Effect of Alkali Treatment on the Properties of Acacia Caesia Bark Fibres

Abstract

As possible substitutes for non-biodegradable synthetic fibre, ligno-cellulosic fibres have attracted much interest for their eco-friendliness; a large number of them are already used for the production of green polymer composites. The search for further green candidates brings into focus other fibres not previously considered, yet part of other production systems, therefore available as by-products or refuse. The purpose of this study is to explore the potential of alkali treatment with 5% sodium hydroxide (NaOH) to enhance the properties of bark-extracted Acacia Caesia Bark (ACB) fibres. The microscopic structure of the treated fibres was elucidated using scanning electron microscopy (SEM). Moreover, the fibres were characterised in terms of chemical composition and density and subjected to single-fibre tensile tests (SFTT). Following their physico-chemical characterisation, fibre samples underwent thermal characterisation by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), and their crystallinity was assessed using X-ray diffraction (XRD). This level of alkali treatment only marginally modified the structure of the fibres and offered some improvement in their tensile strength. This suggested that they compare well with other bark fibres and that their thermal profile showed some increase of degradation onset temperature with respect to untreated ACB fibres. Their crystallinity would allow their application in the form of fibres with an average length of approximately 150 mm, even in thermoplastic biocomposites.

A Review on Surface Modification of Plant Fibers for Enhancing Properties of Biocomposites

“…Extensive research studies have provided detailed information on the chemical treatments used for reinforcement fibers and the improvement of the fiber adhesion properties of the matrix. [12,[52][53][54][55][56]…”

“…To address this issue, researchers have explored chemical treatments to reduce the hydrophilic tendency of reinforcing fibers, thereby improving their compatibility with the matrix. Extensive research studies have provided detailed information on the chemical treatments used for reinforcement fibers and the improvement of the fiber adhesion properties of the matrix [12,52–56] …”

Influence of washing with sodium lauryl sulphate (SLS) surfactant on different properties of ramie fibres

“…In some cases, though, tailoring the treatment duration, consistent improvements are found: specifically, an 8 hours alkali treatment of Borassus fruit fibres makes them 41% higher in tensile strength, 69% stronger in modulus, and 40% better in extension (Reddy et al 2013). Substantial improvements were also observed by the application of a 5% NaOH treatment on Acacia caesia bark fibre, where the alkali was able to remove amorphous constituents of the fibre, yet exposing it very much to the environmental conditions (Sivasubramanian et al 2021). Improved tensile strength and stiffness properties were particularly obtained in Ijuk (Arenga pinnata) fibre when treated with potassium hydroxide (KOH) over other strong basic solutions, such as NaOH and ammonium hydroxide (NH4OH) (Santhiarsa 2016).…”

A review on natural fiber composites: Polymer matrices, fiber surface treatments, fabrication methods, properties, and applications

“…The modification of wood fibers has been researched with more than 40 distinct coupling agents. Among the often used agents are acrylic acid, acetic acid, silane, isocyanates, sodium hydroxide, peroxide, and potassium permanganate 11,61,62 . Chemicals have the capability to introduce functional moieties onto wood fibers via a reaction with the surface functional groups present.…”