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Vargas, Natalia HerreraORCID iD iconorcid.org/0000-0002-2906-2470
Alternative names
Publications (10 of 16) Show all publications
Singh, A. A., Geng, S., Herrera Vargas, N. & Oksman, K. (2018). Aligned plasticized polylactic acid cellulose nanocomposite tapes: Effect of drawing conditions. Composites. Part A, Applied science and manufacturing, 104, 101-107
Open this publication in new window or tab >>Aligned plasticized polylactic acid cellulose nanocomposite tapes: Effect of drawing conditions
2018 (English)In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 104, p. 101-107Article in journal (Refereed) Published
Abstract [en]

Aligned nanocomposite tapes based on plasticized polylactic acid (PLA) and 1 wt.% cellulose nanofibers (CNF) were prepared using uniaxial solid-state drawing, and the effects of drawing conditions including temperature, speed and draw ratio on the material were studied. Microscopy studies confirmed alignment and the formation of ‘shish-kebab’ morphology in the drawn tape. Mechanical properties demonstrate that the solid-state drawing is a very effective way to produce stronger and tougher PLA nanocomposites, and the toughness can be improved 60 times compared to the undrawn tape. Additionally, the thermal properties, i.e. storage modulus, glass transition temperature and degree of crystallinity were improved. These improvements are expected due to the synergistic effect of CNF in the nanocomposite and orientations induced by the solid-state drawing.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Nanocomposites, Mechanical properties, Thermal properties, Microstructural analysis
National Category
Composite Science and Engineering Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-64862 (URN)10.1016/j.compositesa.2017.10.019 (DOI)000418966900010 ()2-s2.0-85032722515 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-11-14 (andbra)

Available from: 2017-07-13 Created: 2017-07-13 Last updated: 2019-09-13Bibliographically approved
Singh, A. A., Wei, J., Vargas, N. H., Geng, S. & Oksman, K. (2018). Synergistic effect of chitin nanocrystals and orientations induced by solid-state drawing on PLA-based nanocomposite tapes. Composites Science And Technology, 162, 140-145
Open this publication in new window or tab >>Synergistic effect of chitin nanocrystals and orientations induced by solid-state drawing on PLA-based nanocomposite tapes
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2018 (English)In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 162, p. 140-145Article in journal (Refereed) Published
Abstract [en]

Uniaxial solid-state drawing was used to orientate plasticized polylactic acid (PLA) and its nanocomposite tapes with 1 and 5 wt% chitin nanocrystals (ChNC). Microscopy studies confirmed the orientation and formation of a ‘shish-kebab’ morphology in the drawn tapes. The mechanical properties demonstrated that the drawing led to stronger and tougher nanocomposites compared to plasticized PLA. The tensile strength increased from 41 MPa to 71 MPa, and the elongation at break increased from 5% to 60% for the nanocomposite with 5 wt% ChNC and a draw ratio of 3. The ChNC had a positive effect on the thermomechanical properties; the tan delta peak shifted to a higher temperature with an increasing ChNC content. These improvements in the mechanical and thermal properties are expected synergistic effects of both the ChNC in the nanocomposite and the alignment of the ChNC together with the polymer chains induced by the solid-state drawing.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-68545 (URN)10.1016/j.compscitech.2018.04.034 (DOI)000438180500017 ()2-s2.0-85046361270 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-05-03 (andbra)

Available from: 2018-04-30 Created: 2018-04-30 Last updated: 2018-08-09Bibliographically approved
Herrera Vargas, N. (2017). Processing and properties of nanocomposites based on polylactic acid, chitin and cellulose. (Doctoral dissertation). Luleå: Luleå University of Technology
Open this publication in new window or tab >>Processing and properties of nanocomposites based on polylactic acid, chitin and cellulose
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The production of bio-based and biodegradable nanocomposites has gained attention during recent years for environmental reasons; however, the large-scale production of these nanocomposites still poses challenges. The objective of this work has been to prepare bio-based and biodegradable nanocomposites via liquid-assisted extrusion and to gain a deeper understanding of the process and the relationship between the process, composition, structure and properties. Extrusion is a common industrial process and thus, the development of this technique for the preparation of bionanocomposites can promote the commercialization of these materials in future.

In this work, nanocomposites based on polylactic acid (PLA), cellulose nanofibers (CNF), cellulose nanocrystals (CNC), and chitin nanocrystals (ChNC) with varying nanomaterial content were prepared via liquid-assisted extrusion using a plasticizer as a dispersing and processing aid. This process consists of dispersing the nanomaterial in a liquid composed of water, a plasticizer and/or a solvent, and then feeding this suspension directly into the extruder during the process. To be able to carry out this process successfully, parameters such as the amount of liquid, the liquid feeding rate or the water-to-solvent ratio, among others, should be taken in account.

CNF and ChNC were produced from banana rachis waste and crustacean waste, respectively, whereas CNC were available as a commercial product. Glycerol triacetate (GTA) and triethyl citrate (TEC) were used as plasticizers, dispersing and processing aids. The effects of the liquids used during extrusion, the plasticizers and the nanomaterials in the PLA properties were studied. Furthermore, the effects of the cooling rate during the compression molding and the solid-state drawing on the properties of the PLA nanocomposites were investigated. Additionally, the effect of ChNC on the processing and properties of blown films was evaluated.

The results presented in this work demonstrated that the use of water and a solvent during the liquid-assisted extrusion did not decrease the molecular weight of the PLA. It was also found that the feeding of nanomaterials in aqueous or aqueous/solvent suspension resulted in PLA micro-composite with lower mechanical properties than PLA. However, when a nanomaterial was fed together with a plasticizer, its dispersion and distribution into the PLA were progressively improved with increasing plasticizer content. The plasticized PLA nanocomposites showed improved properties compared to their respective counterpart without nanomaterials when the plasticizer content was ≥7.5 wt%. Furthermore, it was demonstrated that the properties of PLA can be tailored through the composition of the nanocomposite or during the processing. It was observed that the modification of PLA with only plasticizer in high amounts (20 wt%) resulted in enhanced elongation at break and toughness but it had negative effects on the thermal and mechanical properties; however, the incorporation of nanomaterials minimized these effects. The addition of a small amount of nanomaterial (1 wt%), either CNF, CNC or ChNC, to plasticized PLA resulted in enhanced mechanical properties. It was also demonstrated that the cooling rate during compression molding and the solid-state drawing significantly affected the crystallinity of the PLA nanocomposites and, thus, their final properties. The fast cooling rate during compression molding resulted in more flexible and transparent materials than when a slow cooling rate was used, and as a result, PLA films with different mechanical properties were obtained. The drawing of the PLA/CNF nanocomposite at a drawing temperature slightly above the Tg, a high draw speed and at the highest drawing ratio, resulted in the highest mechanical properties. It was also found that the increased toughness after adding CNF to the plasticized PLA or after drawing the PLA/CNF nanocomposite, was attributed to the occurrence of massive crazing effect as a result of the presence of CNF and its effect on the crystallinity and/or on the spherulite growth. Finally, 6 kg of plasticized PLA nanocomposite with 5 wt% of ChNC was prepared and used as a masterbatch to produce bio-nanocomposite blown films. The nanocomposite material showed easier processability during the film-blowing process when compared with the reference material without nanocrystals. In addition, the nanocomposite blown films exhibited higher tear and puncture strength, lower fungal activity and lower electrostatic attraction properties, which are favorable in packaging applications. 

In conclusion, this thesis shows that the liquid-assisted extrusion process is an excellent approach for producing PLA nanocomposites using cellulose and chitin nanomaterials. The results indicated that the addition of these nanomaterials, together with a plasticizer and further processing, can result in PLA nanocomposites with varied properties that can be used for packing applications. It was also shown that the processing technique presented can be a step forward for the large-scale production of bionanocomposites.

 

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2017
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Keywords
Nanocomposite, Cellulose, Chitin, Extrusion, Polylactic acid
National Category
Composite Science and Engineering
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-64863 (URN)978-91-7583-929-5 (ISBN)978-91-7583-930-1 (ISBN)
Public defence
2017-09-15, E632, Luleå University of Technology, Luleå, 10:00 (English)
Opponent
Supervisors
Available from: 2017-08-11 Created: 2017-07-13 Last updated: 2017-11-24Bibliographically approved
Herrera Vargas, N., Singh, A. A., Salaberria, A. M., Labidi, J., Mathew, A. P. & Oksman, K. (2017). Triethyl Citrate (TEC) as a Dispersing Aid in Polylactic Acid/Chitin Nanocomposites Prepared via Liquid-Assisted Extrusion. Polymers, 9(9), Article ID 406.
Open this publication in new window or tab >>Triethyl Citrate (TEC) as a Dispersing Aid in Polylactic Acid/Chitin Nanocomposites Prepared via Liquid-Assisted Extrusion
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2017 (English)In: Polymers, ISSN 2073-4360, E-ISSN 2073-4360, Vol. 9, no 9, article id 406Article in journal (Refereed) Published
Abstract [en]

The production of fully bio-based and biodegradable nanocomposites has gained attention during recent years due to environmental reasons; however, the production of these nanocomposites on the large-scale is challenging. Polylactic acid/chitin nanocrystal (PLA/ChNC) nanocomposites with triethyl citrate (TEC) at varied concentrations (2.5, 5.0, and 7.5 wt %) were prepared using liquid-assisted extrusion. The goal was to find the minimum amount of the TEC plasticizer needed to enhance the ChNC dispersion. The microscopy study showed that the dispersion and distribution of the ChNC into PLA improved with the increasing TEC content. Hence, the nanocomposite with the highest plasticizer content (7.5 wt %) showed the highest optical transparency and improved thermal and mechanical properties compared with its counterpart without the ChNC. Gel permeation chromatography confirmed that the water and ethanol used during the extrusion did not degrade PLA. Further, Fourier transform infrared spectroscopy showed improved interaction between PLA and ChNC through hydrogen bonding when TEC was added. All results confirmed that the plasticizer plays an important role as a dispersing aid in the processing of PLA/ChNC nanocomposites.

Place, publisher, year, edition, pages
MDPI, 2017
National Category
Composite Science and Engineering Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-64861 (URN)10.3390/polym9090406 (DOI)000411524400023 ()2-s2.0-85028948522 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-09-05 (rokbeg)

Available from: 2017-07-13 Created: 2017-07-13 Last updated: 2017-11-29Bibliographically approved
Vargas, N. H., Roch, H., Salaberria, A. M., Pino, M. A., Labidi, J., Fernandes, S. M., . . . Oksman, K. (2016). Functionalized blown films of plasticized polylactic acid/chitin nanocomposite: Preparation and characterization (ed.). Paper presented at . Materials & design, 92, 846-852
Open this publication in new window or tab >>Functionalized blown films of plasticized polylactic acid/chitin nanocomposite: Preparation and characterization
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2016 (English)In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 92, p. 846-852Article in journal (Refereed) Published
Abstract [en]

Bionanocomposite films prepared with melt compounding and film blowing were evaluated for packaging applications. The nanocomposite masterbatch with 75 wt% polylactic acid (PLA), 5 wt% chitin nanocrystals (ChNCs) and 20 wt% glycerol triacetate plasticizer (GTA) was melt compounded and then diluted to 1 wt% ChNCs with PLA and polybutylene adipate-co-terephthalate (PBAT) prior to film blowing. The morphological, mechanical, optical, thermal and barrier properties of the blown nanocomposite films were studied and compared with the reference material without ChNCs. The addition of 1 wt% ChNCs increased the tear strength by 175% and the puncture strength by 300%. Additionally, the small amount of chitin nanocrystals affected the glass transition temperature (Tg), which increased 4 °C compared with the reference material and slightly enhanced the films degree of crystallinity. The chitin nanocomposite also had lower fungal activity and lower electrostatic attraction between the film surfaces; leading to easy opening of the plastic bags. The barrier and optical properties as well as the thermal degradation of the films were not significantly influenced by the addition of chitin nanocrystals.

National Category
Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-10899 (URN)10.1016/j.matdes.2015.12.083 (DOI)000369191900097 ()2-s2.0-84954525542 (Scopus ID)9c73f46c-c3e5-4bd1-bdb2-e42bc9a9a2f3 (Local ID)9c73f46c-c3e5-4bd1-bdb2-e42bc9a9a2f3 (Archive number)9c73f46c-c3e5-4bd1-bdb2-e42bc9a9a2f3 (OAI)
Note
Validerad; 2016; Nivå 2; 20151218 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Vargas, N. H., Salaberria, A. M., Mathew, A. P. & Oksman, K. (2016). Plasticized polylactic acid nanocomposite films with cellulose and chitin nanocrystals prepared using extrusion and compression molding with two cooling rates: effects on mechanical, thermal and optical properties (ed.). Composites. Part A, Applied science and manufacturing, 83, 89-97
Open this publication in new window or tab >>Plasticized polylactic acid nanocomposite films with cellulose and chitin nanocrystals prepared using extrusion and compression molding with two cooling rates: effects on mechanical, thermal and optical properties
2016 (English)In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 83, p. 89-97Article in journal (Refereed) Published
Abstract [en]

Triacetate citrate plasticized poly lactic acid and its nanocomposites based on cellulose nanocrystals (CNC) and chitin nanocrystals (ChNC) were prepared using a twin-screw extruder. The materials were compression molded to films using two different cooling rates. The cooling rates and the addition of nanocrystals (1 wt%) had an impact on the crystallinity as well as the optical, thermal and mechanical properties of the films. The fast cooling resulted in more amorphous materials, increased transparency and elongation to break, (approx. 300%) when compared with slow cooling. Chitin nanocomposites were more transparent than cellulose nanocomposites; however, microscopy study showed presence of agglomerations in both materials. The mechanical properties of the plasticized PLA were improved with the addition of a small amount of nanocrystals resulting in PLA nanocomposites, which will be further evaluated for film blowing and thus packaging applications.

National Category
Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-7124 (URN)10.1016/j.compositesa.2015.05.024 (DOI)000372383800010 ()2-s2.0-84958867137 (Scopus ID)5711653a-fb96-48fd-a068-58adc0f9bfc6 (Local ID)5711653a-fb96-48fd-a068-58adc0f9bfc6 (Archive number)5711653a-fb96-48fd-a068-58adc0f9bfc6 (OAI)
Note

Validerad; 2016; Nivå 2; 20150604 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Vargas, N. H., Mathew, A. P. & Oksman, K. (2015). Plasticized polylactic acid/cellulose nanocomposites prepared using melt-extrusion and liquid feeding: Mechanical, thermal and optical properties (ed.). Paper presented at . Composites Science And Technology, 106, 149-155
Open this publication in new window or tab >>Plasticized polylactic acid/cellulose nanocomposites prepared using melt-extrusion and liquid feeding: Mechanical, thermal and optical properties
2015 (English)In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 106, p. 149-155Article in journal (Refereed) Published
Abstract [en]

Plasticized polylactic acid (PLA) and its nanocomposite based on cellulose nanofibers (CNF) and glycerol triacetate (GTA) were prepared using a co-rotating twin-screw extruder. GTA was used as a plasticizer, a processing aid to facilitate nanofiber dispersion and as a liquid medium for their feeding. The optical, thermal and mechanical properties were characterized and the toughening mechanism was studied. The addition of GTA (20%) and CNF (1%) resulted in increased degree of crystallinity and decreased optical transparency. Furthermore, these additives showed a positive effect on the elongation at break and toughness, which increased from 2 to 31% and from 1 to 8 MJ/m3, respectively. The combination of slippage of the nanofiber-matrix interface and a massive crazing effect as a result of the presence of CNF is suggested for PLA toughening. CNF were expected to restrict the spherulite growth and therefore enhance the craze nucleation.

National Category
Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-4891 (URN)10.1016/j.compscitech.2014.11.012 (DOI)000347868200016 ()2-s2.0-84919662336 (Scopus ID)2e4361c2-65ef-4231-bacc-e850b5eb33e7 (Local ID)2e4361c2-65ef-4231-bacc-e850b5eb33e7 (Archive number)2e4361c2-65ef-4231-bacc-e850b5eb33e7 (OAI)
Note
Validerad; 2015; Nivå 2; 20141002 (krioks)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Vargas, N. H., Roggio, G. & Oksman, K. (2014). Extrusion of PLA nanocomposites using liquid feeding of cellulose/chitin nanocrystals (ed.). Paper presented at Workshop Green Chemistry and Nanotechnologies in Polymer Chemistry : ECLIPSE Workshop, BIOPURFIL Workshop 09/07/2014 - 11/09/2014. Paper presented at Workshop Green Chemistry and Nanotechnologies in Polymer Chemistry : ECLIPSE Workshop, BIOPURFIL Workshop 09/07/2014 - 11/09/2014.
Open this publication in new window or tab >>Extrusion of PLA nanocomposites using liquid feeding of cellulose/chitin nanocrystals
2014 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

In the current study, poly lactic acid (PLA) composites based on cellulose and chitin nanocrystals were prepared by compounding extrusion using liquid feeding. Triacetate citrate (TEC) was used as additive to facilitate the dispersion and distribution of the nanocrystals as well as liquid vehicle to incorporate them into the extruder. Each nanocrystals material was first dispersed in specific amount of ethanol and then mixed with a fixed amount of TEC in order to prepare nanocomposites with 5 wt% of nanocrystals and 20 wt% of TEC. The prepared nanocomposites were compression molded to films and then characterized. The morphology and the mechanical properties were studied. From the point of view of processing, the liquid feeding of nanocrystals was possible; however some agglomerations were observed but even that the mechanical properties of the plasticized PLA were improved.

National Category
Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-28363 (URN)224c8631-66d3-453f-9f68-a501c66cd396 (Local ID)224c8631-66d3-453f-9f68-a501c66cd396 (Archive number)224c8631-66d3-453f-9f68-a501c66cd396 (OAI)
Conference
Workshop Green Chemistry and Nanotechnologies in Polymer Chemistry : ECLIPSE Workshop, BIOPURFIL Workshop 09/07/2014 - 11/09/2014
Note
Godkänd; 2014; 20141014 (nather)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Vargas, N. H., Mathew, A. P. & Oksman, K. (2014). Manufacturing tougher PLA by the liquid feeding of cellulose nanofiberes and plasticizer (ed.). In: (Ed.), (Ed.), SPE Proceeding ANTEC2014: . Paper presented at ANTEC 2014 : 28/04/2014 - 30/04/2014. : Society of Plastics Engineers Incorporated (SPE)
Open this publication in new window or tab >>Manufacturing tougher PLA by the liquid feeding of cellulose nanofiberes and plasticizer
2014 (English)In: SPE Proceeding ANTEC2014, Society of Plastics Engineers Incorporated (SPE) , 2014Conference paper, Published paper (Refereed)
Abstract [en]

A polylactic acid (PLA) nanocomposite with 9 times higher toughness than neat PLA was prepared by compounding extrusion using cellulose nanofibers (CNFs) as an additive and glycerol triacetate (GTA) as a plasticizer. Liquid feeding was used to incorporate the CNFs and the liquid plasticizer into the extruder. Both additive and plasticizer were used to improve the PLA toughness and the plasticizer was also used to facilitate the dispersion and distribution of CNFs in the PLA matrix

Place, publisher, year, edition, pages
Society of Plastics Engineers Incorporated (SPE), 2014
National Category
Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-35328 (URN)9d0eade4-9080-4a51-b565-ace7db6178de (Local ID)9d0eade4-9080-4a51-b565-ace7db6178de (Archive number)9d0eade4-9080-4a51-b565-ace7db6178de (OAI)
Conference
ANTEC 2014 : 28/04/2014 - 30/04/2014
Note
Godkänd; 2014; 20140818 (krioks)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Vargas, N. H. (2014). Processing and Properties of Nanostructured Biocomposites (ed.). (Licentiate dissertation). Paper presented at . : Luleå tekniska universitet
Open this publication in new window or tab >>Processing and Properties of Nanostructured Biocomposites
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

In this work, nanostructured biocomposite fibers and films with cellulose nanofibers (CNF), cellulose nanocrystals (CNC) and chitin nanocrystals (ChNC) were prepared using solutions mixing followed by electrospinning and melt compounding. The main processing challenges for these materials were to find parameters for: 1) fiber alignment in electrospinning, 2) feeding the nanomaterials into the extruder and 3) dispersion and distribution of the nanomaterials in the polymeric matrix. This thesis consists of three publications, which are summarized below.The first study was about random and aligned cellulose fibers prepared by electrospinning. Cellulose acetate (CA) was used as a matrix and a mixture of acetic acid and acetone (1:1) was used as a solvent. CNC with different concentrations (0–5 wt-%) were used as reinforcement. Microscopy studies showed fibers with smooth surfaces, different morphologies and diameters ranging between 200 and 3300 nm. It was found that the fiber diameters decreased with increased CNC contents. The microscopy studies also indicated well-aligned fibers. Results from dynamic mechanical thermal analysis indicated improved mechanical properties with the addition of CNC. The storage modulus of electrospun CA fibers increased from 81 to 825 MPa for fibers with 1 wt% CNC at room temperature. X-ray analysis showed that the electrospun CA fibers had a crystalline nature and that there was no significant change in crystallinity with the addition of CNC.In the second study, polylactic acid (PLA) and its nanocomposite based on CNF and glycerol triacetate (GTA) were prepared using a co-rotating twin-screw extruder. GTA was used as a plasticizer, a processing aid to facilitate nanofiber dispersion and as a liquid medium for feeding. The optical, thermal and mechanical properties were characterized and the toughening mechanism was studied. The addition of GTA (20%) and CNF (1%) resulted in increased degree of crystallinity and thus decreased optical transparency. Furthermore, these additives showed a positive effect on the elongation at break and toughness, which increased from 2 to 31% and from 1 to 8 MJ/m3, respectively. A combination of nanofiber-matrix interfacial slippage and a massive crazing effect is suggested for PLA toughening. CNF were expected to restrict the spherulite growth and therefore enhance the craze nucleation. In the third study, triacetate citrate plasticized poly lactic acid and its nanocomposites based on cellulose nanocrystals (CNC) and chitin nanocrystals (ChNC) were prepared using a co-rotating twin-screw extruder. The materials were compression molded to films using two different cooling rates. The cooling rates and the addition of nanocrystals (1 wt%) had an impact on the crystallinity as well as the optical, thermal and mechanical properties of the films. The fast cooling resulted in more amorphous materials, increased transparency and elongation to break, (approx. 300%) when compared with slow cooling. Chitin nanocomposites were more transparent than cellulose nanocomposites; however, microscopy study showed presence of agglomerations in both materials. The mechanical properties of the plasticized PLA were improved with the addition of a small amount of nanocrystals resulting in PLA nanocomposites suitable for use in film blowing and thus packaging applications. Summing up, this thesis shows that solution mixing followed by electrospinning can be used to produce reinforced green nanocomposite fibers with random or aligned orientation with, probably, potential to be used in membranes, filters or even in medical applications. It was also shown that PLA-CNF nanocomposites can be prepared using extrusion and liquid feeding and that small amounts of CNF changed the fracture mechanism, resulting in increased toughness. In addition, the cooling rate of the plasticized PLA and its nanocomposite films was found to significantly impact the film properties.

Place, publisher, year, edition, pages
Luleå tekniska universitet, 2014. p. 70
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
National Category
Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-17525 (URN)3ce44d46-2130-496a-9fb1-105b47f8ee91 (Local ID)978-91-7583-173-2 (ISBN)978-91-7583-174-9 (ISBN)3ce44d46-2130-496a-9fb1-105b47f8ee91 (Archive number)3ce44d46-2130-496a-9fb1-105b47f8ee91 (OAI)
Note
Godkänd; 2014; 20141113 (nather); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Natalia Herrera Vargas Ämne: Trä- och bionanokompositer/Wood and Bionanocomposites Uppsats: Processing and Properties of Nanostructured Biocomposites Examinator: Professor Kristiina Oksman, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Diskutant: Forskare Maria Soledad Peresin, Technical Research Centre of Finland Tid: Fredag 19 december 2014 kl 10,00 Plats: D770, Luleå tekniska universitetAvailable from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-2906-2470

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