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Silk fibroin (SF) has been intensively studied as a biobased renewable material for biomedical and other applications. However, its relatively low mechanical properties have limited its use in the applications where an improved strength and structural integrity are desired. In this work, a bio-nanocomposite material consisting of SF/polyvinyl alcohol (PVA) as the matrix, TEMPO-oxidized bacterial cellulose nanofiber (TBC) as the reinforcement, and silver nanoparticles (AgNPs) as an antibacterial agent, was facilely synthesized. SF also functioned as a reducing agent and TBC as an immobilization template during the in-situ synthesis of AgNPs. It was found that TBC and AgNPs were homogeneously dispersed in the nanocomposites after the synthesis, which led to outstanding mechanical properties of the materials. The mechanical properties, hydrophobicity, and water vapor barrier property of the materials could be tailored by adjusting the content of TBC. Moreover, the bio-nanocomposite films exhibited strong UV shielding property, antibacterial activities and low silver leakage. These properties make the SF/PVA/AgNPs/TBC bio-nanocomposites promising materials for active food packaging and seed storage/packaging applications. [ABSTRACT FROM AUTHOR]

Chemically deuterated cellulose fiber was expected to provide novel applications due to its spectral, biological, and kinetic isotope effect. In this research, the performance of the chemically deuterated cotton fibers, including their mechanical property, enzymatic degradation performance, effect on bacterial treatment, and fast identification (near-infrared modeling) was investigated. The breaking tenacity of the deuterated cotton fibers was slightly lower, which might be attributed to the structural damage during the chemical deuteration. The glucose yield by enzymatic hydrolysis was less than that of the protonic cotton fibers, implying the deuterated fibers are less sensitive to enzymatic degradation. Furthermore, the deuterated fibers could promote the growth of bacteria such as Escherichia. coli , which was associated with the released low-level deuterium content. At last, the near-infrared technique combined with partial least squares regression successfully achieved a fast identification of the protiated and deuterated cotton fibers, which significantly promoted the potential application of deuterated cellulose as anticounterfeiting materials (e.g., special paper). [ABSTRACT FROM AUTHOR]

Preparation of deuterium incorporated cellulose is a vital tool to investigate cellulose internal structure and to expand the application fields of cellulose materials. In this study, cellulosic cotton fibers with anti-rehydration (exchange-resistant) deuterium incorporated in cellulose were prepared by chemical hydrogen–deuterium exchange treatment. The chemical hydrogen–deuterium exchange process, along with exchange time, were characterized by nuclear magnetic resonance hydrogen spectroscopy (1H-NMR). The anti-rehydration deuterium incorporation was determined by Fourier Transform infrared spectroscopy (FTIR) and Stable Isotope Ratio Mass Spectrometer (IRSM). The effect of the deuterium hydroxyl substitution on cotton fiber's spectral data, microstructure, crystalline information, degree of polymerization, as well as it's thermogravimetric analysis (charcoalization and combustion) are explored. Analysis of the chemical exchange process indicated that the hydrogen–deuterium exchange occurred preferentially in the amorphous cellulose component over the first several minutes. Deuterium exchange in the anti-rehydration crystalline phase took several hours. Increasing the treatment time, enhanced exchange-resistant deuterium incorporation to as high as about 60% of the cotton fibers' cellulose hydroxyl groups was achieved. The characterization of FTIR, Fourier transform Raman (FT-Raman), and near-infrared spectra (NIR) all exhibited the deuterium spectral isotope effect on cellulose hydroxl groups. While, apart from the effect of reaction temperature, deuterium incorporation isotope effect did not affect the cellulose microstructure, crystalline index and the degree of polymerization properties. Furthermore, the thermogravimetric analysis of deuterated cotton fibers under N2 and air atmosphere were both altered due to the thermodynamic isotope effect. These observations revealed the hydrogen–deuterium exchange treatment process and impacts on cellulose fiber properties, which helped us to better understand the cellulose internal structure and may facilitate the potential utilization of deuterated cellulosic materials. [ABSTRACT FROM AUTHOR]

Production of deuterated cellulose is important from both theoretical and practical perspectives. In this study, cellulose fibers of cotton and Tencel fibers with exchange-resistant deuterium incorporation were prepared by hydrogen–deuterium exchange treatment. The effect of the micro-structure of cellulose crystallinity index as well as the reaction conditions including catalyst, reaction time, and temperature on the exchange-resistant deuterium incorporation process are reported. The ability of deuterated cellulose fibers to resist protium-exchange during H2O washing was also explored. The results found that higher crystallinity index is beneficial to stabilize the deuteration of cellulose fibers. Furthermore, alkaline catalysts such as sodium hydroxide or potassium carbonate and higher exchange temperature as well as longer reaction time contribute significantly to the stabilization of deuterium incorporation in the deuterated cellulose fibers. These observations revealed that the hydrogen–deuterium exchange treatment is effective to obtain exchange-resistant deuterium incorporated cellulose fibers. In addition, cotton fibers with several deuteration levels were produced and could be considered for the study of deuterium effect on cellulose properties. [ABSTRACT FROM AUTHOR]

Degumming is the dominant method to isolate cellulosic fibers in the textile industry. High content of lignin is the principle obstacle in bast-fibers degumming. In order to remove lignin efficiently, the treatment using steam explosion coupled with Fenton oxidation was conducted on kenaf bast in this study. The influence and mechanism of the combined treatment of steam explosion and Fenton oxidation were studied. Fiber microstructure, composition proportion and distribution, cellulose Segal crystallinity and polymerization as well as residual lignin structure were analyzed. The results showed that the pretreatment of steam explosion could sufficiently extract most of the hemicellulose from kenaf bast. Also, the Fenton oxidation followed by alkaline boiling could effectively remove the lignin from the fiber, especially from the fiber surface. The refined dry fibers produced only remained 8.82% of hemicellulose and 9.36% of lignin. And the whole treatment process didn’t change the cellulose crystalline structure but could gradually degrade hemicellulose, lignin and other amorphous gummy matter as well as disordered areas in cellulose, leading to the increase of fiber Segal crystallinity from 62.02 to 70.12%. Part of cellulose was damaged with the increase of degumming intensity, resulting in the decrease of the polymerization degree of cellulose. Meanwhile, the structure of residual lignin changed during the degumming stages of steam explosion, Fenton oxidation and alkaline boiling. All the results revealed that the treatment of combined steam explosion and Fenton oxidation is significantly effectual for isolating bast-fibers. [ABSTRACT FROM AUTHOR]

Abstract: Lotus fibers are the isolated helical secondary cell wall thickenings from tracheary elements of lotus (Nelumbo nucifera Gaertn) petioles. In this study the anatomical characteristics of lotus petioles and microstructures of tracheary elements were studied using light microscopy (LM) and scanning electron microscopy (SEM). The results show that vascular bundles of lotus petioles are scattered throughout ground tissue. Their tracheary elements are of various sizes and there are several patterns of secondary wall thickening present. However, only secondary thickening in a ribbon-like helical pattern can be drawn out from the petiole to form lotus fibers for subsequent utilization. Study of the microstructure of the tracheary elements reveals that there are two pit structures present in the end walls in addition to pits with intact pit membranes: those with porose or web-like remnants pit membrane and those that lack pit membranes. This is an indication of the transitional stage between tracheids and vessel elements. This study provides supportive evidence that lotus fibers are found in both helically thickened tracheids and helically thickened primitive vessels. [Copyright &y& Elsevier]

Abstract: Lotus fiber is a natural cellulose fiber isolated from lotus petiole. Botanically, the fiber is the thickened secondary wall in xylem tracheary elements. In order to obtain essential information for the preparation and processing of lotus fibers, the fine structure and properties of lotus fibers were investigated by the aid of transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM), atomic force microscopy (AFM), X-ray diffraction (XRD), and so on. The results show that lotus fibers display a rough surface topography and an internal structure different from common plant fibers. The percent crystallinity and preferred orientation of crystallites in lotus fibers are 48% and 84%, respectively. Considering the average breaking tenacity and Young''s modulus, lotus fibers are similar to cotton. The elongation of lotus fibers is only about 2.6% while their moisture regain is as high as 12.3%. [Copyright &y& Elsevier]

In this paper, the chemical degumming methods, briefly, peeled bast by hand (Fiber-H) and by machine (Fiber-M), as well as the bacterial degumming method (Fiber-B), were used to obtain the Apocynum venetumfibers and the fibers separately obtained by above-mentioned methods as well as the Bast of the Apocynum venetum had been characterized by the Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and mechanical property measurement. It was found that the Bast showed the structure of cellulose I and the cellulose I structure was well preserved in all treated A. venetum fibers according to the FTIR and XRD results. Meanwhile, as seen from the SEM images, the treated fibers can be directly suitable for textile industry, which was further confirmed by the mechanical property measurements. It is interesting to note that the crystallinity, the degree of orientation and the mechanical properties of Fiber-B only have slight differences with those of Fiber-H and Fiber-M. These results suggested that the bacterial degumming method had more industrial applications due to its high efficiency, low cost and especially environmentally-benign nature than the chemical degumming methods. [Copyright &y& Elsevier]

Artemisia vulgaris is an economic plant that is spreading widely in central China. Its unused bast generates a large amount of biomass waste annually. Utilizing the fibers in Artemisia vulgaris bast may provide a new solution to this problem. This research attempts to strengthen the understanding of Artemisia vulgaris by analyzing its fiber compositions and preparing micro- and nano-cellulose fibers, which can be used as raw materials for composites. In this work, Artemisia vulgaris bast powder (AP) and microcellulose and nanocellulose fibers (AMFs and ANFs) were produced and characterized by optical microscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TG), and bacteriostatic test. The results indicated that cellulose, hemicellulose, and lignin were the main components in the Artemisia vulgaris bast. The cellulose content reached 40.9%. The Artemisia vulgaris single fibers were microcellulose fibers with an average length of 850.6 μm and a diameter of 14.4 μm. Moreover, the AMF had considerable antibacterial ability with an antibacterial ratio of 36.6%. The ANF showed a length range of 250–300 nm and a diameter of 10–20 nm, and it had a higher crystallinity (76%) and a lower thermal stability (initial degradation temperature of 183 °C) compared with raw ANF (233 °C). This study provides fundamental information on Artemisia vulgaris bast cellulose for its subsequent utilization. [ABSTRACT FROM AUTHOR]

• A method for splitting kenaf using microwave combined with lactic acid was proposed. • Fibers have excellent dispersion and suffer minor damage. • The extracted lignin is less damaged and keeps its structural integrity. • Potential for biomass clean production due to low chemicals and time consumption. According to diverse application purposes, different scales of lignocellulosic fibers were obtained from biomass through various preparation conditions. However, the pollution in the fiber separation process restricted the development of the related industry. This research proposed clean fiber separation technology of kenaf bast that combined microwave and lactic acid treatment. The traditional sulfate method was also carried out for comparison. The raw kenaf bast and produced fibers were characterized with wet chemistry analyses, SEM, FTIR, GPC and NMR. The results showed that compared with the traditional method (lignin removal rate 88.3 %, cellulose Mw = 607 kg/mol), the new method had higher lignin removal capacity (94.68 %) and less damage to cellulose (Mw = 1174 kg/mol). TG and NMR analysis showed that the separated crude lignin had a high pyrolysis temperature (350℃), minor structural changes and better uniformity, which was close to natural lignin. In addition, it was calculated that the processing time of the new method was reduced by 82.3 %, which reduced energy loss and waste liquid pollution. This study proved that microwave-assisted lactic acid treatment could separate kenaf fibers efficiently with less damage and pollution. [ABSTRACT FROM AUTHOR]