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Pessoa Filho, Pedro De Alcantara - One of the best experts on this subject based on the ideXlab platform.

  • (Solid + liquid) equilibrium of binary mixtures containing ethyl esters and p-xylene by differential scanning calorimetry
    Hungria, 2020
    Co-Authors: Branco Almeida Bessa, Larissa Castello, Robustillo, Maria Dolores, De Almeida Meirelles, Antonio Jose, Pessoa Filho, Pedro De Alcantara
    Abstract:

    Current concerns regarding the environmental and economic sustainability of petroleum-based transportation fuels, including jet fuel, are driving interest into alternative fuels. To study the feasibility of using biodiesel in aviation engines, a deeper knowledge on solid-liquid equilibrium (SLE) of biodiesel/jet fuel blends is required. This work presents SLE data of binary mixtures containing p-xylene, a representative compound of aviation fuel, and fatty esters present in ethylic biodiesel. Experimental data were obtained through differential scanning calorimetry. A simple eutectic behavior was observed for all binary systems, although small regions of partial miscibility are also present. Observed eutectic temperature and composition (ethyl ester mole fraction) are 259.0 K and 0.45, 269.0 K and 0.32, 275.5 K and 0.22, 280.0 K and 0.15, and 247.7 K and 0.58 for systems containing ethyl laurate, ethyl myristate, ethyl palmitate, ethyl stearate and ethyl oleate, respectively. Good agreement was obtained between experimental and calculated data when using UNIFAC (Dortmund) model or Flory-Huggins Equation, with root-mean-square deviations ranging from 0.47 to 1.90 K. The systems exhibit significant deviations from ideality, which cannot be neglected in model calculations137620172028CAPES - Coordenação de Aperfeiçoamento de Pessoal e Nível SuperiorCNPQ - Conselho Nacional de Desenvolvimento Científico e TecnológicoFAPESP – Fundação de Amparo à Pesquisa Do Estado De São Paulonão tem304906/2014-0; 150950/2014-42018/06956-2; 2014/21252-0; 2010/18355-

  • Influence of additives (isoamyl laurate or isoamyl nonanoate) in the solid–liquid equilibrium of fatty acid ethyl esters
    'American Chemical Society (ACS)', 2020
    Co-Authors: Bessa, Larissa Castello Branco Almeida, Robustillo, Maria Dolores, Erica Corina Da Silva, Tadini, Carmen Cecilia, Meirelles, Antonio José De Almeida, Pessoa Filho, Pedro De Alcantara
    Abstract:

    Solid–liquid equilibrium data of binary mixtures of fatty acid ethyl esters present in biodiesel, namely, ethyl laurate, ethyl palmitate, ethyl myristate, ethyl stearate, and ethyl oleate, and fatty esters of branched-chain alcohols used as additives (isoamyl laurate and isoamyl nonanoate) were obtained through differential scanning calorimetry. Most of these systems presented eutectic behavior, except for the system ethyl laurate + isoamyl laurate, which presented peritectic transition. Equilibrium data were thermodynamically modeled either using two different liquid-phase activity coefficient models or considering that the liquid phase is an ideal mixture. Best correlations were observed for the Flory–Huggins Equation, but good agreement between calculated and experimental data was also obtained when using both the ideal and UNIFAC–Dortmund models64520622074CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP306440/2013-0; 304906/2014-0; 150950/2014-4; 306440/2013-00012018/06956-2; 2016/08566-1; 2015/17946-0; 2013/07914-8; 2014/21252-0; 2010/18355-1We gratefully acknowledge FAPESP (Grant Nos. 2018/06956-2, 2016/08566-1, 2015/17946-0, 2013/07914-8, 2014/21252-0, and 2010/18355-1), CAPES (Finance Code 01), and CNPq (Grant Nos. 306440/2013-0, 304906/2014-0, and 150950/2014-4) for financial suppor

  • Contribuições a modelagem do equilibrio de fases e da partição de moleculas biologicas em sistemas aquosos bifasicos
    [s.n.], 2018
    Co-Authors: Pessoa Filho, Pedro De Alcantara
    Abstract:

    Orientador: Rahoma Sadeg Mohamed.Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia QuimicaResumo: A fonnação de sistemas aquosos bifásicos em conseqüência da adição à água de alguns pares de polímeros, ou de certos polímeros e sais, é um fenômeno bem estabelecido e conhecido. Esses sistemas encontram larga aplicação na separação de moléculas biológicas em laboratório e têm conhecido nos últimos tempos incipiente aplicação industrial; sua correta modelagem tennodinâmica é o objetivo deste trabalho. Inicialmente consideraram-se sistemas formados por dois polímeros. Procurou-se incorporar à equação de Flory-Huggins modificações que levassem em conta a formação de ligações de hidrogênio entre moléculas de água e entre moléculas de água e de polímero, no caso, o poli(etileno glicol). Em uma primeira análise utilizou-se como base do desenvolvimento a teoria quimica, que considera a ligação de hidrogênio uma ligação covalente. Os resultados foram bastante adequados e indicavam que a consideração das ligações cruzadas era suficiente para permitir uma boa modelagem. Assim, outros modelos que levavam em conta a solvatação foram desenvolvidos, em uma primeira abordagem considerando o número de moléculas de água na camada de solvatação constante, depois permitindo que esse valor variasse com a composição. Todos esses modelos tiveram bastante sucesso; entretanto, resultados pouco adequados foram obtidos na utilização da SAFT (teoria estatistica do fluido associativo). A polidispersão da dextrana também foi considerada em alguns cálculos, com sucesso; entretanto, dadas as diferenças existentes entre dados experimentais obtidos em grupos de pesquisa diversos, não foi possivel construir um modelo totalmente preditivo. Estudaram-se também sistemas formados por polímeros e sais. Nesse caso, o esforço teórico foi direcionado à compreensão do papel dos componentes nos tennos devidos à interação eletrostática ¿ por exemplo, polímeros presentes alteram a constante dielétrica e a densidade do meio, devendo portanto alterar a equação de Debye-Hückel, o que, por sua vez, faz com que se prevejam comportamentos irrealistas. Análise acurada revelou que a solução completa do problema demanda a conversão de propriedades obtidas no formalismo de McMillan e Mayer ao formalismo de Lewis e Randall para misturas de solventes ¿ esforço teórico cujo vulto ultrapassa o escopo deste trabalho. Desenvolveu-se também um modelo para sistemas fonnados por polieletrólitos e polímeros neutros. Esse modelo é baseado em uma equação empirica do virial, e considera a ocorrência de várias reações, por meio das quais foi possivel obter um novo modelo de energia de Gibbs excedente que levasse em conta a variação do grau de dissociação iônica em soluções aquosas de polieletrólitos. O modelo fisico de solvatação constante, desenvolvido para sistemas formados por dois polímeros, foi utilizado no estudo da partição de moléculas biológicas. O modelo foi capaz de descrever muito bem resultados de experimentos de partição. Nesse caso, a consideração da polidispersão da dextrana, que afeta muito pouco cálculos de equilíbrio líquido-líquido, modificou de maneira adequada a densidade numérica dessas fases, tomando o modelo mais confiávelAbstract: Aqueous two-phase systems are formed when either two polymers or a polymer and a salt are added to water at certain concentrations. These systems have been widely used to separate biological molecules in laboratory, and have recently found incipient industrial application. This work is aimed at the development of reliable thennodynamic models for these systems. First, systems fonned by two polymers were examined. The Flory-Huggins Equation was modified to account for hydrogen bonding occurring between water molecules (self-association) and between water and polymer molecules (solvation). The first modification uses the chemical theory, according to which hydrogen bonding is considered to be equivalent to a covalent bonding. The results obtained were very good and indicated that cross-association alone might bring about this improvement. Purely physical models accounting for solvation were subsequently developed, first by considering the number of water molecules bonded to each polymer molecule as a constant value, and later allowing it to vary with concentration. These models were found very successful. A similar attempt to use the SAFT (statistical associating fluid theory), however, did not provide good results. Polydispersion in polymers such as Dextran was also successfully accounted for, even though it was not possible to establish a completely predictive model due to the discrepancies in experimental data obtained by different research groups. Systems fonned by polymers and salts were dealt with next. In this case, the theoretical investigation was aimed at the understanding of the role of the different compounds in the ca1culation of the tenn that accounts for long range interactions. For instance, polymers modify the dielectric constant and the specific gravity ofthe surrounding medium, thus modifying the Debye-Hückel Equation; however, accounting for this effect introduces spurious terms in phase equilibrium ca1culations. A more detailed analysis showed that the correct solution to this problem would require the conversion of properties of mixing ca1culated in the McMillan and Mayer forrnalism to that of Lewis and Randal, a serious and challenging theoretical problem whose solution is beyond the scope of this work. A new thennodynamic model tailored for solutions of polyelectrolytes and neutral polymers was also developed. This model is based on an empirical virial Equation and considers the occurrence of some ionic dissociation reactions. Through this picture it was possible to develop a new excess Gibbs energy model accounting for the variation of the ionic dissociation degree in aqueous solutions of polyelectrolytes. The model with constant value for the solvation number, developed for systems fonned by two polymers, was also used to model the partitioning of biological molecules in these systems. The model provided a very good description of partitioning experiments. Accounting for Dextran polidispersion, which has almost no effect on phase equilibrium ca1culations, modifies the numeric density of the liquid phases in equilibrium, and increases the reliability of the modelDoutoradoEngenharia de ProcessosDoutor em Engenharia Químic

PessÔa Filho P. A. - One of the best experts on this subject based on the ideXlab platform.

  • Water activity of aqueous solutions of ethylene oxide-propylene oxide block copolymers and maltodextrins
    Alemanha, 2020
    Co-Authors: Carareto N. D. D., Monteiro Filho E. S., PessÔa Filho P. A., Meirelles A. J. A.
    Abstract:

    The water activity of aqueous solutions of EO-PO block copolymers of six different molar masses and EO/PO ratios and of maltodextrins of three different molar masses was determined at 298.15 K. The results showed that these aqueous solutions present a negative deviation from Raoult's law. The Flory-Huggins and UNIFAC excess Gibbs energy models were employed to model the experimental data. While a good agreement was obtained with the Flory-Huggins Equation, discrepancies were observed when predicting the experimental behavior with the UNIFAC model. The water activities of ternary systems formed by a synthetic polymer, maltodextrin and water were also measured and used to test the predictive capability of both models271173181CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPSem informaçãoSem informaçãoSem informaçã

  • Water activity of aqueous solutions of ethylene oxide-propylene oxide block copolymers and maltodextrins
    Brazilian Society of Chemical Engineering, 2016
    Co-Authors: Carareto N. D. D., Monteiro Filho E. S., PessÔa Filho P. A., Meirelles A. J. A.
    Abstract:

    The water activity of aqueous solutions of EO-PO block copolymers of six different molar masses and EO/PO ratios and of maltodextrins of three different molar masses was determined at 298.15 K. The results showed that these aqueous solutions present a negative deviation from Raoult's law. The Flory-Huggins and UNIFAC excess Gibbs energy models were employed to model the experimental data. While a good agreement was obtained with the Flory-Huggins Equation, discrepancies were observed when predicting the experimental behavior with the UNIFAC model. The water activities of ternary systems formed by a synthetic polymer, maltodextrin and water were also measured and used to test the predictive capability of both models

  • Water activity of aqueous solutions of ethylene oxide-propylene oxide block copolymers and maltodextrins
    'FapUNIFESP (SciELO)', 2016
    Co-Authors: Carareto N. D. D., Monteiro Filho E. S., PessÔa Filho P. A., Meirelles A. J. A.
    Abstract:

    Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The water activity of aqueous solutions of EO-PO block copolymers of six different molar masses and EO/PO ratios and of maltodextrins of three different molar masses was determined at 298.15 K. The results showed that these aqueous solutions present a negative deviation from Raoult's law. The Flory-Huggins and UNIFAC excess Gibbs energy models were employed to model the experimental data. While a good agreement was obtained with the Flory-Huggins Equation, discrepancies were observed when predicting the experimental behavior with the UNIFAC model. The water activities of ternary systems formed by a synthetic polymer, maltodextrin and water were also measured and used to test the predictive capability of both models.271173181Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CAPES_BrasilFAPESP_BrasilCNPq_Brasi

  • Calculation of liquid-liquid equilibrium of aqueous two-phase systems using a chemical-theory-based excess Gibbs energy model
    Brazilian Society of Chemical Engineering, 2015
    Co-Authors: PessÔa Filho P. A., Mohamed R. S.
    Abstract:

    Mixtures containing compounds that undergo hydrogen bonding show large deviations from ideal behavior. These deviations can be accounted for through chemical theory, according to which the formation of a hydrogen bond can be treated as a chemical reaction. This chemical equilibrium needs to be taken into account when applying stability criteria and carrying out phase equilibrium calculations. In this work, we illustrate the application of the stability criteria to establish the conditions under which a liquid-phase split may occur and the subsequent calculation of liquid-liquid equilibrium using a chemical-theory-modified Flory-Huggins Equation to describe the non ideality of aqueous two-phase systems composed of poly(ethylene glycol) and dextran. The model was found to be able to correlate ternary liquid-liquid diagrams reasonably well by simple adjustment of the polymer-polymer binary interaction parameter

  • Calculation of liquid-liquid equilibrium of aqueous two-phase systems using a chemical-theory-based excess Gibbs energy model
    Brazilian Society of Chemical Engineering, 2015
    Co-Authors: PessÔa Filho P. A., Mohamed R. S.
    Abstract:

    Mixtures containing compounds that undergo hydrogen bonding show large deviations from ideal behavior. These deviations can be accounted for through chemical theory, according to which the formation of a hydrogen bond can be treated as a chemical reaction. This chemical equilibrium needs to be taken into account when applying stability criteria and carrying out phase equilibrium calculations. In this work, we illustrate the application of the stability criteria to establish the conditions under which a liquid-phase split may occur and the subsequent calculation of liquid-liquid equilibrium using a chemical-theory-modified Flory-Huggins Equation to describe the non ideality of aqueous two-phase systems composed of poly(ethylene glycol) and dextran. The model was found to be able to correlate ternary liquid-liquid diagrams reasonably well by simple adjustment of the polymer-polymer binary interaction parameter.471478Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

J P Pascault - One of the best experts on this subject based on the ideXlab platform.

  • rubber modified cyanate esters thermodynamic analysis of phase separation
    Polymer, 1995
    Co-Authors: Julio Borrajo, C C Riccardi, Roberto J J Williams, Z Q Cao, J P Pascault
    Abstract:

    Abstract Cloud-point curves were determined for blends of a rubber (butadiene—acrylonitrile random copolymer terminated in non-functional groups, NFBN) and a cyanate ester (4,4′-dicyanate-1,1′-diphenylethane, CE). Measurements were made in the initial blend and in partially polycondensed blends (thermal polycyclotrimerization of the CE monomer). Cloud-point conversions and temperatures were determined for different rubber fractions in the initial formulation. A thermodynamic analysis based on a Flory-Huggins Equation, taking polydispersity of both components into account, led to the following conclusions. (1) Phase separation was the result of the change in two different contributions to the free energy of mixing: (a) a decrease in the entropic contribution due to the increase in the oligomer size; (b) a decrease in the enthalpic contribution as a result of the decrease in the cohesive energy density of the CE-oligomer in the course of polycondensation. (2) Spinodal demixing was excluded as a possible mechanism of phase separation during polycondensation in solutions containing less than 12% rubber by volume.

  • rubber modified epoxies iii analysis of experimental trends through a phase separation model
    Journal of Applied Polymer Science, 1991
    Co-Authors: S M Moschiar, C C Riccardi, Roberto J J Williams, D Verchere, H Sautereau, J P Pascault
    Abstract:

    A phase separation model was used to simulate the morphologies obtained in a system consisting of a diepoxide based on bisphenol-A diglycidylether cured with a cycloaliphatic diamine, in the presence of an epoxy-terminated butadiene-acrylonitrile random copolymer (ETBN). A detailed analysis of experimental factors affecting resulting morphologies was previously reported. The model, based on a thermodynamic description through a Flory–Huggins Equation, and constitutive Equations for polymerization and phase separation rates, could explain most of the observed trends. A nucleation-growth mechanism was believed to take place because of the very low values of interfacial tensions for this type of systems. Conditions which would lead to spinodal demixing are also discussed.

Pedro De Alcântara Pessoa Filho - One of the best experts on this subject based on the ideXlab platform.

  • Contribuições a modelagem do equilibrio de fases e da partição de moleculas biologicas em sistemas aquosos bifasicos
    2017
    Co-Authors: Pedro De Alcântara Pessoa Filho
    Abstract:

    Resumo: A fonnação de sistemas aquosos bifásicos em conseqüência da adição à água de alguns pares de polímeros, ou de certos polímeros e sais, é um fenômeno bem estabelecido e conhecido. Esses sistemas encontram larga aplicação na separação de moléculas biológicas em laboratório e têm conhecido nos últimos tempos incipiente aplicação industrial; sua correta modelagem tennodinâmica é o objetivo deste trabalho. Inicialmente consideraram-se sistemas formados por dois polímeros. Procurou-se incorporar à equação de Flory-Huggins modificações que levassem em conta a formação de ligações de hidrogênio entre moléculas de água e entre moléculas de água e de polímero, no caso, o poli(etileno glicol). Em uma primeira análise utilizou-se como base do desenvolvimento a teoria quimica, que considera a ligação de hidrogênio uma ligação covalente. Os resultados foram bastante adequados e indicavam que a consideração das ligações cruzadas era suficiente para permitir uma boa modelagem. Assim, outros modelos que levavam em conta a solvatação foram desenvolvidos, em uma primeira abordagem considerando o número de moléculas de água na camada de solvatação constante, depois permitindo que esse valor variasse com a composição. Todos esses modelos tiveram bastante sucesso; entretanto, resultados pouco adequados foram obtidos na utilização da SAFT (teoria estatistica do fluido associativo). A polidispersão da dextrana também foi considerada em alguns cálculos, com sucesso; entretanto, dadas as diferenças existentes entre dados experimentais obtidos em grupos de pesquisa diversos, não foi possivel construir um modelo totalmente preditivo. Estudaram-se também sistemas formados por polímeros e sais. Nesse caso, o esforço teórico foi direcionado à compreensão do papel dos componentes nos tennos devidos à interação eletrostática ? por exemplo, polímeros presentes alteram a constante dielétrica e a densidade do meio, devendo portanto alterar a equação de Debye-Hückel, o que, por sua vez, faz com que se prevejam comportamentos irrealistas. Análise acurada revelou que a solução completa do problema demanda a conversão de propriedades obtidas no formalismo de McMillan e Mayer ao formalismo de Lewis e Randall para misturas de solventes ? esforço teórico cujo vulto ultrapassa o escopo deste trabalho. Desenvolveu-se também um modelo para sistemas fonnados por polieletrólitos e polímeros neutros. Esse modelo é baseado em uma equação empirica do virial, e considera a ocorrência de várias reações, por meio das quais foi possivel obter um novo modelo de energia de Gibbs excedente que levasse em conta a variação do grau de dissociação iônica em soluções aquosas de polieletrólitos. O modelo fisico de solvatação constante, desenvolvido para sistemas formados por dois polímeros, foi utilizado no estudo da partição de moléculas biológicas. O modelo foi capaz de descrever muito bem resultados de experimentos de partição. Nesse caso, a consideração da polidispersão da dextrana, que afeta muito pouco cálculos de equilíbrio líquido-líquido, modificou de maneira adequada a densidade numérica dessas fases, tomando o modelo mais confiávelAbstract: Aqueous two-phase systems are formed when either two polymers or a polymer and a salt are added to water at certain concentrations. These systems have been widely used to separate biological molecules in laboratory, and have recently found incipient industrial application. This work is aimed at the development of reliable thennodynamic models for these systems. First, systems fonned by two polymers were examined. The Flory-Huggins Equation was modified to account for hydrogen bonding occurring between water molecules (self-association) and between water and polymer molecules (solvation). The first modification uses the chemical theory, according to which hydrogen bonding is considered to be equivalent to a covalent bonding. The results obtained were very good and indicated that cross-association alone might bring about this improvement. Purely physical models accounting for solvation were subsequently developed, first by considering the number of water molecules bonded to each polymer molecule as a constant value, and later allowing it to vary with concentration. These models were found very successful. A similar attempt to use the SAFT (statistical associating fluid theory), however, did not provide good results. Polydispersion in polymers such as Dextran was also successfully accounted for, even though it was not possible to establish a completely predictive model due to the discrepancies in experimental data obtained by different research groups. Systems fonned by polymers and salts were dealt with next. In this case, the theoretical investigation was aimed at the understanding of the role of the different compounds in the ca1culation of the tenn that accounts for long range interactions. For instance, polymers modify the dielectric constant and the specific gravity ofthe surrounding medium, thus modifying the Debye-Hückel Equation; however, accounting for this effect introduces spurious terms in phase equilibrium ca1culations. A more detailed analysis showed that the correct solution to this problem would require the conversion of properties of mixing ca1culated in the McMillan and Mayer forrnalism to that of Lewis and Randal, a serious and challenging theoretical problem whose solution is beyond the scope of this work. A new thennodynamic model tailored for solutions of polyelectrolytes and neutral polymers was also developed. This model is based on an empirical virial Equation and considers the occurrence of some ionic dissociation reactions. Through this picture it was possible to develop a new excess Gibbs energy model accounting for the variation of the ionic dissociation degree in aqueous solutions of polyelectrolytes. The model with constant value for the solvation number, developed for systems fonned by two polymers, was also used to model the partitioning of biological molecules in these systems. The model provided a very good description of partitioning experiments. Accounting for Dextran polidispersion, which has almost no effect on phase equilibrium ca1culations, modifies the numeric density of the liquid phases in equilibrium, and increases the reliability of the mode

  • water activity of aqueous solutions of ethylene oxide propylene oxide block copolymers and maltodextrins
    Brazilian Journal of Chemical Engineering, 2010
    Co-Authors: N D D Carareto, E Monteiro S Filho, Pedro De Alcântara Pessoa Filho, A J A Meirelles
    Abstract:

    Abstract - The water activity of aqueous solutions of EO-PO block copolymers of six different molar masses and EO/PO ratios and of maltodextrins of three different molar masses was determined at 298.15 K. The results showed that these aqueous solutions present a negative deviation from Raoult's law. The Flory-Huggins and UNIFAC excess Gibbs energy models were employed to model the experimental data. While a good agreement was obtained with the Flory-Huggins Equation, discrepancies were observed when predicting the experimental behavior with the UNIFAC model. The water activities of ternary systems formed by a synthetic polymer, maltodextrin and water were also measured and used to test the predictive capability of both models. Keywords : Water activity; Excess Gibbs energy; Phase equilibrium; Flory-Huggins; UNIFAC. INTRODUCTION The water activity (a w ) of an aqueous solution is the ratio between the fugacity of water in this solution and the fugacity of pure liquid water at the same temperature and pressure. This property is the most directly accessible measure of liquid-phase non-ideality of aqueous solutions of non-volatile solutes, since there are either well documented techniques or electronic devices to accomplish it. Besides its scientific importance, water activity is also related to the stability of foodstuffs, for it represents the amount of water available to microbial or chemical spoilage. In other words, high a

R St John Manley - One of the best experts on this subject based on the ideXlab platform.

  • miscible blends of two crystalline polymers 1 phase behavior and miscibility in blends of poly vinylidene fluoride and poly 1 4 butylene adipate
    Macromolecules, 1996
    Co-Authors: J Penning P And, R St John Manley
    Abstract:

    The phase behavior and miscibility of blends of poly(vinylidene fluoride) (PVF2) and poly(1,4-butylene adipate) (PBA), both semicrystalline polymers, have been investigated using differential scanning calorimetry and light-scattering techniques. The phase diagram of this blend system exhibits a single glass transition temperature over the entire composition range, two distinct melting transitions, and a cloud-point curve above a lower critical solution temperature of 235 °C. A depression of the equilibrium melting point of both PVF2 and PBA is observed. From the melting point data of the high-Tm component, PVF2, a value for the polymer−polymer interaction parameter of χ12 = −0.19 was derived using the Flory−Huggins Equation. This implies that PVF2/PBA blends are thermodynamically miscible in the melt. The extent of the melting point depression for the low-Tm component, PBA, is much smaller than it is for PVF2, which is attributed to the fact that PVF2 is semicrystalline at temperatures of PBA melting. Inf...