Cyclic polyesters: 6. Preparation and characterization of two series of cyclic oligomers from solution ring-chain reactions of poly(ethylene terephthalate)

Bryant, Jonathan J.; Semlyen, J.A.

doi:10.1016/s0032-3861(96)00801-4

Cited by 79 publications

(52 citation statements)

References 15 publications

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“…However, equilibration by means of transesterification catalyst in high boiling inert solvents shifts the ring-chain HIGHLIGHT equilibrium totally to the side of cyclic oligoesters, due to a gain in entropy. [123][124][125][126][127][128][129] This approach allows for a rapid and simple preparation of cyclic PET or PBT oligoesters 125,127,129 and a small scale technical production has been realized.…”

Section: Theory and Technical Polymer Synthesesmentioning

confidence: 99%

Cyclic polymers: Synthetic strategies and physical properties

Kricheldorf

2009

J. Polym. Sci. A Polym. Chem.

401

442

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Syntheses of cyclic polymers including cyclic homopolymers, cyclic block copolymers, sun-shaped polymers, and tadpole polymers are discussed on the basis of a differentiation between synthetic methods and synthetic strategies (e.g., polycondensation, ring-ring equilibration, or ring-expansion polymerization). Furthermore, all synthetic methods are classified as kinetically or thermodynamically controlled reactions. Characteristic properties of cyclic polymers such as smaller hydrodynamic volume, lower melt viscosities, and higher thermostabilities are compared to the properties of their linear counterparts. Furthermore, the nanophase separation of cyclic diblock copolymers is discussed.

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Section: Theory and Technical Polymer Synthesesmentioning

confidence: 99%

Cyclic polymers: Synthetic strategies and physical properties

Kricheldorf

2009

J. Polym. Sci. A Polym. Chem.

401

442

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“…Part of the EI-terminated copolymer is converted back to PET and EI c-2mer through the backbiting reaction with the smallest turning circle (Route 1). The existence of this route is supported by the experimental result that homopolymerization of EI c-2mer is difficult to perform (runs [1][2][3]. The other two routes are thought to occur with equal probabilities.…”

Section: Resultsmentioning

confidence: 92%

“…C 3 . The intensity data were collected on a Rigaku AFC7R diffractometer with graphite-monochromated Mo-K radiation, (Mo K) = 0.71069 A, !-scan, ¼ 1:18 cm À1 , 2117 measured (À9 h 9, À12 k 12, À7 l 0, 2 max ¼ 55:0 ) and 1935 unique reflections (R int ¼ 0:01).…”

Section: Crystal Data For Ei C-2mermentioning

confidence: 99%

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Synthesis of Poly(ethylene terephthalate-co-isophthalate) by Copolymerization of Ethylene Isophthalate Cyclic Dimer and Bis(2-hydroxyethyl) Terephthalate

Nagahata

Sugiyama

Velmathi

et al. 2004

Polym J

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ABSTRACT:Ethylene isophthalate cyclic dimer (EI c-2mer) and bis(2-hydroxyethyl) terephthalate (BHET) were successfully copolymerized in the bulk state by microwave heating to give a polymer with M w > 20000. Terminal functionalities of the copolymers obtained were investigated by the MALDI-TOF mass analysis technique. The first stage of the copolymerization reaction involves homopolymerization of BHET. In the second stage, reactive end-group of poly(ethylene terephthalate) or BHET itself can attack the EI c-2mer and gradually produce an EI-terminated copolymer. In the third stage, the propagation reaction of EI-terminated copolymer occurs through the three types of elementary reaction route.

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“…Eles podem ser extraídos do PET usando o extrator Soxhlet em conjunto com solventes como, clorofórmio [56][57][58][59] , dioxano [57,60] , diclorometano e xileno [61] . Entretanto, no processo de síntese, a remoção desses compostos cíclicos não é feita pela indústria [25] , pois não é econômica e nem ambientalmente viável.…”

Section: Degradação Termomecânicaunclassified

Poli(tereftalato de etileno), PET: uma revisão sobre os processos de síntese, mecanismos de degradação e sua reciclagem

2009

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estabilidade hidrolítica devido a presença de anéis aromá-ticos na cadeia principal [1] . Atualmente, o PET é um dos termoplásticos mais produzidos no mundo, alcançando no final da década de 90 uma produção mundial em torno de 2,4 × 10 10 kg. As aplicações do PET são: fibras têxteis (67%), embalagens processadas por injeção-sopro (24%), filmes biorientados (5%) e polímeros de engenharia (4%). O sucesso deste material deve-se à sua excelente relação entre as propriedades mecânicas, térmicas e o custo de produção [2] . Resumo: Apresentamos uma revisão sobre o poli(tereftalato de etileno) enfatizando os processos de síntese e os mecanismos de degradação. Atualmente o Brasil apresenta um dos maiores índices mundiais de reciclagem mecânica deste polímero, correspondendo a um percentual de 53%. O sucesso desse termoplástico na indústria de reciclagem deve-se à sua ampla diversidade de aplicações, desde a indústria têxtil (multifilamento) até as indústrias de alimentos, onde as embalagens recicladas grau alimentício poderão ser misturadas com a resina virgem em diversas proporções e reprocessadas para o uso. Uma abordagem sobre a atual legislação do uso de PET reciclado em contato com alimentos também é mostrada neste trabalho. No processo de síntese do PET realizado em duas ou três etapas, são usados comonômeros e aditivos para otimizar as condições de processamento do material. Entretanto, tanto durante a síntese como no processo de reciclagem, ocorrem reações de degradação (termomecânica e termo-oxidativa) e reações secundárias, formando acetaldeído, oligômeros, e o dietileno glicol. A presença desses "contaminantes" acelera o processo de degradação do polímero, afetando a qualidade do produto final. Introdução Palavras-chave: Poli(tereftalato de etileno), degradação termomecânica, degradação termo-oxidativa, acetaldeído, oligômeros, dietileno glicol. Poly(Ethylene Terephthalate), PET: A Review on the Synthesis Processes, Degradation Mechanisms and its RecyclingAbstract: We present a review on poly(ethylene terephthalate), emphasizing the synthesis processes and the degradation mechanisms. Brazil is currently among the countries that most recycle PET, with 53% of this polymer being mechanically recycled. The success of this thermoplastic in the recycling industry is due to its large diversity of applications, from the textile industry to food packaging, where the food grade recycled packages will be mixed with the pristine resin for reprocessing and use. We also discuss the present legal aspects concerning PET recycling and its use in contact with food. In the synthesis of PET, usually done in two or three steps, several co-monomers and additives are used to optimize the final properties and processing conditions. Additionally, during the synthesis, processing and recycling, several degradation (thermomechanical and thermo-oxidation) and secondary reactions occur, producing acetaldehydes, oligomers and diethyleneglicol. The presence of these "contaminants" accelerates the degradation process of the polymer affecting...

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Cyclic polyesters: 6. Preparation and characterization of two series of cyclic oligomers from solution ring-chain reactions of poly(ethylene terephthalate)

Cited by 79 publications

References 15 publications

Cyclic polymers: Synthetic strategies and physical properties

Cyclic polymers: Synthetic strategies and physical properties

Synthesis of Poly(ethylene terephthalate-co-isophthalate) by Copolymerization of Ethylene Isophthalate Cyclic Dimer and Bis(2-hydroxyethyl) Terephthalate

Poli(tereftalato de etileno), PET: uma revisão sobre os processos de síntese, mecanismos de degradação e sua reciclagem

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