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A facile approach was utilized to introduce starch nanocrystals (SNCs) onto sisal fiber (SF) to improve the interfacial adhesion between SF and starch. For this, fibers were treated with alkali and then subjected to cold plasma treatment to increase the accessibility with SNCs, which was confirmed through X-ray photoelectron spectroscopy (XPS). It was found that due to the influence of cold plasma treatment, new functional groups were introduced onto SF. The surface characteristics of SF were examined by Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). The observed results suggested that SNCs were successfully distributed onto SF. Tensile strength and interfacial shear strength of fibers treated under different conditions were calculated and compared through a two-parameter Weibull model. The highest interfacial shear strength of 3.05 MPa was obtained by Alkali-300 W-SNCs, which indicated an increase of 80.6% than untreated SF. It has also been proved that the starch nanocrystals produced hydrogen bonding and physical interlocking between sisal fiber and starch. Notably, the outcome of this investigation indicates that SNCs may be applied for the fabrication of high performance, environmentally friendly sisal/starch composites for a range of technological applications. [ABSTRACT FROM AUTHOR]

Certain investigation was done on the removal of heavy metals (Cu2+and Ni2+) from aqueous solution using adsorption process. The prepared cellulose-g-acrylic acid copolymer was used as an adsorbent to remove heavy metal ions from aqueous solutions. The efficiency of the adsorbent was identified from the variation in the adsorption % with contact time, adsorbent dose, and pH. From the observed results, it is evident that the adsorption of metal ions increases with the increase in contact time and metal ion concentration. An optimum pH was found to be 5.0 for both Cu2+and Ni2+onto cellulose-g-acrylic acid. The results of the Langmuir, Freundlich, and pseudo first and second order studies revealed that the adsorption was found to fit well with Freundlich isotherm and follows pseudo second order kinetics. From the results, it was concluded that the graft copolymer was found to be an efficient adsorbent. [ABSTRACT FROM PUBLISHER]

In this study, bio-foam composites are produced using short sisal fiber as the reinforcement and modified castor oil as the matrix, respectively. The foam composites with an average cell size of 200 μm possess properties similar to those of commercial polyurethane foams. The effects of fiber loading, fiber length and foam density on the compressive properties of the foam composites are reported in relation to the interfacial interaction. It is found that the addition of chopped sisal alters cell structure of the foam. Surface pre-treatment of sisal by alkali or silane coupling agent helps to improve the mechanical properties and interfacial adhesion. The exposure of the fibers to the gas cells of the foam reduces the effectiveness of interfacial effect, which is different from the case of conventional bulk composites. As a result, the reinforcing ability of sisal fibers becomes a function of fiber length and so on. [ABSTRACT FROM AUTHOR]

The dynamic mechanical properties of treated sisal fiber-reinforced polyester composites fabricated by resin transfer molding (RTM) have been studied with reference to fiber surface modifications, frequency and temperature. The sisal fibers have been subjected to various chemical and physical treatments like mercerization, heating at 100°C, permanganate, benzoylation and vinyl tris(2-ethoxymethoxy) silane to improve the interfacial bonding with isophthalic polyester resin. Results indicated that treatment changed the storage modulus (E′), loss modulus (E″) and damping factor (tan δ) drastically at a wide range of temperature. The E′ value increased for every treatment, and is maximum for the composites fabricated by benzoylated-treated fibers. The Tg value obtained from the E″ value showed an increase as compared to untreated fiber-reinforced composites. The alkali-treated fiber-reinforced composites showed lower tan δ value. Using Arrhenius' equation the activation energy was calculated and found maximum for the composites fabricated by alkali-treated fiber, which shows good fiber/matrix interactions. [ABSTRACT FROM AUTHOR]

A diamine-based benzoxazine monomer has been synthesized via the Mannich condensation reaction of ethylenediamine, phenol and formaldehyde. The effect of solvent was investigated. The chemical structure and thermal properties of the diamine-based benzoxazine were characterized by FT-IR, NMR, DSC and TGA. Sisal fibers are incorporated in a mixture of benzoxazine and bisphenol-A type epoxy resins to form a unidirectionally reinforced composite. The effects of varying fiber contents and matrix composition on the mechanical properties of the composites are studied. [ABSTRACT FROM AUTHOR]