Mechanism of fiber/matrix bond and properties of wood polymer composites produced from alkaline-treatedDaniella oliveriwood flour

Abstract

The effects of sodium hydroxide (NaOH) concentration and time of treatment on the mechanism of fiber/matrix bond and functional properties of Daniella oliveri reinforced wood polymer composites (WPCs) were investigated. The WPCs were evaluated using Fourier transform infrared spectroscopy, mechanical testing, scanning electron microscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry. The fiber/matrix adhesion mechanism could be attributed to the disruption of hydrogen bonding in the D. oliveri wood fiber network structure and the removal of lignin, wax and oils covering the external surface of the fiber cell wall. This leads to an increase in desirable functional properties as alkaline concentrations reached 4 wt%, but subsequently reduced at higher concentrations, while they increased with treatment time. Analysis of the fractographs of the WPCs suggests optimization of interfacial fiber–matrix adhesion and functional properties when D. oliveri wood fiber was treated with a 4 wt% solution of NaOH for 150 min. POLYM. COMPOS., 37:2657–2672, 2016. © 2015 Society of Plastics Engineers

The effect of size and delignification on the mechanical properties of polylactic acid (PLA) biocomposites reinforced with wood fibres via extrusion

“…35 Olakanmi et al highlighted that wood fibre treated at room temperature with an alkali concentration of up to 4 wt% achieved the isolation of cellulose. 25 In the present work, the degradation behaviour, chemical structure and morphology of the fibres corroborate the reports mentioned above, indicating the removal of hemicellulose and lignin from the wood fibres.…”

“…This was expected since the remaining cellulose is less thermostable than lignin. 22,25 The higher char mass indicates a higher cellulose content. Alkalised fibres have higher char residue due to the absence of waxes (pectin), non-fibre stream tissues (hemicellulose) 26 and cementing substance (lignin) 27 .…”

“…Olakanmi et al reported that fibres of similar average size washed in 4 wt% NaOH solution for 120 minutes demonstrated optimal tensile properties when compressed moulded with HDPE. 25 This indicates that the processing conditions strongly influence the resulting properties in addition to the fibre treatment parameters. For all composites, the coupling mixture delivered an initial better performance; however, the increment of MA levelled off or decreased tensile strength.…”

Characterization of wood plastic composite based on HDPE and cashew nutshells processed in a thermokinetic mixer

“…Good interfacial adhesion between the matrix and the fibers is important to transfer stress from the matrix to the fibers and thus, produce composites with enhanced properties . Moreover, treatments that promote disruption of hydrogen bonding in natural fillers and remove lignin, wax and oils that cover their external surface cell wall can also contribute to improve mechanical properties of WPC . Besides the abovementioned factors, properties of WPC are also dependent on fiber length, morphology and mechanical interlocking .…”

A Method of Managing Waste Oak Flour as a Biocomponent for Obtaining Composites Based on Modified Soybean Oil

“…The reason for obtaining better mechanical properties for compositions containing 5 wt % of mercerized oak flour could be the influence of the concentration of the used NaOH solution. In the case of the application of a solution with a lower concentration, the alkali treatment of the natural filler resulted in the purification of the material and the removal of lignocellulose and hemicelluloses from its structure, which caused the improvement in the adhesion between the filler and a polymer matrix [ 56 ]. On the other hand, an excessive concentration of alkali may adversely affect the surface of the natural filler.…”