Effect of Length of Cellulose Nanofibers on Mechanical Reinforcement of Polyvinyl Alcohol

Cellulose nanofibers (CNF), representing the nano-structured cellulose, have attained an extensive research attention due to their sustainability, biodegradability, nanoscale dimensions, large surface area, unique optical and mechanical performance, etc. Different lengths of CNF can lead to different extents of entanglements or network-like structures through van der Waals forces. In this study, a series of polyvinyl alcohol (PVA) composite films, reinforced with CNF of different lengths, were fabricated via conventional solvent casting technique. CNF were extracted from jute fibers by tuning the dosage of sodium hypochlorite during the TEMPO-mediated oxidation. The mechanical properties and thermal behavior were observed to be significantly improved, while the optical transparency decreased slightly (Tr. > 75%). Interestingly, the PVA/CNF20 nanocomposite films exhibited higher tensile strength of 34.22 MPa at 2 wt% filler loading than the PVA/CNF10 (32.55 MPa) while displayed higher elastic modulus of 482.75 MPa than the PVA/CNF20 films (405.80 MPa). Overall, the findings reported in this study provide a novel, simple and inexpensive approach for preparing the high-performance polymer nanocomposites with tunable mechanical properties, reinforced with an abundant and renewable material.

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Preparation and characterization of graphene oxide and cellulose nanofibers/ polyvinyl alcohol nanocomposite film

Science and Technology Development Journal - Natural Sciences ◽

10.32508/stdjns.v5i3.958 ◽

2021 ◽

Vol 5 (3) ◽

pp. first

Author(s):

Nguyen Tuong Vy ◽

Nguyen Thi Khoi Pham ◽

Lam Quoc Ha

Keyword(s):

Mechanical Properties ◽

Graphene Oxide ◽

Polyvinyl Alcohol ◽

Moisture Absorption ◽

Cold Water ◽

Cellulose Nanofibers ◽

Environmentally Friendly ◽

Nanocomposite Films ◽

Cnf Films

Polyvinyl alcohol (PVA) is well-known in the packaging industry, especially in the food and medical fields with the ability to be completely biodegradable and easily soluble in cold water therefore products made from it are the environmentally friendly materials. However, the disadvantages of this polymer as quick dissolubility in water, poor moisture retention, weak mechanical properties reduce its applications. In this study, PVA, reinforced by “green” components at the nanometer-level such as nanocellulose fibers (CNF), graphene oxide (GO) nanosheets showed improvements in properties. Mechanical properties of all of nanocomposite films showed improvements in stress at break and modulus. Especially, reinforced GO and CNF films increased almost doubled and improved more 40% in modulus than the pure PVA film and films reinforced by only GO or CNF. When immersed in water (neutral pH) at room temperature, graphene oxide-reinforced films not only had effective improvements in swelling time but also supported to decrease water retension of film added CNF. The combined reinforcement also indicated a benefit in reducing the rate of water vapor loss of the film as well as the efficiency in declining the moisture absorption of the nanocomposite films. The PVA films reinforced by nanocellulose fibers and graphene oxide sheets overcomed some of the PVA's shortcomings. This helped expanding its applications in the field of environmentally friendly nanocomposite films.

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Research on the Strengthening Advantages on Using Cellulose Nanofibers as Polyvinyl Alcohol Reinforcement

Polymers ◽

10.3390/polym12040974 ◽

2020 ◽

Vol 12 (4) ◽

pp. 974 ◽

Cited By ~ 2

Author(s):

Quim Tarrés ◽

Helena Oliver-Ortega ◽

Manel Alcalà ◽

F. Xavier Espinach ◽

Pere Mutjé ◽

...

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Polyvinyl Alcohol ◽

High Performance ◽

Cellulose Nanofibers ◽

Cellulosic Fibers ◽

Reinforcement Content ◽

Superior Mechanical Properties ◽

Coupling Factors ◽

Internal Mixer

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 factors near to 0.2, indicating good interphase between CNF and PVA. Overall, it was found that the use of CNF is clearly advantageous to the use of common cellulosic fibers if superior mechanical properties are desired, but there are still some limitations that are related to processing that restrict the reinforcement content at low contents.

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Development of Bioinspired Functional Chitosan/Cellulose Nanofiber 3D Hydrogel Constructs by 3D Printing for Application in the Engineering of Mechanically Demanding Tissues

Polymers ◽

10.3390/polym13101663 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1663

Author(s):

Arnaud Kamdem Tamo ◽

Ingo Doench ◽

Lukas Walter ◽

Alexandra Montembault ◽

Guillaume Sudre ◽

...

Keyword(s):

Mechanical Properties ◽

3D Printing ◽

Composite Structures ◽

Soft Tissues ◽

Mechanical Performance ◽

Cellulose Nanofibers ◽

High Water Content ◽

Natural Polymers ◽

Mechanical Reinforcement ◽

3D Printed

Soft tissues are commonly fiber-reinforced hydrogel composite structures, distinguishable from hard tissues by their low mineral and high water content. In this work, we proposed the development of 3D printed hydrogel constructs of the biopolymers chitosan (CHI) and cellulose nanofibers (CNFs), both without any chemical modification, which processing did not incorporate any chemical crosslinking. The unique mechanical properties of native cellulose nanofibers offer new strategies for the design of environmentally friendly high mechanical performance composites. In the here proposed 3D printed bioinspired CNF-filled CHI hydrogel biomaterials, the chitosan serves as a biocompatible matrix promoting cell growth with balanced hydrophilic properties, while the CNFs provide mechanical reinforcement to the CHI-based hydrogel. By means of extrusion-based printing (EBB), the design and development of 3D functional hydrogel scaffolds was achieved by using low concentrations of chitosan (2.0–3.0% (w/v)) and cellulose nanofibers (0.2–0.4% (w/v)). CHI/CNF printed hydrogels with good mechanical performance (Young’s modulus 3.0 MPa, stress at break 1.5 MPa, and strain at break 75%), anisotropic microstructure and suitable biological response, were achieved. The CHI/CNF composition and processing parameters were optimized in terms of 3D printability, resolution, and quality of the constructs (microstructure and mechanical properties), resulting in good cell viability. This work allows expanding the library of the so far used biopolymer compositions for 3D printing of mechanically performant hydrogel constructs, purely based in the natural polymers chitosan and cellulose, offering new perspectives in the engineering of mechanically demanding hydrogel tissues like intervertebral disc (IVD), cartilage, meniscus, among others.

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Functional Bionanocomposite Fibers of Chitosan Filled with Cellulose Nanofibers Obtained by Gel Spinning

Polymers ◽

10.3390/polym13101563 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1563

Author(s):

Sofia Marquez-Bravo ◽

Ingo Doench ◽

Pamela Molina ◽

Flor Estefany Bentley ◽

Arnaud Kamdem Tamo ◽

...

Keyword(s):

Mechanical Properties ◽

Mechanical Performance ◽

Cellulose Nanofibers ◽

Microstructural Characterization ◽

Fiber Formation ◽

Fiber Direction ◽

Composite Fibers ◽

X Ray Diffraction ◽

Gel Spinning ◽

X Ray

Extremely high mechanical performance spun bionanocomposite fibers of chitosan (CHI), and cellulose nanofibers (CNFs) were successfully achieved by gel spinning of CHI aqueous viscous formulations filled with CNFs. The microstructural characterization of the fibers by X-ray diffraction revealed the crystallization of the CHI polymer chains into anhydrous chitosan allomorph. The spinning process combining acidic–basic–neutralization–stretching–drying steps allowed obtaining CHI/CNF composite fibers of high crystallinity, with enhanced effect at incorporating the CNFs. Chitosan crystallization seems to be promoted by the presence of cellulose nanofibers, serving as nucleation sites for the growing of CHI crystals. Moreover, the preferential orientation of both CNFs and CHI crystals along the spun fiber direction was revealed in the two-dimensional X-ray diffraction patterns. By increasing the CNF amount up to the optimum concentration of 0.4 wt % in the viscous CHI/CNF collodion, Young’s modulus of the spun fibers significantly increased up to 8 GPa. Similarly, the stress at break and the yield stress drastically increased from 115 to 163 MPa, and from 67 to 119 MPa, respectively, by adding only 0.4 wt % of CNFs into a collodion solution containing 4 wt % of chitosan. The toughness of the CHI-based fibers thereby increased from 5 to 9 MJ.m−3. For higher CNFs contents like 0.5 wt %, the high mechanical performance of the CHI/CNF composite fibers was still observed, but with a slight worsening of the mechanical parameters, which may be related to a minor disruption of the CHI matrix hydrogel network constituting the collodion and gel fiber, as precursor state for the dry fiber formation. Finally, the rheological behavior observed for the different CHI/CNF viscous collodions and the obtained structural, thermal and mechanical properties results revealed an optimum matrix/filler compatibility and interface when adding 0.4 wt % of nanofibrillated cellulose (CNF) into 4 wt % CHI formulations, yielding functional bionanocomposite fibers of outstanding mechanical properties.

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Enhanced functional properties of biodegradable Polyvinyl alcohol /carboxymethyl cellulose (PVA/CMC) composite films reinforced with L-alanine surface modified CuO nanorods

10.21203/rs.3.rs-918116/v1 ◽

2021 ◽

Author(s):

Yamanappagouda Amaregouda ◽

Kantharaju Kamanna ◽

Tilak Gasti ◽

Vijay Kumbar

Keyword(s):

Polyvinyl Alcohol ◽

Carboxymethyl Cellulose ◽

Food Packaging ◽

Composite Films ◽

Nanocomposite Films ◽

Soil Burial ◽

High Antibacterial Activity ◽

Active Food Packaging ◽

Surface Modified ◽

Cuo Nanorods

Abstract Herein, we described novel biogenic preparation of the CuO nanorods and its surface modification with L-alanine amino acid accelerated by microwave irradiation. The effect of surface functionalized CuO nanorods on the polyvinyl alcohol/carboxymethyl cellulose film physico-mechanical properties were investigated through various characterization techniques. The tensile strength was improved from 28.58 ± 0.73 MPa to 43.40 ± 0.93 MPa, UV shielding ability and barrier to the water vapors were highly enhanced when PVA/CMC matrices filled with 8 wt% of CuO-L-alanine. In addition, the prepared films exhibited acceptable overall migration limit and readily undergoes soil burial degradation. Nevertheless, CuO-L-alanine incorporated films showed potent antioxidant activity against DPPH radicals and had high antibacterial activity against Staphylococcus aureus and Escherichia coli, and antifungal activity against Candida albicans and Candida tropicalis. Furthermore, the nanocomposite films showed negligible cytotoxic effect on HEK293 and Caco-2 cell lines. In these contexts, the developed nanocomposite films can be implementing as an active food packaging material.

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Mechanically Robust Flexible Multilayer Aramid Nanofibers and MXene Film for High-Performance Electromagnetic Interference Shielding and Thermal Insulation

Nanomaterials ◽

10.3390/nano11113041 ◽

2021 ◽

Vol 11 (11) ◽

pp. 3041

Author(s):

Jun Zhou ◽

Junsheng Yu ◽

Dongyu Bai ◽

Huili Liu ◽

Lu Li

Keyword(s):

Mechanical Properties ◽

Composite Film ◽

Electromagnetic Interference ◽

Multilayer Structure ◽

High Performance ◽

Composite Films ◽

Next Generation ◽

Shielding Effectiveness ◽

Breaking Strain ◽

Practical Applications

In order to overcome the various defects caused by the limitations of solid metal as a shielding material, the development of electromagnetic shielding materials with flexibility and excellent mechanical properties is of great significance for the next generation of intelligent electronic devices. Here, the aramid nanofiber/Ti3C2Tx MXene (ANF/MXene) composite films with multilayer structure were successfully prepared through a simple alternate vacuum-assisted filtration (AVAF) process. With the intervention of the ANF layer, the multilayer-structure film exhibits excellent mechanical properties. The ANF2/MXene1 composite film exhibits a tensile strength of 177.7 MPa and a breaking strain of 12.6%. In addition, the ANF5/MXene4 composite film with a thickness of only 30 μm exhibits an electromagnetic interference (EMI) shielding efficiency of 37.5 dB and a high EMI-specific shielding effectiveness value accounting for thickness (SSE/t) of 4718 dB·cm2 g−1. Moreover, the composite film was excellent in heat-insulation performance and in avoiding light-to-heat conversion. No burning sensation was produced on the surface of the film with a thickness of only 100 μm at a high temperature of 130 °C. Furthermore, the surface of the film was only mild when touched under simulated sunlight. Therefore, our multilayer-structure film has potential significance in practical applications such as next-generation smart electronic equipment, communications, and military applications.

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Characterisation of a High-Performance Al–Zn–Mg–Cu Alloy Designed for Wire Arc Additive Manufacturing

Materials ◽

10.3390/ma13071610 ◽

2020 ◽

Vol 13 (7) ◽

pp. 1610 ◽

Cited By ~ 3

Author(s):

Paulo J. Morais ◽

Bianca Gomes ◽

Pedro Santos ◽

Manuel Gomes ◽

Rudolf Gradinger ◽

...

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Additive Manufacturing ◽

High Performance ◽

Mechanical Performance ◽

Fluorescence Analysis ◽

Cold Metal Transfer ◽

Direction Parallel ◽

X Ray ◽

Wire Arc Additive Manufacturing

Ever-increasing demands of industrial manufacturing regarding mechanical properties require the development of novel alloys designed towards the respective manufacturing process. Here, we consider wire arc additive manufacturing. To this end, Al alloys with additions of Zn, Mg and Cu have been designed considering the requirements of good mechanical properties and limited hot cracking susceptibility. The samples were produced using the cold metal transfer pulse advanced (CMT-PADV) technique, known for its ability to produce lower porosity parts with smaller grain size. After material simulations to determine the optimal heat treatment, the samples were solution heat treated, quenched and aged to enhance their mechanical performance. Chemical analysis, mechanical properties and microstructure evolution were evaluated using optical light microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray fluorescence analysis and X-ray radiography, as well as tensile, fatigue and hardness tests. The objective of this research was to evaluate in detail the mechanical properties and microstructure of the newly designed high-performance Al–Zn-based alloy before and after ageing heat treatment. The only defects found in the parts built under optimised conditions were small dispersed porosities, without any visible cracks or lack of fusion. Furthermore, the mechanical properties are superior to those of commercial 7xxx alloys and remarkably independent of the testing direction (parallel or perpendicular to the deposit beads). The presented analyses are very promising regarding additive manufacturing of high-strength aluminium alloys.

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Structure, Mechanical Performance, and Dimensional Stability of Radiata Pine (Pinus radiata D. Don) Scrimbers

Advances in Polymer Technology ◽

10.1155/2019/5209624 ◽

2019 ◽

Vol 2019 ◽

pp. 1-8

Author(s):

Jinguang Wei ◽

Fei Rao ◽

Yuxiang Huang ◽

Yahui Zhang ◽

Yue Qi ◽

...

Keyword(s):

Mechanical Properties ◽

Pinus Radiata ◽

Dimensional Stability ◽

High Performance ◽

Water Resistance ◽

Mechanical Performance ◽

Three Dimensional ◽

Radiata Pine ◽

Specific Strength ◽

Shearing Strength

Natural wood has certain advantages such as good processability and high specific strength and thus has been used for millennium as a structural material. But the mechanical performance and water resistance, particularly for fast-growing species, are unsatisfactory for high-end applications. In this study, the “new-type” scrimber technology was introduced to radiata pine (Pinus radiata D. Don) scrimbers. The structure, mechanical properties, and dimensional stability of the scrimber panels were investigated. Results showed that OWFMs as basic units of scrimber had been very even in size and superior permeability. The scrimbers exhibited a three-dimensional porous structure, and the porosity had a decrease with increasing density. Both OWFMs and densification contributed to the high performance in terms of mechanical properties and water resistance. The flexural, compressive, and short-beam shearing strength were significantly enhanced with increasing density. As the density was 0.80 g cm−3, the flexural strength (MOR) was approximately 120 MPa, much larger than many selected wood-based panels. Moreover, the water resistance and dimensional stability also were closely related to the density. At the density of 1.39 g cm−3, the water absorption rate and thinness swelling rate of the panels in boiled water were only 19% and 5.7%, respectively.

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Biocomposites from Rice Straw Nanofibers: Morphology, Thermal and Mechanical Properties

Materials ◽

10.3390/ma13092138 ◽

2020 ◽

Vol 13 (9) ◽

pp. 2138 ◽

Cited By ~ 1

Author(s):

José Carlos Alcántara ◽

Israel González ◽

M. Mercè Pareta ◽

Fabiola Vilaseca

Keyword(s):

Rice Straw ◽

Mechanical Performance ◽

Cellulose Nanofibers ◽

Nucleating Agent ◽

Mechanical Analysis ◽

Nanocomposite Films ◽

Chemical Extraction ◽

Poly Vinyl Alcohol ◽

Scanning Calorimetry ◽

The Matrix

Agricultural residues are major potential resources for biomass and for material production. In this work, rice straw residues were used to isolate cellulose nanofibers of different degree of oxidation. Firstly, bleached rice fibers were produced from the rice straw residues following chemical extraction and bleaching processes. Oxidation of rice fibers mediated by radical 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) at pH 10 was then applied to extract rice cellulose nanofibers, with diameters of 3–11 nm from morphological analysis. The strengthening capacity of rice nanofibers was tested by casting nanocomposite films with poly(vinyl alcohol) polymer. The same formulations with eucalyptus nanofibers were produced as comparison. Their thermal and mechanical performance was evaluated using thermogravimetry, differential scanning calorimetry, dynamic mechanical analysis and tensile testing. The glass transition of nanocomposites was shifted to higher temperatures with respect to the pure polymer by the addition of rice cellulose nanofibers. Rice nanofibers also acted as a nucleating agent for the polymer matrix. More flexible eucalyptus nanofibers did not show these two phenomena on the matrix. Instead, both types of nanofibers gave similar stiffening (as Young’s modulus) to the matrix reinforced up to 5 wt.%. The ultimate tensile strength of nanocomposite films revealed significant enhancing capacity for rice nanofibers, although this effect was somehow higher for eucalyptus nanofibers.

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Preparation and Property of Waterborne Polyurethane/Cellulose Nanofiber Nanocomposite Films

Materials Science Forum ◽

10.4028/www.scientific.net/msf.993.631 ◽

2020 ◽

Vol 993 ◽

pp. 631-637

Author(s):

Yu Zhe Lin ◽

Jia Min Zeng ◽

Jing Hong Ma ◽

Jing Hua Gong

Keyword(s):

Mechanical Properties ◽

Cellulose Nanofibers ◽

Waterborne Polyurethane ◽

Tensile Tests ◽

Environmental Safety ◽

Nanocomposite Films ◽

Solution Blending ◽

Low Weight ◽

New Type ◽

Dispersing Medium

Waterborne polyurethane (WPU) is a new type of polyurethane system, which using water instead of organic solvent as dispersing medium. Because of its non-toxicity and environmental safety, WPU is considered as the development direction of coatings and adhesives. However, the mechanical properties of WPU are worse than that of solvent-based polyurethane, therefore, the modification of WPU has received increasingly attention. Meanwhile numerous evidences demonstrate the excellent properties of cellulose nanofibers (CNFs) such as high aspect ratio, low weight and outstanding mechanical strength. Therefore, there is a high expectation for CNFs to be introduced into WPU as reinforcing filler. In this work, a series of CNFs/WPU nanocomposite films were prepared by solution blending. The structure, morphology, thermal behavior and mechanical properties were investigated. SEM results showed that CNFs were evenly dispersed in the WPU matrix. Tensile tests indicated that the modulus and tensile strength of CNFs/WPU nanocomposite films were improved compared with the neat film. While the break elongation of the nanocomposite films decreased with the increase of CNFs content. The synergistic interaction between CNFs and WPU matrix plays an important role in the enhancement of mechanical properties.

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