Enhanced Environmental Degradation of Plastics

Cassidy, Patrick E.; Aminabhavi, Tejraj M.

doi:10.1080/00222358108080926

Cited by 23 publications

(1 citation statement)

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“…A biodegradação é um processo irreversível que em certas condições de umidade, luz, calor e nutrientes orgânicos, gera CO 2 , CH 4 , H 2 O entre outros (ASTM D6400-12, 2012). O primeiro 'review' que abordou a biodegradação de polímeros foi publicado em 1981 (Cassidy & Aminabhavi, 1981). Em seguida muitos trabalhos surgiram discutindo aspectos pertinentes sobre a química da biodegradação e relacionando biodegradabilidade com a estrutura de diversos polímeros (Aminabhavi, Balundgi, & Cassidy, 1990;Swift, 1990;Evans & Sikdar, 1990;Bastiolli et al, 1994).…”

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Novas composições poliméricas obtidas a partir da modificação do amido via extrusão reativa

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A Deus, Aos meus pais, por me ensinarem o valor da honestidade, Ao André, pelo incentivo e apoio às minhas escolhas, DEDICO AGRADECIMENTOS Ao Prof. Dr. Antonio José Felix de Carvalho, pelos anos de trabalho em equipe, ideias e ensinamentos, contribuindo para meu crescimento científico e intelectual. Ao Dr. Alessandro Gandini, pesquisador visitante, pelas ideias e paciência. Ao Prof. Dr. Mohamed Naceur Belgacem, pela atenção, incentivo e principalmente pela sua alegria motivadora durante o desenvolvimento do projeto em Grenoble. À Escola de Engenharia de São Carlos, pela oportunidade de realização do doutoramento. Ao Instituit Polytechnique de Grenoble, pelo suporte e oportunidade de desenvolver parte do projeto pesquisa em seus domínios. À Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), pela concessão da bolsa de doutorado e pelo apoio financeiro e suporte imprescindível para a realização desta pesquisa. Ao Departamento de Química e ao Departamento de Materiais da UFSCar, por colocar à disposição os equipamentos de ressonância magnética nuclear e o reômetro de placas paralelas. Aos alunos e amigos do grupo de pesquisa pelas discussões e parcerias, Adriane,

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Novas composições poliméricas obtidas a partir da modificação do amido via extrusão reativa

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Natural and artificial weathering of low‐density polyethylene (LDPE): Calorimetric analysis

Sebaa

Servens²,

Pouyet

1992

J of Applied Polymer Sci

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SYNOPSISStudies of the thermal and photodegradation of two commercial polymers, stabilized and unstabilized low-density polyethylene, show the effects of weathering on differential scanning calorimetry (DSC) curves. The shape and the size of the melting peak vary significantly in thermal aging and in accelerated photoirradiation, but no change was observed in natural weathering, implying that the crystallinity remains steady in outdoor exposures. The melting temperatures remain steady for all exposure tests. The fall of mechanical properties and the evolution of chemical structure, followed by IR spectroscopy results, especially near the carbonyl regions, were also observed. The resistance to UV light irradiation as probed by deformation at break was superior in stabilized LDPE compared to unstabilized LDPE. Simple correlations observed between the fall of mechanical properties, the rate of oxidation, and morphology. 0 1993 John Wiley & Sons, Inc. I NTRO DUCT10 NWhen the polyethylene films for greenhouse covering are exposed to heat, UV light in the presence of oxygen, they became brittle, and visual signs of deterioration are apparent. Degradation and embrittlement of those films can be related to the evolution of chemical structure and morphology (i.e., the crystallinity, size, and perfection of the crystallites, the deformation of amorphous regions, etc.) .It is now well established that the primary mechanism of degradation of polyethylene when exposed to heat and/or UV light involves the process of thermal and/or photooxidation.1'2 Those reactions lead to the buildup of a vinyl group and of a variety of oxygen-containing groups such as various carbony1 functions. The photochemical degradation of PE results from competing reactions of crosslinking and chain s c i~s i o n .~~~ At first stages of exposures, the crosslinking reactions may predominate, leading to an increase of the Young's m o d~l u s .~.~ Polyethylene is a semicrystalline polymer. Its * To whom correspondence should be addressed.Journal of Applied Polymer Science, Vol. 47, 1897-1903 (1993) structure can be considered as an alternating crystalline and amorphous layers (two-phase system). Neighboring crystalline lamellae are connected by tie molecules, passing through the amorphous interlamellar regions.6 It was assumed that oxidation was restricted to the amorphous region^.^'^ Oxidation damage at the tie molecule region can be responsible of the sudden loss of mechanical properties, especially elongation at break.8*9 It was assumed that the crystallinity increase with oxidation. It seems that this effect is due to the replacement of C -H bonds by C = 0 bonds in the amorphous region^.^ Natural weathering studies were conducted by exposing stabilized LDPE It was concluded that the observed slight increase in crystallinity could not be attributed to the formation of crosslinked structure because of the complete solubility of the sample.During photooxidation, LDPE, is well known to undergo changes of molecular Other works on high pressure crystalli...

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Natural and artificial weathering of low‐density polyethylene (LDPE): Calorimetric analysis

Sebaa

Servens

Pouyet

1993

J of Applied Polymer Sci

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Studies of the thermal and photodegradation of two commercial polymers, stabilized and unstabilized low‐density polyethylene, show the effects of weathering on differential scanning calorimetry (DSC) curves. The shape and the size of the melting peak vary significantly in thermal aging and in accelerated photoirradiation, but no change was observed in natural weathering, implying that the crystallinity remains steady in outdoor exposures. The melting temperatures remain steady for all exposure tests. The fall of mechanical properties and the evolution of chemical structure, followed by IR spectroscopy results, especially near the carbonyl regions, were also observed. The resistance to UV light irradiation as probed by deformation at break was superior in stabilized LDPE compared to unstabilized LDPE. Simple correlations observed between the fall of mechanical properties, the rate of oxidation, and morphology. © 1993 John Wiley & Sons, Inc.

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Enhanced Environmental Degradation of Plastics

Cited by 23 publications

References 131 publications

Novas composições poliméricas obtidas a partir da modificação do amido via extrusão reativa

Novas composições poliméricas obtidas a partir da modificação do amido via extrusão reativa

Natural and artificial weathering of low‐density polyethylene (LDPE): Calorimetric analysis

Natural and artificial weathering of low‐density polyethylene (LDPE): Calorimetric analysis

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