Production of cellulose nanofibers from Alfa grass and application as reinforcement for polyvinyl alcohol (original) (raw)
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Cellulose Nanofibers from Cassava Agro-Industrial Waste as Reinforcement in Pva Films
Química Nova
Cellulose nanofibers (CNF) have been applied in composite systems due to the abundance of raw material, excellent mechanical and thermal properties. In this work, CNF was prepared from agroindustrial waste and used in specified amounts in polyvinyl alcohol (PVA) composites. The FTIR spectra of CNF, chemically purified cellulose (CPC) and Cassava Agro-industrial Waste (CAW) indicate the removal of hemicellulose and lignin. The increase of the crystallinity phase in CNF was observed, by XRD analysis and neither is observed the transition from cellulose I to II. Thermogravimetric analysis showed displacement that the initial degradation of the CNF over 43 °C degradation proceeds at single step. The chemical and dimensional homogeneity of CNF can be observed with the calculation of the crystalline phase content obtained by deconvoluted dTG curve and XRD spectra, obtaining 80% crystallinity by both techniques. SEM micrographs showed fibers with diameters of 22.30 ± 1.52 nm. An increase in the mechanical properties of PVA was observed with the addition of CNF. With 2.5% CNF in the PVA, the elastic module increased by approximately three times, with the addition of 10% CNF, a saturated system with poor mechanical properties was observed.
CELLULOSE NANOFIBERS AND THEIR NANOCOMPOSITES -A REVIEW
SITA, 2021
Cellulose has a multilevel nanofibrillar architecture. This natural polymer is built from elementary fibrils of their bundles called microfibrils having nano scale diameters. Such nanofibrillar architecture promotes the isolation of free nanofibers. In this review, the various methods for isolation of cellulose nanofibers (CNFs) and their main structural features and properties are described. An application of the CNFs as reinforcing nanofiller in various nanocomposites is discussed. A special attention was paid to the use of CNFs in paper compositions, water-soluble and water-miscible polymers, as well as in curable liquid polymer resins. Green nanocomposites made from CNFs and biodegradable polymers are also discussed.
IOP Publishing, 2019
This research was aimed to manufacture polyvinyl alcohol (PVA)/ cellulose nanofiber (CNF) nanocomposite which was isolated from oil palm empty fruit bunches (OPEFB) through steam explosion method combined with a hydrolysis process involving HCl 10%. The isolation process was performed in 2 steps; α-cellulose isolation from empty fruit bunches fibers and then cellulose nanofiber isolation from α-cellulose which was hydrolyzed with acid using ultrasonicator and homogenized in rotational speed of 8000 rpm. The functional group and morphology of nanofibres cellulose were characterized. FT-IR spectrum resulted an absorptions for CO -C group at wavelength of 1059.99 cm-1 which indicated a glycoside bond. Then, C-H group at 2900.94 cm-1 and O-H group at 3348.62 cm-1 were revealed to indicate the cellulose nanofiber. Moreover, TEM was used for morphological analysis and showing a decrease in fibres diameters after experiencing a chemical-mechanical treatment which lead to nanofibres with final diameter size of 20-30 nm. PVA/CNF nanocomposite with the percentage ratio of 80:20 gave a tensile strength of 17.41 Mpa and Modulus Young of 0.9 Gpa. Finally, the product was also morphologically analyzed with SEM and indicating an even distribution on the PVA surface.
Journal of Applied Polymer Science, 2018
Cellulose nanofibers (CNFs) have gained widespread attention due to their extraordinary potential as superior reinforcement to improve physical and mechanical properties of polymer matrix nanocomposites. Biomass residues from local North Dakota represent a potential source for these high value structural constituents. Two types of soybean hull, wheat straw, and softwood flour were subjected to chemical pretreatments followed by mechanical fibrillation to produce CNFs. Atomic force microscopy and scanning electron microscopy results show that nanofibers with uniform diameters in the nanometer range can be easily synthesized. The nanofibers reinforcement potential was then explored via integration of the fibers into a poly(ethylene oxide) polymer matrix. Significant reinforcement effect of the nanofibers was observed from the nanocomposites: tensile modulus and yield strength of the nanocomposites were increased up to 154% and 103%, respectively. The CNFs extracted from the two types of soybean hull and wood flour showed stronger reinforcement (in terms of both modulus and yield strength) than that of the traditional wood pulp based CNFs. The nanofibers extracted from wheat straw showed higher strength but lower modulus compared with those of the traditional CNFs. More work is however needed to improve production reliability/repeatability of the agricultural residue based nanofibers.
International Journal of Engineering
This paper presents an experimental study of addition of cellulose nanofibers (CNF) extracted by the chemical-ultrasonication process from agave cantala leaf plants in the matrix of polyvinyl alcohol (PVA). Combining these materials produce the nanocomposite film with a thickness of 30 μm. The nanocomposite characteristic was investigated by the addition of CNF (0, 2, 5, 8, and 10 wt%) in PVA suspension (3 wt.%). PVA/CNF nanocomposite films were prepared by a casting solution method. The fibrillation of fibers to CNF was analyzed using Scanning Electron Microscopy and Transmission Electron Microscopy. The nanocomposite film functional group's molecular chemical bond and structural analysis were tested using Fourier Transform Infrared and X-ray diffraction. The PVA/CNF nanocomposite film has significant advantages on the ultraviolet barrier, thermal stability tested by Differential Scanning Calorimetry and Thermogravimetric Analyzer, and tensile strength. Overall, the optimal addition of CNF is 8 wt.% in matrix, resulting in the highest crystallinity index (37.5%), the tensile strength and elongation at break was an increase of 79% and 138%, respectively. It has good absorbing ultraviolet rays (82.4%) and high thermal stability (365 o C).
Objective of this work was to compare morphology, crystalline and thermal properties of cellulose nano fibers derived from wheat straw by two different processes (ball milling and acid hydrolysis treatment). The characterization of extracted CNFs was done by Scanning electron micrograph (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Thermogravimetric analysis (TGA). It was found from morphological, crystalline and thermal analyses that isolated cellulose nanofibers have diameter of nano meter ranges (10-25 nm), 68-80 % crystallinity and decomposition temperature of around 284-353o C, depending upon isolation techniques.
Processing of Cellulose Nanofiber-reinforced Composites
Journal of Reinforced Plastics and Composites, 2005
Cellulose nanofibers are obtained from various sources such as flax bast fibers, hemp fibers, kraft pulp, and rutabaga, by chemical treatments followed by innovative mechanical techniques. The nanofibers thus obtained have diameters between 5 and 60 nm. The ultrastructure of cellulose nanofibers is investigated by atomic force microscopy and transmission electron microscopy. The cellulose nanofibers are also characterized in terms of crystallinity. Reinforced composite films comprising 90% polyvinyl alcohol and 10% nanofibers are also prepared. The comparison of the mechanical properties of these composites with those of pure PVA confirmed the superiority of the former.
Polymers, 2020
The present work aims to combine the unique properties of cellulose nanofibers (CNF) with polyvinyl alcohol (PVA) to obtain high-performance nanocomposites. CNF were obtained by means of TEMPO-mediated ((2,2,6,6-Tetramethylpiperidin-1-yl)oxyl) oxidation, incorporated into the PVA matrix by means of compounding in a single-screw co-rotating internal mixer and then processed by means of injection molding. It was found that CNF were able to improve the tensile strength of PVA in 85% when 4.50 wt % of CNF were added. In addition, the incorporation of a 2.25 wt % of CNF enhanced the tensile strength to the same level that when 40 wt % of microsized fibers (stone groundwood pulp, SGW) were incorporated, which indicated that CNF possessed significantly higher intrinsic mechanical properties than microsized fibers. SGW was selected as reference for microsized fibers due to their extended use in wood plastic composites. Finally, a micromechanical analysis was performed, obtaining coupling fa...
This research was aimed to use ball milling method to extract cellulose nanofibers (CNFs) from a bio-waste (i.e. wheat straw), and also to use the extracted cellulose nanofibers as reinforcing materials in polyvinyl alcohol (PVA) thin film. To study the effect of cellulose nanofibers (CNFs) on mechanical and thermal properties of polyvinyl alcohol (PVA) nano-composite films, thin film nano-composites were loaded with different loading of cellulose nanofibers (CNFs) by weight percent (i.e. 1,3,5 and 7% loading). As a result of the research, we found that the tensile and thermal properties of PVA thin composite increased up to 5% loading of cellulose nanofibers (CNFs). In contrast, the tensile as well as thermal properties of PVA nano -composite film degraded because of poor dispersion and agglomeration of CNFs
Fibers and Polymers, 2015
Cellulose nanofibers were isolated from wheat straw by a chemical-mechanical procedure. Chemical process eliminates non-cellulosic materials. This process includes acid hydrolysis, alkali treatment, and bleaching. Since the acid hydrolysis is a critical step in nanofiber extraction, its conditions were optimized based on the highest degree of crystallinity using the statistical response surface methodology. The chemical composition of fibers at different stages were analyzed and showed an increase in α-cellulose content. In the mechanical treatment, obtained chemical-purified cellulose microfibers were defibrillated into nanofibers employing a sonicator at 400 W power. The morphology of nanofibers was characterized using a scanning electron microscope and the average diameter of nanofibers was obtained to be 45 nm. In addition, the thermal properties of nanofibers and untreated fibers were studied by thermal gravimetric analyzer. The degradation temperature of nanofibers was reached beyond 300 o C. These mentioned properties are suitable for cellulosic nanofibers used in polymeric nanocomposites.