Reinforcement of polypropylene with alkali-treated sugarcane bagasse fibers: Mechanism and consequences

Polypropylene composites were prepared from neat and alkali-treated sugarcane bagasse fibers. The results showed that alkali treatment leads to an increase in composite stiffness and strength. A maximum is achieved in these properties at around 5 wt% NaOH content of the treating solution. The increase in properties was assigned to the improvement in inherent fiber characteristics. Acoustic emission testing and electron microscopy showed that the two main local deformation processes related to the fibers are their fracture and debonding; the latter is accompanied by the shear yielding of the matrix. Increased inherent strength of the fibers results in an increase in the fracture initiation stress and fracture energy of the composites. Interfacial adhesion has a slight effect on stiffness, but more significant on strength and impact resistance. Changing adhesion modifies the relative importance of local deformation processes, the number of debonding events decreases, while fiber fracture increases with increasing adhesion. Increased interfacial adhesion improves stress transfer and the load bearing capacity of the fibers as well, but suppresses matrix yielding. Alkali treatment increases inherent fiber strength, which can be directly correlated with composite strength

Alkali treatment of lignocellulosic fibers extracted from sugarcane bagasse: Composition, structure, properties

Lignocellulosic fibers extracted from sugarcane bagasse were treated with NaOH solutions of different concentration (0-40 wt%) to study the effect of alkali treatment on the composition, structure and properties of the fibers. Composition was determined by the van Soest method, structure was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), while mechanical properties by tensile testing. Hemicellulose and lignin content decrease, while cellulose content goes through a maximum as a function of alkali concentration. Crystallinity changes only slightly and microfibril angle (MFA) remains constant thus structural effects and especially MFA are not the primary reasons for changing properties. The Youngs modulus of the fibers shows a slight maximum at around 2-4 wt% NaOH content, while tensile strength goes through a much more pronounced one at around 5-8 wt%. Direct correlation between structure and mechanical properties was not found indicating that composition is more important in the determination of properties than structure. Regression analysis proved that the combination of several compositional variables determines mechanical properties in a non-linear manner. The improvement in fiber properties was explained with the dissolution of weak amorphous fractions and the relative increase of cellulose content

Alkali treatment of lignocellulosic fibers extracted from sugarcane bagasse: Composition, structure, properties

This work reported the study on the effect of alkali treatment using NaOH solutions of different concentration (0-40 wt.%) of sugarcane bagasse fibers on their composition, structure and properties. The results evidenced that treatment modifies the composition, structure and properties of the fibers. The content of hemicellulose and lignin reduce, while cellulose content turns through a maximum as a function of NaOH concentration. A small change in crystallinity was identified and microfibril angle (MFA) remained constant thus structural effects and especially MFA were not the main reasons for altering the properties. The stiffness of the fibers shows a slight maximum at around 2-4 wt.% NaOH content, while a much more pronounced strength found at around 5-8 wt.%. Direct correlation between structure and mechanical properties was not found, indicating that composition is more essential in the determination of properties than structure. The optimum concentration of the treating solution is around 5 wt% NaOH content, if the time of treatment is fixed at 1 hour

Utilization of rarasaponin natural surfactant for organo-bentonite preparation: Application for methylene blue removal from aqueous effluent

Rarasaponin that belongs to the natural surfactant was used as modifying agent for preparation of organo-bentonite. This surfactant was extracted from wild plant Sapindus rarak DC. The modifying process was conducted by microwave thermal irradiation. The characterization of bentonite and its modified form was carried out using FTIR, nitrogen sorption and XRD analysis. In order to test the adsorption capability of organo-bentonite, batch adsorption experiments of methylene blue from aqueous solution using this adsorbent were conducted under several operating conditions. The highest adsorption capacity (qm) of organo-bentonite obtained in this study was 256 mg/g while for raw bentonite was 194 mg/g at 60 °C. The adsorption isotherm and kinetic data were modeled using several well known models. Freundlich isotherm model represented the adsorption equilibrium data better than the Langmuir isotherm model. For the kinetic model, the pseudo-second order gave reasonable parameters and could correlate the kinetic data well. New mechanisms of organo-bentonite formation as well as adsorption of methylene blue on the surface of organo-bentonite were also proposed in this paper