Tribological Behavior of Particles and Fiber-Reinforced Hybrid Nanocomposites

This article discusses the mechanical performance of alumina nanoparticles and randomly distributed short glass/carbon fiber-reinforced hybrid composites through microhardness and wear test. The open mold casting method was adapted to prepare the test coupons. The wear and friction behavior of composites sliding against hardened ground EN 32 steel in a pin-on-disc configuration is evaluated on a wear and friction tester. The microhardness properties of the neat epoxy, alumina nanoparticles, and alumina nanoparticle–embedded glass/carbon fiber–reinforced hybrid composites were determined. The morphology of the worn composites was analyzed with a scanning electron microscope. It was found that the particles as fillers contributed significantly to improve the mechanical properties and wear resistance of the polymer composites. This is because the fillers contributed to enhance the bonding strength between the fiber and the epoxy resin. Moreover, the wear and friction resistance of the glass/carbon fiber composites was increased by increasing the filler weight in the composite materials.     

Production potential of plateau agriculture and food sufficiency in the Kandhamal district of Orissa

The requirement for food grains in the rainfed hill plateaus of the Kandhamal district of the State of Orissa, India was calculated according to accepted nutritional standards over 14 years from 1993 to 2006 and compared with actual production during this time. Owing to the increase in population, the requirement increased from 120 × 10³ MT in 1993 to 142 × 10³ MT in 2006. Production, however, ranged from 68.5 × 10³ MT in 2002 to 134.9 × 10³ MT in 1994 and was only sufficient in 2 of the 14 years. The requirement for food grains for a projected population of 753,542 in 2011 was estimated to be 152 × 10³ MT. At present the area sown is 115 × 10³ ha and would require cultivation 1.83 times per year (cropping intensity 1.83) to produce enough foodgrains for nutritional sufficiency. This could be reduced to 1.64 if the current fallow area of 13 × 10³ ha were cultivated. Increased productivity could be achieved by greater use of irrigation and groundwater.     

A Review on Pineapple Leaf Fibers,Sisal Fibers and Their Biocomposites

Summary: The use of lignocellulosic fibers, pineapple leaf fiber (PALF) and sisal as reinforcements in thermoplastic and thermosetting resins for developing low cost and lightweight composites is an emerging field of research in polymer science and technology. Although, these biofibers have several advantages, such as low densities, low cost, nonabrasive nature, high filling level possible, low energy consumption, high specific properties, biodegradability, etc., over synthetic fibers, the absorption of moisture by untreated biofibers, poor wettability, and insufficient adhesion between the polymer matrix and fiber deteriorate the mechanical properties of composites made up of these biofibers. Therefore, the modification of these fibers is a key area of research at present to obtain optimum fiber‐matrix properties. This review article is concerned with the structure, composition and properties of PALF and sisal, the chemical modifications of these fibers and PALF/sisal‐reinforced thermosets, thermoplastics, rubber, cement, hybrids and biocomposites.

Scanning electron micrograph of tensile fractured surface of alkali treated sisal fiber (magnification ×500).     

Discretization techniques for the efficient solution of the eigenvalue problem in heterostructures

A systematic development of efficient discretization schemes for the numerical evaluation of the eigenvalues of the single‐band effective mass equation that describes the motion of electrons in an ideal periodic crystal is presented. The approach presented makes use of the translational symmetry of the crystal lattice and utilizes the quantum mechanical properties of the momentum operator as the generator of spatial translation. Boundary conditions satisfied at the heterointerfaces are explicitly incorporated in the discretization procedure and the effects of this approach in overall accuracy are evaluated by studying a prototype quantum well heterostructure. Copyright © 2008 John Wiley & Sons, Ltd.     

Effect of cloisite 30B clay and sisal fiber on dynamic mechanical and fracture behavior of unsaturated polyester toughened epoxy network

This study examined the dynamic mechanical properties of sisal fiber reinforced unsaturated polyester (UP) toughened epoxy nanocomposites. The chemical structures changes in Epoxy, UP and UP toughened epoxy (Epoxy/UP) systems were characterized by Proton Nuclear magnetic resonance (¹HNMR) spectroscopy. The morphological alterations of the nanocomposites were analyzed by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The untreated, chemically treated fibers, nanoclays, and the fiber reinforced Epoxy/UP nanocomposites were confirmed by FTIR spectrometer. The obtained mechanical results showed that alkali‐silane treated fibers improve the tensile strength (96%) and flexural strength (60%) of the Epoxy/UP nanocomposite than that of Epoxy/UP blend due to the strong interfacial bonding between the sisal fiber and matrix. The fracture toughness (K_IC) and fracture energy (G_IC) of treated sisal fiber reinforced DGEBA/UP/C30B nanocomposites found to be higher than that of untreated sisal fiber nanocomposites. The dynamic mechanical analysis (DMA) reveals that the fiber reinforced Epoxy/UP nanocomposites contains 30 wt% treated fiber and 1 wt% nanoclays, exhibits the highest storage modulus and better glass transition temperature (T_g) among the other kind of systems. The surface morphology of the fibers, fractured surface of the resins and composites were confirmed by scanning electron microscope (SEM). POLYM. COMPOS., 37:2832–2846, 2016. © 2015 Society of Plastics Engineers     

Novel eco‐friendly biodegradable coir‐polyester amide biocomposites: Fabrication and properties evaluation

Biocomposites are prepared from a cheap, renewable natural fiber, coir (coconut fiber) as reinforcement with a biodegradable polyester amide (BAK 1095) matrix. In order to have better fiber‐matrix interaction the fibers are surface modified through alkali treatment, cyanoethylation, bleaching and vinyl grafting. The effects of different fiber surface treatments and fiber amounts on the performance of resulting bio‐composites are investigated. Among all modifications, cyanoethylated coir‐BAK composites show better tensile strength (35.50 MPa) whereas 7% methyl methacrylate grafted coir‐BAK composites show significant improvement in flexural strength (87.36 MPa). The remarkable achievement of the present investigation is that a low strength coir fiber, through optimal surface modifications, on reinforcement with BAK show an encouraging level of mechanical properties. Moreover, the elongation at break of BAK polymer is considerably reduced by the incorporation of coir fibers from nearly 400% (percent elongation of pure BAK) to 16‐24% (coir‐BAK biocomposites). SEM investigations show that surface modifications improve the fiber‐matrix adhesion. From biodegradation studies we find that after 52 days of soil burial, alkali treated and bleached coir‐BAK composites show significant weight loss. More than 70% decrease in flexural strength is observed for alkali treated coir‐BAK composites after 35 days of soil burial. The loss of weight and the decrease of flexural strength of degraded composites are more or less directly related.