Addition Of Cellulose Nanofibers Research Articles

Rheology, curing temperature and mechanical performance of oil well cement: Combined effect of cellulose nanofibers and graphene nano-platelets

Cellulose nanofibers (CNFs) were prepared through acid hydrolysis and used in combination with graphene nano-platelets (GNPs) as modifiers for oil well cement (OWC). The rheology behavior of CNF/GNP-OWC slurries at three temperatures (i.e., 20, 40, and 60°C) was measured and modeled using four different rheological models. Thermal properties, surface functional groups, morphology, and mechanical performance of the composites were characterized. CNF/GNP-OWC slurry exhibited a typical shear-thinning behavior with reduced shear viscosity at higher shear rates. The use of CNFs and GNPs led to increased yield stresses of fresh CNF/GNP-OWC slurry and temperature significantly influenced the yield stress values. Among these rheology models, the Vom Berg model exhibits the best fitting result of the slurry rheology data (R2=0.999). The addition of CNFs and GNPs increased degree of hydration (DOH) value of CNF/GNP-OWC composites. Both flexural and compressive strengths of the CNF/GNP-OWC composites were enhanced with added CNFs and GNPs. The reinforcing mechanism was attributed to the increased DOH, reduced pores, and bridging effect of CNFs and GNPs in the composites.

Remarkable increase of paper strength by combining enzymatic cellulose nanofibers in bulk and TEMPO-oxidized nanofibers as coating

Cellulose nanofibers (CNF) have been proposed by several authors as a reinforcing additive for papermaking pulps; their use allows one to avoid mechanical refining of pulp fibers, which damages the fibers and reduces their lifespan and consequently recycling cycles. In the present work, use of CNF obtained through enzymatic pretreatment as a bulk pulp additive is studied versus traditional (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)-oxidized CNF. Results indicate that enzymatic CNF improves the overall paper properties in a similar way to TEMPO-oxidized CNF; however, the enzymatic pretreatment is supposed to be significantly cheaper and environmentally friendly compared with the chemical treatment. Paper reinforced with enzymatic CNF was later surface-coated with solution containing TEMPO nanofibers oxidized with 15 mmol NaClO to further promote the mechanical strength. The results indicate that the combination of bulk addition of enzymatic CNF to the papermaking pulp followed by surface application of TEMPO-oxidized CNF induced significant improvement in the mechanical properties of the paper at lower cost than sole use of TEMPO-oxidized CNF as bulk additive. To the best of our knowledge, this is the first work in which enzymatic and TEMPO-oxidized CNF are combined as paper additives for bulk and surface application to improve overall paper properties.

Improving the Properties of Soda Bagasse Pulp by Using Cellulose Nanofibers in the Presence of Cationic Polyacrylamide

Cellulose nanofiber (CNF) was used to improve the optical and strength properties of soda bagasse pulp (500 CSF) in the presence of cationic polyacrylamide (CPAM). Cationic polyacrylamide was added at 0.05, 0.1, and 0.15%, and cellulose nanofiber was added at 0.1, 0.5, 1, and 2% based on pulp O.D. Laboratory handsheets were prepared (60 g/m2), and optical and strength properties were measured according to TAPPI standards. Scanning electron microscopy and atomic force microscopy images showed that empty spaces between fibers decreased under CPAM/CNF treatments. The effect of the additives and their addition level on all the measured paper properties was significant at the 99% confidence level. The light scattering coefficient, brightness, and whiteness increased with the addition of cellulose nanofibers, but the light absorption coefficient, yellowness, and opacity decreased. At the highest levels of the additives (2% CNF and 0.15% CPAM), the tensile and burst strengths of handsheets increased by 33% and 15%, respectively. Generally, cellulose nanofibers/cationic polyacrylamide complexes improved the optical and strength properties of bagasse pulp.

Sugarcane Bagasse Paper Reinforced by Cellulose Nanofiber (CNF) and Bleached Softwood Kraft (BSWK) Pulp

This study explores the effects of bleached softwood kraft pulp (BSWK) as a conventional reinforcing material in comparison with cellulose nanofiber (CNF) as an emerging bionanomaterial on the bleached soda sugarcane bagasse (BSSB) paper furnish. Cationic polyacrylamide was selected as a retention aid along with the CNF addition to retain it on fiber surfaces during the papermaking process. The results showed that though the effects of CNF were similar to those of BSWK in the most of properties but there were some important differences which can industrially be noticeable. In one hand, both of cellulosic elements, when substituted for the BSSB at the 5 or 10 % levels, gave increases in the paper strength, i.e. samples containing 10 % CNF yielded similar tensile strength (53 N m/g) and a more consolidated structure (14 % increment of the density) than those produced with 10 % BSWK. CNF addition had opposite effects on the air-permeability of the resulting paper. Unlike BSKW, the addition of CNF had a strong favorable effect on tear strength, but it was markedly slowed the rate of drainage time when it was especially added at 10 % level of the final furnish.

Cellulose Nanofibers as a Modifier for Rheology, Curing and Mechanical Performance of Oil Well Cement.

The influence of nanocellulose on oil well cement (OWC) properties is not known in detail, despite recent advances in nanocellulose technology and its related composite materials. The effect of cellulose nanofibers (CNFs) on flow, hydration, morphology, and strength of OWC was investigated using a range of spectroscopic methods coupled with rheological modelling and strength analysis. The Vom-Berg model showed the best fitting result of the rheology data. The addition of CNFs increased the yield stress of OWC slurry and degree of hydration value of hydrated CNF-OWC composites. The flexural strength of hydrated OWC samples was increased by 20.7% at the CNF/OWC ratio of 0.04 wt%. Excessive addition of CNFs into OWC matrix had a detrimental effect on the mechanical properties of hydrated CNF-OWC composites. This phenomenon was attributed to the aggregation of CNFs as observed through coupled morphological and elemental analysis. This study demonstrates a sustainable reinforcing nano-material for use in cement-based formulations.

The effect of cellulose nanofibers on the crystallinity and nanostructure of poly(lactic acid) composites

Poly(lactic acid) (PLA) is a semi-crystalline polymer with good transparency, mechanical strength, and melt processability. However, the use of PLA in applications like food packaging is limited by its low heat resistance and slow crystallization rate. The addition of cellulose nanofibers can be an efficient solution to enhance PLA crystallinity and stiffness, maintaining the transparency and biodegradability, which are mandatory for packaging applications. The combined effect of annealing and cellulose nanofibers (surface treated—SCN or untreated—CN) on the crystalline structure of PLA was thoroughly studied at both micro- and nano-scales by differential scanning calorimetry (DSC), mechanical tests, X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM), Peak Force QNM (Quantitative Nanomechanical Mapping) mode. The ability of CN to act as nucleating agents was highlighted by DSC and XRD, both methods pointing out similar trends of crystallinity variation. Higher crystallinity was observed after annealing, 59 % instead of 40 % for PLA, 67 % instead of 48 % for PLA-CN and 57 % instead of 39 % for PLA-SCN, respectively. A mixture of α and α′ crystals was detected in all the samples after annealing but the concentration of the more disordered α′ form was higher in PLA-CN than in PLA-SCN. The transformation of the grained structure specific to amorphous PLA into a crystalline lamellar structure (average lamellar thickness of about 22 nm) after annealing was detected by Peak Force QNM. Nanoindentation tests showed an improvement of the surface modulus and hardness for the composites compared to PLA, after annealing. Thus, modulus increased from 5.9 GPa for PLA to 6.2 GPa for PLA-CN and 6.6 GPa for PLA-SCN. The understanding of PLA nanostructure modification by annealing and CN addition may contribute to adjust post-processing treatments, thus making PLA more suitable for packaging and other applications.

Fabrication of Poly(ε-caprolactone) Scaffolds Reinforced with Cellulose Nanofibers, with and without the Addition of Hydroxyapatite Nanoparticles.

Biomaterial properties and controlled architecture of scaffolds are essential features to provide an adequate biological and mechanical support for tissue regeneration, mimicking the ingrowth tissues. In this study, a bioextrusion system was used to produce 3D biodegradable scaffolds with controlled architecture, comprising three types of constructs: (i) poly(ε-caprolactone) (PCL) matrix as reference; (ii) PCL-based matrix reinforced with cellulose nanofibers (CNF); and (iii) PCL-based matrix reinforced with CNF and hydroxyapatite nanoparticles (HANP). The effect of the addition and/or combination of CNF and HANP into the polymeric matrix of PCL was investigated, with the effects of the biomaterial composition on the constructs (morphological, thermal, and mechanical performances) being analysed. Scaffolds were produced using a single lay-down pattern of 0/90°, with the same processing parameters among all constructs being assured. The performed morphological analyses showed a satisfactory distribution of CNF within the polymer matrix and high reliability was obtained among the produced scaffolds. Significant effects on surface wettability and thermal properties were observed, among scaffolds. Regarding the mechanical properties, higher scaffold stiffness in the reinforced scaffolds was obtained. Results from the cytotoxicity assay suggest that all the composite scaffolds presented good biocompatibility. The results of this first study on cellulose and hydroxyapatite reinforced constructs with controlled architecture clearly demonstrate the potential of these 3D composite constructs for cell cultivation with enhanced mechanical properties.

M704 CFRP(炭素繊維強化複合材料)の機械的特性に及ぼすCNF(セルロースナノファイバ)の添加の効果 : 添加繊維周辺の応力状態のシミュレーションによる検証(GS3 材料力学・計算力学(1),修士研究発表セッション)

M704 CFRP(炭素繊維強化複合材料)の機械的特性に及ぼすCNF(セルロースナノファイバ)の添加の効果 : 添加繊維周辺の応力状態のシミュレーションによる検証(GS3 材料力学・計算力学(1),修士研究発表セッション)

Enzymatic Refining and Cellulose Nanofiber Addition in Papermaking Processes from Recycled and Deinked Slurries

Recycling and deinking processes cause fiber damage because of hornification phenomena and increased external fibrillation. Mechanical refining has been used for many years to enhance the mechanical properties of paper. Biorefining of pulp using enzymes is receiving increasing interest for energy reduction at the refining step of the paper-making process. Moreover, enzymes have also been used for the enhancement of mechanical properties without affecting the drainage rate. As an alternative to mechanical refining treatment, a combination of an enzymatic treatment and cellulose nanofibril (CNF) addition was explored to enhance the mechanical properties of paper. The tests were carried out on a deinked pulp (DIP) suspension made of 50% old newspapers (ONP) and 50% old magazines (OMG). Various enzyme charges and CNF amounts were added to the mixture of ONP and OMG. All pulps (treated and untreated) were characterized from a morphological point of view, and the paper sheets made thereof were mechanically characterized. The combination of the enzymatic treatment with the addition of 3% CNF provided sufficient tensile strength for the paper to be used in high-performance applications

Biodegradability and mechanical properties of reinforced starch nanocomposites using cellulose nanofibers

In this study the effects of chemical modification of cellulose nanofibers (CNFs) on the biodegradability and mechanical properties of reinforced thermoplastic starch (TPS) nanocomposites was evaluated. The CNFs were modified using acetic anhydride and the nanocomposites were fabricated by solution casting from corn starch with glycerol/water as the plasticizer and 10 wt% of either CNFs or acetylated CNFs (ACNFs). The morphology, water absorption (WA), water vapor permeability rate (WVP), tensile, dynamic mechanical analysis (DMA), and fungal degradation properties of the obtained nanocomposites were investigated. The results demonstrated that the addition of CNFs and ACNFs significantly enhanced the mechanical properties of the nanocomposites and reduced the WVP and WA of the TPS. The effects were more pronounced for the CNFs than the ACNFs. The DMA showed that the storage modulus was improved, especially for the CNFs/TPS nanocomposite. Compared with the neat TPS, the addition of nanofibers improved the degradation rate of the nanocomposite and particularly ACNFs reduced degradation rate of the nanocomposite toward fungal degradation.

Effect of cellulose nanofibers concentration on mechanical, optical, and barrier properties of gelatin-based edible films

The effect of gelatin, glycerol, and cellulose nanofiber (CNFs) concentrations on the mechanical properties, water vapor permeability, and color parameters of films was evaluated. The results indicate that the color is only affected by the gelatin concentration. Mechanical tests indicated that with increasing concentration of gelatin and CNFs, there is an increase in tensile strength, whereas an increase in glycerol concentration causes an increase in elongation, making the films more flexible. An increased concentration of gelatin and glycerol makes the film more permeable to water vapor, while an increase in the concentration of CNFs reduces this property. Finally, the addition of CNFs to gelatin-based films improves their mechanical and barrier properties (water vapor) without affecting the appearance (color) of the films.

Effect of cellulose nano fiber (CNF) on fatigue performance of carbon fiber fabric composites

The effect of cellulose nano fibers (CNF): micro-fibrillated cellulose and bacteria cellulose fibers were investigated on the fatigue life of carbon fiber (CF) fabric/epoxy (EP) composites. Epoxy used as the matrix was physically modified with CNF in advance before fabricating the laminates. The high cycle fatigue strength was significantly improved at 0.3wt% CNF. There exists an appropriate CNF content which makes the fatigue life longest. An increase of adhesive strength between CF and matrix results due to physical modification with CNF. The adhesive strength much increases with increasing the CNF content. Almost no interfacial debonding occurs at 0.8wt% CNF content when CF breakage takes place. On the other hand, some debonding occurs along CFs from the breaking point at 0.3wt% CNF. Debonding is more significant in the case of no CNF addition to the matrix. An appropriate interfacial strength brought at 0.3wt% CNF is the key of fatigue life extension.

Preparation and Characterization of Polysulfone/Sulfonated Polysulfone/Cellulose Nanofibers Ternary Blend Membranes

Ternary blend membranes were prepared with polysulfone (PSf), sulfonated polysulfone (SPSf), and cellulose nanofibers (CNF) by a Loeb-Sourirajan (L-S) phase inversion process. The cross-section and bottom surface morphology of the membranes were analyzed by scanning electron microscopy (SEM), and the performance of the membranes was evaluated in terms of pure water flux, bovine serum albumin (BSA) rejection, contact angle, tensile strength, and breaking elongation. The morphology of the cellulose nanofibers (CNF) was detected by transmission electron microscopy (TEM). Results showed that within a certain range, the addition of SPSf improved compatibility between PSf and CNF, and the addition of CNF could improve the hydrophilicity of the membranes. The maximum value of pure water flux reached 137.6 L/m2h, and the minimum value of BSA rejection reached 95.8% when CNF content was 0.3 wt% in casting solution. Also, a certain addition of CNF could enhance the mechanical properties of the membranes.

Influence of Thermal Treatment on Mechanical and Morphological Characteristics of Polyamide 11/Cellulose Nanofiber Nanocomposites

Nanocomposite films were prepared from polyamide 11 (PA11) and cellulose nanofibers (CN) by melt compounding and compression molding. The impact of thermal treatment on the morphology and mechanical behavior of PA11 and nanocomposite films was studied using dynamic mechanical analysis, tensile tests, X-ray diffraction (XRD), and peak force (PF) QNM technique. Slightly higher storage modulus values were obtained for nanocomposites compared to the matrix before the treatment, but a noticeable increase was observed after the treatment. Although CN addition determined increased tensile strength and modulus both before and after the treatment, the increase was much more significant in the case of treated films. The best mechanical properties were shown by treated PA11 films containing 5 wt% CN, with 40% higher Young’s modulus and with 35% higher tensile strength compared to the matrix. Some of the changes pointed out by static and dynamic mechanical tests were explained by the morphological changes determined by the thermal treatment and emphasized by PF QNM and by the increase of XRD crystallinity. A transition from lamellar stack morphology to one involving spherulites was highlighted by AFM. Thermal treatment has proved a valuable method for improving the mechanical properties of PA11/CN composites.

Preparation and properties of wood plastic composite reinforced by ultralong cellulose nanofibers

Wood plastic composites (WPCs) were reinforced by ultralong cellulose nanofibers (CNF), which were extracted from poplar flour. To solve the aggregate problem of CNF in nonpolar high density polyethylene (HDPE), a new method, which was corresponding to preblending the mixture of wood flour and HDPE powder in the CNF suspension with continuously stirring at 80°C for 2 h was used before the extrusion process. The capillary rheological tests showed CNF could increase the apparent viscosity of WPCs obviously. From the SEM images, abundant CNF were distributed on the fracture surface of WPCs uniformly and compactly like “spider web.” Compared with WPC without CNF, the bending strength, bending modulus, and impact strength of WPCs with 20 wt% CNF increased by 93.01, 153.64, and 116.55%, respectively. The thermal expansion coefficient of WPCs with 20 wt% CNF decreased by 61.30%. The storage modulus of WPCs was greatly improved with the addition of CNF. POLYM. COMPOS., 37:1206–1215, 2016. © 2014 Society of Plastics Engineers

Cotton cellulose nanofiber-reinforced high density polyethylene composites prepared with two different pretreatment methods

The reinforcing effect of cellulose nanofibers (CNF), individualized from cotton fibers subjected to a chemical process and a grinding process, has been investigated using high density polyethylene (HDPE) as matrix. In order to solve the agglomeration problem of cotton nanofiber in non-polar HDPE, two pre-treatment methods have been used prior to the extrusion process, one method was relative to the physical pretreatment, and the other corresponded to the polyoxyethylene (PEO) dispersion agent method. The dispersion of cotton CNF in HDPE and reinforcing effect of cotton CNF on HDPE with the two preparation methods were made a comparison. From the SEM images observation, a good dispersion effect and an ideal network structure of the cotton CNF/HDPE composites could be achieved via two preparation methods. However, PEO dispersion agent method could improve the CNF dispersion much better than the physical pretreatment method, but unfortunately reducing the aspect ratio of the cotton CNF. Addition of cotton CNF clearly increased the bending strength (MOR) and bending modulus (MOE) of HDPE. The MOR and MOE of cotton CNF/HDPE composites with the physical pretreatment method were much higher than those of the nanocomposites with the PEO dispersion agent method. A comparative study was also made to find out the effect of two cellulose based nanofillers (CNF and nanocrystalline cellulose (NCC)) on the rheological, thermal, and mechanical properties of HDPE. The results demonstrated that cotton CNF had a better reinforcing effect on HDPE than NCC, while NCC could decrease the thermal expansion of the nanocomposites more significantly.

Effects of hemicellulose pre-extraction and cellulose nanofiber on the properties of rice straw pulp

The aim of this study was to evaluate the influence of mild alkaline pre-extraction on the hemicelluloses removal of rice straw. In addition, the performance of cellulose nanofibers (CNFs) addition on some physico-mechanical properties obtained from extracted and un-extracted (control) samples were investigated. An optimum compromise was found as operating conditions (10% soda, 50°C, and 90min) that provided moderate hemicelluloses removal (48.1%). The residual extracted rice straw particles were subjected to soda–anthraquinone pulping at 160°C for 30–60min with 6 to 18% active alkali charge. Compared with the control samples, the screened yield and Kappa number for extracted pulps decreased slightly. Extracted samples showed better air resistance compared with the un-extracted (control) pulps. However, pre-extraction was found to negatively impact on some mechanical properties such as decrease in burst and tensile indices while addition of CNFs and refining of fibers could improve the strength properties considerably. In general, the addition of CNFs in any concentrations considerably enhanced tensile and burst indices of the sheets in extracted and un-extracted conditions, compared with the unfilled ones. The improvement in mechanical properties was considered one of the key benefits brought by CNFs reinforcement. On the other hand, the stretch properties of the beaten pulps are higher than those of control samples. SEM observations showed that CNFs were deposited on the voids between the rice straw fibers.

Starch based Active Packaging Film Reinforced with Empty Fruit Bunch (EFB) Cellulose Nanofiber

Biopolymer active packaging is known to have low mechanical strength and highly brittle. Regardless to its disadvantage, polymers from natural sources have attracted serious attention since the non-renewable sources for example petroleum, the major precursor of plastic manufacturing become depleted. Starch-Chitosan for instance is a hybrid film that entirely green as it produced from a renewable material and totally degradable. The addition of chitosan in film packaging able to kill pathogen hence increases the food shelf life. Through nanotechnology advance, nanomaterial can be used for material reinforcement. Nowadays, greener approach could be applied by incorporating natural cellulose nanofiber into the film matrix. Oil palm empty fruit bunch (OPEFB) fiber that rich of cellulose contents could be treated chemically to purify the cellulose in the fiber. Cellulose fiber obtained was cut to a nano-size using acid hydrolysis. Transmission Electron Microscopy (T.E.M) obtained shown the nanofiber size was ranged between 1-100nm in diameter. Nanocomposite film formulation, was constructed by varying the cellulose nanofiber incorporation between 2-10% per weight of starch. The strength of the films was measured as well as antimicrobial properties. The addition of 2% cellulose nanofiber into the film matrix exhibits high tensile strength with 5.25Mpa compared to starch-chitosan hybrid film with 3.96Mpa. However, no significant improvement in tensile strength was distinguished beyond that ratio. Antimicrobial analysis shows that the addition of cellulose nanofiber could increase the inhibition effect towards gram-positive bacteria but not towards gram-negative bacteria. The addition of 2% cellulose nanofiber increased the inhibition diameter towards gram positive bacteria, Bacillus subtilis up to 33%. However, inhibition towards Bacillus subtilis decreased with the incorporation of more cellulose nanofiber. In gram-negative bacteria Escherichia coli, the addition of cellulose nanofiber does not give significant effect to bacterial. In General, the addition of the unique structure of cellulose nanofiber in the starch based polymer system could enhance the mechanical strength of the film and increase the inhibition of the gram positive bacteria.

The Synthesis of Cellulose Nanofibers from Sesbania Javanica for Filler in Thermoplastic Starch

This research was aimed to study the synthesis of cellulose nanofibers from Sesbania Javanica and the effect of the cellulose nanofiber (CNF) addition on thermoplastic starch derived from tapioca flour. The mechanical properties, morphological structure and thermal stability of neat thermoplastic starch and their composites were investigated by Tensile testing, Scanning Electron Microscope (SEM) and Thermogravimetric analysis (TGA), respectively. Moreover moisture absorption was also studied. The composites with 0, 1, 2 and 3 phr of cellulose nanofibers content were prepared. Cellulose nanofibers were synthesized in the aqueous suspension (containing 8.63% of dried cellulose nanofibers). The percentage yield was found of 14.8% and the average diameter is about 100 nm. The addition of cellulose nanofibers in thermoplastic starch showed that the modulus of the composites tended to improve, however, the tensile strength did not change significantly and tended to decrease when higher cellulose nanofibers content. SEM revealed the formation of CNF aggregates in the composites, especially the content of 3.0 phr of CNF, that is why no improvement in the tensile strength of the composites. Also, the moisture absorption of the TPS/CNF composite improved with the cellulose nanofibers content.

Physicomechanical properties of nanocomposites based on cellulose nanofibre and natural rubber latex

Cellulose nanofibres (CNF) with diameter 10–60 nm were isolated from raw banana fibres by steam explosion process. These CNF were used as reinforcing elements in natural rubber (NR) latex along with cross linking agents to prepare nanocomposite films. The effect of CNF loading on the mechanical and dynamic mechanical (DMA) properties of NR/CNF nanocomposite was studied. The morphological, crystallographic and spectroscopic changes were also analyzed. Significant improvement of Young’s modulus and tensile strength was observed as a result of addition of CNF to the rubber matrix especially at higher CNF loading. DMA showed a change in the storage modulus of the rubber matrix upon addition of CNF which proves the reinforcing effect of CNF in the NR latex. A mechanism is suggested for the introduction of the Zn–cellulose complex and its three dimensional network as a result of the reaction between the cellulose and the Zinc metal which is originated during the composite formation.