Green approach for the activation and functionalization of jute fibers through ball milling

Abstract

holding, protection against biochemical stress or addition of strength and structure; and hemicellulose, which coordinates cellulose together with lignin (Boerjan et al. 2003; Hansen and Björkman 1998; Panshin and De Zeeuw 1980). Cellulose, as the main constituent of plant cell walls, provides the structural support. It consists of b-D-glucopyranose sugar units, which contain three hydroxyl groups at the C-2, C-3 and C-6 positions. They can form strong hydrogen bonds, constituting the crystalline and amorphous regions within the fibers, which interact with each other to form cellulose microfibrils. Cellulose is known to exist in different polymorphs depending on the molecular orientation and hydrogen-bonding network in crystalline domains. The four main polymorphs of cellulose are cellulose I, cellulose II, cellulose III and cellulose IV. The most extensively investigated are cellulose I, which is the dominant form in natural wood and plants, and cellulose II that can be obtained from cellulose I either by chemical regeneration or mercerization, due to its relatively low thermal stability. Cellulose I, present in native cellulose, exists as cellulose Ia (triclinic unit cell) and cellulose Ib (monoclinic unit cell), both with cellulose chains adopting parallel configurations. In contrast, the chains of cellulose II are in an antiparallel configuration and exist in a monoclinic unit cell (Gong et al. 2017). Despite cellulose I exhibits much better mechanical properties than cellulose II (O'Sullivan 1997; Yu et al. 2014), the later has a more stable structure, making it preferable for various applications. Cellulose can be submitted to a wide variety of chemical modifications due to the three hydroxyl groups present in its structure. Furthermore, reactivity of cellulose can be enhanced through previous Keywords Cellulose Á Jute fibers Á Ball milling Á Isocyanate

Eco-Friendly Oleogels from Functionalized Kraft Lignin with Laccase SilA from Streptomyces ipomoeae: An Opportunity to Replace Commercial Lubricants

“…However, the values of the linear viscoelastic functions clearly increase when lignin is polymerized with laccase giving higher values of G′ and G″, resulting in a qualitatively and quantitatively similar linear viscoelastic response to that found in traditional lithium soap-based lubricating greases. These commercial lubricants maintained G′ standard values since 10 4 –10 5 Pa, which are similar to those corresponding to commercial lubricants containing mineral oils and metallic soaps. , …”

“…These commercial lubricants maintained G′ standard values since 10 4 −10 5 Pa, which are similar to those corresponding to commercial lubricants containing mineral oils and metallic soaps. 28,29 Oleogels obtained in this preliminary assay from functionalized residual lignin were physically stable and exhibited viscoelastic responses that are typical for thickeners usually present in traditional lubricant greases. This behavior is usually attributed, at least partially, to the cross-linking of lignin-based radicals generated as a consequence of their oxidation by SilA.…”

Construction of thermoplastic cellulose esters matrix composites with enhanced flame retardancy and mechanical properties by embedding hydrophobic magnesium hydroxide

“…Because of the strong hydrogen bonding structure and high crystallinity, the accessibility and reactivity of cellulose are poor 31 . In the MASPR process, the strong hydrogen bonding and stable crystal structure of cellulose can be destroyed by intense milling to form active hydroxyl groups, which directly contact and react with the esterifying agent in a solvent‐free condition 32 .…”

Developments in Chemical Treatments, Manufacturing Techniques and Potential Applications of Natural-Fibers-Based Biodegradable Composites

“…Chemical treatments have a considerable effect on NFRPC's mechanical properties [90][91][92], owing to hydroxyl groups from cellulose and lignin [93]. Chemical-treatment strategies commonly rely on reagent functional groups/active groups capable of responding superiorly with natural-fiber structures, just as adequately removing non-cellulosic materials from the fibers [94]. Besides, hydroxyl groups resulting from chemical treatments might be engaged with the hydrogen bonding inside the cellulose atoms, limiting the movement towards the matrix [6,90].…”

“…Among different methods/techniques, alkali treatment is considered to be costeffective and most efficient strategy, resulting in changes in the fiber surface, just as removing amorphous hemicelluloses and lignin [94]. Alkali treatment is a typical method to clean and adjust the fiber surface to lower surface strain and improve the interfacial attachment between natural fiber and a polymer matrix [115].…”