Degradation of poly(ethylene terephthalate)/clay nanocomposites during melt extrusion: Effect of clay catalysis and chain extension

Xu, Xiao; Ding, Yanfen; Qian, Zhongzhong; Wang, Feng; Wen, Bin; Zhou, Hu; Zhang, Shimin; Yang, Mingshu

doi:10.1016/j.polymdegradstab.2008.09.009

Cited by 137 publications

(104 citation statements)

References 42 publications

(55 reference statements)

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“…Generally, graphene sheets exhibits very high thermal stability with little or no weight loss up to 650 °C. Hofmann elimination reaction resulted into decomposition of the intercalated organic ammonium salts of Cloisite 15A,which shows a mass loss of almost 40% in the temperature range 200-400 °C 30 . EVA shows two-step degradation related to deacetylation and main-chain decomposition 29 , while the PCL degrades in a single stage (around 390 to 400 °C) involving simultaneous occurrence of two types of reactions; random chain scission and unzipping from hydroxyl end leading to the formation of ɛ-caprolactone.…”

Section: X-ray Diffraction (Xrd)mentioning

confidence: 99%

“…However, above 450°C the synergy of EG and clay revealed the highest thermal stability compared to the rest. The acceleration of thermal degradation before 450°C might be due to the products of the decomposition of the alkylammonium cations catalyzing the degradation of the polymer matrices 30 . The elimination of the ammonium modifier apparently results in a substitution of the ammonium linkage on the clay with a hydrogen proton due to β-carbon fracture, which acts as a Brθnsted acidic site to accelerate the polymer degradation.…”

Section: X-ray Diffraction (Xrd)mentioning

confidence: 99%

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Synergistic Effect of EG and Cloisite 15A on the Thermomechanical Properties and Thermal Conductivity of EVA/PCL Blend

et al. 2016

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The purpose of this study was to investigate the synergy of expanded graphite (EG) and Cloisite 15A (C15A) on the thermal conductivity and thermomechanical properties of ethylene-vinyl acetate copolymer/poly (ɛ-caprolactone) (EVA/PCL) blend. Scanning electron microscopy (SEM) results showed that the blend had a phase separation, in which the PCL phase (appeared as droplets) was dispersed uniformly in the EVA matrix in all samples. The results from SEM and X-ray diffraction (XRD) showed that as the EG content increases, graphite sheets increase, leading to a high probability of re-stacking and poor dispersion as well, however the synergy rendered an increase in the storage modulus for the composite containing low content of EG (5phr) in both the EG and clay containing samples. The addition of EG showed a slight increase in thermal stability,but the presence of C15A decreased the onset of degradation of EVA/PCL blend. However, at high temperatures the synergistic effect of EG and C15A showed better thermal stability for EVA/PCL blend than EG alone. The addition and increase in EG content improved thermal conductivity of the EVA/PCL blend in both the clay containing and EG containing samples, however the clay-containing samples showed lower values compared to EG only.

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Section: X-ray Diffraction (Xrd)mentioning

confidence: 99%

Section: X-ray Diffraction (Xrd)mentioning

confidence: 99%

Synergistic Effect of EG and Cloisite 15A on the Thermomechanical Properties and Thermal Conductivity of EVA/PCL Blend

et al. 2016

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“…The amide Ι and amide ΙΙ absorption bands suggest that Chitosan is a partially deacetylated product [16] . It is well known that the reducing of the acetylation level in Chitosan ensure the presence of the free amino groups which can be easily protonated in an acid environment making Chitosan water soluble.…”

Section: Ftir Spectroscopymentioning

confidence: 99%

Characterization of Clay/Chitosan Nanocomposites and their Use for Adsorption On Mn(ΙΙ) from Aqueous Solution

El‐Kader¹,

Shehap²,

Bakr³

et al. 2015

IJSEA

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Abstract:: In this study, composites films were prepared from Chitosan biopolymer and Montmorillonite nanoclay (MMT) by dispersion of MMT into Chitosan solution with different weight percentage (2.5, 5, 7.5, 10, 12.5, 15 and 75% wt. /wt. nanoclay/chitosan), using both sonication and casting technique methods to obtain good dispersion of nanoclay. The structural properties of these nanocomposites samples examined by XRD and FTIR . The XRD patterns indicating that formation of an intercalated nanostructure as exfoliated and flocculated structure . Also the complexion of the dopant with the biopolymer was examined by FTIR studies. The experiments of Mn(ΙΙ) ions adsorption were carried out on MMT/chitosan nanocomposites. The effect of various parameters such as pH, contact time, adsorption mass, initial Mn(ΙΙ) concentration and temperature on the adsorption of Mn(ΙΙ) removal onto MMT/chitosan nanocomposites was investigated. Two adsorption isotherm models were applied Freundlich and Langmuir to fit the experimental data. Langmuir isotherm modeling was suitable for description the data at equilibrium state. The kinetic isotherm was found to follow the pseudo-second-order model. Also, the thermodynamics parameters of the adsorption such as Gibbs free energy∆ , entropy ∆ and enthalpy ∆ were discussed and the results demonstrate that the adsorption process is spontaneous and endothermic.

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“…Mesmo na ausência de fluidos agressivos, há relatos de que cargas argilosas aceleram a degradação da matriz de PET [31][32][33] . Essa ação degradativa é atribuída aos grupos hidroxila presentes nas plaquetas de argila, os quais seriam responsáveis por provocar cisão hidrolítica de ligações éster nas moléculas de PET [33] .…”

Section: Influência Na Degradação Do Polímerounclassified

“…Para o PET puro o aumento na concentração favorece um incremento de 32% na degradação, ao passo que para o híbrido o incremento é de 41% (Tabela 5), indicando que a presença de argila favorece o processo degradativo sob elevadas concentrações de solução alcalina. Quanto maior a concentração da solução, maior a quantidade de grupos hidroxila que se somam aos já existentes nas plaquetas da argila para favorecer o ataque químico da matriz polimérica, uma vez que esses grupos são considerados catalisadores da degradação do PET [31,32,34,35] .…”

Section: Figuraunclassified

Falha por stress cracking em híbridos PET/argila

Teófilo

Silva

et al. 2014

Polímeros

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Resumo: O presente estudo investiga a falha por stress cracking em polímeros contendo argila montmorilonítica. Ensaios de tração e de relaxação de tensão foram conduzidos para avaliar a resistência ao stress cracking do PET puro e dos híbridos PET/argila em contato com soluções aquosas de hidróxido de sódio. As análises por difratometria de raios-X evidenciaram que a argila adicionada não gerou uma estrutura esfoliada e sim a obtenção de microcompósitos. Os resultados mostraram que a presença de argila dispersa no PET causa concentração de tensão, o que exerce forte influência no comportamento de stress cracking, com os efeitos sendo afetados pela ordenação lamelar e ao teor de carga, resultando em maiores taxas de relaxação de tensão. A argila com menor regularidade no empilhamento lamelar, embora ocasione menor concentração de tensão, favorece mais o fissuramento superficial da matriz, sugerindo que o efeito de barreira ao fluido não foi efetivo. Medidas de massa molar evidenciaram que a argila acelera o ataque químico da matriz quando elevadas concentrações de solução são utilizadas, porém diminui o efeito da tensão mecânica na degradação.Palavras-chave: PET, argila, stress cracking, nanocompósitos. Stress Cracking Failure of PET/Clay CompositesAbstract: This study investigates stress-cracking failure of polymer/clay composites. Tensile and stress relaxation tests were conducted to evaluate the stress cracking resistance of PET and PET/clay in the presence of sodium hydroxide aqueous solution. The X-ray diffraction analyses showed that the clay formed a typical structure of a microcomposite, and not an exfoliated structure. The presence of clay causes stress concentration, with a strong consequence to the stress cracking behavior, but the effects depend on the lamellar ordering and the content of clay. When the clay lamellae are less ordered the rise in stress concentration is lower, but causes more surface cracks on the polymer, suggesting that the barrier effect was not very effective. Molar mass measurements showed that the clay accelerates the chemical attack of the matrix when higher concentrations of NaOH are used, but reduces the effect of mechanical stress on degradation. Keywords: PET, clay, stress-cracking, nanocomposites.Autor para correspondência: Marcelo Silveira Aabello, Unidade Acadêmica de Engenharia de Materiais, Rua Aprigio Veloso, 882, Campina Grande, PB, Brasil, IntroduçãoO poli (tereftalato de etileno) (PET) é um dos mais importantes plásticos de engenharia da atualidade, sendo um dos termoplásticos mais produzidos no mundo [1] . Apresenta uma excelente combinação de rigidez e tenacidade, alta resistência ao calor, estabilidade dimensional, capacidade de isolamento elétrico, além da possibilidade de se apresentar no estado amorfo (transparente), parcialmente cristalino e orientado (translúcido) e altamente cristalino (opaco) [2] . Entretanto, desvantagens tais como baixa taxa de cristalização e baixa temperatura de distorção térmica têm limitado suas aplicações como um plástico de engenh...

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Degradation of poly(ethylene terephthalate)/clay nanocomposites during melt extrusion: Effect of clay catalysis and chain extension

Cited by 137 publications

References 42 publications

Synergistic Effect of EG and Cloisite 15A on the Thermomechanical Properties and Thermal Conductivity of EVA/PCL Blend

Synergistic Effect of EG and Cloisite 15A on the Thermomechanical Properties and Thermal Conductivity of EVA/PCL Blend

Characterization of Clay/Chitosan Nanocomposites and their Use for Adsorption On Mn(ΙΙ) from Aqueous Solution

Falha por stress cracking em híbridos PET/argila

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