Okra Fiber Research Articles

Mechanical Performance of Hybrid Okra Fibre Reinforced Polyester Composites—Part I: Reinforced with Fresh and Long Time Dried Fibres

Mechanical Performance of Hybrid Okra Fibre Reinforced Polyester Composites—Part I: Reinforced with Fresh and Long Time Dried Fibres

Synthesis and Applications of Functional Polymers from Natural Okra Fibers for Removal of Cu(II) Ions from Aqueous Solution

Functional groups (−COOCH3 and −NH2) in natural okra fiber had been introduced by free radical graft polymerization of methyl methacrylate (MMA) and acrylamide (AAm) from their binary solution using ascorbic acid/H2O2 as a redox initiator at a temperature of 45°C for 90 min. Factors affecting the grafting of lignocellulosic fiber such as feed molarity and comonomer composition were investigated. The grafted copolymers were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM-EDX), and thermogravimetric analysis (TGA). Functional groups were tested for their potential application in the removal of copper ions from aqueous solutions. Batch experiments were performed to evaluate the adsorption capacity of the maximum grafted cellulosic fibers toward the Cu (II) ions. Pseudo-first-order and pseudo-second-order kinetic models were studied to analyze the Cu2+ adsorption process and results showed that the pseudo-second-order model was more suitable than the pseudo-first-order model. Further, Langmuir, Freundlich, and Tempkin models were also applied to describe the adsorption isotherm of Cu2+ by different fiber adsorbents. The results indicate that the Langmuir model fitted the adsorption equilibrium data better than other two models. The maximum monolayer capacity qm calculated using the Langmuir isotherm for raw and MMA+AAm grafted fiber were 4.89 and 33.05 mg/g, respectively.

Functionalized Cellulosic Fibers for Removal of Toxic Metal Ions From Contaminated Water

Functionalization of cellulosic okra fibers was carried out by graft copolymerization of acrylamide in the presence of ascorbic acid and hydrogen peroxide as redox initiator in aqueous medium. Different reaction parameters such as time, temperature, initiator concentration, and monomer concentration were optimized to obtain the maximum graft yield. The graft copolymerized fibers were characterized by FT-IR, TGA, and X-ray diffraction techniques. Further, chemically modified fibers were used for removal of Zn2+ and Cd2+ toxic metal ions from contaminated water. The effect of pH, contact time, and metal ion concentration was studied in batch mode experiments. The kinetics of adsorption were studied using pseudo-first and pseudo-second-order kinetic models. The adsorption isotherm was studied using Langmuir and Freundlich isotherm models. The Langmuir model was found to fit the equilibrium data well.

Okra (Abelmoschus esculentus) Fibre Based PLA Composites: Mechanical Behaviour and Biodegradation

Okra (Lady’s finger, Abelmoschus esculentus) fibres were introduced in a poly(lactic) acid (PLA) polymer matrix as short fibres (5–10 mm), in amounts variable between 10 and 30 %wt. For this purpose, both untreated and alkali treated okra fibres were used. The obtained composites, in view of the envisaged application for sustainable packaging purposes, has been tested morphologically, mechanically and subjected to chemical characterisation, while the biodegradation profile has been studied. The introduction of fibres in the polymer matrix always resulted in a higher stiffness of the obtained composite. The addition of okra fibre to PLA results in an increased ability of the PLA matrix to crystallize due to the nucleation effect of the okra fibre, and this effect was more evident in the composites produced with alkali treated fibres. The biodegradation process was accelerated by the addition of higher contents of fibres into the composites due to preferential degradation of the fibres themselves: this effect was increased when composite fibres are alkali-treated.

Cellulose nanocrystals extracted from okra fibers in PVA nanocomposites

AbstractCellulose nanocrystals (CNC) were extracted from okra bahmia (Abelmoschus Esculentus) bast fibers and inserted in different tenors (1, 2, 5, and 10 wt %) as the reinforcement of a poly(vinyl alcohol) (PVA) matrix. The extraction of cellulose was carried out in a two‐step procedure: the first chemical treatment led to the production of holocellulose by the gradual removal of lignin, while the subsequent sulphuric acid hydrolysis process allowed obtaining cellulose nanocrystals in an aqueous suspension. The dispersion of CNC in the composite appeared effective at low cellulose content (1 wt %), while it presented more problems for higher contents. However, a 5 wt % cellulose content proved ideal to promote a direct mechanical interaction between the PVA and cellulose structures. Thermal analysis demonstrated that the presence of okra did not have a large effect on glass transition temperature, while it sensibly modified the melting temperature of the PVA matrix, as well as the crystallization temperature, due to the nucleating action of the nanofillers. FTIR spectroscopy performed during the exposure to UV light underlined that no oxidative reactions occur after a short‐time exposure and that a longer irradiation times are required to produce oxidation on neat matrix and PVA/CNC nanocomposites. The results confirmed that the presence of CNC does not affect the stability of the neat PVA matrix to the photodegradation after UV irradiation. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Experimental determination of tensile properties of okra, sisal and banana fiber reinforced polyester composites

Increasing the needs for different engineering applications invite the development of new materials. In the present research new natural fiber okra was introduced for the preparation of okra fiber reinforced polyester (FRP) composites. Already established fibers sisal and banana were also extracted for the preparation of sisal and banana FRP composites and to determine tensile properties. The tensile properties of okra FRP composites were compared with sisal and banana FRP composites. Hand lay-up technique was used for the preparation of composites. Chemically treated okra fiber reinforced polyester composites at maximum volume fraction showed tensile strength, modulus of 154.17%, 114.13% and specific tensile strength and modulus of 12.26%, 129.82% higher than that of the pure polyester specimen, respectively.