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![1.1 Transparent film of modified nanocellulose of bacterial cellulose (Reprinted [adapted] with permission from Ifuku S., Nogi M., Abe K., Handa K., Nakatsubo F., Yano H., Biomacromolecules 8 (2007) 1973., [16], Copyright (2007) American Chemical Society)](profile/Sung-Hoon-Ahn/publication/278680288/figure/fig4/AS:267734416097288@1440844267129/11-Transparent-film-of-modified-nanocellulose-of-bacterial-cellulose-Reprinted.png)
1.1 Transparent film of modified nanocellulose of bacterial cellulose (Reprinted [adapted] with permission from Ifuku S., Nogi M., Abe K., Handa K., Nakatsubo F., Yano H., Biomacromolecules 8 (2007) 1973., [16], Copyright (2007) American Chemical Society)
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PP and PE are considered as environmental polluter mainly because of their greater resistance toward biological degradation in the environment upon disposal. Although this property contributes to their popularity for development of medical devices, still the repercussions of PP and PE litter create a serious threat for chocking of water ways, sewag...
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... Moreover, one of the main goals in the production of such materials is that the composites should be environmentally friendly, which is made possible, for example, by the use of renewable fillers. Accordingly, there is growing interest in the use of nanocellulose as an additive for polymer matrices [2], in view of its very good mechanical properties [3]. However, in order for such a cellulosic material to offer resistance to microorganisms, good barrier properties against gas and water vapor [4,5], and enhanced thermal resistance, certain modifications are necessaryfor example, through the production of hybrid materials. ...
Research was undertaken on the design and preparation of advanced polymer biomaterials containing innovative nanocellulose hybrid fillers with functional physicochemical properties, characterized by high mechanical strength, enhanced thermal resistance, and improved gas barrier properties, which are important in the packaging industry. Such innovative polymer composite nanomaterials with renewable fillers, which will reduce the consumption of petroleum raw materials, which is also directly related to the reduction of energy consumption. Novel TiO2-ZnO/nanocellulose hybrid systems were prepared by a solvothermal method, and their structural, textural, morphological, chemical composition, and thermal properties were evaluated. Polymer composites with nanocellulose synthesized using enzymatic hydrolysis and with hybrid fillers, were obtained by two-step extrusion. Various techniques were used to determine the supermolecular structure and nucleation activity of the biomaterials, barrier tests and mechanical properties were also carried out. It was found that the composites containing hybrid fillers exhibited increased nucleation activity, which favored the formation of a pseudohexagonal polymorphic variety of the polymer matrix, providing high tensile strength while maintaining high flexibility. In addition, the use of novel hybrid fillers made it possible to achieve higher barrier properties against oxygen and water vapor in composite films. A significant achievement is the finding of a previously unrecorded relationship between the shaping of supermolecular structure (polymorphism, nucleation) and physicochemical properties (mechanical, barrier), which is of great significance for the design of modern packaging.
... In the process of production with hydrolytic acid, oxidative and enzyme treatment combinations, or directly [14,88,89], the mechanical methods of producing nanoscale cellulose particles have also been extensively studied. They include microfluidisation, ultrasound, homogenization at high pressure, and ball milling. ...
Cellulosic biomass hydrolysis yields a nanoscale substance known as nanocrystalline cellulose (NCC). Gel, liquid, or powder is adaptable to a variety of uses. Nanocrystalline cellulose has unique renewability, biodegradability, and mechanical and physicochemical qualities, and abundance boosts the material’s mechanical strength by many orders of magnitude when introduced into the material matrix (polymer, ceramic, or metal). Nanocrystalline cellulose is not related with any serious environmental issues because it is a natural substance. The progress of this biomaterial as a green and renewable biomaterial for the fabrication of lightweight and biodegradable composite materials gives further impetus. The current aim of nanocrystalline cellulose research is to optimise nanocrystalline cellulose characteristics for dispersion in hydrophilic and hydrophilic media. To assess the nanocrystalline cellulose reinforcing, antibacterial, stability, hydrophilicity, and biodegradability, imaging methods and protocols in complicated matrices will need to be developed. This review includes a discussion on nanocrystalline cellulose biocomposites.
... One of the solutions used to improve the properties of these materials is the use of nanometric fillers. Despite the significant advantages of these materials, there are still major limitations that hinder the largescale use of polypropylene/nanocellulose systems, including the lack of appropriate dispersion of nanofillers in the polymer matrix, and the tendency to form agglomerates (Pandey et al., 2015;Wang et al., 2017aWang et al., , 2018b, which ultimately results in insufficient homogeneity of the filler in the polypropylene matrix and, consequently, deterioration of the mechanical properties. Other issues include the low thermal resistance of nanocellulose (Gan et al., 2020), reduced susceptibility to UV radiation (Sirviö et al., 2016), and the lack of antibacterial properties (Oprea and Panaitescu, 2020). ...
Polymer composite materials with renewable fillers offering multiple functions, including good mechanical, photocatalytic and antibacterial properties, increased temperature and UV resistance, and enhanced gas barrier properties, are urgently needed in packaging production. The present research concerns a simple and inexpensive mechanochemical fabrication of TiO2/nanocellulose hybrids, where nanocellulose was obtained by enzymatic reactions. The effect of the weight ratio of components (TiO2 and nanocellulose) on the physicochemical and functional properties of the final products was examined. The obtained TiO2/nanocellulose hybrids were tested to determine dispersion, morphological and thermal properties. Composites of polypropylene with TiO2/nanocellulose hybrids were produced by a two-stage extrusion process. These composite materials, not previously reported in the literature, were subjected to detailed structural research using the X-ray diffraction method, analysis of phase transition using differential scanning calorimetry, analysis of nucleation and crystallization processes, as well as testing of mechanical properties. The composites with hybrid fillers produced very high values of tensile strength (approx. 55 MPa) and higher values of Young’s modulus (approx. 1700–1800 MPa). Moreover, these unique composites with TiO2/nanocellulose fillers also exhibited very good nucleating properties, including an increase in the crystallization temperature by 5–8 °C, a reduction of half-times of crystallization by approx. 40%, and high nucleation activity and thermal resistance. It was proven that all of the listed important properties of the composite materials strictly depend on the polymorphic structure, chemical composition, and dispersion and morphological properties of TiO2/nanocellulose hybrid fillers. In this work we describe for the first time a method of obtaining innovative polymer composites with TiO2/nanocellulose hybrid fillers, exhibiting properties that indicate a huge potential for application in many industries.
... Due to their nanosize and shape, CNCs have a high surface area of up to 500 m 2 /g and can form liquid crystalline structures [6,7]. For many years, CNCs were mainly used to mechanically reinforce thermoplastic and thermoset matrices such as polyethylene, poly(lactic acid), polyurethanes, and others [8,9]. A major challenge there is overcoming the hydrophilicity of CNCs as they tend in most cases to agglomerate instead of dispersing within the hydrophobic matrix [10]. ...
Despite the many interesting properties of cellulose nanocrystals (CNCs), their hydrophilicity is one of the main challenges for their processing with hydrophobic polymers and matrices. To overcome this challenge, this paper describes the preparation of brush-like CNCs with tailored surface properties by grafting alcohols of different chain lengths onto their surfaces. Ethanol, 1-butanol, 1-hexanol, and 1-octanol were grafted on the CNC surface using 2,4-toluene diisocyanate (TDI) as a linker. The CNCs were characterized for their structural, morphological, surface, and thermal properties. Because of the grafting, the water contact angle of the CNCs significantly increased from 32° to up to 120°, which was dependent on the chain length of the grafted alcohol. The thermal stability of the CNCs was also improved, mainly as a result of the reaction of TDI with the CNC hydroxyl groups. Later, the CNCs were used to reinforce films of poly(butylene succinate) (PBS), which were then characterized using dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). An increase of up to two-fold in the storage modulus was observed using DMA, which was dependent on the chain length of the grafted alcohol. However, no change in the glass transition temperature or degradation temperature of PBS was detected. This approach is proved efficient for tailoring the surface properties of CNCs towards excellent interfacial adhesion in their composites.
... The use of cellulose-based nanomaterials is considered as a promising alternative material as reinforcement for polymer composites because it has very attractive properties as lightness, strength, rigidity, transparency, renewability, biodegradability and its wide availability. Sources like sugarcane bagasse [8], sisal [9], banana [10], cotton [11], hemp [12], soy [13], residues from cellulose production [14], oat husk, among others [15], have been used as reinforcement in polymeric matrices like low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE) polypropylene (PP) and carboxymethyl cellulose (CMC) [16,17,49]. ...
Cellulose nanocrystals (CNC) were obtained from Typha domingensis (an invasive macrophyte) collected from lagoons and wetlands in Altamira, Mexico. Cellulose extraction was carried out by a treatment with aqueous NaOH in a batch reactor followed by NaClO-bleaching and subsequent hydrolysis with sulfuric acid. The fibers were characterized by Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The crystallinity of the cellulose fibers isolated from Typha domingensis increased from 29 % (not treated fibers) to 73 % and the beginning of thermal degradation increased from 246 °C to 312 °C before and after the bleaching. The CNCs isolated from this plant show average values of 20 nm in diameter and 190 nm in length. Micrographs of the Typha domingensis fibers and the cellulose isolated therefrom as well as bleached cellulose indicate the removal of hemicellulose, lignin, and waxes from the fibers, which corroborates the XRD and FTIR results.
... In contrast, utilization of conventional melt processing methods widely used for thermoplastic materials such as extrusion has been challenging due to the difficulty of effective dispersion of CNC in the matrix, as well as, thermal degradation of the CNC at typical elevated processing temperatures [22,23]. A large number of studies have been focused on preparation of CNC-based nanocomposites using extrusion process with various polymer matrices including polyethylene [22,23], polypropylene [24,25], polystyrene [26], polylactic acid (PLA) [10,27], polyvinyl chloride [28] and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) [29],poly(ε-caprolactone) [30] and thermoplastic starch [31]. Different strategies have been developed in order to improve the dispersion of CNC and enhance its compatibility with the polymer melt (for e.g., wrapping polymer layer such as poly(vinyl alcohol) [32] in a PLA matrix or PEO layer in a polyethylene matrix [22]). ...
Polyamide 6 (PA6) nanocomposites containing cellulose nanocrystals (CNCs) were prepared via a multi-step process consisting of in-situ anionic ring-opening polymerization and subsequent melt extrusion. The effect of surface modification of the CNCs with aminopropyl triethoxysilane (APS) was studied in detail using microscopic, mechanical and rheological techniques and compared with that of the neat CNC nanocomposites. Solid-state ²⁹Si NMR analysis was used to confirm the interfacial bond formation between the PA6 matrix and surface modified CNCs. SEM images showed that upon surface modification, the morphology of CNCs within the matrix transformed from a fibrillar structure towards more individually dispersed nanocrystals with enhanced dispersion and higher interfacial area. The matrix-particle interphase was further investigated using quantitative nanomechanical mapping (QNM) to study the role of interfacial modification on thickness of interphase and development of a broader modulus gradient across the interface. The quality of dispersion and development of the rigid interfacial layer in the modified system resulted in significant improvement in solid-state mechanical properties of the nanocomposites. In addition, melt rheological studies showed significant improvements of melt elasticity and strength in shear and elongational flow in the nanocomposites systems.
... In relation to what has been previously published in the area of polymer cellulose nano-composites via extrusion technology, the published research has been predominantly focused on using polar thermoplastic such as polylactide (PLA) [25][26][27] with only a handful of papers using non-polar polyolefins such as polypropylene and polyethylene [23,24,[28][29][30]. It has been mentioned elsewhere that uniform dispersion of cellulose nano-fibers into polypropylene and polyethylene has not been successful to date because of aggregation issues [31]. Dufresne et al. have shown that chemically modifying cellulose nano-whiskers by esterification with organic acid chloride could be used as an alternative approach to ensure homogenous dispersion within polyethylene matrix [32] using a melt extrusion technique. ...
Background:
The technology of food packaging is responding to significant market dynamics such as the rapid growth in e-commerce and preservation of fresh food, a sector that accounts for over 40% of plastic waste. Further, mandates for sustainability and recent changes in national governmental policies and regulations that include banning single-use plastic products as observed in sweeping reforms in Europe, Asia, and several US States are forcing industries and consumers to find alternative solutions.
Scope and approach:
This review highlights an ongoing shift of barrier coatings from traditional synthetic polymers to sustainable breakthrough materials for paper-based packaging and films. Advantages, challenges and adapting feasibility of these materials are described, highlighting the implications of selecting different materials and processing options. A brief description on progress in methods of coating technologies is also included. Finally, the end fate of the barrier materials is classified depending on the packaging type, coating materials used and sorting facility availability.
Key findings and conclusions"
Different types of coatings, such as water-based biopolymers, due to their greater environmental compatibility, are making inroads into more traditional petroleum-based wax and plastic laminate paperboard products for fresh food bakery, frozen food, and take-out containers applications. In addition, nano-biocomposites have been studied at an accelerating pace for developing active and smart packaging. Based on the momentum of recent developments, a strong pace of continuing developments in the field can be expected.
In the last few years, the scientific community around the world has devoted a lot of attention to the search for the best methods of obtaining nanocellulose. In this work, nanocellulose was obtained in enzymatic reactions with strictly defined dispersion and structural parameters in order to use it as a filler for polymers. The controlled enzymatic hydrolysis of the polysaccharide was carried out in the presence of cellulolytic enzymes from microscopic fungi—Trichoderma reesei and Aspergillus sp. It has been shown that the efficiency of bioconversion of cellulose material depends on the type of enzymes used. The use of a complex of cellulases obtained from a fungus of the genus Trichoderma turned out to be an effective method of obtaining cellulose of nanometric dimensions with a very low polydispersity. The effect of cellulose enzymatic reactions was assessed using the technique of high-performance liquid chromatography coupled with a refractometric detector, X-ray diffraction, dynamic light scattering and Fourier transform infrared spectroscopy. In the second stage, polypropylene composites with nanometric cellulose were obtained by extrusion and injection. It was found by means of X-ray diffraction, hot stage optical microscopy and differential scanning calorimetry that nanocellulose had a significant effect on the supermolecular structure, nucleation activity and the course of phase transitions of the obtained polymer nanocomposites. Moreover, the obtained nanocomposites are characterized by very good strength properties. This paper describes for the first time that the obtained cellulose nanofillers with defined parameters can be used for the production of polymer composites with a strictly defined polymorphic structure, which in turn may influence future decision making about obtaining materials with controllable properties, e.g., high flexibility, enabling the thermoforming process of packaging.
The utilization of organic industrial wastes as source for production of cellulose nanocrystals (CNCs) is very attractive and has a huge advantage in comparison with traditional sources as plants, bacterial or commercial cellulose (MCC), because it has the potential of increasing the value chain of these materials. The aim of this study is to analyze the utilization of Euphorbia Antisyphilitica bagasse, a waste of the wax industry, as source for CNC's prepared by two different techniques, namely acid hydrolysis and TEMPO mediated oxidation. Cellulose extraction was performed by a treatment with aqueous NaOH followed by a bleaching process with NaClO. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and conductometric titration. The CNCs samples have a diameter of around 17 nm and a length between 220 and 310 nm with a degree of crystallinity above 70 % and a very different thermal behavior depending of the isolation method. On one hand charge densities are 2.135 e/nm 2 and 1.933 e/nm 2 , on the other hand root-mean-square roughness is around 2.1 and 2.3 nm (films were deposited on a glass surface), depending on the isolation technique.
