Cellulose最新文献

The structure and physico-mechanical properties of Canabinus sativa L. fibre from a specific agro-climatic region of India were thoroughly studied. The fine structure of the fibre was examined by FTIR, TGA, XRD, component analysis, and SEM. SEM shows heterogeneous morphology with prominent longitudinal ridges having cracks and surface impurities. XRD shows a moderate degree of crystallinity (49%) but sharp peaks indicating the presence of an appreciable amount of cellulose matter. FTIR reveals the presence of large quantities of hydroxyl and aldehyde along with phenolic groups. The fine structure of European hemp fibre was compared with the Indian hemp fibres. Component and thermal analyses indicate the presence of hemicellulose and cellulose as major constituents along with lignin. The breaker carded fibre shows that hemp is longer, finer, lighter, stronger, more extensible, more flexible, and has lower crystalline fibre than jute. Its colour value is also better than that of jute. Hemp yarn is better than jute yarn, especially in bulk, flexibility, elongation, and modulus. Blended yarn is better in strength and work of rupture but inferior in hairiness. Studies show that hemp fabric has better properties than jute fabric, especially in terms of flexibility, bulk, and strength. A jute processing system may be a very good option for hemp fibre and can be used to make jute blended yarn and 100% hemp yarn for apparel and furnishing grade fabric with better functional properties.

Cellulose from corn straw was oxidized by Fenton-type reagents (FeSO₄. 7H₂O or CuCl₂. 2H₂O) using alkaline metal salts (LiCl; NaCl). Cellulose pre-treatment using alkali metal salts (LiCl; NaCl) coupled with a high H₂O₂ loading (up to 500 kg per ton of pulp) are used as a novel approach to improve the oxidation rate of oxidized celluloses. The oxidation rate was determined by measuring the carboxylic acid and total carbonyl contents of the oxidized cellulose. The oxidized celluloses were characterized by Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR), X-ray diffraction (XRD) and thermogravimetric analyses (TGA). The results show that the oxidation efficiency was improved by using the metal salts and increasing the H₂O₂ loading for both catalytic systems (Fe²⁺ or Cu²⁺). The oxidization rate increased gradually with H₂O₂ loading up to a maximum 500 kg/t of pulp tested without a considerable loss of cellulose structure. The FTIR results revealed that oxidized celluloses exhibit almost similar predominant hydroxy-based structure as native cellulose with the presence of bands in the regions of 1640–1742 cm⁻¹ characteristic of aldehyde and carboxylic acid groups. The XRD results showed that the crystallinity index slightly decreased from 69.4 to 67–68 and 62–64% after oxidation of the cellulose. The equilibrium moisture contents of oxidized celluloses increased compared to the raw cellulose pulp. The moisture curves fit the page model and exhibits a sub-diffusion process.

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Bio-based materials as flame retardants meet the requirements of green strategy and sustainable development. Here nitrogen and phosphorus-modified bio-based cellulose nanocrystal composite (NPCNCs) were designed and added to epoxy resin (EP) to determine fire safety and mechanical properties. NPCNCs were successfully synthesized using ice bath polymerization and exhibited a fibrous appearance with rough surface. When corresponding into EP, NPCNCs endowed EP composite with excellent flame retardancy. For EP/6NPCNCs, the LOI value was 27.6% which was higher than that of pure EP (23.5%). Compared with pure EP, the total heat release, peak heat release rate, total smoke production and peak smoke production rate values of EP/6NPCNCs decreased by 27.27%, 43.34%, 70.21% and 66.67%. This was attributed to catalysis-dehydration and carbonization, carbon support of cellulose nanocrystals and gas phase dilution. In addition, the flame retardant EP composite mechanical properties were basically maintained compared with the pure EP. This article will provide a new way for the design bio-based P and N-modified flame retardants.

The egg white (EW)-gelatin-sodium carboxymethylcellulose (CMC) hydrogel has excellent self-adhesive properties and can adhere stably to various material surfaces. Here, the EWg-CMC_0.3 hydrogel sensor was prepared with good self-adhesion (bond strength = 255 kPa), self-healing (25 min, HE = 224.5%), high swelling, strain sensing (sensitivity, GF = 0.74), stress sensing (3—7 kPa, GF = 0.019%/KPa), and temperature and humidity sensing capabilities, and the sensor demonstrated a stable signal at 20% strain for 500 cycles. This study provides good prospects for wearable, biocompatible, and edible electronic skin applications.

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Stretch-denim is a unique, trendy, and sturdy fabric produced with coarser cotton yarns requiring high consumption of cotton fiber. With the increasing expenses of cotton and the adverse ecological effects linked to its cultivation, it became necessary to investigate an alternative fiber. In this context, a novel elastic jute yarn was created by incorporating elastane in the core, marking the first instance of such innovation, aimed at producing articles with a pleasant stretch for enhanced comfort. To accurately predict the elastane draw ratio, an I-optimal design, which is a part of the response surface methodology, was employed using design expert software. The study involved nine experimental runs to produce 276 tex elastic jute core-spun yarns at different elastane draw ratios ranging from 1.4 to 4.6. Surface response models were developed and found statistically significant for mass variation, imperfection, hairiness, tenacity, and elongation of yarn, with p-values below 0.05. Using the optimized formulation obtained from the response models, the optimum elastane draw ratio was determined to be 3.42, which was then used to produce optimized core-spun yarn. The quality parameters of produced yarn closely matched the predicted values, suggesting the effectiveness of the response model in navigating and predicting the characteristics of jute core-spun yarn. The newly developed elastic jute yarn is expected to widen the applications of jute yarns where elasticity is necessary, especially in producing stretch denim products by replacing the cotton counterpart.

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Adhesives are widely used in daily life. However, during their preparation or application, traditional adhesives easily release toxic gases, which adversely affect the human body and the environment. Herein, a physically crosslinked tannic acid (TA)-based adhesive is prepared by forming hydrogen bonding between cellulose nanocrystals (CNCs), polyacrylamide (PAM), and TA. Different characteristics of the prepared adhesives, including morphology, water content, biocompatibility, curing time, and adhesion properties, were investigated. Lap shear strength of the adhesive depends on the water content and curing time, reaching a maximum at a curing time of 48 h. The addition of CNCs enhances the lap shear strength, with the adhesive sample with 6.0 g CNCs exhibiting a high lap shear strength of 5.5 MPa on wood, which is 34% higher than that of the PAM/TA adhesive. Moreover, TA-based adhesives have excellent biocompatibility. These CNC/PAM/TA adhesives have excellent potential for application in the furniture, construction, and building industries.

Bacterial cellulose (BC) is widely used in various fields due to its excellent physicochemical properties. However, the main drawback is its high production cost. The present research exploited the preparation of BC by combining the hydrothermal process using acetic acid and enzyme treatment for the hydrolysis of corncob. The BC production was further improved by optimizing the key factors. The concentration of reducing sugar was 22.7 g/L after thermohydrolysis at 180 °C for 80 min and enzyme hydrolysis in 6 U/mL cellulase buffer solution for 24 h. It supported about 1.36 g/L as the sole culture medium, which was 5.6 times more than corncob hydrolysate without detoxification (0.25 g/L) and more than Hestrin-Schramm (HS) standard medium (1.12 g/L). The BC products were characterized by FT-IR spectroscopy, XRD, TG, and SEM analysis. Compared to the BC produced by HS medium, the morphology of BC produced by detoxification corncob hydrolysate showed a lower value of the coefficient of variation (37.59%) and higher mean diameter (55.23 nm). XRD data showed higher crystallinity (77.50%) and TG analysis showed high thermal stability. The current study demonstrated that corncob is a promising carbon source for the sustainable production of BC.

The use of organic materials in optics/photonics is highly attractive due to its promising applications in bioimaging, optoelectronic devices, photonic pigments, etc. However, the absence of π units in polysaccharides like cellulose or chitosan represents a disadvantage as these aromatic rings or double bonds are crucial to reduce non-radiative transitions in organic materials. To our knowledge, the mechanism to achieve photoluminescence (PL) in carbohydrate polymers without π units yet to be studied. Herein, we studied the effect of the drying of cellulose samples on PL, analyzing the effect of a thermal treatment by FTIR and UV-Vis. On one hand, the dominant wavelength of all PL spectra is at 520 nm, all samples show an increment in maximum intensity of PL between 29 and 49% and diffuse reflectance after the dehydration. A blueshift was found in the PL spectra, which was confirmed by chromaticity measurements. On the other hand, there is a relationship between the reduction of the adsorbed water and OH intermolecular stretching vibrations (FTIR) and the increment in PL, specifically in bands corresponding to the intermolecular H-bonds of O₃-H···O₅ and O₂-H···O₆. According to all data collected, an energy level diagram of cellulose samples was proposed indicating a phonon induced character of luminescence.

Nanocellulose fibres are known to enhance the mechanical properties of biopolymers when added as a filler. Nanocellulose irreversibly agglomerates upon drying and is therefore sold as an aqueous gel or suspension, increasing shipping cost and limiting application. This work studied the utility of xanthan gum as a dispersant aid for dried nanocellulose fibres. At levels as low as 15% xanthan gum addition, based on the mass of nanocellulose, prior to drying, agglomeration was significantly decreased. Mild shear rates could disperse the dried nanocellulose to a similar degree as ultrasonication when xanthan gum was present. Several complementary techniques, such as rheology, turbidimetry, and SEM- and TEM-imaging, proved that the native nanocellulose properties could be recovered after drying. Xanthan gum and nanocellulose, when incorporated into thermoplastic starch, showed a synergistic effect regarding the increase in tensile strength of the resultant biopolymer film. The addition of previously dried nanocellulose/xanthan, in a 4:1 ratio, to thermoplastic starch at a starch-cellulose ratio of 20:1, increased the tensile strength from 5.4 to 23.0 MPa. The ability to produce a dispersible and dry nanocellulose product that retains its properties has clear commercial benefits.

This study explores the upcycling of cotton residues from textile industry as a feedstock in a biorefinery model. The proposed process is to enzymatically digest the crude biomass to produce bioethanol, transforming the non-hydrolyzed residue into both carboxymethylcellulose (CMC) and cellulose acetate (CA). Enzymatic hydrolysis experiments of the raw cotton (without any chemical pretreatment) were performed in batch mode to evaluate the effects of enzyme dosage and biomass concentrations. The highest glucose level (113.2 g/L) was obtained with 20% m/v biomass concentration and 15 FPU/g_biomass, corresponding to 46.8% cellulose-to-glucose conversion. Fed-batch strategies (substrate feeding (S1) or substrate and enzyme feeding (S2)) were also studied. 60.2% cellulose-to-glucose conversion was achieved for S2 strategy with substrate and enzyme feeding within the first 48 h. Both CMC and CA were successfully synthesized (degree of substitution equal to 2 and 3, respectively) from the remaining cotton, which indicates the introduction of two carboxymethyl groups in the hydroxyls of each glycosidic unit of cellulose in CMC and three acetyl groups in the case of CA. Using the best condition, it would be possible to estimate a yield of 301.2, 237, and 238 g of ethanol, CMC, and CA, respectively, per 1 kg of cotton scraps. The proposed route shows the viability of upcycling cotton waste into biofuels and bioproducts, driving the circular economy and fostering the textile industry.