Addition Of Cellulose Nanocrystals Research Articles

Effect of anthocyanin indicator addition on cellulose nanocrystals/gellan gum‐based intelligent packaging films

AbstractFood spoilage often causes a change in pH inside the package. As a type of intelligent packaging, pH freshness indication packaging, with its simplicity, sensitivity, and efficiency, can monitor food quality and inform consumers promptly. In this study, Clitoria ternatea anthocyanin (CT) was added to gellan gum (GG), glycerol and cellulose nanocrystal (CNC) matrix to prepare a pH‐sensitive indicator film. The addition of CT disrupted the network structure, forming a new hydrogen bond and a smooth and continuous cross‐section of the film, giving the film excellent mechanical properties. The addition of CNC locked the CT firmly into the indicator film while improving the film's water resistance. Anthocyanin improved the light‐blocking ability of the film and gave an excellent pH response to the indicator film. The pH response tests showed a significant color change in the film at pH in the range of 3–12 when anthocyanin was added at 20% and 30%, suggesting the potential application of the developed intelligent indicator film in monitoring food freshness.Novelty impact statement Excellent mechanical properties (Tensile strength: 33.47 MPa; Elongation at break: 27.12%), even with the addition of anthocyanins. High water contact angle (88.4°) provided excellent moisture resistance to the film. Excellent pH responsiveness and new ideas for real‐time material monitoring of food packaging.

Injectable pH Thermo-Responsive Hydrogel Scaffold for Tumoricidal Neural Stem Cell Therapy for Glioblastoma Multiforme.

Glioblastoma multiforme (GBM) is the most common malignant brain tumor in adults and despite recent advances in treatment modalities, GBM remains incurable. Injectable hydrogel scaffolds are a versatile delivery system that can improve delivery of drug and cell therapeutics for GBM. In this report, we investigated an injectable nanocellulose/chitosan-based hydrogel scaffold for neural stem cell encapsulation and delivery. Hydrogels were prepared using thermogelling beta-glycerophosphate (BGP) and hydroxyethyl cellulose (HEC), chitosan (CS), and cellulose nanocrystals (CNCs). We evaluated the impact of neural stem cells on hydrogel gelation kinetics, microstructures, and degradation. Furthermore, we investigated the biomaterial effects on cell viability and functionality. We demonstrated that the incorporation of cells at densities of 1, 5 and 10 million does not significantly impact rheological and physical properties CS scaffolds. However, addition of CNCs significantly prolonged hydrogel degradation when cells were seeded at 5 and 10 million per 1 mL hydrogel. In vitro cell studies demonstrated high cell viability, release of TRAIL at therapeutic concentrations, and effective tumor cell killing within 72 h. The ability of these hydrogel scaffolds to support stem cell encapsulation and viability and maintain stem cell functionality makes them an attractive cell delivery system for local treatment of post-surgical cancers.

Effect of cellulose nanocrystals on bacterial cellulose hydrogel for oil-water separation

Cellulose hydrogels reveal potential application for oil-water emulsion separation. However, they still suffer from lower flux, resulting from their stable hydration layers. In this work, bacterial cellulose (BC)/cellulose nanocrystals (CNC) hydrogels were prepared via the immersion method. The hydrogels also showed good superhydrophilicity/underwater-superoleophobicity. They can separate oil-in-water and water-in-oil emulsions with separation efficiency > 97.6 %. More importantly, the addition of CNC improved the crystallinity of BC hydrogels and decreased the accessibility to water molecules, which increased the water flux of hydrogels. This work provides a feasible strategy to enhance the separation flowrate for oil-water emulsions.

Polyvinyl Alcohol-Cellulose Nanocrystal Hydrogel Containing Anti-inflammatory Agent

Hydrogel wound dressings were developed through cross-linking reactions of polyvinyl alcohol (PVA) with glutaraldehyde and by the addition of diclofenac sodium and rutin as anti-inflammatory agents. Cellulose nanocrystals (CNC) were added to improve mechanically and release properties. CNC was isolated from pineapple leaf fibers through the ammonium persulfate method resulting in a mixture of rod-like whisker and spherical morphology. The mechanical properties of hydrogels are increasing with the addition of CNC. Hydrogels containing 8% CNC exhibited 7.266 N/mm2 tensile strength, 156.3% maximum strain, and 700.3 N/mm2 elastic modulus. Drug release tests containing sodium diclofenac were done by taking incubated phosphate buffer saline samples in a pH 7.4 environment and showed that all CNC variations tested are controllable for the first 30 min compared to the sample without CNC. Sodium diclofenac is easily eluted from hydrogel due to its polar properties, and all samples almost demonstrated the same release profile. PVA hydrogels showed fluctuating concentrations of diclofenac compared to others. While hydrogels containing rutin showed a controlled release mode, the addition of CNC in PVA resulted in a slower release of rutin, possibly due to the better binding between CNC and rutin. To conclude, CNC has successfully improved the performance of PVA hydrogels, including the drug release properties.

Intelligent films based on pectin, sodium alginate, cellulose nanocrystals, and anthocyanins for monitoring food freshness

To address consumer-level food waste, and pollution from commercial plastics, we developed intelligent films using sodium alginate (SA), pectin (PC), cellulose nanocrystals (CNCs), and anthocyanins extracted from red cabbage (RCA). We also investigated two methods of reinforcing these films – cross-linking (CL), and the addition of CNCs. Both together and separately, these methods improved SA/PC films’ mechanical properties and thermal stability. The optimal SA/PC/CNCs/RCA/CL films exhibited pH-dependent color-response properties and high water resistance. These were then tested as colorimetric freshness indicators for shrimp samples, both through seepage and the monitoring of volatile compounds. The colors of the indicators changed from lilac to dark green to greenish-yellow after storage at 25 °C for 72 h, whereas at 4 °C, they changed much more slowly over the same time period. This demonstrated the excellent potential of such films to reduce food waste by providing real-time warnings of pH variation resulting from spoilage.

Effect of the Addition of Corn Husk Cellulose Nanocrystals in the Development of a Novel Edible Film.

The cellulose from agroindustrial waste can be treated and converted into nanocrystals or nanofibers. It could be used to produce biodegradable and edible films, contributing to the circular economy and being environmentally friendly. This research aimed to develop an edible film elaborated with activated cellulose nanocrystals, native potato starch, and glycerin. The activated cellulose nanocrystals were obtained by basic/acid digestion and esterification with citric acid from corn husks. The starch was extracted from the native potato cultivated at 3500 m of altitude. Four film formulations were elaborated with potato starch (2.6 to 4.4%), cellulose nanocrystals (0.0 to 0.12%), and glycerin (3.0 to 4.2%), by thermoforming at 60 °C. It was observed that the cellulose nanocrystals reported an average size of 676.0 nm. The films mainly present hydroxyl, carbonyl, and carboxyl groups that stabilize the polymeric matrix. It was observed that the addition of cellulose nanocrystals in the films significantly increased (p-value < 0.05) water activity (0.409 to 0.447), whiteness index (96.92 to 97.27), and organic carbon content. In opposition to gelatinization temperature (156.7 to 150.1 °C), transparency (6.69 to 6.17), resistance to traction (22.29 to 14.33 N/mm), and solubility in acidic, basic, ethanol, and water media decreased. However, no significant differences were observed in the thermal decomposition of the films evaluated through TGA analysis. The addition of cellulose nanocrystals in the films gives it good mechanical and thermal resistance qualities, with low solubility, making it a potential food-coating material.

Improvement in mechanical and physical properties of starch-based films provided by cellulose nanocrystals extracted from rice straw

Films based on starch (ST) have been widely used for food packaging; however, it is necessary to improve their mechanical properties. In this context, eco-friendly starch films incorporated with cellulose nanocrystal (CNC) were prepared using the casting method. CNCs were isolated using acid hydrolysis from rice straw (RS) as raw material and characterized by FESEM, TEM, FIIR, XRD, TGA and zeta potential analyzer. The isolated CNC presented a rod-like structure, high crystallinity (75%) with a diameter of around 12 nm. Subsequently, the starch-based films reinforced with various concentrations of CNC (2, 5, 10, and 15 wt%) were characterized for their morphological features, mechanical, barrier, and thermal properties and compared with control film. It was shown that the addition of CNCs to the film improved the mechanical properties and decreased the water vapor permeability, as important characteristics in food packaging materials.

Magnetic cellulose nanocrystals as efficient support for indium(III) in the synthesis of tetrazoles and phthalazines

Catalysts, especially heterogeneous catalysts, play an essential role in organic transformation reactions. Hence, we use a composite of cellulose nanocrystals (CNC) and Fe3O4 NPs as new support for indium(III) and evaluate the performance of fabricated Fe3O4/CNC-In(III) catalyst in the synthesis of two different heterocyclic compounds: Tetrazole and phthalazine derivatives. Although metal oxides and metal NPs are in the spotlight due to their excellent catalytic activity, they are limited in application due to their self-agglomeration in the reaction mixture, resulting in reduced performance. The addition of CNC to Fe3O4 NPs due to rich-hydroxyl sites on the CNC surface and its interaction turns Fe3O4/CNC into a stable and appropriate substrate for the immobilization of indium(III). The formation and physicochemical properties of the catalyst were endorsed by FT-IR, SEM, TEM, EDS, XRD, TGA, and elemental mapping analysis. In addition, the synthesis of substituted 2-(1H-tetrazole-5-yl) acrylonitrile and 2H-indazolo[2,1-b]phthalazinetriones was performed under solvent-free conditions; this feature is another advantage of the current procedure. Utilization of sustainable natural materials and low-cost chemicals, short reaction time, high catalytic activity, magnetic feature and easy separation with external magnet, excellent reusability without showing substantial activity loss for six runs, and uniform distribution are some of the significant advantages of this catalyst.

Improved Properties of Composite Edible Films Based on Chitosan by Using Cellulose Nanocrystals and Beta-Cyclodextrin

The aim of this study was to produce innovative edible films and coatings with various combinations of materials, in order to achieve the best possible resulting properties. More specifically, the effect of cellulose nanocrystals (CNC) or beta-cyclodextrin (CD) addition to chitosan (CH) films and the development of composite CH–CNC–CD films were investigated. According to the results, most properties of both CH–CNC and CH–CD edible films were improved. The viscosity of the solutions was decreased up to 50% while the surface tension was minimally changed even at high levels of CNC or CD addition. Furthermore, oxygen and water vapor permeability of the CH–CNC and the CH–CD edible films was decreased, whereas transparency and heterogeneity were increased. On the other hand, the study of the composite CH–CNC–CD films, showed that CNC improved viscosity, supporting thus the coating procedure. Moreover, CNC led to more stable structures with enhanced mechanical properties. Finally, CD mostly contributed to the improvement of the optical properties (lighter color and increased transparency).

Simultaneous wettability and stiffness control of UV-curing vegetable oil resin composites by lignocellulosic components

Acrylic resins have various applications, which range from coatings to 3D printing, among others. Following green chemistry and environmental preservation trends, the demand for bio-based acrylic resins is growing. Vegetable oil-based resins have arisen to meet the present challenge. However, the performance and tuning of sustainable resin properties still need improvement. Hence, we undertook this study to research tuneable and durable vegetable oil-based UV-curing composite resins. This work reports on vegetable oil-based resin loaded with lignocellulosic components of cellulose nanocrystals (CNC), cellulose nanofibres (CNF), hemicellulose (HC), and lignin (LN). The effects of lignocellulosic components on thermal stability, thermomechanical properties, transparency, surface morphology, and wettability were evaluated in detail. In addition, the interaction of lignocellulosic components with the polymer matrix and interface was thoroughly investigated. The intense interaction between lignocellulosic components and the polymer matrix helps to form a strong interface and creates a polymer composite with enhanced thermomechanical properties. The composite surface morphology and wettability can be tuned depending on the lignocellulosic component, i.e., with the addition of HC, CNC, and CNF. Hydrophilic affinity is improved and water wetting angles as low as 8° can be achieved, but with LN a value of 96° was observed, a slight increase in hydrophobicity compared to the vegetable oil (VO) matrix value of 90°. Adding HC and CNC reduced transparency at 500 nm by 14 and 16%, while adding LN and CNF by 18 and 25%, respectively. Fourier-transform infrared spectroscopy revealed strong interfacial interactions through the hydrogen bonding between CNC, CNF, HC, and the VO polymer. This work will shed light on the lignocellulosic components' future role in UV-curing resin applications. It also broadens lignocellulosic particles' application as reinforcing additives for UV-light sensitive polymeric resins.

Intelligent pH-sensing film based on polyvinyl alcohol/cellulose nanocrystal with purple cabbage anthocyanins for visually monitoring shrimp freshness

We aimed to prepare a new pH-sensing film based on the immobilization of purple cabbage anthocyanins (PCA) into Polyvinyl alcohol (PVA) reinforced by cellulose nanocrystals (CNC). FT-IR, XRD and TGA were used to assess the intermolecular interactions and thermo-stability of films. The addition of CNC and PCA resulted in an enhancement in UV–vis barrier, mechanical properties and moisture resistance. Inclusion of PCA imparted intelligent properties to the films. PCA-loaded films displayed strong visually detectable colorimetric responses to pH (2−13) and volatile ammonia. When applied to monitor shrimp freshness at 4 °C, PVA/CNC films containing 0.6 % PCA exhibited conspicuous color fluctuations from purple to gray blue upon deterioration. As a result, PVA/CNC-PCA colorimetric films were considered as intelligent packaging labels with significant mechanical, water vapor barrier properties and pH-sensing qualities for visual quality evaluation of fresh seafood products.

Synthesis, Characterization, and Physical Properties of Maleic Acid-Grafted Poly(butylene adipate-co-terephthalate)/Cellulose Nanocrystal Composites.

New sequences of nanocomposites including numerous maleic acid-grafted poly(butylene adipate-co-terephthalate) (g-PBAT) and cellulose nanocrystals (CNC) were efficaciously fabricated via transesterification and polycondensation processes with the covalent bonds between the polymer and reinforcing fillers. The grafting interaction of maleic acid onto PBAT was successfully demonstrated using Fourier transform infrared (FTIR) and 13C-nuclear magnetic resonance (NMR) spectra. The morphology of g-PBAT/CNC nanocomposites was investigated by wide-angle X-ray diffraction and transmission electron microscopy. Both results indicate that the CNC was randomly dispersed into the g-PBAT polymer matrix. The storage modulus at −80 and 25 °C was significantly enhanced with the incorporation of CNC into g-PBAT matrix. The crystallization rate of g-PBAT/CNC nanocomposites increased as the loading of CNC increased. With the incorporation of 3 wt% CNC, the half-time for crystallization of the g-PBAT/CNC composite decreased about 50~80% as compared with the same isothermal crystallization of pure polymer matrix. All water vapor permeation (WVP) values of all g-PBAT/CNC nanocomposites decreased as the loading of CNC increased. The decrease in WVP may be attributed to the addition of stiff CNC, causing the increase on the permeation route in the water molecules in the g-PBAT polymer matrix.

Modifying cellulose nanocrystal dispersibility to address the permeability/selectivity trade-off of thin-film nanocomposite reverse osmosis membranes

Thin-film nanocomposite reverse osmosis (TFN-RO) membranes with hydrophilic nanoparticles usually face a trade-off between water permeance and salt rejection. In this study, TFN membranes were produced by embedding different loadings of cellulose nanocrystals (CNCs) into the polyamide (PA) active layer by dispersing the CNCs in an organic monomer solution as opposed to the traditional approach where hydrophilic nanoparticles are added to the aqueous monomer solution. To facilitate the addition of the hydrophilic CNCs to the organic monomer solution, the CNCs were acetylated to form ACNCs with different degrees of substitution (DS = 0.7 and 1.7) of the hydroxyl groups. The successful incorporation of the CNCs and ACNCs into TFN-RO membranes was confirmed with ATR-FTIR spectroscopy, surface zeta potential, scanning electron microscopy, atomic force microscopy and water contact angle measurements. The NaCl rejection of ACNC-based TFN membranes remained stable (98–99 %) while water permeance increased by 40 % in comparison to CNC-TFN membranes. Compared to a reference thin-film composite (TFC) membrane, a two-fold water permeance increase was achieved (2.60 vs. 1.27 L/m2.h.bar) with a 0.4 wt% loading of ACNC2 in the TFN membrane. The ACNC-TFN membranes were significantly closer to the so-called upper-bound line than the best CNC-TFN membranes and the reference TFC membrane. This study shows the potential of using hydrophilic green nanoparticles in overcoming the permeance-selectivity trade-off of TFN-RO membranes. Hydrophobic functionalization of hydrophilic nanoparticles was demonstrated to be an effective approach in overcoming the limit of CNC nanoparticle incorporation in CNC-TFN membranes.

Biodegradation improvement of bioinspired crosslinked and noncrosslinked polyvinyl alcohol nanocomposites with cellulose nanocrystals extracted from rice straw through natural soil burial exposure

AbstractPolyvinyl alcohol with different cellulose nanocrystals (CNC) content extracted from rice straw were prepared by using solution casting method and their biodegradability in natural soil burial were studied. Ethanedioic acid (EA) was introduced as a crosslinker. The synthesized noncrosslinked and crosslinked PVOH/CNC nanocomposites films and their biodegradation were characterized with Fourier transform infrared spectroscopy (FTIR), tensile test, weight loss, Field Emission Scanning Electron Microscopy (FESEM), differential scanning calorimetry (DSC). The changes in chemical properties before and after biodegradation were confirmed through FTIR. Tensile test revealed that the tensile strength and elongation at break reduced as time of soil burial increases. Morphological study showed the extent of surface deterioration before and after soil burial, where the addition of CNC displayed greater deterioration. Melting temperature and crystallinity increased with addition of CNC but decreased after crosslinking. However, melting temperature and crystallinity of all nanocomposites increased after biodegradation. PVOH degrading bacteria were isolated and identified to be Bacillus cereus strain CCM 2010 and Bacillus cereus strain ATCC 14579. Biodegradation of the bionanocomposites were concluded to be in the following decreasing order: PVOH/CNC &gt; PVOH/EA/CNC &gt; PVOH &gt; PVOH/EA.

Experiment and molecular dynamics simulation of functionalized cellulose nanocrystals as reinforcement in cement composites

This study evaluated the potential effect of cellulose nanocrystal and coated polyethylene fiber on the mechanical properties of mortar. Two kinds of cellulose nanocrystals (CNC) directly as Nano-materials, and indirectly as film coated onto the polypropylene fibers were employed as cement-based reinforcement materials. The fluidity, flexural and compressive strength, and the microstructure of each specimen were measured. In the direct method, mortar mixed with the CNC containing carboxyl groups (CNC-C) showed superior properties compared to the CNC containing sulfo groups (CNC-S). The addition of CNC impacted the process of hydration and compactness of hydration products. The results of X-Ray polycrystalline diffractometer (XRD) and heat of hydration showed that CNC accelerated hydration process. Energy spectrum analysis (EDS) measured ratio of calcium to silicon (C/S) of calcium silicate hydrate (C-S-H) and proved that CNC-C increased the tightness of C-S-H while CNC-S decreased. The results of scanning electron microscopy (SEM) indicated that cellulose nanocrystals were interspersed in C-S-H, forming Nano-bridge and arresting Nano-crack. In the indirect method, the maximum increase in flexural strength of sample between all groups was the specimen that adding 0.3% (volume ratio of fiber to mortar) of CNC-C coated polypropylene fibers. The flexural and compressive strength of the mortar were increased by 22.81% and 10.65% compared to the control, respectively. The results of SEM indicated that coating enhanced bond of the fibers/matrix. Molecular dynamics simulation (MD) analyzed the binding energy, microstructure, dynamic characteristics and adsorption conformation between two CNCs and C-S-H at the molecular scale. MD presented clearly that the adsorption energy between CNC-S and C-S-H was much smaller than CNC-C and C-S-H. This was identical with CNC-C enhancing the mechanical properties of the mortar and CNC-S reducing the mechanical properties.

Poly(3-hydroxybutyrate) Nanocomposites with Cellulose Nanocrystals.

Poly(3-hydroxybutyrate) (PHB) is one of the most promising substitutes for the petroleum-based polymers used in the packaging and biomedical fields due to its biodegradability, biocompatibility, good stiffness, and strength, along with its good gas-barrier properties. One route to overcome some of the PHB’s weaknesses, such as its slow crystallization, brittleness, modest thermal stability, and low melt strength is the addition of cellulose nanocrystals (CNCs) and the production of PHB/CNCs nanocomposites. Choosing the adequate processing technology for the fabrication of the PHB/CNCs nanocomposites and a suitable surface treatment for the CNCs are key factors in obtaining a good interfacial adhesion, superior thermal stability, and mechanical performances for the resulting nanocomposites. The information provided in this review related to the preparation routes, thermal, mechanical, and barrier properties of the PHB/CNCs nanocomposites may represent a starting point in finding new strategies to reduce the manufacturing costs or to design better technological solutions for the production of these materials at industrial scale. It is outlined in this review that the use of low-value biomass resources in the obtaining of both PHB and CNCs might be a safe track for a circular and bio-based economy. Undoubtedly, the PHB/CNCs nanocomposites will be an important part of a greener future in terms of successful replacement of the conventional plastic materials in many engineering and biomedical applications.

Exploration of multifunctional properties of garlic skin derived cellulose nanocrystals and extracts incorporated chitosan biocomposite films for active packaging application

For many years, garlic has been used as a condiment in food and traditional medicine. However, the garlic skin, which accounts for 25% of the garlic bulk, is considered agricultural waste. In this study, cellulose nanocrystals (CNCs) and garlic extract (GE) from garlic skin were isolated and used as fillers to manufacture biocomposite films. The films were characterized in terms of UV barrier, thermal, mechanical, biodegradability, and antimicrobial activity. The chitosan-containing films and CNCs have significantly improved the films' tensile strength, Young's modulus, and elongation but decreased the film transparency compared to chitosan films. The combination of the CNCs and GE, on the other hand, slightly reduced the mechanical properties. The addition of CNCs slightly decreased the film transparency, while the addition of GE significantly improved the UV barrier properties. Thermal studies revealed that the incorporation of CNC and GE had minimal effect on the thermal stability of the chitosan films. The degradability rate of the chitosan composite films was found to be higher than that of the neat chitosan films. The antimicrobial properties of films were studied against Escherichia coli, Streptomyces griseorubens, Streptomyces alboviridis, and Staphylococcus aureus, observing that their growth was considerably inhibited by the addition of GE in composite films. Films incorporating both CNCs and GE from garlic skin hold more promise for active food packaging applications due to a combination of enhanced physical characteristics and antibacterial activity.

Wholly Biobased Polyamide Thermoplastic Elastomer‐Cellulose Nanocomposites

AbstractPolymers play a prominent role in daily lives; however, there is a growing concern on the depleting fossil resources triggering the research for sustainable alternatives. Here, novel wholly biobased nanocomposites are prepared from polyamide 36,36 (PA36,36) thermoplastic elastomer and cellulose nanocrystals (CNCs). Further, the influence of CNC addition and CNC loading on the morphological features, thermal and mechanical properties of PA36,36 is studied. The presence of CNC in PA36,36 affects the thermal degradation of PA36,36. The additions of 10 and 30 wt% CNCs to the PA36,36 improve the tensile strength and Young's modulus by up to 700% and 750% to 9.6 and 6.8 MPa, respectively, while still maintaining relatively high elongation at break values. The hardness of the polymer increases significantly after the inclusion of CNC. The PA36,36/CNC nanocomposites also show relatively good resilience when exposed to 100% strain. Overall, these biobased thermoplastic elastomer nanocomposites can be potential alternatives for some existing rubbers with low or medium hardness.

Biobased plasticizer and cellulose nanocrystals improve mechanical properties of polylactic acid composites

Biopolymers are a fundamental part of contemporary life due to their biodegradable and biocompatible nature. Among different biopolymers, polylactic acid (PLA) with ease of processability, is one of the most commercially available biopolymers used in additive manufacturing. However, the low ductility and impact strength limits its application in commercial plastic products. One of the methods to enhance the ductility of PLA is addition of biobased reinforcing agents and plasticizers. The objective of this research is to use biobased materials for improving the mechanical properties of PLA composites. Cellulose nanocrystals (CNC) and distillers dried grains with solubles (DDGS) were selected as reinforcing agents, polyethylene glycol (PEG) as a plasticizer and maleic anhydride (MA) as a coupling agent. Biocomposites containing distillers DDGS (10%), CNC (0.25–1%), PEG (2%), maleic anhydride (0.25%) and PLA (86.75–87.75%) were manufactured using melt blending. To investigate the effects of CNC, PEG, and MA on PLA composites the morphological, ductile, and mechanical, properties of the composites were examined. Morphological changes were characterized by using optical microscopic images, mechanical properties by differential scanning calorimetry and ductility by tensile testing. The results demonstrate that addition of CNC and PEG to PLA improved its mechanical and ductile properties whereas maleic anhydride helped in dispersion of CNC. The observed improvements were attributed to the increased DDGS-CNC-matrix interactions. Optical microscopy also revealed some non-uniform dispersion of CNC. Overall, the results suggest that addition of CNC, plasticizer and coupling agent can aid in improving the physical, mechanical properties of PLA composites.

A hydrophobic coating on cellulose nanocrystals improves the mechanical properties of polyamide-6 nanocomposites

Recent demands for high-performance lightweight materials have brought researchers’ attention to various nanoparticles to reinforce polymeric materials. As such, sustainable and stiff cellulose nanocrystals (CNC) have become a popular candidate as nano-reinforcements. While CNC can offer great advantages, such as high mechanical properties and low density, it might agglomerate even in hydrophilic polymers because of its strong affinity to itself (intra and intermolecular hydrogen bonds) which prevents its broader use in industrial applications. This study aims to improve the compatibility between CNC and polyamide 6 (PA6) by a chemical modification that produces a surface polarity drastically different from non-modified CNC. The surface of CNC was rendered by the covalent coupling of stearic acid (SA) to the surface hydroxyl groups to produce stearate modified CNC (CNC SA). The effect of the modification was analyzed for CNC SA reinforced PA6 nanocomposites, and the results are compared to that of non-modified CNC reinforced PA6 samples. The addition of unmodified CNC to PA6 provided a modest improvement while the addition of CNC-SA provided substantial improvement on the modulus and tensile strength of the nanocomposite films.