Properties of poly(lactic acid) in presence of cellulose and chitin nanocrystals
Plastic based materials are widely used for packaging applications. However, disposal of such petroleum-based materials e.g. polyethylene (PE) and polypropylene (PP) has become a huge threat to the environment due to its non-biodegradable behavior and complexity for waste management. For a sustainab...
| Autor: | |
|---|---|
| Formato: | tesis doctoral |
| Fecha de publicación: | 2020 |
| País: | España |
| Recursos: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/346401 |
| Acesso em linha: | https://hdl.handle.net/2117/346401 https://dx.doi.org/10.5821/dissertation-2117-346401 |
| Access Level: | acceso abierto |
| Palavra-chave: | Poly(lactic acid) Chitin nanocrystals Cellulose nanocrystals Crystallization Nanocomposites Mechanical properties Àrees temàtiques de la UPC::Enginyeria dels materials |
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Properties of poly(lactic acid) in presence of cellulose and chitin nanocrystals |
| title |
Properties of poly(lactic acid) in presence of cellulose and chitin nanocrystals |
| spellingShingle |
Properties of poly(lactic acid) in presence of cellulose and chitin nanocrystals Singh, Shikha Poly(lactic acid) Chitin nanocrystals Cellulose nanocrystals Crystallization Nanocomposites Mechanical properties Àrees temàtiques de la UPC::Enginyeria dels materials |
| title_short |
Properties of poly(lactic acid) in presence of cellulose and chitin nanocrystals |
| title_full |
Properties of poly(lactic acid) in presence of cellulose and chitin nanocrystals |
| title_fullStr |
Properties of poly(lactic acid) in presence of cellulose and chitin nanocrystals |
| title_full_unstemmed |
Properties of poly(lactic acid) in presence of cellulose and chitin nanocrystals |
| title_sort |
Properties of poly(lactic acid) in presence of cellulose and chitin nanocrystals |
| dc.creator.none.fl_str_mv |
Singh, Shikha |
| author |
Singh, Shikha |
| author_facet |
Singh, Shikha |
| author_role |
author |
| dc.contributor.none.fl_str_mv |
Oksman, Kristiina Maspoch Rulduà, M. Lluïsa Geng, Shiyu |
| dc.subject.none.fl_str_mv |
Poly(lactic acid) Chitin nanocrystals Cellulose nanocrystals Crystallization Nanocomposites Mechanical properties Àrees temàtiques de la UPC::Enginyeria dels materials |
| topic |
Poly(lactic acid) Chitin nanocrystals Cellulose nanocrystals Crystallization Nanocomposites Mechanical properties Àrees temàtiques de la UPC::Enginyeria dels materials |
| description |
Plastic based materials are widely used for packaging applications. However, disposal of such petroleum-based materials e.g. polyethylene (PE) and polypropylene (PP) has become a huge threat to the environment due to its non-biodegradable behavior and complexity for waste management. For a sustainable industrial and economic development, it is indeed an urgency to develop packaging materials, which are environmentally benign, easy for waste treatment and recycling, and less/non-toxic. However, developing suitable and efficient plastic-substituents needs multiple requirements to be fulfilled viz., logistics and cost-effectiveness, good mechanical, thermal, optical and barrier properties, structural integrity of the constituents and morphological properties of the films. In this regard, utilizing bio-based polymers such as poly(lactic acid) (PLA), which originates from the natural resources, can be a viable and practical option due to its low toxicity, biodegradability, and eco-friendly behavior. Moreover, PLA has good optical and mechanical properties, which are similar or comparable to the some of the petroleum-based materials. However, pristine PLA possess few challenges such as slow crystallization rate, low crystallinity, poor toughness, and poor barrier properties, which need to be modified and fine-tuned. Utilizing nano-reinforcements, such as nanocellulose and nanochitin, is a promising approach for modifying PLA because of raw materials abundancy; easily obtainable from forest-based and bio-waste, hence, utilizing such materials also help the sustainable bioeconomy. Chitin nanocrystals (ChNCs) and cellulose nanocrystals (CNCs) possess unique properties, such as, low density, biodegradability, low toxicity, good mechanical, and barrier properties; therefore, can act as suitable nano-reinforcements for PLA. First segment of the research was aimed to understand and gain an insight about the role of ChNCs on the crystallization behavior of PLA and optimize the isothermal crystallization conditions. ChNCs, due to large surface area, acted as better nucleating agent and improved the overall crystallization rate of PLA by reducing the crystallization time and size of the spherulites. In second part of the research, knowledge gained about crystallization behavior was further explored to produce isothermally crystallized films at larger scale. The effect of crystallinity on the thermal, optical, barrier, and hydrolytic degradation properties of the nanocomposites were investigated. Noticeably, at 110ºC, the highest rate of crystallization achieved within 5 min. Furthermore, homogenous crystallization and smaller spherulite size (7 nm) of PLA achieved with ChNCs, significantly improved the crystallinity, thermal, barrier, and hydrolytic degradation properties. Third part of the research involved the study of mechanical properties of oriented films (PLA/ChNCs) achieved by a combination of solid-state and melt-state drawings. These oriented PLA nanocomposites films exhibited excellent mechanical properties. For example, a tensile strength with 360%, elongation at break with 2400%, and the toughness with 9500% increment achieved as compared to un-oriented nanocomposite films. The degree of crystallinity of highly oriented nanocomposite films increased from 8% to 53% with respect to the un-oriented nanocomposite films and smaller crystallites sizes were observed. Finally, in the fourth part, mechanical properties of the surface modified PLA/CNCs nanocomposites were investigated by a conventional tensile test and compared with the small punch test. Surface modification of CNC facilitated the dispersion of CNC into PLA matrix and increased the elastic modulus of the PLA/CNC nanocomposites. Knowledge and results gained in this thesis demonstrate the potential path for the development of the PLA nanocomposites with higher properties for packaging applications. |
| publishDate |
2020 |
| dc.date.none.fl_str_mv |
2020 2020-10-09 2021 2021-05-30 |
| dc.type.none.fl_str_mv |
doctoral thesis http://purl.org/coar/resource_type/c_db06 VoR http://purl.org/coar/version/c_970fb48d4fbd8a85 |
| dc.type.openaire.fl_str_mv |
info:eu-repo/semantics/doctoralThesis |
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doctoralThesis |
| dc.identifier.none.fl_str_mv |
https://hdl.handle.net/2117/346401 https://dx.doi.org/10.5821/dissertation-2117-346401 |
| url |
https://hdl.handle.net/2117/346401 https://dx.doi.org/10.5821/dissertation-2117-346401 |
| dc.language.none.fl_str_mv |
Inglés eng |
| language_invalid_str_mv |
Inglés |
| language |
eng |
| dc.rights.none.fl_str_mv |
open access http://purl.org/coar/access_right/c_abf2 |
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info:eu-repo/semantics/openAccess |
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open access http://purl.org/coar/access_right/c_abf2 |
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openAccess |
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application/pdf |
| dc.publisher.none.fl_str_mv |
Universitat Politècnica de Catalunya |
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Universitat Politècnica de Catalunya |
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reponame:UPCommons. Portal del coneixement obert de la UPC instname:Universitat Politècnica de Catalunya (UPC) |
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Universitat Politècnica de Catalunya (UPC) |
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UPCommons. Portal del coneixement obert de la UPC |
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UPCommons. Portal del coneixement obert de la UPC |
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Properties of poly(lactic acid) in presence of cellulose and chitin nanocrystalsSingh, ShikhaPoly(lactic acid)Chitin nanocrystalsCellulose nanocrystalsCrystallizationNanocompositesMechanical propertiesÀrees temàtiques de la UPC::Enginyeria dels materialsPlastic based materials are widely used for packaging applications. However, disposal of such petroleum-based materials e.g. polyethylene (PE) and polypropylene (PP) has become a huge threat to the environment due to its non-biodegradable behavior and complexity for waste management. For a sustainable industrial and economic development, it is indeed an urgency to develop packaging materials, which are environmentally benign, easy for waste treatment and recycling, and less/non-toxic. However, developing suitable and efficient plastic-substituents needs multiple requirements to be fulfilled viz., logistics and cost-effectiveness, good mechanical, thermal, optical and barrier properties, structural integrity of the constituents and morphological properties of the films. In this regard, utilizing bio-based polymers such as poly(lactic acid) (PLA), which originates from the natural resources, can be a viable and practical option due to its low toxicity, biodegradability, and eco-friendly behavior. Moreover, PLA has good optical and mechanical properties, which are similar or comparable to the some of the petroleum-based materials. However, pristine PLA possess few challenges such as slow crystallization rate, low crystallinity, poor toughness, and poor barrier properties, which need to be modified and fine-tuned. Utilizing nano-reinforcements, such as nanocellulose and nanochitin, is a promising approach for modifying PLA because of raw materials abundancy; easily obtainable from forest-based and bio-waste, hence, utilizing such materials also help the sustainable bioeconomy. Chitin nanocrystals (ChNCs) and cellulose nanocrystals (CNCs) possess unique properties, such as, low density, biodegradability, low toxicity, good mechanical, and barrier properties; therefore, can act as suitable nano-reinforcements for PLA. First segment of the research was aimed to understand and gain an insight about the role of ChNCs on the crystallization behavior of PLA and optimize the isothermal crystallization conditions. ChNCs, due to large surface area, acted as better nucleating agent and improved the overall crystallization rate of PLA by reducing the crystallization time and size of the spherulites. In second part of the research, knowledge gained about crystallization behavior was further explored to produce isothermally crystallized films at larger scale. The effect of crystallinity on the thermal, optical, barrier, and hydrolytic degradation properties of the nanocomposites were investigated. Noticeably, at 110ºC, the highest rate of crystallization achieved within 5 min. Furthermore, homogenous crystallization and smaller spherulite size (7 nm) of PLA achieved with ChNCs, significantly improved the crystallinity, thermal, barrier, and hydrolytic degradation properties. Third part of the research involved the study of mechanical properties of oriented films (PLA/ChNCs) achieved by a combination of solid-state and melt-state drawings. These oriented PLA nanocomposites films exhibited excellent mechanical properties. For example, a tensile strength with 360%, elongation at break with 2400%, and the toughness with 9500% increment achieved as compared to un-oriented nanocomposite films. The degree of crystallinity of highly oriented nanocomposite films increased from 8% to 53% with respect to the un-oriented nanocomposite films and smaller crystallites sizes were observed. Finally, in the fourth part, mechanical properties of the surface modified PLA/CNCs nanocomposites were investigated by a conventional tensile test and compared with the small punch test. Surface modification of CNC facilitated the dispersion of CNC into PLA matrix and increased the elastic modulus of the PLA/CNC nanocomposites. Knowledge and results gained in this thesis demonstrate the potential path for the development of the PLA nanocomposites with higher properties for packaging applications.Para un desarrollo industrial y económico sostenible, es urgente disponer de materiales para envases y embalajes que sean ambientalmente benignos, cuyos residuos sean fáciles de tratar y reciclar y que sean atóxicos. Sin embargo, el desarrollo de sustituyentes plásticos adecuados y eficientes requiere que se cumplan múltiples requisitos, a saber, rentabilidad y buenas propiedades mecánicas, térmicas, ópticas y de barrera, así como integridad estructural de los constituyentes. En este sentido, la utilización de polímeros biobasados, como el ácido poliláctico (PLA), que se obtiene de fuentes renovables, puede ser una opción viable debido a su baja toxicidad, biodegradabilidad y baja huella de carbono. Además, el PLA tiene buenas propiedades ópticas y mecánicas, que son similares o comparables a algunos de los materiales obtenidos a partir del petróleo. Sin embargo, presenta algunos inconvenientes, como su lenta velocidad de cristalización, baja cristalinidad, fragilidad y deficientes propiedades barrera, que deberían modificarse y ajustarse para su uso industrial extensivo. La utilización de nano-refuerzos, como la nanocelulosa y la nanoquitina, es un enfoque prometedor para modificar y mejorar el desempeño del PLA. Estos refuerzos proceden de materias primas abundantes, son fácilmente obtenible a partir de residuos forestales y biorresiduos, por lo que la utilización de dichos materiales también ayuda al desarrollo de una economía más sostenible. Los nanocristales de quitina (ChNC) y los nanocristales de celulosa (CNC) poseen propiedades únicas, como baja densidad, biodegradabilidad, baja toxicidad, buenas propiedades mecánicas y de barrera; por lo tanto, pueden actuar como nano-refuerzos adecuados para mejorar el PLA. La primera etapa de la investigación tuvo como objetivo comprender el papel de las ChNC en el proceso de cristalización del PLA y optimizar las condiciones de cristalización isotérmica. Los ChNC, debido a su gran área superficial, actuaron como un buen agente nucleante y mejoraron la tasa de cristalización general de PLA al reducir el tiempo de cristalización y el tamaño de las esferulitas. En la segunda parte de la tesis, se exploró más a fondo el conocimiento adquirido sobre el comportamiento de la cristalización para producir películas cristalizadas isotérmicamente a mayor escala. Se investigó el efecto de la cristalinidad sobre varias propiedades de los nanocompuestos obtenidos. Se puede destacar que a 110ºC, en 5 min se alcanzó la mayor tasa de cristalización. Además, la cristalización fue homogénea y se obtuvo el tamaño esferulítico de PLA más pequeño (7 nm), mejoraron significativamente las propiedades térmicas, barrera y la degradación hidrolítica. En tercer lugar, se estudiaron las propiedades mecánicas de películas de (PLA / ChNC) orientadas, obtenidas mediante una combinación de estiramiento en estado sólido y en estado fundido. Estas películas de nanocomposites de PLA orientado exhibieron excelentes propiedades mecánicas, con incrementos del 360% de la resistencia a la tracción, 2400% de la elongación a la rotura y 9500% de la tenacidad en comparación con las películas de nanocompuestos no orientados. El grado de cristalinidad de las películas de nanocompuestos altamente orientados aumentó del 8% al 53% con respecto a las películas no orientadas y se observaron tamaños de cristalitas más pequeños. Finalmente, se investigaron las propiedades mecánicas de nanocompuestos PLA / CNC mediante ensayos de tracción convencionales y se compararon con los resultados de los ensayos de "small punch" (SPT). La modificación superficial de los CNC facilitó su dispersión en la matriz de PLA e incrementó el módulo elástico de dichos materiales. El conocimiento y resultados obtenidos con esta tesis demuestran el potencial para desarrollar nanocomposites de PLA con altas propiedades para aplicaciones de envase y embalajes.Universitat Politècnica de CatalunyaOksman, KristiinaMaspoch Rulduà, M. LluïsaGeng, Shiyu20202020-10-0920212021-05-30doctoral thesishttp://purl.org/coar/resource_type/c_db06VoRhttp://purl.org/coar/version/c_970fb48d4fbd8a85info:eu-repo/semantics/doctoralThesisapplication/pdfhttps://hdl.handle.net/2117/346401https://dx.doi.org/10.5821/dissertation-2117-346401reponame:UPCommons. Portal del coneixement obert de la UPCinstname:Universitat Politècnica de Catalunya (UPC)Inglésengopen accesshttp://purl.org/coar/access_right/c_abf2info:eu-repo/semantics/openAccessoai:upcommons.upc.edu:2117/3464012026-05-27T15:37:01Z |
| score |
15,198674 |