Determination of transition points and thermodynamic interaction parameters of poly(2,6-dimethyl-1,4-phenylene oxide)

Abstract

The specific retention volumes V _g⁰ of n-butyl acetate, isobutyl acetate, isoamyl acetate, n-undecane, n-dodecane, n-tridecane, ethyl benzene, n-propyl benzene, isopropyl benzene and chloro benzene on poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) were obtained by inverse gas chromatography. Below glass transition temperature, two secondary transition points of PPO which occur at 90 and 130°C were observed from the retention diagrams of n-butyl acetate, isobutyl acetate and isoamyl acetate.

Weight fraction activity coefficient at infinite dilution Ω ₁^∞, Flory–Huggins polymer–solvent interaction parameter χ ₁₂^∞, hard core polymer–solvent interaction parameter χ ₁₂^* and effective exchange energy parameter X _eff were determined from the experimental V _g⁰ of studied solvents on PPO at temperatures above 220°C by inverse gas chromatography.     

Polymer multilayer films for high temperature capacitor application

Advanced film capacitors require polymers with high thermal stability, high breakdown strength, and low loss for high temperature dielectric applications. To fulfill such requirements, two polymer multilayer film systems were coextruded via the forced assembly technique. High glass transition temperature (T _g) polycarbonate (HTPC, T_g = 165 °C) and polysulfone (PSF, T_g = 185 °C) were multilayered with a high dielectric constant polymer, poly(vinylidene fluoride) (PVDF), respectively. The PSF/PVDF system was more thermally stable than the HTPC/PVDF system because of the higher T_g for PSF. At temperatures lower than 170 °C, the HTPC/PVDF system exhibited comparable breakdown strength and hysteresis loss as the PSF/PVDF system. While at temperatures above 170 °C, the PSF/PVDF system exhibited a higher breakdown strength because of the higher T_g of PSF. The electric displacement-electric field (D-E) loop behavior of the PSF/PVDF system was studied as a function of temperature. Moreover, a melt-recrystallization process could further decrease the hysteresis loss for the PSF/PVDF system due to better edge-on crystal orientation. These results demonstrate that PSF/PVDF and HTPC/PVDF systems are applicable for high temperature film capacitors. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47535.     

Determination of Flory interaction parameters between polyimide and organic solvents by HSP theory and IGC

Summary  Flory-Huggins interaction parameter χ₁₂ is an important parameter used for characterizing the interaction intensity between polymer and solvent. In this work, two methods were used to calculate the χ₁₂ values of a polyimide (HQDPA-DMMDA) and twelve organic solvents. One method was inverse gas chromatography (IGC) technique, another was Hansen Solubility Parameters (HSP) theory. For the IGC experiment, χ₁₂ was measured with an extrapolation method for the carrier gas when the temperature was changed from 50^circC to 80^°C. For the HSP approach, the Beerbower group contribution method was used to calculate the HSP values of the polyimide. It was found that the χ₁₂ values of the polyimide and the organic solvents calculated from the two methods were similar. Consequently, the Beerbower group contribution method can be used to calculate HSP, and the HSP can be used to rapidly estimate the Flory–Huggins interaction parameter χ₁₂.     

Thermodynamic characterization of poly (caprolactonediol) by inverse gas chromatography

Specific retention volumes, V _g ⁰, were determined for 21 solute probes on poly (caprolactonediol) (PCLD) in the temperature range 323.15–403.15 K by inverse gas chromatography. The retention diagrams drawn between ln V _g ⁰ versus 1/T are linear for all the solutes since PCLD with ten repeating units in its chain behaving like a non polymeric material under the conditions applied. The stationary phase with melting temperature ~321 K is in the liquid state in the GC column over the temperature range studied and hence found to be suitable to determine infinite dilution partial molar thermodynamic properties of mixing for solutes on PCLD. The V _g ⁰ values have been used to calculate weight fraction activity coefficients Ω^∞ and Flory–Huggins interaction parameters, χ ₁₂^∞. The average partial molar enthalpy of solution, [`(\Updelta H)]<sub>1</sub><sup>S</sup> , \overline{\Updelta H}_{1}^{S} , and partial molar enthalpy of mixing, [`(\Updelta H)]₁^￥ , \overline{\Updelta H}_{1}^{\infty } , are calculated using V _g ⁰ and Ω^∞ respectively. The average molar enthalpy of vaporization ΔH ₁ ^V for solutes have been calculated using [`(\Updelta H)]<sub>1</sub><sup>￥</sup> \overline{\Updelta H}_{1}^{\infty } and [`(\Updelta H)]₁^S \overline{\Updelta H}_{1}^{S} values and compared with the literature values at 363.15 K which is the average column temperature. The partial molar entropy of mixing, [`(\Updelta S)]<sub>1</sub><sup>￥</sup> \overline{\Updelta S}_{1}^{\infty } calculated at 363.15 K are in good correlation with the average [`(\Updelta H)]₁^￥ \overline{\Updelta H}_{1}^{\infty } values. The total solubility parameter due to Guillet and the Hansen solubility parameters (HSP) are calculated for PCLD using χ ₁₂^∞ values. In the present work the Hansen solubility parameters have been calculated using a new method following the Hansen theory and Huang method with less weight on polar and hydrogen bonding components. The errors in the solubility HSP are lower and the correlation coefficients are better in both the methods compared to unweighted three dimensional model.     

Determination of exchange enthalpy and entropy parameters of the equation‐of‐state theory for poly(dimethyl siloxane) and some aromatic solvents by inverse gas chromatography

The specific retention volumes, V_g^o of toluene, ethyl benzene, n‐propyl benzene and isopropyl benzene on poly(dimethyl siloxane)(PDMS) were measured at temperatures between 333 and 403 K by inverse gas chromatography. The parameters of hard‐core interaction, χ_t^∞, effective exchange energy, X ₁₂, exchange enthalpy, X₁₂, and exchange entropy, Q₁₂ in the equation‐of‐state theory were determined. The parameters χ_t^∞ of the isopropyl benzene‐PDMS pair decreased from 0.65 to 0.60 while those of others decreased from around 0.77 to 0.69 with increasing temperature. The values of the parameters X₁₂ also decreased as molecular weight of the substituted aliphatic group on the benzene ring of the solvent increased, ie 15 J cm⁻³ in toluene and 5 J cm⁻³ in isopropyl benzene. Both X₁₂ and Q₁₂ show negligible dependence on temperature. © 2000 Society of Chemical Industry     

Measurement of the Surface Free Energy of Amorphous Cellulose by Alkane Adsorption: A Critical Evaluation of Inverse Gas Chromatography (IGC)

Surface energies of amorphous cellulose “beads” were measured by IGC at different temperatures (50 to 100°C) using n-alkane probes (pentane to undecane). The equation of Schultz and Lavielle was applied which relates the specific retention volume of the gas probe to the dispersive component of the surface energy of the solid and liquid, γ^d _s and γ^d _l, respectively, and a parameter (“a”) which represents the surface area of the gas probe in contact with the solids. At 50°C, γ^d _s was determined to be 71.5 mJ/m², and its temperature dependence was 0.36 mJ m^?2 K^?1. Compared with measurements obtained by contact angle, IGC results were found to yield higher values, and especially a higher temperature dependence, d(γ^d _s)/dT. Various potential explanations for these elevated values were examined. The surface energy, as determined by the Schultz and Lavielle equation, was found to depend mostly on the parameter “a”. Two experimental conditions are known to affect the values of “a”: the solid surface and the temperature. While the surface effect of the parameter “a” was ignored in this study, the dependence of the surface energy upon temperature and probe phase was demonstrated to be significant. Several optional treatments of the parameter “a” were modeled. It was observed that both experimental imprecision, but mostly the fundamental difference between the liquid-solid vs the gas-solid system (and the associated theoretical weakness of the model used), could explain the differences between γ^d _s and d(γ^d _s)/dT measured by contact angle and IGC. It was concluded that the exaggerated temperature dependence of the IGC results is a consequence of limitations inherent in the definition of parameter “a”.     

Molecular probe studies of crystallinity in polyethylene

The molecular probe technique uses a standard gas chromatograph modified to obtain a printed digital record of retention time vs. column temperature to be obtained automatically. From this the observed specific retention time, V_g, can be calculated. If V_g is the theoretical value it can be deduced that: % Crystallinity = [1 ? V_g/V_g′ ] × 100. Experimental results using Tenite 800 and Tenite 3310 polyethylene produced and sold by Eastman Chemical Products Inc., Kingsport, Tennessee, U.S.A. justify this equation.     

Influence of solvent and filler on some physical properties of a fluoroelastomer

Samples of virgin and a crosslinked fluorinated rubber, containing different amounts of carbon black and solvated with methylethyl ketone, have been investigated by differential scanning calorimetry. Although the polymer–solvent interaction increases with decreasing temperature, a process of solvent separation was observed for all of the systems. This process can be attributed to a T_g regulation effect in which solvent crystallization occurs only when the crystallization temperature is higher than the T_g of the system. The interaction between rubber and filler, approximately temperature independent, was found to not influence the glass transition of the rubber–methylethyl ketone systems, even when the carbon black content is on the order of 35 wt %. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 377–384, 1999     

Determination of polymer–polymer interaction parameters using inverse gas chromatography

A modified method is discussed that is based on Farooque and Deshpande's method to obtain polymer–polymer interaction parameters using inverse gas chromatography (IGC) data. In the Farooque and Deshpande method, the ratio of the difference of probe–polymer interaction parameters between two polymers and the probe volume [(χ₁₂ ? χ₁₃)/V₁] is used as the abscissa. In the modified method, the ratio [(?₂χ₁₂ + ?₃χ₁₃)/V₁] is used as the abscissa. Experimental data previously reported for a poly(?‐caprolactone)‐polyepichlorohydrin (PCL/PECH) blend and a poly(ethyl acrylate)‐poly(vinyl propionate) (PEA/PVPr) blend are analyzed. It is found that the slopes obtained by the new method had smaller deviations from the theoretical values than the Farooque and Deshpande method. The standard deviations of both slopes and intercepts obtained from the new method are also smaller. Using the new method, the polymer–polymer interaction parameters obtained from the intercept are negative numbers for the PCL/PECH system and very small positive numbers for PEA/PVPr. Explanations are given for the probe and concentration dependency of the polymer–polymer interaction parameters that are generally observed in IGC studies. A new method for selecting the best probe for calculating the interaction parameter is discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 671–680, 2003     

Aqueous processing based novel composite electrode for Li-ion batteries using an environmentally benign binder

Along with the high energy density and safer battery materials, easy and environment benign electrode processing is also one of the major concerns for the battery manufacturing industries. Therefore, herein, water-based electrode processing is used which reduces manufacturing cost and makes easy and cost-effective recycling of discarded batteries. In addition, the increasing use of Li-ion batteries from portable electronics to electric vehicles has imposed a threat to the environment due to hazardous materials used. The present study also focuses on the replacement of polyvinylidene difluoride (PVDF) non-conducting binder dissolves in toxic solvent N-methyl 2-pyrrolidone with water-soluble poly (3,4-ethylene dioxythiophene): poly (styrene sulfonate) (PEDOT:PSS) conducting binder. The entire study is performed on the synergistic effect of PEDOT:PSS with multi-walled carbon nanotubes (MWCNTs or MC) and carbon black (CB) on Li-ion battery performance using LiFePO₄ cathode active material. The discharge capacities were found 144 mAh g⁻¹ and 160 mAh g⁻¹ at 0.1C for composite electrodes LFP/CB-9P and LFP/MC-9P, respectively having 9 wt% PEDOT:PSS. Whereas the composite electrodes LFP/CB-10PV and LFP/MC-10PV having 10 wt% PVDF binder show only capacities 117 mAh g⁻¹ and 134 mAh g⁻¹, respectively. The composite electrode LFP/MC-9P shows the highest capacities up to 20C rate and maximum retention capacity of 84% at 5C after 500 cycles among all samples studied. Whereas electrodes prepared with PVDF binder could not perform well at more than 5C current rate, capacity retention is also found nearly 0% after 500 cycles. Therefore, superior results of PEDOT:PSS and MWCNTs with LiFePO₄ propose an environmentally benign composite electrode of next generation Li-ion batteries for electric vehicles.     

LB energy-saving high temperature shift catalyst and its adsorption thermodynamics

This study prepared an LB energy-saving high temperature shift catalyst by optimizing its prepare parameters with artificial neural network, and measured its catalytic activities at various steam-gas ratios. It shows that the LB catalyst performs well at a lower steam-gas ratio. The chromatographic retention parameters of CO, CO₂, and H₂O on LB catalyst were experimentally determined by means of inverse gas chromatography (IGC). Adsorption enthalpies, Gibbs adsorption free energies and adsorption entropies of different gases were estimated by their retention volumes in infinite dilution region. The interaction parameters (χ) between absorbate gases and LB catalyst were calculated according to Flory-Huggins theory, and were inversely linear with temperature. The thermodynamics mechanism of the adsorption process was discussed from the view of the microcosmic factors of molecular structure and thermodynamic properties.     

Examination of the surface properties of kaolinites by inverse gas chromatography: Dispersive properties

The application of inverse gas chromatography (IGC) for the examination of the surface properties of untreated kaolinite and kaolinites surface-treated with titanate coupling agents is discussed. This paper presents and discusses the dispersive properties expressed by γ_S^D, the dispersive component of the surface free energy, as determined at various temperatures. The γ_S^D values of all the samples were negatively correlated with the temperature of IGC measurement. At the same temperature of IGC measurement, the values of γ_S^D determined by IGC were significantly lower for the surface-treated kaolinites than for the untreated ones. The γ_S^D value of the kaolinite surface-treated with isopropyl triisostearoyl titanate (ITT) at 150°C exhibited a surface energy close to that (28.3 mJm^-2) of polyethylene with no surface polarity.     

Effect of cathode binder on capacity retention and cycle life in transition metal phosphate of a rechargeable lithium battery

With an objective of understanding the differences in the capacity retention behavior and cycle life of cathode consisting transition metal phosphate, Cr_0.5Nb_1.5(PO₄)₃, active material and the binder polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE), the role of these binders have been analyzed. An electrochemical analysis of the active material mixed with the binders PVDF or PTFE reveals that the PTFE cell experiences an additional discharge capacity of 93 mA h g⁻¹ during the discharge cycle compared to the PVDF cell. The results of X-ray photoelectron spectroscopy studies of the PTFE mixed cathode reveals nearly the same intensity of F (1s) spectra for before and after discharge cycles suggests that the fluorine atom is not decomposed but permits high utilization of the reactant to be achieved in the cathode during discharge/charge cycles. A remarkable improvement in cell performance in terms of capacity and cycle life for PTFE suggests that the binder PTFE should be an attractive candidate in lithium batteries than that of PVDF.     

Thermodynamic interactions of solvents with styrene–butadiene–styrene triblock copolymers

Fundamental thermodynamic interaction data for various solvents with two styrene–butadiene–styrene triblock copolymers (Kraton D-1101 and Kraton D-1300X) have been collected by the use of inverse gas chromatography at infinite dilution. Experimental results are presented for nine D-1101/solvent systems and nine D-1300X/solvent systems at 308, 328. and 348 K. Weight-fraction activity coefficients and Flory–Huggins χ interaction parameters have been calculated from the retention volumes. The χ parameter is used as a measure of the strength of interaction and therefore as a guide in the prediction of polymer–solvent compatibility. In addition, partial molar heats of mixing, ΔH_m^∞, and heats of solution, ΔH_s, were determined. The Hildebrand–Scatchard solubility theory was combined with the Flory theory in order to estimate the solubility parameter of the thermoplastic rubbers at the three different temperatures.     

Understanding of intermolecular interaction in PVDF/PTW blends: Crystallization behavior,thermal, and dynamic mechanical properties

Poly(vinylidene fluoride) (PVDF)/ poly(ethylene–butylacrylate–glycidyl methacrylate) (PTW) blends were directly prepared by melt blending and the interaction and properties of PVDF/PTW blends were explored systematically. The crystallization behavior, thermal stability, dynamic mechanical property, and morphological features of PVDF/PTW blends with different ratios have been studied by XRD, attenuated total reflection Fourier transform infrared spectroscopy, differential scanning calorimeter analysis (DSC), thermal gravimetric analysis (TGA), dynamic mechanical analysis, and polarized optical microscopy (POM). The results showed that the crystalline structure of neat PVDF was dominantly α‐phase crystalline and the incorporation of PTW had no effect on the crystalline structure of PVDF in the PVDF/PTW blends. And T_g of PVDF in PVDF/PTW blends shifted to higher temperature compared with that of neat PVDF, indicating the weak interaction between PVDF and PTW, which was corresponding to DSC and TGA results. An increase in the coarseness and ring‐band spacing observed from POM further substantiated the weak interaction between PVDF and PTW. This work provided a way for preparing improved properties of PVDF/PTW blends for the coating material. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43908.     

Use of Flory–Huggins parameters in the characterization of polymer–filler compositions

Any quantitative information on the strength of interactions between an inorganic filler and polymer is substantial for the future application of the composite. The magnitude of adhesion of two phases may be deduced from results collected by various experimental techniques. A Flory–Huggins interaction parameter (χ₂₃^′) was earlier successfully used in the characterization of polymer blends. We propose to express the magnitude of modified filler/polymer interactions by using χ₂₃^′. It was calculated from retention data of test solutes during an inverse gas chromatography (IGC) experiment. IGC is an extension of conventional gas chromatography in which a nonvolatile material to be investigated is immobilized on a column. Parameters determined during IGC experiments may be successfully used in the characterization of polymers and their blends, composites, fillers, and other materials and the quantification of the interactions between the components of polymer mixtures, including the interactions between polymeric components and filler surfaces. Here this method is applied to the characterization of a series of poly(ether urethane)/modified carbonate–silicate filler systems containing different amounts of a filler (5, 10, and 20 wt %). The possibilities and limitations of the IGC method are shown. The usefulness of some methods for minimizing the Δχ effect (the dependence of χ₂₃^′ on the type of test solute) is examined and discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Determination of Hansen solubility parameters for cellulose acrylate by inverse gas chromatography

The solubility parameters of cellulose acrylate (CEA) were examined by inverse gas chromatography (IGC). The test probes were pentane, hexane, heptane, octane, nonane, ether, acetone, tetrahydrofuran, toluene, chloroform, isopropanol, and hexanol. The minimal test probe was injected into chromatographic column in order to achieve the infinite dilution conditions. The retention times of the test probes were determined and Flory–Huggins interaction parameters (χ) and solubility parameters (δ ₂) were calculated according to DiPaola-Baranyi and Guillet method from experimentally collected retention data for the series of carefully selected test probes. The Hansen’s three-dimensional solubility parameters concept is applied to determine the components (δ _d, δ _p, δ _h) of total solubility parameter (δ _T). The solubility parameter (δ _T) was increased with increasing temperature.     

Gas–liquid chromatographic study of polystyrene–n‐alkane interactions

Gas–liquid chromatography is used to study the thermodynamic interactions between polystyrene and n‐alkanes (C₆–C₁₀). Polystyrene is used as a stationary phase with n‐alkanes as the probe molecules. Retention times and specific retention volumes are measured over the temperature interval of 60 to 170°C. Partial molar free energy of mixing, polymer–solvent interaction parameter, glass‐transition temperature, and solubility parameter of polystyrene at infinite dilution are calculated. Experimental results are discussed in terms of the theoretical calculations and size of the probe molecules. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1291–1298, 2001     

Thermodynamics of sorption in and free volume of poly(5,6-bis(trimethylsilyl)norbornene)

Thermodynamics of sorption of n-alkanes C₄-C₁₁ in poly(5,6-bis(trimethylsilyl)norbornene) was studied using the Inverse Gas Chromatography (IGC). Temperature dependences of the specific retention volume V_g and solubility coefficient S of various alkanes were obtained in the range 60-140 °C. For solubility coefficients, the following equation holds: where T_c is the critical temperature of solutes, T is the experimental temperature and S is expressed in cm³(STP)/cm³ atm. The partial molar enthalpies ΔH_m and entropies ΔS_m of mixing of different n-alkanes in this glassy polymer vary in much wider range than in rubbers and display positive correlations: for more exothermic mixing process the larger negative ΔS_m values are observed. It was shown that the ΔH_m in poly(5,6-bis(trimethylsilyl)norbornene) pass through a minimum, when the size of solutes increases. The coordinates of ΔH_m at minimum versus solute size provide an estimate of the size of free volume elements in this polymer. This conclusion was supported by variation of permeability in different glassy polymers studied using IGC and by the results of other methods for probing free volume in glassy polymers.     

Determination of crystallinity ratio and some physicochemical properties of poly(4‐methyl‐1‐pentene)

It was determined that the thermal stability of poly(4‐methyl‐1‐pentene) (P4MP) was maintained up to 424°C in an inert atmosphere by thermogravimetric analysis. The retention diagrams of ethyl acetate, tert‐butyl acetate, and benzene on P4MP were plotted at temperatures between 30 and 280°C by inverse gas chromatography (IGC) technique. Melting temperature of the polymer was determined as 230 and 239.5°C by IGC and differential scanning calorimetry (DSC), respectively. The percent crystallinity of P4MP was obtained from the retention diagrams at temperatures below melting point. The percent crystallinity obtained by IGC is in good agreement with the ones obtained by DSC. Then, specific retention volume, V, weight fraction activity coefficient, Ω, Flory‐Huggins polymer‐solvent interaction parameter, χ, equation‐of‐state polymer‐solvent interaction parameter, χ, and effective exchange energy parameter, X_eff of octane, nonane, decane, undecane, dodecane, tridecane, n‐butyl acetate, isobutyl acetate, isoamyl acetate with P4MP, were determined between 240 and 280°C by IGC. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009