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Determination of volatile organic compounds in recycled polyethylene terephthalate and high-density polyethylene by headspace solid phase microextraction gas chromatography mass spectrometry to evaluate the efficiency of recycling processes

DUTRA, Camila; PEZO, Davinson; FREIRE, Maria Teresa de Alvarenga; NERIN, Cristina; REYES, Felix Guillermo Reyes
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
67.1%
A method for the determination of volatile organic compounds (VOCs) in recycled polyethylene terephthalate and high-density polyethylene using headspace sampling by solid-phase microextraction and gas chromatography coupled to mass spectrometry detection is presented. This method was used to evaluate the efficiency of cleaning processes for VOC removal from recycled PET. In addition, the method was also employed to evaluate the level of VOC contamination in multilayer packaging material containing recycled HDPE material. The optimisation of the extraction procedure for volatile compounds was performed and the best extraction conditions were found using a 75 mu m carboxen-polydimethylsiloxane (CAR-PDMS) fibre for 20 min at 60 degrees C. The validation parameters for the established method were linear range, linearity, sensitivity, precision (repeatability), accuracy (recovery) and detection and quantification limits. The results indicated that the method could easily be used in quality control for the production of recycled PET and HDPE. (C) 2011 Elsevier B.V. All rights reserved.; CAPES; CNPq, Brazil; Gobierno de Aragon, through the GUIA group of Grupo Consolidado de Investigacion T-10-Universidad de Zaragoza

Aderência e formação do biofilme por Staphylococcus aureus ao polietilenotereftalato (PET) usado como embalagem para acondionamento de medicamentos e cosméticos

Yokoo, S.; Pizzolitto, A. C.; Pozetti, G. L.; Pizzolitto, E. L.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 37-39
POR
Relevância na Pesquisa
47.13%
The polyethylene terephthalate (PET) is used for package drugs and cosmetics. The aim of this research was examine by scanning electron microscopy (SEM) a Staphylococcus aureus attachment and biofilm formation on a polyethylene terephthalate (PET) surface and hydrophobicity of S. aureus by adherence to hydrocarbons. A suspension of S. aureus was prepared in Mueller-Hinton broth and, coupons of polyethylene terephthalate were incubated for 30 minutes, two, 24 and 48 hours, 15 and 30 days. Afteron the coupons were removed and prepared for scanning electron microscope analysis. The attachment and biofilm formation was observed on the surfaces of PET. The SEM revealed adhesion and biofilm formation on PET surfaces. The hydrophobicity test classified S. aureus as hydrophobic.

Solid-state hydrolysis of postconsumer polyethylene terephthalate after plasma treatment

Mancini, Sandro Donnini; Nogueira, Alex Rodrigues; Rangel, Elidiane Cipriano; Cruz, Nilson Cristino da
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 1989-1996
ENG
Relevância na Pesquisa
56.75%
Plasma treatments were applied on the surface of postconsumer polyethylene terephthalate (PET) bottles to increase their wettability and hasten the subsequent hydrolysis process. Sixty-four treatments were tested by varying plasma composition (oxygen and air), power (25-130 W), pressure (50-200 mTorr), and time (1 and 5 min). The best treatment was the one applied in air plasma at 130 W and 50 mTorr for 5 min, as it provided the lowest contact angle, 9.4°. Samples of PET before and after the optimized plasma condition were subjected to hydrolysis at 205°C. Although the treatment changed only a thin surface layer, its influence was evident up to relatively high conversion rates, as the treated samples presented more than 40% higher conversion rates than the untreated ones after 2 h of reaction. Infrared spectroscopy showed that the terephthalic acid obtained from 99% of depolymerization was similar to the commercial product used in PET synthesis. © 2012 Wiley Periodicals, Inc.

Remoção de corante de poli(tereftalato de etileno) (PET) através de recristalização e sua posterior despolimerização em meio ácido; Removing dye from poly(ethylene terephthalate) (PET) by recrystallization and its subsequent depolymerization in acid medium

Talita Katiuska Takizawa Dias Stefanelli
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 18/10/2013 PT
Relevância na Pesquisa
56.78%
O consumo de polímeros sintéticos no Brasil e no mundo vem aumentando há décadas, numa clara demonstração do enorme sucesso conseguido por esses materiais nas mais variadas aplicações. As características típicas dos polímeros sintéticos, como seu custo praticamente irrisório, baixo peso, boa resistência mecânica, impermeabilidade, transparência e capacidade de coloração mais impressão lhe conferiram trunfos irresistíveis para seu uso massivo na forma de embalagens, uma aplicação extremamente importante numa sociedade voltada para o consumo. O grande problema dos polímeros sintéticos reside na sua curta vida útil, o que conduz a um rápido aumento da corrente de resíduos, como é o caso das embalagens. Dentro desse âmbito, a reciclagem passa ser uma alternativa promissora. Por definição, a reciclagem é um processo de transformação dos materiais previamente separados para posterior utilização; é a recuperação de resíduos mediante uma série de operações que permitem que materiais processados sejam aproveitados como matéria-prima no processo gerador ou em outros. A primeira etapa deste trabalho foi a tentativa de fazer a despolimerização de PET utilizando o processo de destilação molecular. Os resultados mostraram que não é possível utilizar o destilador molecular na despolimerização do PET. Na segunda etapa deste trabalho o pet pósconsumo foi submetido à recristalização para remoção do corante...

Determination of volatile organic compounds in recycled polyethylene terephthalate and high-density polyethylene by headspace solid phase microextraction gas chromatography mass spectrometry to evaluate the efficiency of recycling processes

DUTRA, Camila; PEZO, Davinson; FREIRE, Maria Teresa de Alvarenga; NERIN, Cristina; REYES, Felix Guillermo Reyes
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
67.02%
A method for the determination of volatile organic compounds (VOCs) in recycled polyethylene terephthalate and high-density polyethylene using headspace sampling by solid-phase microextraction and gas chromatography coupled to mass spectrometry detection is presented. This method was used to evaluate the efficiency of cleaning processes for VOC removal from recycled PET. In addition, the method was also employed to evaluate the level of VOC contamination in multilayer packaging material containing recycled HDPE material. The optimisation of the extraction procedure for volatile compounds was performed and the best extraction conditions were found using a 75 mu m carboxen-polydimethylsiloxane (CAR-PDMS) fibre for 20 min at 60 degrees C. The validation parameters for the established method were linear range, linearity, sensitivity, precision (repeatability), accuracy (recovery) and detection and quantification limits. The results indicated that the method could easily be used in quality control for the production of recycled PET and HDPE. (C) 2011 Elsevier B.V. All rights reserved.; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

New enzymes with potential for PET surface modification

Fischer-Colbrie, Gudrun; Heumann, Sonja; Liebminger, Stefan; Almansa, Eva; Paulo, Artur Cavaco
Fonte: Taylor & Francis Publicador: Taylor & Francis
Tipo: Artigo de Revista Científica
Publicado em //2004 ENG
Relevância na Pesquisa
46.86%
This work describes newly isolated organisms and their potential to modify the surface of polyethylene terephthalate (PET). Out of the different screening processes, four bacterial and five fungal strains were isolated. A PET model substrate was synthesized (bis (benzoyloxyethyl) terephthalate) and used in the screening process, mimicking the polymer in its crucial properties and having the advantage of defined hydrolysis products. On this model substrate, extracellular enzyme preparations from the isolated microorganisms showed a maximum activity of 8.54 nkat/L. All enzyme preparations showed esterase activity on p-nitrophenyl-acetate while no activity was found on p-nitrophenyl decanoate or p-nitrophenyl palmitate. Increased hydrophilicity of PET fabrics after enzyme treatment was found based on rising height and water dissipation measurements.

Properties and durability of concrete containing polymeric wastes (tyre rubber and polyethylene terephthalate bottles) : an overview

Torgal, Fernando Pacheco; Ding, Yining; Jalali, Said
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em 16/01/2012 ENG
Relevância na Pesquisa
66.88%
The volume of polymeric wastes like tyre rubber and polyethylene terephthalate bottles (PET) is increasing at a fast rate. An estimated 1000 million tyres reach the end of their useful lives every year and 5000 millions more are expected to be discarded in a regular basis by the year 2030. Up to now a small part is recycled and millions of tyres are just stockpiled, landfilled or buried. As for PET bottles annual consumption represent more than 300,000 million units. The majority is just landfilled. This paper reviews research published on the performance of concrete containing tyre rubber and PET wastes. Furthermore it discusses the effect of waste treatments, the size of waste particles and the waste replacement volume on the fresh and hardened properties of concrete.

Hidrólise parcial da superfície do polyethylene terephthalate (PET): transformando um rejeito em um material de troca catiônica para aplicação ambiental

Rosmaninho,Marcelo G.; Jardim,Erika; Ferreira,Gilmara L.; Araújo,Maria H.; Lago,Rochel M.; Moura,Flávia C. C.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2009 PT
Relevância na Pesquisa
47.2%
In this work it is proposed a simple and versatile undergraduate chemical experiment in polymer and environmental technology based on the process of polyethylene terephthalate (PET) hydrolysis. Polyethylene terephthalate from post-consume bottles is submitted to a controlled partial hydrolysis which allows the students to follow the reaction by a simple procedure. The students can explore the reaction kinetics, the effect of catalysts and the exposed polyethylene terephthalate surface area on the hydrolysis reaction. The second and innovative part of this experiment is the technological and environmental application of the hydrolyzed polyethylene terephthalate as a material with cation exchange properties. The surface hydrolyzed polyethylene terephthalate can be used as adsorbent for cationic contaminants.

Ultrafiltration membranes from waste polyethylene terephthalate and additives: synthesis and characterization

Rajesh,Smitha; Murthy,Zagabathuni Venkata Panchakshari
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 EN
Relevância na Pesquisa
66.94%
The synthesis and characterization of asymmetric ultrafiltration membranes from recycled polyethylene terephthalate (PET) and polyvinylpyrrolidone (PVP) is reported. PET is currently used in many applications, including the manufacture of bottles and tableware. Monomer extraction from waste PET is expensive, and this process has not yet been successfully demonstrated on a viable scale. Hence, any method to recycle or regenerate PET once it has been used is of significant importance from scientific and environmental research viewpoints. Such a process would be a green alternative due to reduced raw monomer consumption and the additional benefit of reduced manufacturing costs. The membranes described here were prepared by a phase-inversion process, which involved casting a solution containing PET, m-cresol as solvent, and polyethylene glycol (PEG) of different molecular weights as additives. The membranes were characterized in terms of pure water permeability (PWP), molecular weight cut-off (MWCO), and flux and membrane morphology. The results show that the addition of PEG with high molecular weights leads to membranes with higher PWP. The presence of additives affects surface roughness and membrane morphology.

The effect of hot multistage drawing on molecular structure and optical properties of polyethylene terephthalate fibers

Haji,Aminoddin; Rahbar,Ruhollah Semnani; Kalantari,Bahareh
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2012 EN
Relevância na Pesquisa
66.88%
In this work, mechanical and structural parameters related to the optical properties of polyethylene terephthalate (PET) fibers drawn at hot multistage have been investigated. The changes in optical parameters upon changing draw ratio are used to obtain the mechanical orientation factors

Enhancing the Dyeability of Polypropylene Fibers by Melt Blending with Polyethylene Terephthalate

Mirjalili, Fereshteh; Moradian, Siamak; Ameri, Farhad
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Publicado em 30/10/2013 EN
Relevância na Pesquisa
46.88%
Attempts were made to modify polypropylene fibers by melt blending with polyethylene terephthalate in order to enhance the dyeability of the resultant fiber. Five blends of polypropylene/polyethylene terephthalate/compatibilizer were prepared and subsequently spun into fibers. Three disperse dyes were used to dye such modified fibers at boiling and 130°C. The dyeing performance of the blend fibers, as well as the morphological, chemical, thermal, and mechanical properties, of the corresponding blends was characterized by means of spectrophotometry, polarized optical microscopy, scanning electron microscopy (SEM), FT-IR spectroscopy, differential scanning calorimetry (DSC), and tensile testing.

Histological characteristics and ultrastructure of polyethylene terephthalate LARS ligament after the reconstruction of anterior cruciate ligament in rabbits

Yu, Shao-Bin; Yang, Rong-Hua; Zuo, Zhong-Nan; Dong, Qi-Rong
Fonte: e-Century Publishing Corporation Publicador: e-Century Publishing Corporation
Tipo: Artigo de Revista Científica
Publicado em 15/09/2014 EN
Relevância na Pesquisa
47.25%
Polyethylene terephthalate LARS ligament were the remnant of LARS ligament used for repairing posterior cruciate ligament obtained from operation. We want to study histological characteristics and ultrastructure of polyethylene terephthalate LARS ligament after the reconstruction of anterior cruciate ligament in rabbits. Therefore, we replaced the original ACL with polyethylene terephthalate LARS ligament which was covering with the remnant of ACL in 9 rabbits (L-LARS group), while just only polyethylene terephthalate LARS ligament were transplanted in 3 rabbits (LARS group) with the remnant of ACL. Compared with group LARS, inflammatory cell reaction and foreign body reaction were more significant in group L-LARS. Moreover, electron microscopy investigation showed the tissue near LARS fibers was highly cellular with a matrix of thin collagen fibrils (50-100 nm) in group L-LARS. These above findings suggest the polyethylene terephthalate LARS ligament possess the high biocompatibility, which contributes to the polyethylene terephthalate LARS covered with recipient connective tissues.

LASER TRANSMISSION WELDING OF POLYBUTYLENE TEREPHTHALATE AND POLYETHYLENE TEREPHTHALATE BLENDS

KHOSRAVI, SINA
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
46.86%
Laser Transmission Welding (LTW) involves localized heating at the interface of two pieces of plastic (a laser transparent plastic and laser absorbing plastic) to be joined. It produces strong, hermetically sealed welds with minimal thermal and mechanical stress, no particulates and very little flash. An ideal transparent polymer for LTW must have: a low laser absorbance to avoid energy loss, a low level of laser scattering so it can provide a maximum energy flux at the weld interface and also have a high resistance to thermal degradation. The objective of the project was to analyze the effect of blend ratios of polybutylene terephthalate and polyethylene terephthalate (PBT/PET) on these laser welding characteristics. The blends were manufactured by DSM (Netherlands). They were characterized using Differential Scanning Calorimetry (DSC) and Thermal Gravimetry Analysis (TGA). The latter technique was used to estimate the order (n), activation energy (ΔH) and frequency factor (A’) of the degradation reaction of the polymer blends. The normalized power profile of the laser after passing through the transparent polymer was measured using a novel non-contact technique and modeled using a semi-empirical model developed by Dr.Chen. Adding more PET ratio to the blend...

Effect of the agitation on the adsorption and hydrolytic efficiency of cutinases on polyethylene terephthalate fibres

O'Neill, Jaime Alexandre Antunes; Araújo, Rita; Casal, Margarida; Gübitz, Georg M.; Paulo, Artur Cavaco
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /06/2007 ENG
Relevância na Pesquisa
46.88%
The effect of agitation on adsorption, desorption and hydrolytic efficiency of a native and a genetically modified cutinase (L182A) on polyethylene terephthalate fibres is reported in this paper. The effect of mechanical agitation was studied using a shaker bath with orbital agitation and a Rotawash machine with vertical agitation with and without extra steel discs inside the reaction pots. The results obtained indicate that mechanical agitation combined with enzymatic action enhances the adsorption and activity of cutinases towards PET (polyethylene terephthalate) fibres. L182A showed higher adsorption than the native enzyme for all the levels of mechanical agitation. Lower units of L182A lead to similar yields of terephthalic acid formed in all levels of mechanical agitation. The highest increase of hydroxyl surface groups was found for the genetically modified L182A at the lowest level of mechanical agitation with a shaker bath. These results indicate that enzymatic functionalization of PET is favoured with a process with lower levels of mechanical agitation.

High density polyethylene (HDPE) containers as an alternative to polyethylene terephthalate (PET) bottles for solar disinfection of drinking water in northern region, Ghana; HDPE containers as an alternative to polyethylene terephthalate (PET) bottles for solar disinfection of drinking water in northern region, Ghana

Yazdani, Iman
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 115 leaves
ENG
Relevância na Pesquisa
46.99%
The purpose of this study is to investigate the technical feasibility of high density polyethylene (HDPE) containers as an alternative to polyethylene terephthalate (PET) bottles for the solar disinfection of drinking water in the Northern Region of Ghana, in a process know as SOLAIR. This study is in line with the intention of Pure Home Water, a registered non-profit organization in Ghana, to offer a variety of low-cost household water treatment and safe storage (HWTS) products as it continues to grow, including the possibility of offering a solar disinfection product in the future. If successful, SOLAIR is practically advantageous over SODIS, which uses smaller PET bottles, chiefly due to the ability to use a larger water container (2-25L), and one that is more likely to be available in a rural setting, given the widespread use of HDPE jerry cans as water collection and storage vessels in many developing countries. The main idea behind the SOLAIR system is to keep high dissolved oxygen (DO) levels in the water which, in turn, enhances disinfection. A study done by Meyer et al. (2000), in South Africa, showed that regular shaking of the water-filled HDPE container keeps DO at sufficiently high levels to augment disinfection.; (cont.) The SOLAIR results...

Structural changes in polyethylene terephthalate (PET) wastes materials caused by pyrolysis and CO2 activation

Parra Soto, José Bernardo; Ovín Ania, María Concepción; Arenillas de la Puente, Ana; Rubiera González, Fernando; Pis Martínez, José Juan; Palacios, José María
Fonte: Multi Science Publishing Publicador: Multi Science Publishing
Tipo: Artículo Formato: 918459 bytes; application/pdf
ENG
Relevância na Pesquisa
56.78%
11 pages.; For ecological reasons, there is an increasing demand for recycling polyethylene terephthalate (PET) wastes in developed countries. Although one potential application might be its utilisation for the production of activated carbons, the behaviour of these wastes when subjected to different heat treatments and activation processes is still not very well known.; In the present work, samples with different degrees of burn-off were prepared by pyrolysis in an inert atmosphere and subsequent CO2 activation at high temperatures. The derived changes in the textural and structural properties of the residual solids were studied by helium picnometry, N2 and CO2 adsorption isotherms, powder XRD, Raman spectroscopy and XPS. The study reveals that CO2 activation of PET wastes develops a carbonaceous matrix with micropores. Helium measurements showed that the mass density of the activated samples increased as the degree of burn-off increased. Characterisation studies revealed that the structural changes derived from pyrolysis and further CO2 activation mostly involved a progressive decrease in the number of structural units.; Peer reviewed

Effect of micro-patterning on bacterial adhesion on PET (polyethylene terephthalate) surface

Wang, Liyun; Chen, Wei; Terentjev, Eugene
Fonte: Sage Publicador: Sage
Tipo: Article; accepted version
EN
Relevância na Pesquisa
66.88%
This is the accepted manuscript. The final version is available from Sage at http://jba.sagepub.com/content/early/2014/12/16/0885328214563998.refs.; Bacterial adhesion on surfaces commonly used in medicine and food industry could lead to infections and illnesses. Topographically patterned surfaces recently have shown to be a promising alternative to chemical antibacterial methods, which might release cytotoxin and promote antibiotic resistance. In this study we fabricated micro-patterned polyethylene terephthalate surfaces, and quantitatively explored the amount and localization of Escherichia coli MG1655 cells attached on a series of defined topographies. The adhesion was conducted in static conditions and under a weak flow, in both physiological buffer and nutritious solutions. The results showed that in the presence of weak shear force live bacteria could still maintain sensing ability in nutritious culture, but not in buffer solution. The finely textured surface, which could inhibit bacterial adhesion in the early stage of attachment, reversed its effect to enhance the adhesion after 24 h incubation, indicating that microbial cells seemed to be able to sense the disadvantageous condition and eventually overcome it. In terms of adhesion localization...

Determination of Global Extractives in Polyethylene Terephthalate by Heating the Solvent in a Microwave Oven

Parikh, Anuj
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
67.07%
DETERMINATION OF GLOBAL EXTRACTIVES IN POLYETHYLENE TEREPHTHALATE BY HEATING THE SOLVENT IN A MICROWAVE OVEN By Anuj Vinodchandra Parikh The purpose of this research is to evaluate a method of determining extractives. Instead of a conventional oven, a microwave oven is used to heat the solvent. Attempts are made to duplicate the extraction methodology proposed by the Food and Drug Administration (FDA) in a way that it can be used to determine extractives for microwave-only packages. A test package consisting of crystalline polyethylene terephthalate and paper was selected for the test. A product consisting of a dehydrated mix of pasta and cheese sauce was evaluated to determine the test parameters including the solvent, time, and temperature. Distilled deionized water was selected as a solvent. It was exposed in two different package shapes to counter any microwave heating irregularities. The solvent was heated in packages for 10 minutes in a 700 watt microwave oven at maximum power. The extractives, in each case, were obtained by evaporating the solution under reduced temperature of 60°F (15.5°C) and in vacuum, a method commonly referred to as vacuo. A Rotavapor machine was used for this purpose. The extractives were then dried and weighed. They were further dissolved in chloroform. Chloroform-insoluble extractives were filtered out and further extraction was performed on the solution. The temperature was maintained at 35°F (1.7°C). It was found that the amount of extractives obtained by the conventional FDA method were comparable to the ones obtained by this procedure. In both cases the amount of total extractives for this package fell within the specified limits set by the FDA in milligrams per square inch of contact surface.

The Suitability of polyethylene terephthalate copolyester for radiation sterilized dry small volume parenterals

Drucker, Steven M.
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
66.88%
Small volume parenterals (SVP) are typically terminally sterilized through autoclaving. This technique works when the containers are filled with a liquid. However, in the case of sterile powders, autoclaving is not a viable method nor is dry heat since most products can not withstand 2 50C for a half hour. Thus gamma irradiation may be an acceptable method to terminally sterilize this class of product. One of the drawbacks of gamma irradiation is that it will discolor glass which is currently the package material of choice due to superior barrier properties and relative inertness. This paper explores the possibility of packaging one product in a manner to accept gamma irradiation sterilization. In doing so, the various reguirements of SVP's are reviewed. The package used was a polyethylene terephthalate copolyester (PETG) vial that could withstand the required level of radiation without any discernible effects. The product was tested to determine what level of radiation it could withstand. Finally, product was irradiated and placed on stability to determine whether this package and process are suitable. The PETG vial was found to inadequately protect this product from moisture.

A Study on Physical Aging of Semicrystalline Polyethylene Terephthalate below the Glass Transition Point

Farhoodi,M.; Mousavi,S. M.; Sotudeh-Gharebagh,R.; Emam-Djomeh,Z.; Oromiehie,A.; Mansour,H.
Fonte: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico Publicador: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2012 EN
Relevância na Pesquisa
66.88%
Physical aging of semicrystalline polyethylene terephthalate was studied using differential scanning calorimetry (DSC). PET samples with crystallinity content of 0.28 were aged at two different temperatures, 25 and 45°C. The samples were stored for several days and periodically tested using DSC method. The glass transition temperature for the samples aged at 25°C was about 73-74°C, and the position and intensity of endothermic peaks were approximately constant. Higher glass transition of the samples aged at 45°C, 73-86°C, was attributed to the enthalpy relaxation process of amorphous regions of semicrystalline PET. For the samples aged at 45°C, the endothermic peaks shifted to higher temperatures with increasing aging time. The position of the endothermic peaks determined by the temperature of the maximum, Tmax, tended to increase with aging time for samples aged at 45°C, and the intensity of the peaks continuously increased with time; however, the results showed that the aging of PET samples at 45°C even after 120 days continued the enthalpic relaxation of semicrystalline PET and that the process could be studied by DSC method. The results also showed that the aging process could affect the final degree of crystallinity of c-PET samples and the samples stored at 45°C showed higher degree of crystallinity than the samples aged at 25°C.