Vinay Kumar Singh

Silica—Styrene—Butadiene Rubber Filled Hybrid Composites: Experimental Characterization and Modeling

The mechanical behavior of epoxy matrix composites filled with nanosized silica particles and styrenebutadiene rubber is discussed. Scanning electron microscopy analysis and tensile test carried out at different crosshead speeds on the silicastyrenebutadiene rubber epoxy nanocomposites indicated the absence of particle aggregation and a reinforcing effect in terms of increased elastic modulus, yield, and ultimate strength. The results of wear test in pin-on-disc mode and hardness test on Rockwell R scale showed that the nanosized silica particles could improve the wear resistance of the epoxy matrix even though the content of the filler is at a relatively low level (1.02.0 wt%). This makes it possible to develop novel type of epoxy-based material with improved wear resistance for various applications. About 4070% increase in impact strength has been noticed due to addition of 0.51.5 wt% of styrenebutadiene rubber in 1.0 wt% silica-filled epoxy compos- ite. A good correlation between mechanical properties and weight contents of the filler materials, hardness and ultimate strength, and hardness and wear rate has been observed.The mechanical behavior of epoxy matrix composites filled with nanosized silica particles and styrene-butadiene rubber is discussed. Scanning electron microscopy analysis and tensile test carried out at different crosshead speeds on the silica-styrene-butadiene rubber epoxy nanocomposites indicated the absence of particle aggregation and a reinforcing effect in terms of increased elastic modulus, yield, and ultimate strength. The results of wear test in pin-on-disc mode and hardness test on Rockwell R scale showed that the nanosized silica particles could improve the wear resistance of the epoxy matrix even though the content of the filler is at a relatively low level (1.0-2.0 wt%). This makes it possible to develop novel type of epoxy-based material with improved wear resistance for various applications. About 40-70% increase in impact strength has been noticed due to addition of 0.5-1.5 wt% of styrene-butadiene rubber in 1.0 wt% silica-filled epoxy composite. A good correlation between mechanical properties and weight contents of the filler materials, hardness and ultimate strength, and hardness and wear rate has been observed.

In silico analysis of sequential, structural and functional diversity of wheat cystatins and its implication in plant defense.

Phytocystatins constitute a multigene family that regulates the activity of endogenous and/or exogenous cysteine proteinases. Cereal crops like wheat are continuously threatened by a multitude of pathogens, therefore cystatins offer to play a pivotal role in deciding the plant response. In order to study the need of having diverse specificities and activities of various cystatins, we conducted comparative analysis of six wheat cystatins (WCs) with twelve rice, seven barley, one sorghum and ten corn cystatin sequences employing different bioinformatics tools. The obtained results identified highly conserved signature sequences in all the cystatins considered. Several other motifs were also identified, based on which the sequences could be categorized into groups in congruence with the phylogenetic clustering. Homology modeling of WCs revealed 3D structural topology so well shared by other cystatins. Protein-protein interaction of WCs with papain supported the notion that functional diversity is a consequence of existing differences in amino acid residues in highly conserved as well as relatively less conserved motifs. Thus there is a significant conservation at the sequential and structural levels; however, concomitant variations maintain the functional diversity in this protein family, which constantly modulates itself to reciprocate the diversity while counteracting the cysteine proteinases.

Human Hair: A Biodegradable Composite Fiber - A Review

Biological fibers have recently became eye-catching to researchers, engineers and scientists as an alternative reinforcement for FRP (fiber reinforced polymer) composites, due to their low cost, fairly good mechanical properties and high aspect strength. One of the immaculate biological fibers is the human hair. On the whole, three to four tons of human hair fibers are wasted in India annually; hence they pose an environmental challenge. In order to find commercial application the wasted human hair fibre is nowadays finding its use in the field of material science. Human hair is basically a nano-composite biological fiber with well characterized microstructures. Different techniques and technologies have been employed to study the different characteristics of the human hair to prove it a biological composite fiber. The main component of hair is keratin which is tough, insoluble and incredibly strong. An important aspect is that a single strand of hair can withstand the load of 100-150 grams. Hair is elastic and it is capable of regaining its original position on removal of the deformation load. Therefore, the present review paper reports the current scenario of human hair as biological composite fiber and its application in various fields.

Mode I fracture toughness of bio-fiber and bio-shell particle reinforced epoxy bio-composites

The effect of bio-fibres and bio-particles on the fracture toughness has been investigated. Epoxy resin is used as matrix material and different bio-fibers such as banana fiber, bagasse fiber, coconut fiber and particles such as silica and walnut shell particle with different wt% are added as reinforcing material. The mode I fracture toughness tests are conducted in a servo hydraulic universal testing machine. The results show that the fracture toughness of bio-composites reinforced with 20u2009wt% bagasse or 10u2009wt% coconut fiber are 1.108u2009MPa √m and 1.094u2009MPa √m, respectively which are about 8% and 7% higher than neat epoxy. Addition of 2u2009wt% of silica with 20u2009wt% of bagasse shows 60% increment of fracture toughness with respect to bagasse and 72% increment with respect to neat epoxy. Hybridisation of bagasse with banana fibers shows 54% decrease in fracture toughness as compared to bagasse and 13% increase as compared to banana. The overall fracture toughness of hybrid bio-composite of 10u2009wt% coconut fiber and 20u2009wt% of walnut shell particle is 1.367u2009MPa √m which is about 25% higher than coconut fiber reinforced bio-composite.

Experimental Evaluation of Mixed Mode Stress Intensity Factor for Prediction of Crack Growth by Phoelastic Method

Determination of stress intensity factors KI, KII, and constant stress term, σox is investigated. A theory of determining the stress intensity factors using photo-elastic method is formulated taking three stress terms. Three-parameter method of fracture analysis for determining the mixed mode stress intensity factors under biaxial loading conditions from photo-elastic isochromatic fringe data is used. A special biaxial test rig is designed and fabricated for loading the specimen biaxially. A simplified and accurate method is proposed to collect the data from isochromatic fringes. Taking specimen geometry and boundary conditions into account, regression models are developed for estimation of fracture parameters.

Water absorption and thickness swelling behavior of almond (Prunus amygdalus L.) shell particles and coconut (Cocos nucifera) fiber hybrid epoxy-based biocomposite

Abstract In this research, the suitability of almond shell and coconut fiber as a renewable agricultural residue for the manufacturing of biocomposite to be used as a replacement of wood was investigated. The use of agriculture waste as a reinforcement in composite may result in several environmental and socioeconomic benefits. A biocomposite containing different weight percentages of almond shell particle (10, 20, 30, 40, and 50 wt%) and coconut fiber (2, 4, and 6 wt%) mixed with 20 wt% almond shell particles was made using epoxy resin and 0.5 wt% tricresyl phosphate. The water absorption (WA), thickness swelling (TS), and morphology [scanning electron microscopy (SEM)] test of the biocomposite were determined. The rate of WA is less in saline water (SW) compared to rainwater (RW). The influence of the addition of coconut fiber is more compared with the almond shell particles for both the WA and TS.

Effect of Specimen Geometry on Stress Intensity Factors of Inclined Crack by Finite Element Method

A rectangular plate with inclined cracks of different crack lengths at different crack inclination angles under biaxial loading condition are being analyzed in mixed mode condition using finite element method (FEM) for the determination of stress intensity factors (SIFs). With increases of the width of the plate and the crack length ratio, SIF increases up to 45° of crack inclination angle and then decreases; maximum value is obtained at 45° of crack inclination angle. With the increasing value of size factor, the value of SIF starts decreasing. The accuracy of the results of the proposed method is validated by comparing with the previously obtained results by theoretical and experimental methods. The FEM results give significant result for the two-dimensional mixed mode loading conditions.

Studies on Fracture Performance of Bio-fiber-Silica-glass Fiber Reinforced Epoxy Hybrid Composites

In the present investigation, fibers from banana stem and Bagasse are used in addition to low wt% of silica to cast bio composites. Extraction of the banana fibers, Bagasse fibers and preparation of both banana and Bagasse fibers were carried out as explained elsewhere in literature. The lengths of the fibers are kept between 180 to 425 micrometer. Composites, containing lower fiber content of Bagasse and banana (10 wt %) and higher fiber content (20 wt %) were used with silica (2 wt%) and mixed with epoxy CY 230 epoxy resin. Different mechanical properties such as tensile, compressive, impact, flexural, fracture strength etc are discussed and characterized.

PCR Recipe: A Program for Setting Up PCR Reactions

The polymerase chain reaction (PCR) is a powerful molecular biology tool that has proven to be a sensitive and specific means for detecting minute quantities of nucleotide sequences. It is a technique sensitive enough to amplify DNA fragments over a billion-fold. The generation of complete DNA-analysis and webbased software packages that design PCR primers and optimize reaction conditions. We have developed a software program for calculating how many different components of PCR mixture will need to be added to the master mix and then dispensed into the individual tubes.

Experimental investigation of chicken feather fiber and crumb rubber reformed epoxy resin hybrid composite: mechanical and microstructural characterization

Abstract In this experimental investigation, the mechanical characterization and microstructure study of chicken feather fiber (CFF) and crumb rubber filled epoxy resin hybrid composite has been done. The surface of the fibers was treated with sodium hydroxide to improve the interphase bonding. Chicken feathers were taken in different weight percentages of 1, 3, 5 and 7. A composite was fabricated with epoxy resin using the hand lay-up technique. After conducting various mechanical tests in accordance with the ASTM standards, it was observed that 5 wt% of CFF recorded the optimum results. Hybrid composites were then fabricated with 5 wt% CFF and varying weight percentages of crumb rubber, i.e. 0, 0.5, 1, 1.5, 2 and 2.5. On the basis of mechanical testing conducted on hybrid composite, tensile strength, flexural strength and impact strength showed a significant improvement. The justification of trend was given through the microstructural tests, which were a scanning electron microscopy (SEM) and X-ray diffraction analysis. It was concluded that 1 wt% of crumb rubber with 5 wt% CFF hybrid composites showed the optimum results amongst various combinations. Thus, properties showed significant improvement in the case of hybrid composite as compared to pure fiber-based composite.