Jitendra K. Pandey

Cellulose nano whiskers from grass of Korea

Polymer composites form a fascinating interdisciplinary area by bringing together biology and material science for wide verity of applications ranging from construction to biomedical technology. A deliberate interest in the development of eco-friendly material motivated the efforts toward research on cellulose composites due to its cheap, sustainable, recyclable, degradable nature and remarkable reinforcing properties at 167.5 GPa of Young’s modulus along the chain axis per theoretical estimations. The use of natural fiber for technical applications like automobile industry is restricted due to its incompatibility with generally hydrophobic host matrix and increase in weight of resulting products which provide a poor cost performance ratio. After resolving the incompatibility issues up to a satisfactory extent by adequate modification either in host or filler, it was assumed that dispersion and material properties may be enhanced with reduction in the size and increase in surface area by introducing nano fillers. Nano size (5-20 nm cross sections with length to several μm depending on source) rod like cellulose crystallites particles, known as cellulose nano whiskers (CNW), can be extracted from laterally stabilized fibrils bundle by removing amorphous region through controlled acid hydrolysis. These whiskers have been employed in reinforcing several polymers, which result in comparatively better mechanical properties. Nevertheless, such fibers have conquered many obstacles against industrial practices due to time consuming preparation procedure with very low yield, commercial unavailability, and most importantly, comparative higher cost through expensive source such as tunicate, bacterial, algal (valonia), brown algae (Oomycota) and commercially available microcrystalline cellulose. The low yield and availability of raw materials of these sources generally inhibit the penetration of this tremendous reinforcer for the development of daily use biodegradable products. The current attempt was made to obtain the cellulose nano whiskers from the cheapest source, grass of Koera for the first time, which may further broaden the use of these bio fillers ranging from commodity to constructive applications.

Mechanical Properties and Sound Insulation Effect of ABS/Carbon-black Composites

This article describes an evaluation of the mechanical properties and sound insulation effects of composites made of acrylonitrile butadiene styrene (ABS) and carbon-black using the design of experiment (DOE) approach. The solution blending process and method are presented. The effect of the acetone content in ABS during the drying process was studied by conducting tensile tests of injection-molded specimens. ABS was dissolved in acetone, and carbon-black was dispersed in the ABS/acetone mixture with varying conditions according to the orthogonal array table used to reduce similar experiments. The tensile specimens were produced by injection molding in each of the DOE cases, and the elastic modulus and maximum tensile strength of ABS/carbon-black composites were evaluated with a tensile test to determine the main effects of those factors. A sound insulation test was conducted with a modified impedance tube by using the DOE orthogonal array table, and a correlation between carbon-black and the sound insulation was revealed by a main effect analysis. An additional sound insulation test was conducted to verify the sound insulation effect of ABS/carbon-black composites as a function of the carbon-black percentage. The results indicate that the increase of carbon-black affected the mechanical properties as well as the sound insulation effects of ABS/carbon-black composite.

Evaluation of morphological architecture of cellulose chains in grass during conversion from macro to nano dimensions

Abstract The cellulose nanowhiskers (CNW) are of imminent importance in the development of ecofriendly green material for environment. Morphological study of their structure was carried out after extraction from grass. The controlled alkali and acid hydrolysis after soxhlet extraction of bleached fiber in ethanol and water provided a mixture of micro/nano fiber which can be further converted into CNW by mechanical treatment. Width of obtained CNW were found to be ~10-65 nm with length of several nanometers as evidenced by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The changes in dimensions during alkali treatment, bleaching and acid hydrolysis of grass exhibited an interesting architecture and clarify the phenomenon of separation of nano level fibrils from the matrix of hemicellulose and lignin which starts after swelling of fibers and opening from middle followed by splitting from each other. The nanofibers were embedded in the matrix surrounded by amorphous layers. The size of fibers was directly associated with the extent of treatments. The crystalline part of fiber was intact during hydrolysis which must be attributed to easy removal of amorphous region by penetration of hydronum ions from acid. The results of SEM and TEM were correlated with the Scanning Ion Microscopy (SIM) which showed a direct evidence of breaking of thick fiber strands resulting in the formation of sharp edged crystalline entities composed of cellulose crystals.

Preparation and structural evaluation of nano reinforced composites from cellulose whiskers of grass and biodegradable polymer matrix

Biocomposites of polylactic acid with cellulose whiskers from grass were prepared and reinforced with nanolayer-filled ionomer (Surlyn®). Three types of polymer composites were fabricated by filling the whiskers in polylactic acid at 5, 10, and 15% concentration. The analysis of resulting products was conducted by monitoring the functional group variation, crystallinity, and thermal behavior. The addition of clay-filled ionomer appeared to enhance the interfacial adhesion between filler and matrix by chemical and physical bonding. The migration tendency of different components inside silicate layers was also studied where the confinement of host polymer chains occurred between clay platelets, after modification through ionomer.

SURFACE MODIFICATION OF POLYETHYLENE (PE) BY THE DEPOSITION OF TITANIUM DIOXIDE (TiO2) NANOPARTICLES TO ENHANCE THE PHOTOCATALYTIC ACTIVITIES

In recent years, there has been growing interest in the preparation of TiO2-deposited materials for the application in different fields of photocatalytic activities, such as photocatalysis, dye-sensitized solar cells, antireflective coatings, and electro-chromic devices. TiO2 particles were deposited on the PE surface by spraying method at room temperature. The deposition analysis was conducted by atomic force microscopy (AFM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (FE-SEM) for monitoring the variation in morphology and different properties. It was found that the surface was deposited uniformly with higher concentration of particles and did not affect the inherent properties of polymers. The deposited TiO2 particles favor the photodegradation of synthetic nonbiodegradable polymeric materials, which will ultimately decompose in the environment.

SELF HEALING POTENTIAL OF GREEN NANOCOMPOSITES FROM CRYSTALLINE CELLULOSE

In plant cell walls, stiff semicrystalline nano dimensional cellulose microfibrils are embedded in a pliable amorphous matrix where the size and shape of the cellulose fibrils are controlled by the dimensions of crystalline regions, providing them a unique structural and physical combination to be applied as load-bearing constituent in composites. The qualities such as specific orientation under magnetic field, extraction through simple process, abundantly available source from nature and desirable modifications have deliberately directed the intense research efforts in a number of disciplines ranging from commodity to higher applications, not only in the area of high performance polymer based composites but also to develop biosensors, magnetic strips and optical devices. The present work is focused on the use of cellulose nano-fillers for creating the self-healing function and their effect on material properties of resulting composites. The present work is in initial stage and reviews the use of cellulose nano-fillers for creating the self-healing function and their effect on material properties of resulting composites.

Dispersion of Nanocellulose (NC) in Polypropylene (PP) and Polyethylene (PE) Matrix

PP and PE are considered as environmental polluter mainly because of their greater resistance toward biological degradation in the environment upon disposal. Although this property contributes to their popularity for development of medical devices, still the repercussions of PP and PE litter create a serious threat for chocking of water ways, sewage pipes, etc. Since one of the main objectives to use NC as reinforcer for polymer matrixes is to develop environmentally friendly composites, it is essential to review the potential of NC-based PP and PE composites as environment friendly natural nanofiller. Highly crystalline nature, aspect ratio, well-established extraction processes, renewability, and sustainability of NC make it one of the best nanofillers to improve the material properties of different hydrophilic polymer. The mechanical performance of resulting hybrids is mainly governed by the proper dispersion of NC inside polymer. Because of their highly hydrophilic nature, it is always a challenge to mix NC with hydrophobic polymer matrixes such as PP and PE. The present chapter is aimed to discuss the dispersion of NC in PP and PE matrix and associated challenges with brief description of possible solutions and future direction.

Cellulose nanofiber assisted deposition of titanium dioxide on fluorine-doped tin oxide glass

Microspores, highly ordered, 300–340 nm thick blocks of titanium dioxide (TiO2) nanoparticles (5–10 nm) were deposited on fluorine-doped tin oxide (FTO) glass by using low concentration of cellulose nanofibers from bacterial origin, through sol–gel process followed by spin coating.

The Processing and Mechanical Performance of Cellulose Nanofiber-based Composites

Nanocomposites based on cellulose nanofibers have been studied for a considerable time since its first introduction, however real applications seem to have hardly developed to these days. The high-strength of cellulose nanofibers suggests the potential to reinforce plastics to produce composites for semi-structural or even structural applications. This paper discusses some of the attempts to produce such high-strength nanocomposites and the main challenges that have to be overcome to bring them into commercial products.

Bionanocomposites of Grass

Cellulose nano whiskers (CNW) are recently known for their tremendous applicability in development of eco-friendly material for various applications. Present attempt was aimed to extract the nano crystals of cellulose from grass of Korea and fabricate the composites with poly (lactic acid) in presence of compatibilizer after modification. Functional group variation, thermal behavior, surface morphology, and crystallinity were monitored by FT-IR, TGA, SEM, and XRD respectively. The water sensitivity measurements were also carried out for study of moisture resistance of composites. It was found that CNW have lower thermal stability than alkali treated long fiber whereas the crystalline nature of composites decreased significantly. The effect of modification of whiskers on the mechanical properties was also discussed in which increase in modulus was observed.