Mahuya Das

Bio: Mahuya Das is an academic researcher from JIS College of Engineering. The author has contributed to research in topics: Silver nanoparticle & Natural fiber. The author has an hindex of 13, co-authored 28 publications receiving 568 citations. Previous affiliations of Mahuya Das include Indian Institute of Engineering Science and Technology, Shibpur & University of Calcutta.

Influence of alkali treatment on the fine structure and morphology of bamboo fibers

Abstract: Bamboo fibers in the form of strips and dust were treated with NaOH solution of varying concentration (10, 15, and 20%). These treated and untreated samples were then subjected to FTIR and morphological studies. Again XRD study was carried out on those treated and untreated bamboo samples in both strip and dust form. It was found that during alkali treatment a lattice transformation from cellulose-I to cellulose-II took place. It is observed from IR index value that the conversion is maximum in between 15 and 20% of alkali treatment. Swelling in NaOH introduces considerable changes in crystallinity, orientation angle, etc. Degree of crystallinity and crystallinity index for bamboo strips increases with increasing treatment concentration of alkali and falls off after 15% alkali concentration. This is also supported by d-spacing value. Orientation factor fx was calculated from the FWHM and it was found that fx value has been increased from 0.9879 to 0.9915 for 15% alkali treated and again lowered to 0.8522 for 50% alkali treated samples. Same observation of X-ray study was obtained for dust samples but at an earlier concentration. Morphological study of bamboo dust with scanning electron microscope indicates fibrillation at higher alkali concentration. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5050–5056, 2006

Evaluation of improvement of physical and mechanical properties of bamboo fibers due to alkali treatment

Abstract: Bamboo strips treated with caustic solutions of different concentrations, e.g., 5%, 10%, 15%, 20%, 25%, and 50%, were subjected to mechanical testing giving stresses on tensile strength, percent elongation at break, flexural strength, flexural modulus, and toughness. The change in average density was −15%, and the weight loss value shows a maximum of 21.94% at 50% alkali treatment. The mechanical properties of bamboo strips increase steadily with increasing concentration of caustic soda, showing a comparable increased value at 15 and 20%, and then exhibiting a gradual fall. The percent elongation at break corroborates these observations showing a continuous decreasing trend. The properties under investigation exhibit a clear transition in between 15 and 20% alkali concentration. The morphology of strips was studied by scanning electron microscope and polarizing light microscope. The crystal structure of both untreated and treated strips was compared by XRD analysis. In both cases, the breakdown of the crystal structures of the cellulose fibers and the recrystallization or reorientation of the degraded chains that are devoid of hemicellulose are quite apparent. However, at a very high concentration (to the extent of 25%) the breakdown of structure predominates much more over the reorientation or recrystallization. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Green synthesis of antibacterial and antifungal silver nanoparticles using Citrus limetta peel extract: Experimental and theoretical studies

Abstract: Process byproducts of the fruit industry may represent an inexpensive and reliable source of green reducing and capping agents to be applied in current bio-nano synthesis. This study reports a novel method of one pot green synthesis of silver nanoparticles (AgNPs) from the Citrus limetta peel extract (CPE). UV–vis spectrophotometry, dynamic light scattering (DLS) and transmission electron microscopy (TEM) studies confirmed synthesis of AgNPs of average size 18 nm, which were stable up to 120 days. FTIR study suggested that alcoholic groups of CPE mainly responsible for the stabilization of AgNPs. Theoretical simulation using Density Functional Theory (DFT) indicated that among different alcoholic compounds of CPE, 3-allyl-6-methoxy phenol showed the highest interaction energy (128.49 KJ/mole) with AgNPs, and is mainly responsible for stabilization of the latter. The synthesized AgNPs have both antibacterial (Micrococcus luteus, Streptococcus mutans, Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli) and antifungal (candida species) activities with potent anti-biofilm and cell membrane permeabilization ability. These nanoparticles have superior antimicrobial potency than earlier reports specially against topical pathogens. Therefore, these AgNPs can be an effective alternative in pharmaceutical industries against topical pathogens.

Effects of mercerization of bamboo strips on mechanical properties of unidirectional bamboo–novolac composites

Abstract: Bamboo strip reinforced novolac resin composites were fabricated using bamboo strips that were treated with varying concentrations of sodium hydroxide solution at a constant filler loading (25%). The mechanical properties of various composites (flexural modulus, toughness, tensile strength, and elastic modulus) were determined. The physical characteristics, such as the wetting ability of the alkali treated reinforcements, were increased because of alkali treatment. With increasing concentrations of alkali, a higher percent loss in weight occurred. The mechanical properties were increased with increasing mercerizing strength. Maximum improvement in properties was achieved with 16–20% of caustic treated reinforcements. An FTIR study indicated aryl alkyl ether formation with OH groups of cellulose and methylol groups of novolac resin. Beyond 20% there was degradation in all strength properties because of the failure in the mechanical properties of the reinforcements. A correlation was found to exist between the mechanical properties and the developed morphology. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:238–244, 2006

The Effect of Alkalization and Fiber Loading on the Mechanical Properties of Bamboo Fiber Composites, Part 1: -Polyester Resin Matrix

Abstract: Bamboo strips [10 cm × 1.5 cm × (1−1.5) mm] were treated with caustic solutions for 1 h at different concentrations e.g., 0, 10, 15, 20, and 25%. Bamboo strips reinforced polyester resin composites were fabricated by hand-lay-up technique using both alkali-treated and untreated bamboo strips, using a room temperature curing system for the polyester resin. This study aims at the evaluation of the influence of caustic concentration on the mechanical properties of bamboo strips reinforced polyester resin composites at a constant 50% loading of reinforcement. Maximum improvement in property was achieved possibly with 20% of caustic treated strip reinforcements. Beyond 20%, there was degradation in all the strength properties because of failure in mechanical properties of the reinforcements itself. The effect of fiber loading variation upon mechanical properties was also studied. It was observed that superior mechanical properties were obtained with 60% filler loading. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Recent Developments in Chemical Modification and Characterization of Natural Fiber-Reinforced Composites

Abstract: A critical review of the literature on the various aspects of natural fibers and biocomposites with a particular reference to chemical modifications is presented in this paper. A notable disadvantage of natural fibers is their polarity which makes it incompatible with hydrophobic matrix. This incompatibility results in poor interfacial bonding between the fibers and the matrix. This in turn leads to impaired mechanical properties of the composites. This defect can be remedied by chemical modification of fibers so as to make it less hydrophilic. This paper reviews the latest trends in chemical modifications and characterizations of natural fibers. The structure and properties of natural fibers have been discussed. Common chemical modifications and their mechanisms have also been elaborated. The importance of chemical modifications and the resultant enhancement in the properties of the composites have also been reviewed. Recent investigations dealing with chemical modifications of natural fiber-reinforced composites have also been cited. POLYM. COMPOS., 29:187‐