There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Nature And Properties Of Soils

Elements Of X Ray Diffraction

In recent years, natural fibers reinforced composites have received much attention because of their lightweight, nonabrasive, combustible, nontoxic, low cost and biodegradable properties. Among the various natural fibers; flax, bamboo, sisal, hemp, ramie, jute, and wood fibers are of particular interest. A lot of research work has been performed all over the world on the use of natural fibers as a reinforcing material for the preparation of various types of composites. However, lack of good interfacial adhesion, low melting point, and poor resistance towards moisture make the use of natural fiber reinforced composites less attractive. Pretreatments of the natural fiber can clean the fiber surface, chemically modify the surface, stop the moisture absorption process, and increase the surface roughness. Among the various pretreatment techniques, graft copolymerization and plasma treatment are the best methods for surface modification of natural fibers. Graft copolymers of natural fibers with vinyl monomers provide better adhesion between matrix and fiber. In the present article, the use of pretreated natural fibers in polymer matrix-based composites has been reviewed. Effect of surface modification of natural fibers on the properties of fibers and fiber reinforced polymer composites has also been discussed. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers

Pretreatments of Natural Fibers and their Application as Reinforcing Material in Polymer Composites—A Review

In materials science, “green” synthesis has gained extensive attention as a reliable, sustainable, and eco-friendly protocol for synthesizing a wide range of materials/nanomaterials including
 metal/metal oxides nanomaterials, hybrid materials, and bioinspired materials. As such, green synthesis is regarded as an important tool to reduce the destructive effects associated with the traditional methods of synthesis for nanoparticles commonly utilized in laboratory and industry. In this review, we summarized the fundamental processes and mechanisms of “green” synthesis approaches, especially for metal and metal oxide [e.g., gold (Au), silver (Ag), copper oxide (CuO), and zinc oxide (ZnO)] nanoparticles using natural extracts. Importantly, we explored the role of biological components, essential phytochemicals (e.g., flavonoids, alkaloids, terpenoids, amides, and aldehydes) as reducing agents and solvent systems. The stability/toxicity of nanoparticles and the associated surface engineering techniques for achieving biocompatibility are also discussed. Finally, we covered applications of such synthesized products to environmental remediation in terms of antimicrobial activity, catalytic activity, removal of pollutants dyes, and heavy metal ion sensing.

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‘Green’ synthesis of metals and their oxide nanoparticles: applications for environmental remediation

In this paper, the morphological transformations in Hibiscus sabdariffa (Roselle) stem fibre on graft copolymerisation with acrylonitrile (AN) as principal monomer and its binary mixture with 2–vinyl pyridine (2–VP), styrene (Sty), and butyl acrylate (BA), using a ceric ammonium nitrate–nitric acid initiator system, are reported. Different reaction parameters, such as temperature, time, initiator concentration, monomer concentration, and pH, have been optimised. The graft copolymers were characterised by FTIR, SEM, XRD, TGA, and DTA techniques. The percentage crystallinity and crystallinity index were found to decrease with increase in percentage grafting. The swelling behaviour of graft copolymers in methanol, n-butanol, water, and dimethylformamide was studied, and screening for dye uptake behaviour in 0.1% gentian violet dye over a 7 h was carried out. The graft copolymers were found to possess moisture, chemical, and thermal resistance. These graft copolymers could be utilised for various advanced applications.

Evaluation of the Morphological Transformations in Novel Graft Copolymers Obtained from Hibiscus Sabdariffa (Roselle) Stem Fibre

Reactions of isothiocyanates with n-acyl-o-alkylhydroxylamines and benzyloxyamine

The use of synthetic glass fiber as reinforcement is hazardous and its degradation is not easy, although these composites are useful for various applications. Hibiscus sabdariffa (Sorrel) has high (73.9%) cellulose content, tensile strength, and is present in abundance in nature through-out the world, but it is fragile and weather prone, that can be improved by graft copolymerization. Sorrel stem fiber was graft copolymerized with binary vinyl monomeric mixtures that transformed the properties and behavior of the fiber. These physico-chemico-thermally resistant graft co-polymers were then used as reinforcement in phenol-formaldehyde polymer matrix, and subjected to characterization and evaluation by advanced technique. Mechanical potential such as tensile strength, compressive strength, wear resistance, modulus of elasticity, modulus of rupture, stress at the limit of proportionality and hardness were screened to compare the change with the phenoplast. These fibers reinforced bio-composites exhibited physicochemico- thermal resistance and improved mechanical strength for better scientific and industrial applications. The graft copolymerization of waste biomass caused transformation in the properties of the fiber, and made it useful for reinforcement in polymer matrix that improved its bioremediation and biodegradation

Fabrication and Physico-chemico-thermo-echanical Accreditation of Green Composite

Present investigation deals with the modification of biopolymer to improve physio-chemical and thermal properties. In air synthesis of graft copolymers of soy protein concentrate (SPC) with vinyl monomer mixtures of ethylmethacrylate (EMA) with methylmethacrylate (MMA), methylacrylate (MA) and ethylacrylate (EA) was carried-out using ascorbic acid/ potassium persulphate (AAc/ KPS) redox initiator system. Graft copolymers formed were characterized using techniques like FTIR, SEM and XRD. Initial optimization of different reaction parameters was carried out for graft copolymerization of principal monomer EMA onto soy protein concentrate to get maximum graft yield (134.12%). The maximum graft yields with binary monomer mixtures; EMA+MMA, EMA+EA and EMA+MA were 120.54%, 142.38% and 293.58%, respectively. The graft copolymers were studied for thermal stability and were found to show high thermal stability. Modified protein was found to show improved chemical resistance toward acid and base. Moreover, grafted protein also showed enhanced moisture retardance.

/pdf/evaluation-of-physio-chemical-and-thermal-properties-of-soy-43qslevr7g.pdf

Balbir Singh Kaith

Papers

Evaluation of the Morphological Transformations in Novel Graft Copolymers Obtained from Hibiscus Sabdariffa (Roselle) Stem Fibre

Reactions of isothiocyanates with n-acyl-o-alkylhydroxylamines and benzyloxyamine

Fabrication and Physico-chemico-thermo-echanical Accreditation of Green Composite

Evaluation of Physio-chemical and Thermal properties of Soy Protein Concentrate and Different Binary Mixtures Based Graft Copolymers

Synthesis of biodegradable composites from peanuts using resorcinol-formaldehyde as crosslinker.