The alpha cellulose of softwoods (microfibers) was turned to cellulose Nano fibers using ultra-fine friction grinding process, as a simple, fast and one-step downsizing method. The effect of grinding on fiber diameter, crystallite size, crystallinity, suspension stability, together with the transparency and air permeability of sheets made from micro-and Nano fibers was investigated. The average diameter of microfibers and Nano fibers was 33±10 µm and 28±11 nm, respectively. The results of X-ray scattering demonstrated that the crystallinity and crystallite size of microfiber was 79% and 5.1 nm, respectively. During grinding process, the crystallinity and crystallite size decreased to 73% and 4.6 nm, respectively. The suspension of microfibers was unstable over checking stability time, while the nanofiber suspension had a long-term stability. The air-permeability of microfiber and Nano fiber sheets was 320 and 1.06 mmPa-1s-1, respectively. The qualitative transparency of microfiber sheet was distinguishably lower than that of Nano fiber sheet.

Background and objectives: In recent years, the development of biodegradable and environmentally friendly materials for packaging applications has attracted significant attention due to growing environmental concerns and the different limitations associated with the use of synthetic polymers. Bio-nanocomposites have been introduced as sustainable alternatives for food packaging. Among them, bio-nanocomposites composed of cellulose nanofibers as the reinforcing phase and chitosan as the matrix phase have gained considerable interest owing to their unique characteristics, including renewability, biodegradability, biocompatibility, and antibacterial properties. Cellulose nanofibers, due to their high mechanical strength and ability to form network structures, play a crucial role in enhancing the mechanical and barrier properties of packaging films. On the other hand, the chitosan matrix contributes antimicrobial and antioxidant properties, which are essential for extending the shelf life of food products and reducing spoilage. Therefore, the combination of these two nanomaterials can lead to the fabrication of a bio-nanocomposite with suitable mechanical and physical performance and high potential for food packaging applications. In this study, an innovative method (partial dissolution) was employed to facilitate the fabrication of a cellulose nanofiber–chitosan bio-nanocomposite, followed by the characterization of the resulting specimens in terms of their physical, mechanical, and antibacterial properties.Materials and methods: In this study, two types of raw materials were used: cellulose nanofiber gel and chitosan nanofiber gel, both supplied by Nanonovin Polymer Company. Prior to the fabrication process of the bio-nanocomposites, the exact concentration of each gel was determined, and based on predefined ratios, the various combinations of the gels were prepared. The gels were mixed with a specific amount of distilled water and homogenized using a magnetic stirrer to obtain a uniform suspension. This homogeneous mixture was then transferred to a vacuum filtration system for nanopaper fabrication. Once the initial nanopaper mat was formed, it was removed from the apparatus and dried completely in a vacuum oven at 70 °C for 24 h. In the subsequent step, these pure and hybrid raw nanopapers were transformed into cellulose nanofiber–chitosan bio-nanocomposites using a dissolution method. For this purpose, the specimens were immersed in a 0.5% acetic acid solution for 4 minutes and then neutralized using a 1% NaOH solution. After stabilizing the physical structure through multiple washing steps with distilled water, the samples were thoroughly dried. Finally, in order to evaluate the properties of the fabricated nanopapers and bio-nanocomposites, several tests were conducted, including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), fourier transform infrared (FTIR) spectroscopy, static tensile, and antibacterial activity assessment.Results: The results showed that the integration of cellulose nanofibers and chitosan nanofibers significantly enhanced the structural and functional properties of the fabricated nanopapers and bio-nanocomposites. XRD and FTIR analyses confirmed the successful formation of chemical bonds between the composite components and the development of a crystalline structure suitable for the formation of reinforcing and matrix phases. The FE-SEM micrographs revealed that both cellulose and chitosan nanofibers were within the actual nanoscale range (1-100 nm) and that cellulose nanofibers were uniformly dispersed within the chitosan matrix as the reinforcing phase. So that the nanobiocomposite obtained from the combination of 70% nanofiber cellulose and 30% nanofiber chitosan increased by 25.6 and 94.8% compared to the pure nanopapers obtained from nanofiber cellulose and nanofiber chitosan, respectively. In addition, the results of the antimicrobial test (colony count method) showed that the prepared nanobiocomposites have an effective inhibitory property against pathogenic bacteria, which can increase the shelf life of food.Conclusion: Overall, the innovative method employed for the fabrication of cellulose–chitosan bio-nanocomposites was successfully implemented, and the resulting materials demonstrated great potential as alternatives to conventional packaging materials.

Background and Objectives: Today, the use of cellulosic nanofibers is widely researched for the production of various products, such as paper and paperboard. Cellulose nanofibers are made from pulp produced from various lignocellulosic sources in various methods. The quality of these materials can be evaluated in different ways. Meanwhile, the rheology indices of cellulosic nanofibers are one of the simplest and least costly methods to evaluate the quality of this material. In this paper, specifically, the relationship between indices of rheology of cellulosic nanofibers and their ability to improve paper and board strengths for papermaking are introduced. Materials and Methods: In this article, materials were categorized in terms of rheology sciences and cellulose nanofibers were specified among them. Then, important indices of rheology of cellulose nanofibers such as yield point, damping coefficient, storage modulus, loss modulus, and yield strain were introduced by presenting some of the results of measuring the rheological indices of cellulosic nanofibers. In the following, the relationship between rheological indices and strengthening ability of cellulose nanofibers to improve tensile and burst strengths of paper and paperboard production were investigated. Results: The more storage modulus, as the most sensitive parameter in viscoelastic measurements compared to the loss modulus, the more viscoelastic ability and more elastic tendency. For cellulose nanofibers, if the ratio of the storage modulus is about 4 times greater than the loss modulus in the same concentrations, this indicates that the material is viscoelastic with considerable elasticity. If the amount of damping coefficient for cellulose nanoparticle gel is less than 0. 3, this indicates that these gels are highly elastic with components in the nanometer scale and these characteristics indicate the presence of tangled cellulose nanofiber network and as a result, more strengthening feature is available for a variety of applications as strengthening paper and paperboard products. The critical strain on the behavior of the cellulosic nanofiber’ s rheology appears almost independent of its dry matter content which implies the sustainability of the viscoelastic properties of these gels. The thick and dilute produced nanofiber gels have an exponential, with power 3, relationship with dry content ( ). The exponential, with power 3, relationship between the modulus and dry matter percentage is one of the criteria for the achievement of a gel of nanoscale cellulosic fibres. Conclusion: In general, cellulose nanofibers gel is considered as a viscoelastic and thixotropic fluid and when used in paper and paperboard productions, the higher elastomeric index of it creates more strength properties of products. Therefore, in order to predict the achievement of nanosized fibres gel during production, a cheaper evaluation of the cellulosic rheology indices could be used instead of expensive images and even with the comparison of two types of cellulosic nanofibers, their rheological properties predict their performance for reinforcing paper and paperboard.

In this research, the effect of cellulose nanofibers on the properties of handsheet paper made from industrial bagasse pulp was investigated. Nanofibers, produced from alpha cellulose of softwoods using grinding method, were added 20 wt% to the handsheet paper. Nanopaper- handsheet composed of 100% cellulose nanofibers- was also prepared. Results indicated that using nanofibers increased water drainage time of the pulp. Addition of nanofibers to the handsheets increased the optical transparency and density while sheet thickness decreased. Papers made with 20 wt% nanofibers showed higher tensile strength than those prepared with pure bagasse fibers. Nanopaper possessed the highest tensile strength. Tear strength was negatively affected by using cellulose nanofibers in such a way that the lowest tear strength obtained for nanopaper. Never eless with Addition of nanofibers to the handsheets in said conditions tear strength decrease but this decreasing of statistical viewpoint wasn’t meaningful.

This study aimed to enhance probiotics thermal stability and viability in the digestive tract through encapsulation using hybrid fibers of cellulose acetate and polyvinyl alcohol with single-jet electrospinning. This study used Lactiplantibacillus plantarum NIMBB003 as an encapsulated probiotic strain in engineered sandwich nanofibers (cellulose acetate/polyvinyl alcohol and Lactiplantibacillus plantarum/cellulose acetate). Regarding nanostructure, polyvinyl alcohol and cellulose acetate nanofibers were spun independently; when these layers were set on top of each other, they could act as an integrated system. Results of scanning electron microscope images and Fourier transform infrared spectrometry have verified the micro/nanoencapsulation structure of probiotics. The layered structure demonstrated increased protection against environmental factors, particularly heat and acidity. Thermogravimetric analysis verified that cellulose acetate-polyvinyl alcohol and probiotic-cellulose acetate nanofibers maintained the structural stability up to 530 °C, while encapsulated probiotics showed 89.8% encapsulation efficiency or 9% improvement, compared to single-layer polyvinyl alcohol and probiotic fibers. Moreover, probiotic survival under simulated gastrointestinal conditions (75 °C and stomach acid exposure) was extended to 8 min, whereas unencapsulated probiotics were entirely destroyed within 5 min. Scanning electron microscopy and Fourier transform infrared spectroscopy validated the formation of nanofiber encapsulation and probiotic integration. This engineered nanofiber sandwich structure offers enhanced probiotic protection, making it a promising candidate for food and pharmaceutical uses.