Cellulose Nanocrystal Composites Research Articles

Polyphenol assisted nano-reinforced chitosan films with antioxidant and antimicrobial properties

Active packaging with nano-reinforcement has appeared as an emerging strategy to replace the conventional plastic packaging films. In this contribution, Quercetin/rutin/vanillic acid incorporated chitosan nanocomposites with a reinforcement effect of cellulose derived cellulose nanocrystals (CNC) or chicken feather derived nano-keratin (NK) were developed using solvent casting method. Polyphenol incorporated CNC reinforced films displayed 69% increase in tensile strength whereas only 38% rise in strength was depicted by nano-keratin reinforcement. Quercetin incorporated CNC reinforced films exhibited 22% decline in film's permeability to water vapors and almost 38% upsurge in opacity. The crosslinking between hydroxyl, amino and carboxyl groups of polyphenols, Chitosan and CNC respectively was confirmed by FTIR. XRD and SEM analysis suggested dispersed nano fillers in chitosan matrix and depicted intercalated morphologies with rough surface. The thermal transitions of prepared films were found to be comparable to chitosan control. Quercetin incorporated CNC reinforced films exhibited 70% DPPH free radical scavenging activity with highest phenolic content. Quercetin and rutin incorporated CNC composites showed anti-microbial activity which may be due to polyphenols in the film's structure. Moreover, baby carrots wrapped with quercetin incorporated CNC reinforced chitosan films exhibited least weight loss and maintained overall acceptability over one-week storage. Comparatively, among all blends, combining quercetin and chitosan along with CNC reinforcement, can aid in development of active films with improved mechanical strength, enhanced UV protection, free radical scavenging ability and antimicrobial properties appropriate for food preservation.

Screening of salt hydrates and cellulose nanocrystal composites for thermochemical energy storage using life cycle assessment

Salt hydrate systems via thermochemical reactions can provide thermal storage for renewable-sourced alternatives to traditional heating systems like natural gas. In this study, we use life cycle analysis (LCA) along with the material prices to screen salts based on environmental impact and cost. Additionally, we performed LCA of producing a composite material of salt and cellulose nanocrystals (CNC) at a weight ratio of four to one. CNC is a stabilizing agent for salt. We assessed the salt-CNC composites based on a laboratory scale and scaled-up processing to identify low environmental impact formulations and to identify high environmental impact processes in the composite production. In general, lanthanum chloride, lithium hydroxide, and lithium chloride should be avoided due to high environmental impact or cost. For pure salts, our results showed magnesium sulfate, zinc sulfate, and calcium chloride are typically preferred with a close second tier of magnesium and strontium chlorides and strontium bromide. For the composite material, magnesium sulfate was preferred followed by zinc sulfate, sodium sulfide, and strontium chloride. CNC has a significant environmental impact, contributing over 50% of the environmental impact for these composites. Therefore, CNC production with lower environmental impacts needs to be pursued. In composite production, the environmental impact of mixing and sonication can be reduced by scaling production. However, drying remains a high-impact process. These results can help guide salt selection for other salt-based thermochemical materials and further development of the salt-CNC composite.

Chiral nematic cellulose nanocrystal composites: An organized review

AbstractCellulose nanocrystals (CNCs) are commercially available materials derived from cellulose, the most abundant biopolymer on our planet. Due largely to their high strength, high surface area‐to‐volume ratio, tailorable surface chemistry, and the abundance of biomass feedstocks with which to produce them, CNCs have attracted significant interest in applications spanning the paints and coatings, composites, packaging, and biomedical sectors. However, and perhaps most interestingly, CNCs will self‐assemble (or, as I've teased in the title, organize) to form highly ordered chiral nematic liquid crystal phases when concentrated in suspension. Upon complete solvent evaporation, this chiral nematic order is ‘locked’, yielding films with structural colour—colour arising not due to chemical pigments, but rather due to the physical structure of a material itself. In the pursuit of novel multi‐functional materials, research interest has shifted recently towards the incorporation of functional additives to form composite chiral nematic films. Along with introducing the basics of liquid crystals and self‐assembly, this review discusses the main approaches used in order to form CNC‐based composite films: co‐assembly, templating, and post‐processing, and highlights exceptional examples in each case. Finally, I give my uniquely Canadian perspective on the current status, future prospects, and major challenges associated with the development of CNC‐based chiral nematic composite materials.

Recent Progress on Photonic Cellulose Nanocrystal Films for Sensing Applications

Abstract: Cellulose nanocrystals (CNCs) have triggered considerable research interest in the last few years owing to their unique optical, biodegradation, and mechanical behavior. Herein, recent progress on the sensing application of photonic CNC films is summarized and discussed based on the analyses of the latest studies. We briefly introduce the three approaches for pre-paring CNCs: mechanical treatment, acid hydrolysis, and enzymatic hydrolysis, recapitulating their differences in preparation and properties. Then, when the aqueous suspension of cellu-lose nanocrystals (CNCs) reaches a specific concentration, it will self-assemble to form a left-handed nematic liquid crystal structure, and this structure can be maintained in films after water evaporation, which has strong photonic crystal properties. The periodic layered structure in the film interferes and diffracts with light, showing a rainbow color. Photonic CNC com-posites that combine CNCs and functional materials have good properties and broad prospects. Finally, we highlight the advanced applications of photonic CNC films, including mechanical sensing, thermal sensing, and humidity sensing. The prospects and ongoing challenges of pho-tonic CNC films were summarized.

Antibacterial activity and dielectric properties of the PVA/cellulose nanocrystal composite using the synergistic effect of rGO@CuNPs

This work aims to enhance the performance of the polyvinyl alcohol (PVA) composite by using cellulose nanocrystal (CNC) as reinforcement and copper nanoparticles (CuNPs)/reduced graphene oxide (rGO) as conducting and antimicrobial reagents. Firstly, rGO was loaded onto CuNPs using an eco-friendly microwave method. Different techniques characterized the components and prepared composites, which indicated the incorporation of cellulose nanocrystals and rGO@CuNPs within the polyvinyl alcohol matrix. Utilizing the clear zone of inhibition, the antibacterial test was quantified. Compared to the neat composite, the rGO@CuNPs loaded polyvinyl alcohol/ cellulose nanocrystal composites exhibited no bacterial growth against S. aureus, E. coli, and C. albicans. However, all composites did not have antifungal activity against A. niger. The combination of conductivity and interfacial polarization is the reason for the abrupt increase of permittivity with decreasing frequency. Besides, adding rGO@CuNPs improved the electrical conductivity. DC-Conductivity increased about a decade after adding cellulose nanocrystal to polyvinyl alcohol, then another decade after adding CuONPs. The electric loss modulus representation shows a systematic shift in the peak position towards higher frequencies, decreasing the so-called conductivity relaxation time. This is the main reason for the enhancement of conductivity. The systematic attenuation of peaks' height with increasing conductivity is still unclear.

Tannic acid adsorption properties of cellulose nanocrystalline/fish swim bladder gelatin composite sponge

Foods and beverages with excessive tannins acid (TA) content taste astringent and bitter. The overconsumption of TA could result in nutritional and digestive problems. In this study, the cellulose nanocrystals (CNC)/fish swim bladder gelatin (FG) composite sponge was prepared with glutaraldehyde as a crosslinking agent. The TA adsorption performance of the sponge was discussed. The freeze-dried CNC/FG composite sponge had a porous network structure. CNC was combined into the FG matrix as a reinforcing phase. The mechanical strength, thermal stability, and swelling properties of the composite sponge were improved with the addition of an appropriate amount of CNC. Although CNC decreased the porosity of composite sponge, the increase in active adsorption sites resulted in an overall positive effect on its TA adsorption properties. Under the optimal adsorption conditions, the TA removal rate of 1.0 % CNC composites reached 80.4 %. Furthermore, the sponge retained a TA removal rate of 54 % after five cycles of adsorption and desorption using 50 % ethanol. The results demonstrated that CNC/FG composite sponge has application potential in the field of adsorption materials for TA.

Development of reduced graphene oxide (rGO) reinforced poly(lactic) acid/ cellulose nanocrystal composite through melt mixing: Effect of nanofiller on thermal, structural, biodegradation and antibacterial properties

The intent of this research work was to synthesised a synthetic polymer that is biodegradable, bioresorbable, and biocompatible, while also exhibiting favorable thermal characteristics. The present study reports the successful fabrication of bionanocomposites by incorporating Cellulose nanocrystals (CNCs) and Reduced graphene oxide (rGO) into host matrix (PLA) using the melt-mixing technique. Various weight percentages (wt%) of rGO were employed in the process and various characterization techniques, including BET analysis, XRD, FTIR and field emission scanning electron microscopy (FE-SEM) were used to verify the efficient fabrication of a number of nanoformulations and nanofiller’s effect. Introduction of CNC and rGO in PLA matrix increases the surface area as well as porosity of the composites, established by BET analysis. DSC results indicate that the assimilation of rGO into the polymer matrix improved thermal stability of the composite material and leads to boost in the degree of crystallinity which was supported by XRD analysis. TGA results found no noticeable change in glass transition temperature (Tg) due to the addition of Nanofiller (rGO). The wettability analysis was done by contact angle measurement to determine the hydrophilicity of the composite and it is shown that with the increasing amount of rGO, hydrophilicity increases and contact angle reaches to 69° for 0.75 wt% of rGO in composite in comparision to 100° Neat PLA. The rGO/CNC/PLA nanocomposites exhibit a unique antibacterial effectiveness against both the S. aureus (Gram-positive) and E. coli (Gram-negative) bacterial strains. The highest antimicrobial activity was obtained in the nanocomposite tested against S. aureus. Biodegradation through Lysozyme in PBS solution shows promising result after incorporation of nanofillers. Hence, the nanocomposite manufactured through melt mixing process has promising uses in the biomedical and food packaging industries.

Bouligand nanocomposites: Self-assembly of cellulose nanocrystals with a thermo-responsive polymer

Cellulose nanocrystals (CNCs) naturally self-assemble into helical structures that effectively deflect crack propagation and exhibit structural coloration based on the pitch. To further tune the structural coloration via environmental conditions, a thermoresponsive polymer poly(diethylene glycol methyl methacrylate) (PMEO2MA) was incorporated into CNC composites. Nanocomposite films of PMEO2MA-CNC with 0–30 mass % PMEO2MA loadings were prepared via controlled evaporation-induced self-assembly. As the polymer infiltrates CNCs' helical structure, the resulting films’ reflectance wavelength transitions from blue to red. PMEO2MA-CNC nanocomposites exhibited reversible temperature responses in the solid-state between 26 °C and 29 °C under variable humidity conditions, demonstrating the tunability of the self-assembled films. Fluorescence lifetime imaging microscopy (FLIM) provided insights to polymer dynamics in response to temperature.

Exploring the Core Parameters of CNC-Based Chiral Nematic Structures for Enhancing the Dissymmetry Factor of Right-Handed Circularly Polarized Luminescence.

The chiral nematic nanostructure formed from cellulose nanocrystal (CNC) self-assembly has shown great potential as a matrix for generating circularly polarized luminescent (CPL) light with a high dissymmetry factor. Exploring the relationship between the device composition and structure and the light dissymmetry factor is crucial to a common strategy for a strongly dissymmetric CPL light. In this study, we have compared the single-layered and double-layered CNC-based CPL devices with different luminophores, such as rhodamine 6G (R6G), methylene blue (MB), crystal violet (CV), and silicon quantum dots (Si QDs). We demonstrated that forming a double-layered structure of CNCs nanocomposites is a simple but effective pathway for enhancing the CPL dissymmetry factor for CNC-based CPL materials containing different luminophores. The |glum| values of double-layered CNC devices (dye@CNC5||CNC5) versus that of single-layered devices (dye@CNC5) are 3.25 times for Si QDs, 3.7 times for R6G, 3.1 times for MB, and 2.78 times for CV series. The different enhancement degrees of these CNC layers with a similar thickness may be due to the different pitch numbers in the chiral nematic liquid crystal layers whose photonic band gap (PBG) has been modified to match the emission wavelengths of dyes. Furthermore, the assembled CNC nanostructure has great tolerance to the addition of nanoparticles. Gold nanorods coated with the SiO2 layer (Au NR@SiO2) were added for enhancing the dissymmetry factor of MB in CNC composites (named MAS devices). When the strong longitudinal plasmonic band of the Au NR@SiO2 matched the emission wavelength of MB and the PBG of assembled CNC structures simultaneously, the increase in the glum factor and quantum yield of MAS composites was obtained. The good compatibility of the assembled CNC nanostructures makes it a universal platform for developing strong CPL light sources with a high dissymmetry factor.

Analysis of transverse elastic modulus and compressive deformation mechanism of cellulose crystals based on molecular dynamics

Cellulose nanocrystals (CNCs) have been widely used as reinforcing agents for composite materials due to their excellent mechanical properties. CNC composites are inevitably deformed by external forces during use. In order to reduce the damage of CNC composites in application and improve their service life, their mechanical properties and deformation mechanisms need to be studied in depth. In this study, cellulose Iβ crystals were selected for molecular dynamics simulation of nanoindentation to predict the transverse elastic modulus of cellulose crystals. The simulation results were compared with existing nanoindentation tests to verify the simulation accuracy. The impact of the loading depth, loading speed, and radius of the spherical indenter on elastic modulus and surface deformation of a system was explored. The results show that the loading depth and loading speed of the indenter have weak influence on the elastic modulus, and the small radius of the indenter (1 nm) will lead to the distortion of the elastic modulus. The compression deformation mechanism of cellulose crystal at the molecular level was analyzed by analyzing changes in cellulose crystal indentation morphology, molecular potential energy and hydrogen bond number during compression simulation. As the indenter radius and loading depth increase, the deformation degree of cellulose crystal also increases, whereas the loading speed within the 50–150 m/s range does not significantly influence on the deformation degree of cellulose crystal. These results may guide the production of nanocomposites with cellulose crystal reinforcements, which can be useful for preventing material damage and enhancing material efficiency.

Room-temperature self-healing polyurethane–cellulose nanocrystal composites with strong strength and toughness based on dynamic bonds

Self-healing materials suffer from a trade-off relationship between their self-healing ability and mechanical strength, which limits their applications. Therefore, we developed a room-temperature self-healing supramolecular composite based on polyurethane (PU) elastomer, cellulose nanocrystals (CNCs), and multiple dynamic bonds. In this system, the abundant hydroxyl groups on the surfaces of the CNCs form multiple hydrogen bonds with the PU elastomer, yielding a dynamic physical cross-linking network. This dynamic network enables self-healing without degrading the mechanical properties. As a result, the obtained supramolecular composites exhibited high tensile strength (24.5 ± 2.3 MPa), good elongation at break (1484.8 ± 74.9 %), favourable toughness (156.4 ± 31.1 MJ m−3, which is equivalent to that of spider silk and 5.1-times higher than that of aluminium), and excellent self-healing efficiency (95 ± 1.9 %). Notably, the mechanical properties of the supramolecular composites were almost completely retained after reprocessing three times. Further, using these composites, flexible electronic sensors were prepared and tested. In summary, we have reported a method for preparing supramolecular materials having high toughness and room temperature self-healing ability that have applications in flexible electronics.

Crystallization and mechanical property of fully biobased poly(hexamethylene 2,5-furandicarboxylate)/cellulose nanocrystals composites

Through a common solution and casting method, novel fully biobased poly(hexamethylene 2,5-furandicarboxylate) (PHF)/cellulose nanocrystals (CNC) composites were prepared in this research at low contents of CNC. Scanning electron microscopy result showed that CNC uniformly dispersed in the PHF matrix without obvious aggregations, even CNC content reached 1 wt%. CNC, as a relatively effective heterogeneous nucleating agent, promoted the melt crystallization of PHF under different conditions. In addition, to explore the nucleation effect, the nucleation activity as well as the nucleation efficiency of CNC were quantitively determined. In the composites, the crystallization mechanism and crystal structure of PHF remained unchanged despite the presence of CNC. Low loadings of CNC improved both the Young's modulus and the yield strength of PHF to some degree, indicating that CNC nanofiller reinforced PHF matrix. In sum, CNC improved both the crystallization and the mechanical property of PHF, favoring the potential wider application of PHF/CNC composites due to the fully biobased feature.

Improved mechanical and antibacterial properties of polyvinyl alcohol composite films using quaternized cellulose nanocrystals as nanofillers

Cellulose nanocrystals (CNC) are natural, renewable, and biocompatible materials that have been widely used as new sustainable reinforcing nanofillers in polymer composites. We present polyvinyl alcohol (PVA)/CNC composites with improved mechanical and antibacterial properties using CNC-based nanofillers. The surface esterified CNC (ECNC) was prepared by 6-bromohexanoyl chloride via surface esterification. Subsequently, the alkyl bromide group of the ECNC was transferred to quaternary ammonium groups for preparing quaternized CNC (ECNC-Qn) by introducing tertiary amino groups with different carbon chain lengths (C8–C16). Then, ECNC-Qn were blended with a PVA matrix to prepare PVA/ECNC-Qn nanocomposite films via a solvent casting procedure. Diverse features, including light transmission, mechanical properties, and antibacterial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria were investigated. Compared with pure PVA films, the PVA/ECNC-Qn nanocomposite films had higher tensile strength and higher antibacterial activity. Specifically, the maximum tensile strength and elongation at break of PVA/ECNC-Qn nanocomposite films were 45.4 MPa and 318.4%, respectively, which were 37.2% and 94.3% higher than those of pure PVA film, respectively. Moreover, the ECNC-Q8 exhibited the highest antibacterial efficiency, leading to the best antibacterial activity for PVA/ECNC-Q8 nanocomposite films among all films. This study demonstrates an efficient method for preparing a functional, environment-friendly PVA composite film. The prepared PVA/ECNC-Qn nanocomposite films exhibited considerable application potential in the packaging field, owing to their good mechanical and antibacterial barrier properties.

Self-assembly of cellulose nanocrystals of different lengths

HypothesisThe self-assembly (SA) of cellulose nanocrystals (CNC) in suspensions is important both from the fundamental and advanced technology development perspective. CNC of different lengths self-assemble differently in suspensions by balancing attractive and repulsive interactions which depends strongly on morphology, surface chemistry and concentrations.ExperimentsTwo different commercial CNC samples (CNC-M and CNC-C) of different lengths were dispersed in Milli-Q water at different concentrations (0.5–10 wt%). CNC-M is provided as a gel at a solid concentration of 10.3 wt% which was diluted in Milli-Q water. CNC-C is sold as a powder which was dispersed in Milli-Q water with a mixer to achieve the desired concentrations. TEM was used to determine morphology of CNC. Polarised optical microscopy is performed to get microscale visualisation of the chiral nematic self-assembly. High flux synchrotron SAXS is applied to evaluate and compare the nanoscale self-assembly mechanisms of CNC of different lengths.FindingsThe SA of two different types of CNC rods of similar diameter but different lengths is investigated. SAXS analysis shows the short rods in suspension form an isotropic phase (randomly oriented) at lower concentration (0–4 wt%); as concentration is increased, the rods become systematically aligned in a nematic phase. The interrod distance d varies as c−0.33 at the lower concentration, which changes to c−0.5 and even c−1 at the higher concentrations. In contrast, the long rods in suspension remain in the isotropic phase throughout the measured concentration range from 0.5 to 10 wt%. The interrod distance also follows the isotropic power law slope of c−0.33. Suspensions made of the short CNC rods show long range order and large interrod distance compared to those formed by the long rods. POM agrees with the SAXS results. A specific equilibrium between attractive and repulsive forces is required to maintain SA and ordering of the rods. DLVO calculations reveal that the long rods maintain van der Waal attractive force dominating over the electrostatic repulsion, which hinders rods alignment in an ordered manner. However, for the short rods, the weaker attractive interactions are well compensated by the repulsive force which aligns rods in an ordered assembly. This fundamental understanding of the SA of rods in suspensions facilitates the engineering of novel CNC composites of unique optical properties which enables novel applications such as in sensors and bio-diagnostics.

Shear exfoliated few-layer graphene and cellulose nanocrystal composite as biocompatible anode with efficient charge transfer

Electroconductive composites of graphene and cellulose nanocrystals (CNC) were prepared by direct exfoliation of natural flake graphite in CNC suspensions. Using the scalable high-shear exfoliation method, we show that the environmentally friendly CNC is an excellent graphene stabilizer as we prepared aqueous graphene-CNC dispersions with a high concentration (4.0 mg ml−1) and yield (4.0%) after only 2 h exfoliation time. With this fast and facile method, we exfoliated graphite using CNC with different amounts of negatively charged sulfate ester groups. We found that the graphene concentration is proportional to zeta potential of the CNC suspension suggesting that electrostatic repulsion plays a key role in graphene stabilization. Albeit the insulating nature of CNC, the spray-coated composite films were electrically conductive with conductivity up to 280 S m−1, depending on the CNC amount. Cyclic voltammetry measurements showed a reversible redox response for the Fe(CN)63-/4− couple proving that the electron transfer was efficient in the composite film. Furthermore, biocompatibility studies with photosynthetic microorganisms revealed no toxic effects as the cells maintained their photosynthetic performance and growth when placed in direct contact with the composite. The cytocompatibility, electroactivity and good water-stability make the composite film a promising anode for bioelectrochemical applications.

Click chemistry-induced modification of acrylated cellulose nanocrystals for application in PVA-based nanocomposites

The surface functionalization of cellulose nanocrystals (CNC) is crucial for promoting their diverse applications, especially regarding their use as sustainable biobased polymer reinforcements. In this study, we develop poly (vinyl alcohol) (PVA)–CNC composites with improved tensile strength and gas-barrier performance using CNC-based nanofillers. Acrylated CNCs (ACNCs) were prepared from cellulose via one-pot acid hydrolysis/Fischer esterification; subsequently, surface modification was performed through a thiol–ene reaction to obtain surface-thiolated ACNCs, namely, DACNC, MACNC, and PACNC. The various functional groups on the surface-thiolated ACNCs not only affect the dispersion stability but also alter their interfacial interactions with the PVA matrix, thus realizing the PVA nanocomposites with tailored properties, including the thermal properties, mechanical properties, and gas barrier performance. This study demonstrates that surface-thiolated ACNCs with appropriate surface chemistry and loading levels can serve as excellent nanofillers for PVA, forming biobased composites with desired properties.

Model development of aqueous diffusion softening transition in thermoplastic polyurethane cellulose nanocrystal composites

The mechanical adaptivity of polymer composites containing cellulose nanocrystals (CNCs) is of broad interest for the development of smart materials. The mechanism leading to diffusion-dependent mechanical softening in response to water uptake in these materials is well understood, however, the mass transport driving this phenomenon has not been completely resolved. Understanding such behavior would further enable the mechanism to be controlled and exploited for various applications. Here, we show that swelling of the bulk polymer composite during moisture uptake results in a decreased apparent diffusivity with increasing CNC concentration, despite the equilibrium water uptake increasing concurrently. Further, we demonstrate that a modification to the widely used percolation model predicts the full time-dependent evolution of storage modulus during the softening process by associating mass transport directly to the softening response. This model will be pertinent to studies of mechanical responses in CNC-polymer composites and is expected to be generally applicable to percolating networks which deactivate in response to a given stimulus.

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.

Removal of dye and heavy metals from industrial wastewater by activated charcoal-banana rachis cellulose nanocrystal composites filter

ABSTRACT Heavy metal contamination in wastewater has been an issue for the environment and human health nowadays. If these wastewaters are exposed directly to the environment, it will be hazardous for the environment and personal health. So, it is very necessary to treat these ground and surface wastewater before exposing into environment. For this, an effective technique were developed which removed heavy metals from wastewater easily, economically and effectively. The cellulose nano-crystals (CNC) were isolated from banana rachis fibres by a series of chemical treatments as well as 50% H2SO4 hydrolysis successively. On the other hand, raw Indonesian type’s bituminous coal was collected from Noapara industrial area, Jashore, Khulna and was pyrolysed at 700°C, activated by 2M HCl at 700°C and also carbonised at 500°C followed by activation with 30% H3PO4 acid. In this process, adsorbent of modified charcoal-CNC composites was used for the removal of methyl orange dye and five heavy metals, such as Ni(II), Pb(II), Cr(III), Cd(II) and Co(II)), from wastewater and the uptake capacity, selectivity and removal efficiency were also discussed. The filtering efficiency of wastewater purifications were characterised by FTIR, X-RD, TGA, SEM analysis. Finally, wastewater solution and the filtrates solutions were characterised by UV-Vis, and AAS techniques.

Properties of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/Polycaprolactone Polymer Mixtures Reinforced by Cellulose Nanocrystals: Experimental and Simulation Studies.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/polycaprolactone (PHBV/PCL) polymer mixtures reinforced by cellulose nanocrystals (CNCs) have been obtained. To improve the CNC compatibility with the hydrophobic PHBV/PCL matrix, the CNC surface was modified by amphiphilic polymers, i.e., polyvinylpyrrolidone (PVP) and polyacrylamide (PAM). The polymer composites were characterized by FTIR, DSC, TG, XRD, microscopy, BET surface area, and tensile testing. The morphological, sorption, thermal, and mechanical properties of the obtained composites have been studied. It was found out that with an increase in the CNC content in the composites, the porosity of the films increased, which was reflected in an increase in their specific surface areas and water sorption. An analysis of the IR spectra confirms that hydrogen bonds can be formed between the CNC hydroxyl- and the –CO– groups of PCL and PHBV. The thermal decomposition of CNC in the PHBV/PCL/CNC composites starts at a much higher temperature than the decomposition of pure CNC. It was revealed that CNCs can either induce crystallization and the polymer crystallite growth or act as a compatibilizer of a mixture of the polymers causing their amorphization. The CNC addition significantly reduces the elongation and strength of the composites, but changes Young’s modulus insignificantly, i.e., the mechanical properties of the composites are retained under conditions of small linear deformations. A molecular-dynamics simulation of several systems, starting from simplest binary (solvent-polymer) and finishing with multi-component (CNC—polymer mixture—solvent) systems, has been made. It is concluded that the surface modification of CNCs with amphiphilic polymers makes it possible to obtain the CNC composites with hydrophobic polymer matrices.