‐dimethyl‐1, 4‐phenylene oxide)/branched polystyrene blends

Although the self‐condensing atom transfer radical polymerization (SCATRP) of inimers with typical comonomers has been extensively performed, there have been few reports to correlate the reactivity ratio with the growth of the molecular weights (MWs) and the development of branched structures. Thus, the SCATRP of inimers of different reactivity ratios, namely, 4‐chloromethylstyrene (CMS) and maleimide (MI) inimers, with a large excess of styrene (St) were carried out, respectively, to examine the effect. The conversion and MW were monitored by gas chromatography, gel permeation chromatography, and multiangle laser light scattering. The results suggested that CMS merely functioned as an initiator for St at the early stage; this led to linear macroinimers, which underwent SCATRP and gave rise to randomly branched polystyrene (PS) only at high conversion. The MI inimers formed charge‐transfer complexes with St and underwent the SCATRP to result in hyperbranched copolymers at first; this initiated the atom transfer radical polymerization of St and led to star‐shaped PS. With the objective of improving the processability and melt fluidity, the physical properties of poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) blends with linear, randomly branched, and star‐shaped PS were compared. In comparison with those with linear PS, the PPO/branched PS blends exhibited a higher glass‐transition temperature, a higher melt flow index, and a comparable thermal stability because of the spherical architecture of the branched PS. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

New poly(phenylene oxide)/polystyrene blend nanocomposites with clay: Intercalation,thermal and mechanical properties

We present the first study and results on the preparation and characterization of montmorillonite clay filler based polymer blend nanocomposites of the miscible poly(phenylene oxide)/polystyrene blend. Intercalated nanocomposites, prepared by a melt‐processing method with 2–6 wt % commercially available organically modified sodium montmorillonite, have been characterized with wide‐angle X‐ray diffraction, transmission electron microscopy analysis, thermal analysis (thermogravimetric analysis and differential scanning calorimetry), and mechanical tensile tests. We show that nanocomposites can be successfully prepared in a batch mixer at temperatures much below the conditions conventionally used for this blend without organic degradation. Thermal stability is enhanced by nanoscale hybrid formation. The level of intercalation (change in the d‐spacing) does not change with the clay loading. Better dispersion of clay in the blend matrix has been observed at a low level of clay content. The nanocomposites show improved tensile modulus (by 31%) in comparison to the blend, whereas the tensile strength (stress at break) and elongation decrease in the presence of the filler with an increase in the clay loading. The Halpin–Tsai model is able to predict the modulus of the nanocomposites in very good agreement with the experimental data. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Characterization of polymer systems based on sulfonated poly(2,6‐dimethyl‐1,4‐phenylene oxide)

The sulfonation reaction of poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) has been carried out, incorporating the resulting product into pure PPO to study, in forthcoming research, the electrical and mechanical features of the composites with regard to their performance in fuel cells. Pure sulfonated polymers and their blends have been characterized from a microstructural and electrical point of view, by means of X‐ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC) and complex impedance spectroscopy. Membranes have been manufactured with excellent ionic conductivity at room temperature. © 2000 Society of Chemical Industry     

Molecular simulation of miscibility of poly(2,6‐dimethyl‐1,4‐phenylene ether)/poly(styrene‐co‐acrylonitrile) blend with the compatibilizer triblock terpolymer SBM

Polymer blend of poly(2,6‐dimethyl‐1,4‐phenylene ether) (PPE) and poly(styrene‐co‐acrylonitrile) (SAN), which has broad commercial interest, has limited miscibility. A triblock terpolymer, polystyrene‐block‐polybutadiene‐block‐poly(methyl methacrylate) (SBM), is often used as compatibilizer to improve the miscibility of PPE/SAN. In this work, dissipative particle dynamics and molecular dynamics of Material Studio were used to study the essentials that influence miscibility of the blend systems, and then Flory–Huggins parameter χ, radial distribution function (RDF) and morphologies are analyzed. It shows that the blends with more content of styrene in SAN (above 90 wt%), whose mass percentage is 60%, are best miscible. For the systems of PPE/SAN added with SBM, the miscibility increases and then decreases with the increase of SBM content. A longer chain of styrene (S) in SBM leads to wrapped structure of PMMA by PB, wrapped by PS, resulting in decrease of the miscibility. From studies and simulation of χ and RDF, the best blend system for commercial and industrial use is the one with mass ratio of PPE/SAN/SBM 36/54/10, in which S content in SAN is above 90 wt%. For SBM, the ratio of chain length styrene (S)/butadiene (B) is lessthan 1, while B and M are the same in chain length. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Characterization of the mechanical and thermal properties and morphological behavior of biodegradable poly(L‐lactide)/poly(ε‐caprolactone) and poly(L‐lactide)/poly(butylene succinate‐co‐L‐lactate) polymeric blends

Two series of biodegradable polymer blends were prepared from combinations of poly(L ‐lactide) (PLLA) with poly(?‐caprolactone) (PCL) and poly(butylene succinate‐co‐L ‐lactate) (PBSL) in proportions of 100/0, 90/10, 80/20, and 70/30 (based on the weight percentage). Their mechanical properties were investigated and related to their morphologies. The thermal properties, Fourier transform infrared spectroscopy, and melt flow index analysis of the binary blends and virgin polymers were then evaluated. The addition of PCL and PBSL to PLLA reduced the tensile strength and Young's modulus, whereas the elongation at break and melt flow index increased. The stress–strain curve showed that the blending of PLLA with ductile PCL and PBSL improved the toughness and increased the thermal stability of the blended polymers. A morphological analysis of the PLLA and the PLLA blends revealed that all the PLLA/PCL and PLLA/PBSL blends were immiscible with the PCL and PBSL phases finely dispersed in the PLLA‐rich phase. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

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     

Microporous membranes prepared from blends of polysulfone and sulfonated poly(2,6‐dimethyl‐1,4‐phenylene oxide)

Membranes were prepared from solutions containing Udel‐type polysulfone (PSf) and sulfonated poly(2,6‐dimethyl‐1,4‐phenylene oxide) (SPPO). Polymer solutions in 1‐methyl‐2‐pyrrolidone were cast on a nonwoven textile and precipitated in a water bath. The permeabilities and selectivities of the prepared membranes depended on the concentrations of both polymers in the casting solution. The higher the concentration of PSf, the lower were the permeabilities to water and average pore sizes of the membranes. On the other hand, a very small amount of SPPO in the casting solution (about 1–4 wt % relative to the casting solution weight) brought about a considerable increase in water permeabilities and had a small influence on the average pore sizes. The effects were most pronounced if SPPO with a degree of sulfonation of 20–40% was used. The considerable increase in water permeabilities was explained by separation of the PSf and SPPO phases during precipitation in water and by the concentration of hydrophilic SPPO on the surface of the membrane and its pores. The determinations of the oriented concentration potentials proved the presence of a negative surface charge in the membranes. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 134–142, 2001     

Synthesis of styrene–maleic anhydride random copolymer and its compatibilization to poly(2,6‐dimethyl‐1,4‐phenylene ether)/brominated epoxy resin

Styrene–maleic anhydride random copolymer (R‐SMA_7.5), with a low content of maleic anhydride (MAH) of about 7.5 mol%, has been prepared, and the copolymer was characterized by fourier‐transform infrared (FTIR) and ¹³C NMR techniques showing that the product contained only random copolymer without blocks. The miscibility between poly(2,6‐dimethyl‐1,4‐phenylene ether) (PPE) and R‐SMA, was investigated by differential scanning calorimetry (DSC), showing that PPE was miscible with R‐SMA synthesized in our laboratory over the entire composition with low MAH content. A blend of R‐SMA₁₈ (MAH content is about 18 mol%) and PPE was also studied by DSC, which showed that PPE was immiscible when R‐SMA was the major component, although it was miscible with limited composition. FTIR investigation showed that R‐SMA could react with bromide epoxy (BEP) resin at high temperature (180°). The heat‐resistance and mechanical properties of R‐SMA/PPE/BEP systems were tested and analyzed, and results indicated that R‐SMA could improve the miscibility of PPE and BEP with increasing T_g of the BEP phase and decreasing the T_g of the PPE slightly, improving the breaking elongation and breaking energy, which resulted from good miscibility between PPE and BEP with R‐SMA as the compatibilizer. Finally, the properties of the composites (copper clad laminate) with R‐SMA_7.5 are studied and discussed. Copyright © 2003 Society of Chemical Industry     

Proton exchange composite membranes from blends of brominated and sulfonated poly(2,6‐dimethyl‐1,4‐phenylene oxide)

New composite proton exchange membrane was prepared by mixing a 1‐methyl‐2‐pyrrolidone (NMP) solution of sulfonated poly(2,6‐dimethyl‐1,4‐phenylene oxide) (SPPO) in sodium form and brominated poly(2,6‐dimethyl‐1,4‐phenylene oxide) (BPPO) for hydrophilic‐hydrophobic balance, then casting the solution as a thin film, evaporating the solvent, and treating the membrane with aqueous hydrochloric acid. The resulting membranes were subsequently characterized using FTIR‐ATR, SEM‐EDXA, and TGA instrumentation as well as measurements of basic properties such as ion exchange capacity (IEC), water uptake, proton conductivity, methanol permeability, and single cell performance. Water uptake, IEC, proton conductivity, and methanol permeability all increased with a corresponding increase of SPPO content. By properly compromising the conductivity and methanol permeability, membranes with 60–80 wt % SPPO content exhibited comparable proton conductivity to that of Nafion^® 117, with only half the methanol permeability, thereby demonstrating higher single cell performance. The membranes developed in this study could thus be a suitable candidate electrolyte for proton exchange membrane fuel cells (PEMFCs). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012