Satyendra Mishra

The compatibilising effect of maleic anhydride on swelling and mechanical properties of plant-fiber-reinforced novolac composites

In the present work, fibers of banana, hemp and sisal are used as fillers in novolac resin. These fibers have been esterified with maleic anhydride and the effect of maleic anhydride on the swelling and mechanical properties of plant fiber polymer composites has been assessed. Higher absorption of steam and water is observed in untreated fiber composites. The Youngs modulus increases with increase in fiber content up to 45 and 50% in untreated and MA treated fiber composites, respectively. The impact strength and Shore-D hardness have been found to be higher in maleic-anhydride-treated fiber composites than the untreated-fiber composites.

Absorption of Water at Ambient Temperature and Steam in Wood-Polymer Composites Prepared from Agrowaste and Polystyrene

Hemp, banana, and agave fibers were employed for the preparation of wood-polymer composites using polystyrene in the ratio of 50 : 50 w/w. These fibers were esterified with maleic anhydride (MA) and the effect of MA was studied on the absorption of water at ambient temperature and steam in wood-polymer composites made from said fibers and polystyrene. The absorption of water increases with increase in time from 2 to 30 h in all fiber composites. The maximum absorption of water was found in hemp fiber composites, and the minimum in agave fiber composites. The MA- esterified fiber composites showed less absorption of water than did the untreated fiber composites. Steam absorption in MA-treated and untreated fiber composites is higher than the water absorption in the respective fiber composites. Untreated fiber com- posites show more absorption of steam in comparison to MA-treated fibers composites. q 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 681-686, 1998

Effect of maleic anhydride treatment on steam and water absorption of wood polymer composites prepared from wheat straw, cane bagasse, and teak wood sawdust using Novolac as matrix

Wheat straw, cane bagasse, and teak sawdust (agrowaste) were sieved up to a 425-μm mesh size and employed for sheet preparation with and without maleic anhydride (MA) treatment using Novolac resin in a 50 : 50 (w/w) ratio. The shore D hardness of MA treated and untreated wood polymer composites (WPCs) was measured. The MA treated WPCs showed 2–3 times more hardness than that of the untreated respective WPCs. Moisture absorption had a detrimental effect on the mechanical properties of the WPCs. MA treatment restricted swelling and water and steam absorption in the agrowaste. Teak sawdust showed the best results in all respects among the three WPCs.

Ultrasound assisted synthesis of polyacrylic acid–nanoclay nanocomposite and its application in sonosorption studies of malachite green dye

Synthesis of nanoclay nanocomposite has been undertaken by using polyacryalic acid (PAA) in aqueous medium and ultrasound environment and its application in dye removal has been investigated. The synthesized product was characterized by using FTIR and XRD techniques. The sonosorption capacity of the product namely PAA-nanoclay composite was determined by choosing malachite green (MG) dye as a model pollutant. The effects of various parameters such as nanocomposite loading, pH, various process conditions etc. have been studied. On comparing the results obtained with that of nanoclay as an adsorbent, it was found for an initial concentration of 500mg/l, the PAA-nanoclay nanocomposite exhibited higher percentage of pollutant removal (68%) and for nanoclay it was 54%. The adsorption data has been correlated using Langmuir and Freundlich models. The fit of the Freundlich isotherm model was found to be good in the entire range of concentration for the experimental sorption data obtained on the nanoclay nanocomposite. A plausible reaction mechanism for use of PAA-nanoclay nanocomposite as an adsorbent is also proposed.

Absorption of steam and water at ambient temperature in wood polymer composites prepared from agro‐waste and Novolac

Banana (Musa paradisica), Hemp (Hibiscus cannabinus), and Agave (Agave jourcroydes) fibers were treated with Novolac resin for the formation of their composites in the ratio of 50: 50 (wt/wt). These fibers were also treated with maleic anhydride, and it was found that composites based on treated fibers showed higher absorption of steam ( at 100°C) up to 12 h; and beyond 18 h, it is less than the untreated fiber composites. However, at ambient temperature, the absorption of water is lesser for composites based on maleic anhydride-treated fiber than for composites based on untreated fibers. The SHORE-D hardness was commonly higher for composites based on maleic-anhydride-treated fibers.

Synthesis and sensing applications of polyaniline nanocomposites: a review

A comprehensive review on the synthesis of PANI nanocomposites and their applications as gas sensors and biosensors has been presented. The multi-functionality of PANI nanocomposites have been extensively exploited in diverse applications with impressive results. The synergistic effects between the constituents have made these materials particularly attractive as sensing elements for gases and biological agents. Not only do PANI nanocomposites allow room temperature sensing of a large number of combustible or toxic gases and pollutants with high selectivity and sensitivity, they also enable immobilization of bioreceptors such as enzymes, antigen–antibodies, and nucleic acids onto their surfaces for detection of an array of biological agents through a combination of biochemical and electrochemical reactions. Efforts are on towards understanding the working mechanism of PANI nanocomposites which will increase their potential fields of applications.

Effect of Treatment of Maleic Anhydride on Mechanical Properties of Natural Fiber: Polystyrene Composites

Abstract: In the present work, banana, hemp, and sisal fibers are employed as fillers for the formation of natural fiber:polystyrene composites in the ratios of 55:45, 50:50, 45:55, and 40:60 (wt/wt). The natural fibers were treated with maleic anhydride. The Youngs modulus, flexural modulus, impact strength, and Shore-D hardness all decreased with increasing amounts of fibers in the natural fiber:polystyrene composites. The sisal fiber composites show the highest mechanical strength for all ratios. A maleic anhydride treatment shows significant improvement in Youngs modulus, flexural modulus, impact strength, and Shore-D hardness compared with the untreated fiber composites.

Studies on dynamic and static crosslinking of ethylene vinyl acetate and ethylene propylene diene tercopolymer blends

The effect of blend ratio on the crosslinking characteristics of ethylene vinyl acetate and ethylene propylene diene tercopolymer (EVA-EPDM) blends was studied by differential scanning calorimetry and a torque rheometer (Rheocord-90). The activation energy decreases with an increase in EVA content in the blend. The cure rate increases whereas the optimum cure time and energy consumption for curing decrease with an increase in the EVA/EPDM ratio. The dynamic curing obtained by the torque rheometer is very fast compared to the static curing obtained by differential scanning calorimetry.

Preparation, Characterization and Properties of Poly(vinyl chloride)/CaSO4 Nanocomposites

Poly(vinyl chloride)/CaSO4 nanocomposites were prepared on Brabender plasticorder. Moreover, for comparison PVC/ commercial CaSO4 composites was prepared. The amount of loadings of nano CaSO4 and commercial CaSO4 was in the range of 0–12 wt%. Nano CaSO4 was synthesized by matrix-mediated growth technique. The size and shape of nano CaSO4 were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). These PVC nanocomposites were then subjected to mechanical, thermal analysis on UTM, and TGA respectively. Morphology studies of PVC nanocomposites were done on scanning electron microscope (SEM). The morphology study showed that nano CaSO4 get exfoliated and intercalated with the PVC matrix. Notched Charpy impact strengths of PVC nanocomposites was drastically improved compared to that of pristine PVC and commercial CaSO4 composites. PVC/CaSO4 nanocomposites showed higher values of tensile strength, elongation at break and impact strength than PVC/CaSO4 (commercial) composites. Impact strengths also gives some drastic dependence on nano CaSO4 content and give a maximum value at certain CaSO4 loadings.

Studies on Mechanical, Thermal, and Flame Retarding Properties of Polybutadiene Rubber (PBR) Nanocomposites

An effect of nanosize CaCO3 on physical, mechanical, thermal and flame retarding properties of PBR was compared with commercial CaCO3 and fly ash filled PBR. CaCO3 at the rate of 9, 15, and 21 nm were added in polybutadiene rubber (PBR) at 4, 8 and 12 wt.% separately. Properties such as swelling index, specific gravity, tensile strength, Youngs modulus, elongation at break, modulus at 300% elongation, glass transition temperature, decomposition temperature, flame retardency, hardness, and abrasion resistances were determined. The swelling index decreased and specific gravity increased with reduction in particle size of fillers in PBR composites. There was significant improvement in physical, mechanical, thermal and flame-retarding properties of PBR composites due to a reduction in the particle size of fillers. Maximum improvement in mechanical and flame retarding properties was observed at 8 wt.% of filler loading. This increment in properties was more pronounced in 9 nm size CaCO3. The results were not appreciable above 8 wt.% loading of nano fillers because of agglomeration of nanoparticles. In addition, an attempt was made to consider some thermodynamically aspects of resulting system. The cross-linkage density has been assessed by Flory-Rehner equation in which free energy was increased with increase in filler content.