Three lignin–carbohydrate complex (LCC) preparations were isolated to elucidate the variations of chemical linkages during growth in the early development stages of Neosinocalamus affinis bamboo culms.
Hemicelluloses are widely used to prepare gel materials because of their renewability, biodegradability, and biocompatibility. Here, molecular chain extension of hemicelluloses was obtained in a two-step process. Composite hydrogels were prepared via free radical graft copolymerization of crosslinked quaternized hemicelluloses (CQH) and acrylic acid (AA) in the presence of crosslinking agent N,N’-methylenebisacrylamide (MBA). This chain extension strategy significantly improved the mechanical performance of the resulting hydrogels. The crosslinking density, compression modulus, and swelling capacities of hydrogels were tuned by changing the AA/CQH and MBA/CQH contents. Moreover, the biocompatibility test suggests that the hemicelluloses-based hydrogels exhibited no toxicity to cells and allowed cell growth. Taken together, these properties demonstrated that the composite hydrogels have potential applications in the fields of water absorbents, cell culture, and other functional biomaterials.
Wood auto-hydrolysates (WAH) are obtained in the pulping process by the hydrothermal extraction, which contains lots of hemicelluloses and slight lignin. WAH and chitosan (CS) were introduced into this study to construct WAH-based films by the casting method. The FT-IR results revealed the crosslinking interaction between WAH and CS due to the Millard reaction. The morphology, transmittance, thermal properties and mechanical properties of composite WAH/CS films were investigated. As the results showed, the tensile strength, light transmittances and thermal stability of the WAH-based composite films increased with the increment of WAH/CS content ratio. In addition, the results of oxygen transfer rate (OTR) and water vapor permeability (WVP) suggested that the OTR and WVP values of the films decreased due to the addition of CS. The maximum value of tensile strengths of the composite films achieved 71.2 MPa and the OTR of the films was low as 0.16 cm3·μm·m−2·24 h−1·kPa−1, these properties are better than those of other hemicelluloses composite films. These results suggested that the barrier composite films based on WAH and CS will become attractive in the food packaging application for great mechanical properties, good transmittance and low oxygen transfer rate.
Bio-based composite films were produced by incorporating wood autohydrolysate (WH), chitosan (CS), and cellulose nanocrystals (CNC). In this work, WH was directly utilized without further purification, and CNC was introduced as the reinforced material to prepare WH-CS-CNC composite films with excellent properties. The effects of CNC on the properties of WH-CS-CNC composite films were investigated by characterizing their structures, mechanical properties, oxygen barrier, and thermal stability properties. The results suggested that CNC could improve tensile strength of the composite films, and the tensile strain at break could be up to 4.7%. Besides, the oxygen permeability of the prepared composite films could be as low as 3.57 cm 3 /day⋅m 2 ⋅kPa, making them suitable for the food packaging materials. These above results showed that the addition of CNC is an effective method to enhance the toughness of composite films. In addition, WH-CS-CNC composite films have great potential in the field of sustainable food packing materials.
Biobased nanocomposite films for food packaging with high mechanical strength and good oxygenbarrier performance were developed using a hot-water wood extract (HWE). In this work, a facile approach to produce HWE/montmorillonite (MMT) based nanocomposite films with excellent physical properties is described. The focus of this study was to determine the effects of the MMT content on the structure and mechanical properties of nanocomposites and the effects of carboxymethyl cellulose (CMC) on the physical properties of the HWE-MMT films. The experimental results suggested that the intercalation of HWE and CMC in montmorillonite could produce compact, robust films with a nacre-like structure and multifunctional characteristics. This results of this study showed that the mechanical properties of the film designated F CMC0.05 (91.5 MPa) were dramatically enhanced because the proportion of HWE, MMT and CMC was 1:1.5:0.05. In addition, the optimized films exhibited an oxygen permeability below 2.0 cm 3 μm/day·m 2 ·kPa, as well as good thermal stability due to the small amount of CMC. These results provide a comprehensive understanding for further development of highperformance nanocomposites which are based on natural polymers (HWE) and assembled layered clays (MMT). These films offer great potential in the field of sustainable packaging.Natureal load-bearing materials, such as seashell nacre, are well known for their extraordinary mechanical properties that result from their highly ordered brick-mortar architecture. Nacre has inspired the fabrication of synthetic layered nanocomposite materials 1-3 . The introduction of clay into a polymer matrix can considerably enhance the thermal and mechanical properties of the polymer film and reduce oxygen permeability 4,5 . Therefore, a potential route for improving the oxygen barrier and mechanical properties of polymer films is the addition of layered clays such as montmorillonite (MMT) to form polymer/clay nanocomposites. In recent years, special attention has been given to the synthesis and characterization of nanocomposites that are based on natural polymers and assembling layered clays 6 . Increased attention is being paid to renewable resources, hence the feature of hemicelluloses including their abundance, biodegradability and biocompatibility have made them attractive 7,8 . However, using hemicelluloses to produce materials on an industrial scale is hampered by the high production costs associated with obtaining these materials with a high degree of purity 9 . It is well known that a major fraction of wood is present in the form of hemicelluloses and lignin which are present in the waste pulping liquor and must be removed during pulping to yield undegraded cellulose fibers 10 . Thus, extracting the valuable noncellulosic components from wood chips prior to pulping and converting them into biofuels or the value-added materials is financially beneficial to the pulping industry. The purpose of the proposed hot-water extraction (autohydrolysis processing, which could lead t...
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