Photoacoustic Monitoring of Internal Plastification in Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Copolymers: Measurements of Thermal Parameters

Sánchez, R.; Rieumont, Jacques; Cardoso, Simone C.; Silva, Marcelo Gomes da; Sthel, Marcelo Silva; Massunaga, M. S. O.; Gatts, Carlos N.; Vargas, H.

doi:10.1590/s0103-50531999000200004

Cited by 12 publications

(6 citation statements)

References 14 publications

(28 reference statements)

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“…2 /s. These values are slightly higher than those reported by previous authors, 21 who also observed the tendency for saturation of thermal diffusivity. The differences can be attributed to the sample preparation procedure.…”

contrasting

confidence: 70%

Photothermal methods and atomic force microscopy images applied to the study of poly(3‐hydroxybutyrate) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) dense membranes

Poley

Legey

Silva

et al. 2005

J of Applied Polymer Sci

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Thermal and transport properties of some polyhydroxyalkanoates (PHAs), poly-3-hydroxybutyrate and poly-3-hydroxybutyrate-co-3-hydroxyvalerate copolymers at different concentrations (8, 14, and 22%), were studied by using photoacoustic and photothermal techniques. Mass diffusion coefficients were obtained for carbon dioxide and oxygen by using a gas analyzer. Specific heat capacity measurements were performed by monitoring temperature of the samples under white light illumination against time. Thermal diffusivities were determined by using the open photoacoustic cell configuration. The results were discussed considering the incorporation of hydroxyvalerate units in the poly(3-hydroxybutyrate) unit cell and were correlated with atomic force microscopy images of the upper surface of membranes. New information on transport properties of PHAs is provided.

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contrasting

confidence: 70%

Photothermal methods and atomic force microscopy images applied to the study of poly(3‐hydroxybutyrate) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) dense membranes

Poley

Legey

Silva

et al. 2005

J of Applied Polymer Sci

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“…Specific thermal capacity of CA/PHB blends was obtained by the photothermal technique through the use of an experimental arrangement composed by an argon laser (Omicron Model 543‐AP) whose beam was modulated with a mechanical chopper (EG&G Model 650). The technique is essentially based on the measurement of temperature fluctuation of a given sample due to the absorption of modulated radiant energy .…”

Section: Methodsmentioning

confidence: 99%

“…The thermocouple monitors the variations of the temperature (Δ T ) with time ( Eq. 2 ) .

Δ T = true(\frac{I_{0} τ}{l_{s} ρ C_{p}} true) true(1 - e^{- \frac{t}{τ}} true) .

where I 0 is the intensity of the white light, l s is the film thickness, ρC p is the specific thermal capacity of bulk unit, t is the time.…”

Section: Methodsmentioning

confidence: 99%

Compatibilization of cellulose acetate/poly(3-hydroxybutyrate) blends by grafting copolymer

et al. 2016

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Blends of cellulose acetate (CA) and poly(3-hydroxybutyrate) (PHB) were prepared by the solvent-casting method in both the presence and the absence of a compatibilizer agent. The compatibilizer was synthesized by reactive processing between CA and PHB. From the differential scanning calorimetric analysis, it has been identified that CA/PHB blends are immiscible in the range of PHB content studied. The existence of interactions between the components was observed due to the displacement of glass transition temperature relative to PHB phase in the blend. The grafting copolymer promoted the increase of interactions between the phases specifically to compatibilized CA/40%wtPHB blend. This composition shows significant changes in crystalline percentage compared to the uncompatibilized blend. The existence of phase interactions modified the viscoelastic behavior of the compatibilized blends by introducing changes in the chain segment mobility due to the addition of compatibilizer as the dynamic mechanical analysis has pointed out. It was observed that different of the blends with lower PHB content, CA/40%wtPHB compatibilized blend with same compatibilizer content did not reach PHB saturation. This difference in behavior can be attributed to the fact that the content of compatibilizer agent used was the proper amount to promote both PHB domain size reduction and dispersion. POLYM. ENG. SCI., 56:689-696, 2016.

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“…A copolimerização aleatória de poli(3-hidroxibutirato-co-3-hidroxivalerato) foi estudada desta forma. Além de informações sobre a velocidade de plastificação interna, foram obtidos dados sobre condutividade e difusividade térmica [57] . O número de cadeias poliméricas presentes como partícu-las coloidais é proporcional à quantidade de monômero polimerizado.…”

Section: Outros Métodosunclassified

Fotopolimerização: princípios e métodos

Rodrigues

Neumann

2003

Polímeros

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Resumo: O interesse na Fotoquímica de Polímeros tem crescido nas últimas décadas devido não somente ao grande número de novas aplicações como também à repercussão do ponto de vista econômico, técnico e ecológico. A fotopolimerização/fotocura tem recebido a atenção especial devido às incontáveis aplicações e a sua importância na área de Materiais. A cinética destes processos necessita de métodos analíticos precisos e rápidos para ser avaliada. Entre os métodos analíticos convencionais, os mais usados são a gravimetria e a medida de propriedades macroscópicas, como resistência à tração, à deformação e dureza. Entretanto, para determinações mais analíticas é conveniente usar métodos que permitam estudar a cinética de fotopolimerização em tempo real. Neste sentido têm sido usadas técnicas como dilatometria, espectroscopia Raman, calorimetria, e espectroscopia de infravermelho por transformada de Fourier em tempo real. A atividade no campo da polimerização continua a se expandir em muitas áreas e, recentemente, o interesse nos sistemas do fotoiniciação envolvendo a polimerização via radicais livres, iniciada por luz visível, tem recebido atenção especial. Recentemente, estudos sobre fotopolimerização catiônica induzida pela luz visível começaram a ser pesquisados novamente devido à grande variedade de monômeros que são polimerizáveis por via catiônica mas não por via radicar, como, por exemplo, oxiranas e éteres vinílicos. Palavras-chave: Fotopolimerização catiônica, fotopolimerização via radicalar, dilatometria, calorimetria, gravimetria, espectroscopia de infravermelho por transformada de Fourier. Photopolymerization: Principles and MethodsAbstract: The interest for Polymer Photochemistry has been growing in the last decades as a consequence not only of the great number of new applications as well as due to the repercussion of economical, technical and ecological characters. The photopolymerization -photocuring processes have received special attention due to the countless and important applications in the area of Materials. The kinetics of these processes needs fast and precise analytic methods to be evaluated. Among the conventional analytic methods, the most used are gravimetry and the determination of macroscopic properties, as resistance to traction, deformation and hardness. However, for a better insight in the reactions it is convenient to use more advanced analytic methods, in order to study the photopolymerization kinetics in real time. Dilatometry, Raman spectroscopy, calorimetry, and real time Fourier transform infrared spectroscopy are some of the techniques that have been used. Activity in the field of photopolymerization continues to expand in many areas and recently, the interest in photoinitiation systems involving the initiation of free-radical polymerization with visible light irradiation has been retaken. Additionally, studies on cationic photopolymerization induced by visible light started again to be studied because of the large variety of monomers that can be photopolymerized by via cation ini...

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Photoacoustic Monitoring of Internal Plastification in Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Copolymers: Measurements of Thermal Parameters

Cited by 12 publications

References 14 publications

Photothermal methods and atomic force microscopy images applied to the study of poly(3‐hydroxybutyrate) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) dense membranes

Photothermal methods and atomic force microscopy images applied to the study of poly(3‐hydroxybutyrate) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) dense membranes

Compatibilization of cellulose acetate/poly(3-hydroxybutyrate) blends by grafting copolymer

Fotopolimerização: princípios e métodos

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