Nanofibrillated cellulose/nano SiO2/poly(vinyl alcohol) composite films: Evaluation of properties (original) (raw)
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PREPARATION AND CHARACTERIZATION OF NANOFIBRILLATED CELLULOSE/POLY (VINYL ALCOHOL) COMPOSITE FILMS
Poly (vinyl alcohol) based composite films with different loadings of cellulose nanofibrils were prepared using a solvent casting method and their tensile, optical and wettability properties were tested. The morphology of both neat poly (vinyl alcohol) and nanocomposites was explored by using a field emission scanning electron microscope technique. Results indicated that the tensile strength and Young's modulus of poly (vinyl alcohol) composite films were significantly improved with the increase of cellulose nanofibrils loading. However, the percentage of elongation at break decreased with increasing of cellulose nanofibrils. The films became increasingly opaque with increasing cellulose nanofibrils contents, although the composites also retained moderate transparency. The samples containing cellulose nanofibrils exhibited higher hydrophobicity compared with that of neat poly (vinyl alcohol). Field emission scanning electron microscope micrographs revealed that the cellulose nanofibrils were homogeneously dispersed in the poly (vinyl alcohol) matrix.
Composites Part A: Applied Science and Manufacturing, 2009
Cellulose fibrils in micro and nanoscales generated from biomass are relative new reinforcing materials for polymer composites, which have potential lightweight and high strength and are biodegradable. The objective of this study was to reinforce biodegradable polymers by cellulose fibrils generated from several cellulose sources by ultrasonic treatment in order to utilize biomass to fabricate high-value products. The geometrical characteristics of the fibrils were investigated by polarized light microscopy (PLM) and atomic force microscopy (AFM). The degree of fibrillation of the fibers evaluated by water retention value was significantly increased after treatment. The treated cellulose and separated fibrils were used to reinforce poly(vinyl alcohol) (PVA) to make biodegradable nanocomposites by film casting. The mechanical properties of PVA were significantly improved by most of the small fibrils. The morphological characteristics of the nanocomposites were investigated with PLM, scanning electron microscopy, and AFM.
Journal of Nanomaterials, 2013
The effect of incorporating cellulose nanocrystals from corncob (CNC) on the tensile, thermal, and barrier properties of poly(vinyl alcohol) (PVA) nanocomposites was evaluated. The CNC were prepared by sulfuric acid hydrolysis at 45 ∘ C for 60 minutes, using 15 mL of H 2 SO 4 (9.17 M) for each gram of fiber. The CNC 60 presented a needle-shaped morphology, high crystallinity (83.7%), good initial degradation temperature (236 ∘ C), average length ( ) of 210.8 ± 44.2 nm, diameter ( ) of 4.15 ± 1.08 nm, and high aspect ratio ( / ) of 53.4 ± 15.8. PVA/CNC nanocomposite films with different filler loading levels (3, 6, and 9% by wt) were prepared by casting. The ultimate tensile strength (UTS), thermal stability (TS), light transmittance (Tr) and water vapor permeability ( ) of the nanocomposites were measured. When compared to neat PVA film, the UTS of the nanocomposites improved significantly, by 140.2%, decreased up to 28.73%, and there were no significant changes in TS. The nanocomposites also showed excellent Tr in the visible region, maintaining substantially equivalent transparency. These improvements in the nanocomposites' properties suggest a close association between filler and matrix, besides indicating that the CNC were well dispersed and adherent to the polymer matrix.
Cellulose, 2021
Nanocellulose is abundant, renewable, biocompatible, and a good candidate as reinforcement agent in nanocomposites; however, its hydrophilicity leads to poor dispersion in hydrophobic polymers. Recently, both in situ polymerization and cellulose surface modification have been used to improve dispersion, but emulsion polymerization is rarely adopted, and when it is, the reinforcement agent is usually cellulose nanocrystal (CNC), with gain in mechanical properties being the main focus of the research. Therefore, this work aims to explore the influence of adding either CNC or microfibrillated cellulose (MFC), both without surface modification, on the mechanical resistance, thermal degradation, and water vapor permeability of poly(vinyl acetate) composites obtained by either in situ emulsion polymerization or mixing. The results showed that despite having similar impacts on thermal and barrier properties, MFC and CNC affect the mechanical properties of their composites differently. Both cause decrease of the thermal degradation rate and do not have a significant impact on water vapor permeability. However, the addition of CNC during synthesis increased composite mechanical resistance significantly while the addition of MFC did not show improvement. Mechanical resistance is also strongly dependent on the procedure used to produce the composites.
Carbohydrate Polymers, 2021
Nanofibrillated cellulose films have garnered attention due to their interesting proprieties such as transparency and high mechanical strength. However, they are brittle, very hydrophilic, which is decreasing their potential applications. We have successfully achieved a simple and effective chemical modification based on polymer grafting and through plasticizer additions to increase the performance of the films as well as to improve the compatibility within conventional polymer. A 24 preliminary study shows the possibility of using this film as an interlayer in safety glazing and/or 25 bulletproof glass with polyvinyl butyral (PVB). The modified NFC films displays high optical 26 transmittance (93%), increases tensile stretch and is more hydrophobic (83°). A higher flexibility 27 was also achieved, as the film was greatly stretched and bended without cracking or breaking. The 28 POSTPRINT VERSION. The final version is published here: Lassoued, M., Crispino, F., & Loranger, E. (2020). Design and synthesis of transparent and flexible nanofibrillated cellulose films to replace petroleum-based polymers.
Advances in Polymer Technology
This paper presents the reinforcement of nanocellulose (NC) in polyvinyl alcohol (PVA) to examine the effect of the amount of reinforcement on the properties of PVA. The nanocellulose was successfully extracted by sulfuric acid hydrolysis method and ultrasonication, and successively reinforced with polyvinyl alcohol by the solvent-casting method. After incorporating nanocellulose into the PVA matrix, the effect of nanocellulose on the tensile strength, elongation at break, water absorption capacity, transmittance, thermal stability, and biodegradability of PVA was investigated. The tensile strength increased from 24.5 ± 0.53 MPa to 35.5 ± 0.55 MPa and 40.6 ± 0.73 MPa with the addition of 2%NC and 5%NC, respectively. The elongation at break increased from 40 ± 0.53 % to 45.7 ± 0.53 % with 2%NC, and after the reinforcement of 7%NC, it decreased to 32.2 ± 0.75 % . The water absorption capacity result reveals that neat PVA absorbs the highest amount of water which is 84.6 ± 0.56 %...
PVA Based Composite Films with Cellulose Fibers Prepared by Acid Hydrolysis
MATERIALE PLASTICE
Two types of cellulose fibers were obtained from microcrystalline cellulose (MCC) by acid hydrolysis and ultrasound treatment using different concentrations of sulphuric acid. The effect of acid concentration on cellulose fibers characteristics was studied by scanning electronic microscopy (SEM), dynamic light scattering (DLS), and X-ray diffraction analysis (XRD), pointing out interesting features from the standpoint of different end-use properties. An important increase of MCC crystallinity, from 51.4% to 74.3%, was observed by XRD analysis after the treatment with 60% sulphuric acid. The cellulose fibers were used as reinforcements in a polyvinyl alcohol (PVA) matrix and the crystallinity, transparency and mechanical properties of the resulted composites being investigated. The incorporation of the two types of cellulose fibers into PVA led to transparent composites films with improved mechanical properties. A steady improvement of the tensile modulus of PVA composites was observed with the increasing amount of fibers, an increase of 83.3 % being obtained with cellulose fibers resulted from MCC treatment with higher acid concentration (60%).
Procedia Chemistry, 2012
Nanocomposites of bacterial cellulose (BC) and poly(vinyl alcohol) (PVA) were prepared by cast-drying method as an easy way in producing nanocomposite films and to expand the use of BC. The contribution of PVA in nanocomposites was evaluated by measurement of cross-sectional surface, moisture uptake and mechanical properties. Morphological analysis shows that PVA covered a number of cellulosic fibres and formed denser material as a function of PVA addition. Based on the tensile test, the addition of PVA causes a very slight reduction compared with bacterial cellulose itself. The BC/PVA nanocomposites still have similar stiffness to BC with elongation at break less than 5%, while PVA film shows ductile properties with elongation at break more than 80%. On the other hand, the presence of BC fibres in the PVA matrix enhanced the tensile strength and the elastic modulus of pure PVA about two to three times, but it decreased the toughness of pure PVA. The highest tensile strength and elastic modulus of the nanocomposites are 164 MPa and 7.4 GPa, respectively at BC concentration of 64%. Increasing BC concentration is proportional to reducing moisture uptake of BC/PVA nanocomposites indicating that the existence of BC bres inhibits moisture absorption.