Crystallization kinetics of PHB/PVAc blends using time resolved dielectric spectroscopy

Madbouly, Samy A.; Mansour, Ahmed S.; Abdou, Nahed Y.

doi:10.1016/j.eurpolymj.2007.06.020

Cited by 30 publications

(32 citation statements)

References 49 publications

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“…Por outro lado, dados de SAXS indicam que há segregação interlamelar das cadeias de PVAc durante a cristalização do PHB. [40][41][42] Madbouly et al 43 estudaram a cinética de cristalização das blendas de PHB/PVAc utilizando espectroscopia de relaxação dielétrica e DSC, concluindo que a presença de PVAc retarda a cristalização. Os estudos 43 Chiu 44 estudou a morfologia de blendas PHB/PVAc e blendas P(HB-co-10HV)/PVAc, que foram preparadas por casting utilizando DMF como solvente.…”

Section: Phb/poli(acetato De Vinila) -Pvacunclassified

Blendas de PHB e seus copolímeros: miscibilidade e compatibilidade

Quental¹,

Carvalho²,

Tada³

et al. 2010

Quím. Nova

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Recebido em 12/5/09; aceito em 29/7/09; publicado na web em 8/1/10 BLENDS OF PHB AND ITS COPOLYMERS: MISCIBILITY AND COMPATIBILITY. Poly(hydroxybutyrate) and its copolymers are linear polyesters behaving as conventional thermoplastic materials. However, they are totally biodegradable and produced by a wide variety of bacteria from renewable sources. Some properties and high production cost are still preventing future applications. In an attempt to improve the properties and to reduce cost blending PHB with others polymeric materials is one of the most efficient method. In this paper, miscibility, compatibility, morphological and mechanical aspects of PHB blends will be reviewed. An extensive revision over twenty last years was realized about works of blends based on PHB and its copolymers.Keywords: blends; PHB; miscibility. INTRODUÇÃO Poli(hidroxibutirato) -PHBO PHB e seus copolímeros são produzidos naturalmente por bactérias a partir de fontes renováveis de energia, e são biodegradados por uma enorme quantidade de bactérias e fungos presentes na natureza. 1,2 No Brasil, a produção de PHB foi desenvolvida por uma joint venture entre a Copersucar (Cooperativa dos Produtores de Canade-açúcar do Estado de São Paulo), o IPT (Instituto de Pesquisas Tecnológicas) e pelo ICB (Instituto de Ciências Biomédicas da USP).3,4 A produção de PHB, encontrou condições excepcionalmente favoráveis no Brasil devido às características da indústria de açúcar e álcool, bastante desenvolvida durante o programa PROALCOOL. A disposição de açúcar a baixos preços e grandes quantidades, que é utilizado como substrato para o crescimento das bactérias do PHB, é uma das principais características que favorecem a produção desse polímero.De 1995 a 2000, a primeira produção em planta piloto do PHB no Brasil, utilizando o processo Copersucar-IPT-ICB, foi realizada na usina de açúcar e álcool Usina da Pedra. Os principais objetivos dessa planta piloto foram testar a viabilidade do processo, desenvolvê-lo e realizar uma avaliação econômica do custo de produção de PHB. 4 Em 2000, a produção comercial de PHB se iniciou com a criação da empresa PHB Industrial, em Serrana, próxima à Usina da Pedra. 4 A produção de PHB pela PHB Industrial é a única produção industrial de PHB a partir de cana-de-açúcar e integrada em usina sucroalcooleira. Essa empresa opera desde 2005 com uma planta de capacidade máxima de 60 toneladas de PHB por ano. "Enquanto na Europa, o PHB é produzido a US$10-20,00/kg, no Brasil esses custos estão entre US$2,5-5,00/kg (...)".3 No entanto, esse preço ainda é muito superior aos preços dos polímeros sintéticos da indústria petroquímica, o que desestimula a ampla comercialização do PHB.A biodegradabilidade não pode ser o único atrativo no PHB ou em qualquer polímero biodegradável. Para ser aceito em larga escala, estes polímeros têm de possuir os atrativos dos termoplásticos convencionais como: (i) suprir a demanda do mercado, ou seja, ser produzido em grande quantidade; (ii) correta compostagem para preservar a sua biodegradação; (iii)...

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Section: Phb/poli(acetato De Vinila) -Pvacunclassified

Blendas de PHB e seus copolímeros: miscibilidade e compatibilidade

Quental¹,

Carvalho²,

Tada³

et al. 2010

Quím. Nova

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“…

\begin{matrix} true \\ right τ = τ_{0} prefixexp ((), \frac{E_{α}}{k_{normalB} T}) \end{matrix}

where k B is the Boltzmann constant and E a is the apparent activation energy. The linear relationship between τ max and 1/ T is a typical behavior for the local dynamics of amorphous, semicrystalline, and thermoset polymers . Clearly, insignificant changes in the dynamics of the two local relaxation processes were observed with changing sample composition.…”

Section: Resultsmentioning

confidence: 93%

“…Compared with DMA, BDRS covers a much wider range of frequencies suitable for observing the relaxation phenomena mentioned above in a single‐frequency scan measurement based on the nature of the material and the temperature range of each relaxation process. Recently, we have used this BDRS technique to study the miscibility of polymer blends, the kinetics of phase separation, and crystallization kinetics in amorphous/crystalline mixtures . BDRS is also a very sensitive technique to monitor any change in the molecular dynamics and dynamical constraints associated with thermoset formation, branching, crosslinking density, and the corresponding bulk properties.…”

Section: Introductionmentioning

confidence: 99%

Broadband Dielectric Relaxation Spectroscopy of Functionalized Biobased Castor Oil Copolymer Thermosets

Madbouly

Xia

Kessler

2013

Macro Chemistry & Physics

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Novel biorenewable copolymer thermosets are successfully synthesized by the ring‐opening metathesis polymerization (ROMP) of norbornenyl‐functionalized castor oil (NCO) and norbornenyl‐functionalized castor oil alcohol (NCA) with controlled amounts of 0.8 and 1.8 norbornene rings per fatty acid chain, respectively. The NCO and NCA monomers are mixed in different concentrations and simultaneously polymerized via ROMP using Grubbs catalyst. Broadband dielectric relaxation spectroscopy (BDRS) is used to investigate the molecular dynamics of the fully cured copolymer thermosets over a wide range of frequencies (5 × 10−2 to 0.5 × 107 Hz) at different constant temperatures (−70 to 125 °C). Four phenomena, namely α‐, β‐, and γ‐relaxation processes and ionic conductivity are observed for all the measured samples.

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“…It is seen that, tan(δ) exhibits α'-and α-relaxation processes at 366 K and 389 K, respectively. α'-relaxation process has been reported for PVC [7,21,22] but this effect is weak and is not always observed in compassion with the main α-relaxation process. α'-peak always observed for methyl ester form polymer.…”

Section: Miscibility Study Based On Tg Analysismentioning

confidence: 93%

“…where the thermally stimulated depolarization current (TSDC) of CPVC-PES blend exhibits only α-relaxation process. Also, PVC/ethylene vinyl acetate carbon monoxide polymer blends have been reported to be miscible [22] on the basis of the specific interaction between C=O and α-hydrogen of C-Cl groups for PVC structure. It is well known that, for a highly miscible blend, tan(δ) curve shows only a single peak in between the glass transition temperatures of the component polymers, whereas broadening of the transition occurs in the case of partially miscible system.…”

Section: Miscibility Study Based On Tg Analysismentioning

confidence: 99%

Miscibility Behavior of Poly Ethylene Glycol or Poly Ethylene Succinate/Chlorinated Poly Vinyl Chloride Blends Studied by Dielectric Relaxation Spectroscopy

Hanafy¹

2013

AMPC

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The miscibility of chlorinated poly vinyl chloride (CPVC) and poly ethylene glycol (PEG) or poly ethylene succinate (PES) had been investigated using dielectric relaxation spectroscopy (DRS) over frequency and temperature ranges; 10 kHz -4 MHz and 300 -450 K, respectively. Three relaxation processes namely ρ-, α'-, and α-relaxation processes were observed for tan(δ) and the electric modulus M" of pure components and blends. The first one was attributed to the space charge polarization or the Maxwell-Wagner polarization. The second one was related to the amorphous regions located between the lamellar crystal stacks. The third one was due to the micro-Brownian motion of CPVC main chains. This process was found to be dependent in respect of temperature and frequency. The molecular dynamics of α-relaxation process were influenced by blending, i.e., the dielectric strength (Δε), the peak broadness, and the peak maximum of tan(δ) were found to be compositional dependent. Electric modulus analysis reveals that there is a role of electrode polarization for the dielectric relaxation.

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Crystallization kinetics of PHB/PVAc blends using time resolved dielectric spectroscopy

Cited by 30 publications

References 49 publications

Blendas de PHB e seus copolímeros: miscibilidade e compatibilidade

Blendas de PHB e seus copolímeros: miscibilidade e compatibilidade

Broadband Dielectric Relaxation Spectroscopy of Functionalized Biobased Castor Oil Copolymer Thermosets

Miscibility Behavior of Poly Ethylene Glycol or Poly Ethylene Succinate/Chlorinated Poly Vinyl Chloride Blends Studied by Dielectric Relaxation Spectroscopy

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