Effects of poly[styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene] on the charge distributions of low‐density polyethylene/polystyrene blends

The effect of the triblock copolymer poly[styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene] (SEBS) on the formation of the space charge of immiscible low‐density polyethylene (LDPE)/polystyrene (PS) blends was investigated. Blends of 70/30 (wt %) LDPE/PS were prepared through melt blending in an internal mixer at a blend temperature of 220 °C. The amount of charge that accumulated in the 70% LDPE/30% PS blends decreased when the SEBS content increased up to 10 wt %. For compatibilized and uncompatibilized blends, no significant change in the degree of crystallinity of LDPE in the blends was observed, and so the effect of crystallization on the space charge distribution could be excluded. Morphological observations showed that the addition of SEBS resulted in a domain size reduction of the dispersed PS phase and better interfacial adhesion between the LDPE and PS phases. The location of SEBS at a domain interface enabled charges to migrate from one phase to the other via the domain interface and, therefore, resulted in a significant decrease in the amount of space charge for the LDPE/PS blends with SEBS. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2813–2820, 2004     

Quantifying phase behavior in partially miscible polystyrene/poly(styrene‐co‐4‐bromostyrene) blends

The phase behavior of thin‐film blends of polystyrene (PS) and the random copolymer poly(styrene‐co‐4‐bromostyrene) (PBS) was studied with atomic force microscopy (AFM) and small‐angle X‐ray scattering (SAXS). Phase behavior was studied as a function of the PBS and PS degree of polymerization (N), degree of miscibility [controlled via the volume fraction of bromine in the copolymer (f)], and annealing conditions. The Flory–Huggins interaction parameter χ was measured directly from SAXS as a function of temperature and scaled with f as χ = f²χ_S–BrS [where χ_S–BrS represents the segmental interaction between PS and the homopolymer poly(4‐bromostyrene)] Simulations based on the Flory–Huggins theory and χ measured from SAXS were used to predict phase diagrams for all the systems studied. The PBS/PS system exhibited upper critical solution temperature behavior. The AFM studies showed that increasing f in PBS led to progressively different morphologies, from flat topography (i.e., one phase) to interconnected structures or islands. In the two‐phase region, the morphology was a strong function of N (due to changes in mobility). A comparison of the estimated PBS volume fractions from the AFM images with the PBS bulk volume fraction in the blend suggested the encapsulation of PBS in PS, supporting the work of previous researchers. Excellent agreement between the phase diagram predictions (based on χ measured by SAXS) and the AFM images was observed. These studies were also consistent with interdiffusion measurements of PBS/PS interfaces (with Rutherford backscattering spectroscopy), which indicated that the interdiffusion coefficient decreased with increasing χ in the one‐phase region and dropped to zero deep inside the two‐phase region. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 255–271, 2002     

Study of hydrogen‐bonding strength in poly(ϵ‐caprolactone) blends by DSC and FTIR

The hydrogen‐bonding strength of poly(?‐caprolactone) (PCL) blends with three different well‐known hydrogen‐bonding donor polymers [i.e., phenolic, poly(vinyl‐phenol) (PVPh), and phenoxy] was investigated with differential scanning calorimetry and Fourier transform infrared spectroscopy. All blends exhibited a single glass‐transition temperature with differential scanning calorimetry, which is characteristic of a miscible system. The strength of interassociation depended on the hydrogen‐bonding donor group in the order phenolic/PCL > PVPh/PCL > phenoxy/PCL, which corresponds to the q value of the Kwei equation. In addition, the interaction energy density parameter calculated from the melting depression of PCL with the Nishi–Wang equation resulted in a similar trend in terms of the hydrogen‐bonding strength. Quantitative analyses on the fraction of hydrogen‐bonded carbonyl groups in the molten state were made with Fourier transform infrared spectroscopy for all systems, and good correlations between thermal behaviors and infrared results were observed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1348–1359, 2001     

A thermodynamic analysis of specific interactions in homoblends of poly(styrene‐co‐4‐vinylpyridine) and poly(styrene‐co‐methacrylic acid)

Miscibility and strong specific interactions that occurred within homoblends of poly(styrene‐co‐4‐vinylpyridine) containing 15 mol % of 4‐vinylpyridine (PS4VP15) and poly(styrene‐co‐methacrylic acid) containing 15 mol % of methacrylic acid (PSMA15) have been examined by Fourier Transform infrared spectroscopy and DSC. The observed positive deviation of the glass transition temperature of the blends from the linear average line, was analyzed by the frequently used theoretical conventional approaches including the one very recently proposed by Brostow. A better fit was obtained when this latter is used. A reasonable agreement with experimental values was also obtained when the theoretical fitting parameter free method developed by Coleman, is applied to predict the composition dependence of the T_g of this system. A thermodynamic analysis of hydrogen bonding in this system was carried using the Painter‐Coleman association model and the variation of the Gibbs function of mixing and its different contributions and corresponding phase diagrams as a function of temperature and composition were estimated. This analysis predicted PSMA15 to be miscible with PS4VP15 in the whole composition range up to 150 °C. Above this temperature, a partial miscibility is predicted when the PS4VP15 is in excess. The DSC results are in agreement with these predictions. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 923–931, 2009     

Miscibility behavior and hydrogen bonding in blends of poly(vinyl phenyl ketone hydrogenated) and poly(2‐ethyl‐2‐oxazoline)

The miscibility behavior of poly(2‐ethyl‐2‐oxazoline) (PEOx)/poly(vinyl phenyl ketone hydrogenated) (PVPhKH) blends was studied for the entire range of compositions. Differential scanning calorimetry and thermomechanical analysis measurements showed that all the PEOx/PVPhKH blends studied had a single glass‐transition temperature (T_g). The natural tendency of PVPhKH to self‐associate through hydrogen bonding was modified by the presence of PEOx. Partial IR spectra of these blends suggested that amide groups in PEOx and hydroxyl groups in PVPhKH interacted through hydrogen bonding. This physical interaction had a positive influence on the phase behavior of PEOx/PVPhKH blends. The Kwei equation for T_g as a function of the blend composition was satisfactorily used to describe the experimental data. Pure‐component pressure–volume–temperature data were also reported for both PEOx and PVPhKH. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 636–645, 2004     

Effect of aromatic substitution on phase behavior of blends of halogenated polystyrene and conventional polystyrene

Miscibility phase behavior in blends of poly(bromostyrene) with polystyrene (PS) has been investigated by means of time‐resolved light scattering, optical microscopy, and DSC. Cloud point phase diagrams of blends of conventional PS with poly‐(2‐bromostyrene) (P2BrS), poly‐(3‐bromostyrene), and poly‐(4‐bromostyrene) of comparable molecular weights were established by light scattering. Of particular interest is the fact that ortho, meta, and para substitutions in the styrenic aromatic rings of poly(bromostyrene) show profound effects on the composition–temperature phase diagrams of their blends with PS, exhibiting a lower critical‐solution temperature (LCST), an upper critical solution temperature (UCST), and combined LCST/UCST diagrams, respectively. Poly‐(2‐chlorostyrene) exhibits an LCST behavior very close to that of the P2BrS blend, suggesting that these types of halogen atoms may be inconsequential to phase behavior. A similar study has been extended to a PS blend containing commercial brominated PS (66 mol % bromine substitution) to determine what location of bromine substitution is crucial for miscibility enhancement in the flame‐retardant brominated PS blends. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1605–1615, 2001     

Miscibility of polysulfone blends with poly(1‐vinylpyrrolidone‐co‐styrene) copolymers and their interaction energies

The miscibility of polysulfone (PSf) with various hydrophilic copolymers was explored. Among these blends, PSf gave homogeneous mixtures with poly(1‐vinylpyrrolidone‐co‐styrene) [P(VP–S)] copolymers when these copolymers contained 68–88 wt % 1‐vinylpyrrolidone (VP). Miscible PSf blends with P(VP–S) copolymers underwent phase separation on heating caused by lower critical solution temperature (LCST)‐type phase behavior. The phase behavior depended on the copolymer composition. Changes in the VP content of P(VP–S) copolymers from 65 to 68 wt % shifted the phase behavior from immiscibility to miscibility and the LCST behavior. The phase‐separation temperatures of the miscible blends first increased gradually with the VP content, then went through a broad maximum centered at about 80 wt % VP, and finally decreased just before the limiting content of VP for miscibility with PSf. The interaction energies of binary pairs involved in PSf/P(VP–S) blends were evaluated from the phase‐separation temperatures of PSf/P(VP–S) blends with lattice‐fluid theory combined with a binary interaction model. The decrease in the contact angle between water and the membrane surface with increasing VP content in P(VP–S) copolymers indicated that the hydrophobic properties of PSf could be improved via blending with hydrophilic P(VP–S) copolymers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1401–1411, 2003     

Interplay of fractionated crystallization and morphology in polypropylene/poly(ϵ‐caprolactone) blends

The thermal behavior of melt‐mixed polypropylene (PP)/poly(?‐caprolactone) (PCL) blends was investigated with differential scanning calorimetry, and it was quantitatively related to the morphology observed through scanning electron microscopy. The PP/PCL blends were immiscible in the whole composition range; however, some interesting phenomena were found. Blends with low PP contents crystallized in a fractionated fashion. By applying a self‐nucleation procedure, we demonstrated that this occurred because of a lack of highly active heterogeneities within the confined PP domains. On the other hand, PP acted as a nucleating agent for PCL, and when the PP content was reduced, the higher surface/volume ratio increased its nucleating activity. The nucleating effect was improved when the PP was self‐nucleated because of the better nucleating effect of PP annealed crystals. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1365–1379, 2007     

Molecular weight dependence of phase behavior of PEO/P(EO‐b‐DMS) blends: Application of Sanchez‐Lacombe lattice fluid theory

Molecular weight dependence of phase separation behavior of the Poly (ethylene oxide) (PEO)/Poly(ethylene oxide‐block‐dimethylsiloxane) (P(EO‐b‐DMS)) blends was investigated by both experimental and theoretical methods. The cloud point curves of PEO/P(EO‐b‐DMS) blends were obtained by turbidity method. Based on Sanchez‐Lacombe lattice fluid theory (SLLFT), the adjustable parameter, (quantifying the interaction energy between different components), was evaluated by fitting the experimental data in phase diagrams. To calculate the spinodals, binodals, and the volume changes of mixing for these blends, three modified combining rules of the scaling parameters for the block copolymer were introduced. The calculated binodals with those modified combining rules show good agreement with the experimental data. Furthermore, the calculated volume changes during mixing decrease with increasing molecular weight of PEO, and the relationship between the volume changes and temperature is quite different for the mixtures with different molecular weight of PEO. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 452–459, 2008     

ESR studies in γ‐irradiated and PS‐radiation‐grafted poly(vinylidene fluoride)

The fluoropolymer poly(vinylidene fluoride) was irradiated with γ rays to induce a polystyrene (PS) radiation grafting via an indirect method. Electron spin resonance and Fourier transform infrared studies were performed to identify the species that initiated the PS grafting. Specific experiments were performed to prove separately the importance of each kind of radical. A localization of the radicals in this irradiated polymer is proposed, and a kinetic model of the grafting is given. © 2001 John Wiley & Sons, Inc. J Polym Sci B Part B: Polym Phys 39: 1437–1448, 2001     

Alkyl side chain length dependent compatibility of poly(4‐n‐alkylstyrene)s and 1,4‐rich polyisoprene blends

We investigated the compatibility of blends of 1,4‐rich polyisoprene (1,4‐PI) and poly(4‐n‐alkylstyrene)s with six kinds of n‐alkyl side groups, that is, methyl, ethyl, propyl, butyl, hexyl, and octyl focusing on carbon number of alkyl groups. Poly(4‐methylstyrene)/1,4‐PI blend was turned out to be immiscible at all temperature range adopted in this work and poly(4‐ethylstyrene)/1,4‐PI blend revealed UCST type phase behavior, while the others were found to be compatible. The phase diagrams of poly(4‐ethylstyrene)/1,4‐PI blends were obtained by optical microscopy, and the temperature dependence of the Flory‐Huggins interaction parameter χ has been estimated to be χ = ?0.036 + 24/T by applying lattice theory, where T is the absolute temperature. From this relationship χ value at room temperature (298 K) was calculated to be 0.045, the value is reasonably low for miscible polymers system. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55 , 1791–1797     

Total‐reflection X‐ray diffraction study of friction‐transferred poly(tetrafluoroethylene) film

The orientational structure of the friction‐transferred poly(tetrafluoroethylene) (PTFE) film, which consists of highly oriented polymer strands, was evaluated with energy‐dispersive total‐reflection X‐ray diffractometry. In the film, each PTFE molecule is oriented along the friction direction, and PTFE crystallites have a preferred orientation with respect to the substrate surface. The orientational distribution of the chain direction was quantitatively evaluated. The half‐width of the distribution was determined to be about 3°. The dependence of the orientational distribution on temperature is discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 432–438, 2001     

Miscibility,melting, and crystallization of poly(butylene‐2,6‐naphthalate)/poly(ether imide) blends

We prepared blends of poly(butylene‐2,6‐naphthalate) (PBN) and poly(ether imide) (PEI) by solution‐casting from dichloroacetic acid solutions. The miscibility, crystallization, and melting behavior of the blends were investigated with differential scanning calorimetry (DSC) and dynamic mechanical analysis. PBN was miscible with PEI over the entire range of compositions, as shown by the existence of single composition‐dependent glass‐transition temperatures. In addition, a negative polymer–polymer interaction parameter was calculated, with the Nishi–Wang equation, based on the melting depression of PBN. In nonisothermal crystallization investigations, the depression of the crystallization temperature of PBN depended on the composition of the blend and the cooling rate; the presence of PEI reduced the number of PBN segments migrating to the crystallite/melt interface. Melting, recrystallization, and remelting processes occurring during the DSC heating scan caused the occurrence of multiple melting endotherms for PBN. We explored the effects of various experimental conditions on the melting behavior of PBN/PEI blends. The extent of recrystallization of the PBN component during DSC heating scans decreased as the PEI content, the heating rate, the crystallization temperature, and the crystallization time increased. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1694–1704, 2004     

Diblock copolymers of polystyrene‐b‐poly(1,3‐cyclohexadiene) exhibiting unique three‐phase microdomain morphologies

The synthesis and molecular characterization of a series of conformationally asymmetric polystyrene‐block‐poly(1,3‐cyclohexadiene) (PS‐b‐PCHD) diblock copolymers (PCHD: ～90% 1,4 and ～10% 1,2), by sequential anionic copolymerization high vacuum techniques, is reported. A wide range of volume fractions (0.27 ≤ ?_PS ≤ 0.91) was studied by transmission electron microscopy and small‐angle X‐ray scattering in order to explore in detail the microphase separation behavior of these flexible/semiflexible diblock copolymers. Unusual morphologies, consisting of PCHD core(PCHD‐1,4)–shell(PCHD‐1,2) cylinders in PS matrix and three‐phase (PS, PCHD‐1,4, PCHD‐1,2) four‐layer lamellae, were observed suggesting that the chain stiffness of the PCHD block and the strong dependence of the interaction parameter χ on the PCHD microstructures are important factors for the formation of this unusual microphase separation behavior in PS‐b‐PCHD diblock copolymers. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1564–1572     

Effect of residual water and free volume on the glass‐transition temperature and heat capacity in polystyrene/poly(vinyl acetate‐co‐butyl acrylate) structured latex films

The dynamic heat capacity and glass‐transition temperature of polystyrene (PS)/poly(vinyl acetate‐co‐butyl acrylate) (VAc–BA) (50:50 w/w) structured latex films as a function of annealing time at 70, 77, and 85 °C were examined with modulated‐temperature differential scanning calorimetry. The PS and poly(vinyl acetate‐co‐n‐butyl acrylate) components were considered to be the cores and shells, respectively, in the structured latex. The dynamic heat capacity decreased with time. The glass‐transition temperatures of the PS and VAc–BA phases shifted to higher values after annealing. The results of thermogravimetry showed that there existed about 1.8% residual water in the films. The mean free volume and relative concentration of holes at room temperature (before and after annealing) and 85 °C, as a function of time, were obtained with positron annihilation lifetime spectroscopy (PALS). The PALS results indicated no significant change in free volume during annealing. It is believed that the loss, by diffusion, of residual water mainly caused a decrease in heat capacity and an increase in the glass‐transition temperatures. As little as 1.8% residual water in the structured latex films had a significant influence on the thermal properties. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1659–1664, 2001     

Brittle–ductile transition in high‐density polyethylene/glass‐bead blends: Effects of interparticle distance and temperature

The toughness of high‐density polyethylene (HDPE)/glass‐bead blends containing various glass‐bead contents as a function of temperature was studied. The toughness of the blends was determined from the notch Izod impact test. A sharp brittle–ductile transition was observed in impact strength–interparticle distance (ID) curves at various temperatures. The brittle–ductile transition of HDPE/glass‐bead blends occurred either with reduced ID or with increased temperature. The results indicated that the brittle–ductile‐transition temperature dropped markedly with increasing glass‐bead content. Moreover, the correlation between the critical interparticle distance (ID_c) and temperature was obtained. Similar to the ID_c of polymer blends with elastomers, the ID_c nonlinearly increased with increasing temperature. However, this was the first observation of the variation of the ID_c with temperature for polymer blends with rigid particles. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1855–1859, 2001     

Characterization of stress‐strain behavior for binary blends of isotactic polypropylene with ethylene‐α‐olefin copolymer

The characterization of the mechanical nonlinear behavior of isotactic polypropylene/ethylene‐1‐hexene copolymer blends with various kinds of morphology was carried out using a nonlinear constitutive equation in which the plastic deformation and the anharmonicity of elastic response are taken into account. It was found that the mechanical nonlinearity of the incompatible blends showing phase separation is much greater than that of the compatible blends having rubbery components in the interlamellar regions. Moreover, the mechanical behavior is governed by the plastic deformation for the incompatible blends, whereas the anharmonicity strongly affects the mechanical behavior for the compatible blends. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1513–1521, 1999     

Blends of poly(3‐hydroxybutyrate)/4,4′‐thiodiphenol and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/ 4,4′‐thiodiphenol: Specific interaction and properties

The specific interaction between poly(3‐hydroxybutyrate) [P(3HB)] and 4,4′‐thiodiphenol (TDP) and between poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) and TDP was investigated by Fourier transform infrared (FTIR) spectroscopy. Interassociated hydrogen bonds were found between the polyester chains and the TDP molecules in the binary blends. The fractions of associated carbonyl groups, F_b 's, in the blends first increased and then decreased as the TDP content increased. The thermal and dynamic mechanical properties of P(3HB)–TDP and PHBV–TDP blends were investigated by differential scanning calorimetry and dynamic mechanical thermal analysis, respectively. Thermal analysis revealed that the P(3HB)–TDP blends possessed eutectic phase behavior. Furthermore, it was found that the thermal and dynamic mechanical properties of P(3HB) and PHBV were greatly modified through blending with TDP. Environmental degradability in river water was evaluated by a biochemical oxygen demand tester, and it was clarified that TDP lowered the degradation rate of P(3HB). The results suggest that TDP is effective in modifying the physical properties as well as the biodegradability of polyesters. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2891–2900, 2000     

Melt‐processable blends of ionic poly(p‐phenylene terephthalamide) and poly(4‐vinylpyridine): Relaxation behavior

Melt‐processable blends were prepared from rigid molecules of an ionically modified poly(p‐phenylene terephthalamide) (PPTA) and flexible‐coil molecules of poly(4‐vinylpyridine) (PVP). Dynamic mechanical analyses of blends with 50% or more of the ionic PPTA component revealed the presence of two distinct phases. The glass‐transition temperature of the more stable, ionic PPTA‐rich phase increased linearly with the ionic PPTA content. The second phase present in these blends was an ionic PPTA‐poor, or a PVP‐rich, phase. For this phase, a reasonably good fit of the data, showing the glass‐transition temperature as a function of the ionic PPTA content, was achieved between the results of this study and the reported results of previous investigation of molecular composites of the same two components with ionic PPTA contents of 15 wt % or less. The possible influence of annealing on the blend structure of a 90/10 blend of ionic PPTA and PVP was examined. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1468–1475, 2003     

Thermoelectric behavior (PTC) of carbon black‐containing TPX/UHMWPE and TPX/XL‐UHMWPE blends

This article describes the structure and electrical performance of positive‐temperature‐coefficient/negative‐temperature‐coefficient (PTC/NTC) effects of the following three‐component blends: poly(4‐methyl pentene‐1)/ultra‐high molecular weight polyethylene/carbon black (TPX/UHMWPE/CB), poly(4‐methyl pentene‐1)/crosslinked‐ultra‐high molecular weight polyethylene/carbon black (TPX/XL‐UHMWPE/CB), and γ‐irradiated, compression‐molded plaques of these blends. CB particles are preferentially attracted to the UHMWPE and XL‐UHMWPE particles, which constitute the dispersed phase within the TPX matrix, but practically cannot or can only very slightly penetrate them because of their extremely high viscosity. Thus, CB particles initially form conductive networks on the UHMWPE phase; this is followed by distribution in the TPX matrix, electrically connecting the CB‐covered UHMWPE particles. This unusual CB distribution results in a reduced percolation threshold of all blends. A double‐PTC effect is exhibited by the XL‐UHMWPE‐containing samples. Irradiation of compression‐molded plaques improves their thermoelectric behavior by amplifying the PTC effect and reducing the NTC effect. A schematic model of the double‐PTC effect is suggested, describing the morphological changes of 70TPX/30XL‐UHMWPE/CB blends at different stages of heating with respect to their thermoelectric behavior. Irradiation of TPX/UHMWPE/CB plaques converts these systems into high‐intensity PTC materials free of the NTC effect. © 2001 John Wiley & Sons, Inc. J Polym Sci B Part B: Polym Phys 39: 1415–1428, 2001