Rashmi R. Devi

Chemical modification of rubber wood with styrene in combination with a crosslinker: effect on dimensional stability and strength property

Chemical modification of rubber wood (Hevea Brasiliensis) was carried out by impregnating the wood with styrene and in combination with a crosslinker Glycidyl Methacrylate (GMA). Polymerization was carried out by catalyst heat treatment. The dimensional stability in terms of % volumetric swelling and anti-shrink efficiency was determined and found to be improved on treatment. Water absorption was also found to be decreased considerably for treated wood samples. Mechanical strength of the treated samples in terms of modulus of rupture and modulus of elasticity were also found to be improved. The wood polymer interaction was confirmed by FT-IR spectroscopy. Biodegradability of the wood/polymer composites was determined and found to be improved on treatment with styrene/styrene-GMA.

Chemical modification of simul wood with styrene–acrylonitrile copolymer and organically modified nanoclay

Simul wood (Salmalia malabarica) was chemically modified by treatment with styrene–acrylonitrile copolymer (SAN), glycidyl methacrylate (GMA), and organically modified nanoclay. The physical properties of wood polymer composites (WPC) were improved due to the addition of GMA and nanoclay. XRD analysis indicated a decrease in crystallinity in WPC. FTIR study confirmed the presence of clay in WPC. The presence of clay in cell lumen and cell wall was evidenced by SEM study. WPC containing lower percentage of clay showed better thermal stability compared to WPC loaded with higher percentage of clay.

Nano rod-shaped and reusable basic Al2O3 catalyst for N-formylation of amines under solvent-free conditions: A novel, practical and convenient ‘NOSE’ approach

An expeditious, simple, highly efficient, practical and green protocol for the N-formylation of alkyl/aryl amines and indole derivatives catalyzed by novel nano rod-shaped basic Al2O3 under solvent-free conditions has been developed. The catalyst is efficiently recycled up to the 5th run, an important point in the domain of green chemistry. The methodology provides cleaner conversion, shorter reaction times and high selectivity which makes the protocol attractive.

Defluoridation of water using nano-magnesium oxide

Nano-sized magnesium oxide (nano-MgO) was investigated for adsorption of fluoride from water. The pure and fluoride adsorbed nano-MgO were characterised by Brunauer–Emmett–Teller, high resolution transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray analyses. The surface area of the adsorbent was found to be 92.46 m2/g. Maximum (90%) fluoride removal was obtained with 0.6 g/L dosage of nano-MgO. Fluoride adsorption by nano-MgO was found to be less sensitive to pH variations. Fluoride sorption was mainly influenced by the presence of OH− ion. The presence of other ions studied did not affect the fluoride adsorption capacity of nano-MgO significantly. It has been observed that Freundlich model was better fitted as compared to Langmuir model which indicated the multilayer adsorption of the adsorbent following a pseudo-second order kinetics. Regeneration study showed that 1 M HCl was the best eluent with 95% desorption capacity towards fluoride removal followed by NaOH (2 M) with 25% regeneration of the adsorbent.

CuO nanorods: a potential and efficient adsorbent in water purification

The present work deals with a simple in situ soft chemical synthesis of nanoscale copper(II) oxide, together with its characterization and a study of the adsorption and desorption behaviors of Pb(II) on nanoscale CuO. The nanoparticles are characterized by XRD, FESEM, TEM and BET surface area analyses. Electron microscopy clearly reveals a rod-like morphology of rhombohedral CuO, with an average diameter of ∼5 nm and a length extending up to 50 nm. BET shows the average surface area of the nanorods to be ∼52.57 m2 g−1. In an adsorption study, the influence of operational conditions, such as the contact time, the initial concentration of Pb(II), the initial pH of the solution and the temperature, on the adsorption of Pb(II) has also been examined. Studies also reveal that the uptake of Pb(II) onto CuO is a fast process; >70% of the uptake occurred within the first 10 min of contact time and uptake reached >92% within 60 min. The maximum sorption capacity of Pb(II) is 3.31 mg g−1 at 298 K. The +ve ΔS° value and the +ve ΔH° value of 37.77 kJ mol−1 indicate the endothermic nature of the adsorption process, whereas a decrease of Gibbs free energy (ΔG°) with increasing temperature indicates the spontaneous nature of the adsorption process. The adsorbent can be up to 84.1% regenerated using dilute acid and shows potential for the removal of lead from contaminated water.

Physical properties of simul (red-silk cotton) wood (Bombax ceiba L.) chemically modified with styrene acrylonitrile co-polymer and nanoclay

Abstract Wood plastic composites have been prepared based on simul wood (Bombax ceiba L.), which was vacuum impregnated with the styrene acrylonitrile (SAN) co-polymer nanoclay (nnc) intercalating system in the presence of glycidyl methacrylate (GMA), a crosslinking agent. The impact of nanoclay was investigated on the mechanical, thermal, dynamic mechanical behavior, and the biodegradability of the resultant wood polymer nanocomposite (WPCnnc) was investigated. The tensile strength, tensile modulus, flexural strength, and flexural modulus of the composite were relatively higher in the presence of 2 phr nanoclay. The limiting oxygen index values showed self-extinguishing behavior of the WPCnnc. Furthermore, the storage moduli (E′) and damping index (tan δ) of these products were high. WPCSAN/GMA/nnc exhibit higher biodegradability compared to WPCSAN/GMA.

In situ polymerized wood polymer composite: effect of additives and nanoclay on the thermal, mechanical properties

This study concerns the preparation and characterization of wood polymer nanocomposites based on impregnation of styrene acrylonitrile co-polymer-nanoclay intercalating system in presence of glycidyl methacrylate (GMA), a cross linking agent, and vinyl trichloro silane (VTCS) as additives into Simul (Bombex ceiba, L.), a soft wood. The effect of nanoclay and VTCS on the properties of the resultant wood polymer nanocomposites (WPNC) has been evaluated. FTIR spectroscopy shows the interaction among wood, polymers, GMA, nanoclay and VTCS. The penetration of polymer and nanoclay into the wood cell wall is supported by SEM study. The distribution of nanoclay in the SAN polymer matrix present within the wood cell wall has been evidenced by TEM study. TGA results show an improvement in the thermostability of the resultant composites. The inclusion of VTCS enhances the self extinguishing behaviour of the WPNC as revealed by limiting oxygen index (LOI) test. Due to treatment, the resultant WPNC exhibits an improvement in all the properties like water repellancy, dimensional stability, hardness, flexural, tensile and thermal stability compared to untreated wood.

Studies of properties of rubber wood with impregnation of polymer

Impregnation of rubber wood has been carried out under different conditions by using styrene as grafting monomer and glycidyl methacrylate (GMA) as crosslinker. Properties such as dimensional stability, water absorption, hardness, tensile strength, flexural strength, etc of the impregnated wood have been checked and found to be improved by incorporation of GMA as the crosslinker with styrene. The polymerimpregnated wood has also been characterized by FTIR spectroscopy and DSC.

Effect of nano-SiO2 on properties of wood/polymer/clay nanocomposites

Wood polymer nanocomposites (WPNC) based on nano-SiO2 were prepared by impregnation of styrene acrylonitrile copolymer (SAN), SiO2 nanoparticles modified with γ-trimethoxy silyl propyl methacrylate (MSMA), and nanoclay into wood. The structure of modified SiO2 nanoparticles and WPNC was characterized by Fourier transform infrared spectroscopy (FTIR). XRD analysis showed the delaminated structure of SAN/SiO2/clay-treated wood composites. The synergistic effect of nano-SiO2 and nanoclay was investigated. Thermal stability of SiO2 nanoparticles decreased after modification, while that of wood treated with SAN, SiO2, and nanoclay improved. Morphological characteristics were examined by scanning electron microscopy (SEM). Mechanical properties, water uptake (%), dimensional stability, hardness, and flammability were found to improve due to incorporation of SiO2 and nanoclay into wood polymer composites. Maximum improvement in properties was observed in the wood polymer composites containing SiO2 and nanoclay at the ratio of 1:1.

Studies on properties of softwood (Ficus hispida)/PMMA nanocomposites reinforced with polymerizable surfactant-modified nanoclay

Soft wood (Ficus hispida) was chemically modified by impregnation of methyl methacrylate monomer, glycidyl methacrylate (GMA), a cross-linking agent, and montmorillonite (MMT) using catalyst heat treatment. MMT was modified by using a polymerizable surfactant 2-acryloloxy ethyl trimethyl ammonium chloride (ATAC) and a mixture of surfactants ATAC and cetyl trimethyl ammonium bromide (CTAB) in a molar ratio of (1:1). A comparative study on different properties of the prepared wood polymer nanocomposite (WPNC) based on impregnation of intercalating mixture containing MMA/GMA/clay modified by both the surfactants (ATAC and CTAB) and MMA/GMA/clay modified by only surfactant ATAC were done. FTIR, XRD, and TGA studies were employed for the characterization of clay and WPNC. WPNC prepared by using combined surfactant-modified clay along with MMA/GMA exhibited improved dimensional stability, chemical resistance, thermal stability, mechanical properties, and lower water uptake than that of WPNC prepared by using single surfactant-modified clay and MMA/GMA system.