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2010 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis

Abstract [en] : Nanocomposites in the form of continuous and aligned cellulose fibers have been obtained by electrospinning. Cellulose acetate (CA) was used as matrix and a mixture of acetic acid and acetone (1:1) was used as solvent. Cellulose nanowhiskers (CNWs) with different concentrations (0.2: 0.6: 0.9: 1.2 and 1.8 % w/w) were used as the reinforcement phase. The results showed that the alignment was affected by parameters such as voltage, distance of the gap and collection time. Electrospinning experiments performed at 11 kV with 3 cm as distance of the gap provided the best alignment. SEM cross section images showed electrospun cellulose fibers with non-uniform size and shape. The measurements on the height AFM images showed that the fibers diameters varied between 300 and 3000 nm. A tendency to decrease the fiber diameters by the incorporation of cellulose nanowhiskers into cellulose acetate was found. The results from both SEM and AFM images also showed the presence of some porosity, beads, nanofibers doublets, cellulose nanowhiskers agglomerations and bundles in all the compositions: however, the formation of beads and cellulose whiskers aggregations were more prominent at higher cellulose whiskers concentration. Mechanical properties of aligned cellulose nanofibers were determined using a Dynamic Mechanical Thermal Analysis (DMTA). Maximum tensile strength and Young’s modulus of electrospun fibers decreased by 72% and 53% respectively with the addition of cellulose nanowhiskers whereas the maximum strain was almost unaffected. These results could be explained due to presented defects such as beads, porosity and cellulose nanowhiskers aggregations on the fibers as well as could be due to the testing procedures.

Place, publisher, year, edition, pages: 2010.

Keyword [en] : Physics Chemistry Maths, Electrospinning, cellulose nanowhiskers, cellulose acetate, alignment, microscopy, mechanical properties

Keyword [sv] : Fysik, Kemi, Matematik

Identifiers: URN: urn:nbn:se:ltu:diva-56665ISRN: LTU-PB-EX--10/053--SELocal ID: d6bfb350-62ef-478d-8c89-f17c1989f557OAI: diva2:1030052

Subject / course: Student thesis, at least 30 credits

Educational program: Materials Engineering, master's level

Examiners : Oksman, Kristiina

Note: Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

Autor: Herrera Vargas, Natalia



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