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dc.contributor.author
Quispe, Mayte Milenka
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dc.contributor.author
Lopez, Olivia Valeria
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dc.contributor.author
Villar, Marcelo Armando
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dc.date.available
2020-06-25T17:53:55Z
dc.date.issued
2019-04
dc.identifier.citation
Quispe, Mayte Milenka; Lopez, Olivia Valeria; Villar, Marcelo Armando; Oxidative Degradation of Thermoplastic Starch Induced by UV Radiation; Tech Science Press; Journal of Renewable Materials; 7; 4; 4-2019; 383-391
dc.identifier.issn
2164-6325
dc.identifier.uri
http://hdl.handle.net/11336/108246
dc.description.abstract
Among biopolymers, thermoplastic starch (TPS) is a good candidate to obtain biomaterials because of its natural origin, biodegradable character, and processability. Exposure to ultraviolet (UV) radiation causes significant degradation of starch-based materials, inducing photooxidative reactions which result in breaking of polymer chains, production of free radical, and reduction of molar mass. These changes produce a deterioration of TPS mechanical properties, leading to useless materials after an unpredictable time. In this work, changes induced on TPS by UV radiation, analyzing structural properties and mechanical behavior, are studied. TPS was obtained through thermo-mechanical processing of native corn starch in the presence of water (45 % w/w) and glycerol (30 % w/w) as plasticizers. Films were obtained by thermocompression and, before testing, specimens were conditioned to reduce material fragility. Photodegradation process was performed by exposing TPS to 264 h UV radiation in a weathering test chamber. Specimens weight loss was determined gravimetrically. Chemical changes were studied by Fourier Transform Infrared Spectroscopy (FTIR) and morphological modifications were analyzed by Scanning Electron Microscopy (SEM). Reduction of weight average molar mass was measured by Static Light Scattering (SLS). Changes in mechanical properties were studied from tensile tests. After 96 h exposure, TPS specimens presented a weight reduction of 4-6%, mainly attributed to plasticizers lost by evaporation. SEM observations showed that UV radiation induced morphological changes on TPS, evidenced by an increment of specimens cracking. By FTIR, it was detected the presence of an additional band located at 1726 cm-1 in samples submitted to UV radiation, attributed to the formation of -C=O groups. Weight average molar mass of native starch was in the order of 107 g mol-1. TPS exposure to UV radiation decreased significantly its molar mass, confirming molecular degradation of the biopolymer. When TPS was exposed during 48 h, it was detected a considerable decrease in elongation at break values (~ 85%), indicating that TPS flexibility was reduced. On the other hand, after 48 h exposure, TPS elastic modulus was 55 times higher than those of the unexposed specimens, evidencing an increase in material rigidity. TPS maximum tensile strength was also increased by UV light, with an increment of ~ 400% after 48 h exposure. Results revealed that starch-based materials can be degraded by exposure to UV radiation, modifying their microstructure and mechanical performance.
dc.format
application/pdf
dc.language.iso
eng
dc.publisher
Tech Science Press
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dc.rights
info:eu-repo/semantics/openAccess
dc.rights.uri
https://creativecommons.org/licenses/by/2.5/ar/
dc.subject
THERMOPLASTIC STARCH
dc.subject
UV RADIATION
dc.subject
STRUCTURAL PROPERTIES
dc.subject
MECHANICAL PROPERTIES
dc.subject.classification
Ingeniería de los Materiales
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dc.subject.classification
Ingeniería de los Materiales
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dc.subject.classification
INGENIERÍAS Y TECNOLOGÍAS
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dc.title
Oxidative Degradation of Thermoplastic Starch Induced by UV Radiation
dc.type
info:eu-repo/semantics/article
dc.type
info:ar-repo/semantics/artículo
dc.type
info:eu-repo/semantics/publishedVersion
dc.date.updated
2020-02-26T20:21:36Z
dc.journal.volume
7
dc.journal.number
4
dc.journal.pagination
383-391
dc.journal.pais
Estados Unidos
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dc.journal.ciudad
Nevada
dc.description.fil
Fil: Quispe, Mayte Milenka. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina
dc.description.fil
Fil: Lopez, Olivia Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina
dc.description.fil
Fil: Villar, Marcelo Armando. Universidad Nacional del Sur. Departamento de Ingeniería Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina
dc.journal.title
Journal of Renewable Materials
dc.relation.alternativeid
info:eu-repo/semantics/altIdentifier/url/http://www.techscience.com/JRM/2019/doi.php?id=5730
dc.relation.alternativeid
info:eu-repo/semantics/altIdentifier/doi/http://dx.doi.org/10.32604/jrm.2019.04276
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