Cattaneo–Christov heat flux model for nanofluid flow over a curved stretching sheet: An application of Stefan blowing

The present work investigates the thermophoresis and Brownian motion effects in nanofluid flow over a curved stretching sheet (CSS). Also, the Cattaneo–Christov heat flux and Stefan blowing (SB) conditions are considered for studying heat and mass transport characteristics. The present work's novelty is associated with considerations of convective boundary and SB conditions in nanomaterial flow over a CSS. The coupled partial differential equations are changed to ordinary differential equations by employing suitable similarity variables, and the resultant model is numerically handled using Runge–Kutta–Fehlberg's fourth fifth-order method with the shooting scheme. The stimulation of the involved parameters/numbers on the flow, mass, and heat fields is broadly deliberated using suitable graphs. The present analysis's significant relevant outcomes are that the inclination in thermophoresis and Brownian motion parameters increases the heat transfer. The inclined values of the Brownian motion parameter decay the mass transfer. Furthermore, the increased values of both Schmidt number and SB parameter drop the mass transport. The increased values of the Brownian motion parameter and Schmidt number decays the rate of mass transference.     

Effect of polyethylene oxide–polyethylene glycol content and humidity on performance of electro‐active paper actuators based on cellulose/polyethylene oxide–polyethylene glycol microcomposite

The effect of humidity and polyethylene oxide (PEO)–polyethylene glycol (PEG) content on the actuator performance of cellulose/PEO–PEG microcomposites was studied. Upon blending 5% PEO–PEG, the maximum bending displacement of the actuator increased nearly twice compared to that of cellulose EAPap actuator. However, further increase of PEO–PEG content resulted in decreased actuator performance. This might be due to the increased intermolecular interaction by hydrogen bonding that reduces the mobility of the molecules. The actuator performance test showed that the increase in humidity level rather reduced the maximum displacement of the actuators. X‐ray diffractogram and Fourier transform infrared spectrum analysis suggested a structural change of the microcomposites as well as disruption of cellulose/PEO–PEG association attributed to the actuator performance degradation at high humidity level. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

Friction and dry sliding wear behavior of carbon and glass fabric reinforced vinyl ester composites

Friction and dry sliding wear behavior of glass and carbon fabric reinforced vinyl ester composites have been presented. The results show that the coefficient of friction and wear rate increased with increase in load/sliding velocity and depends on type of fabric reinforcement and temperature at the interphase. The excellent tribological characteristics were obtained with carbon fiber in vinyl ester. It is believed that a thin film formed on counterface was seems to be effective in improving the tribological characteristics. The worn surfaces examined through SEM, showed higher levels of broken glass fiber in vinyl ester compared to carbon-vinyl ester composites.     

Hybrid nanocomposite based on cellulose and tin oxide: growth,structure, tensile and electrical characteristics

A highly flexible nanocomposite was developed by coating a regenerated cellulose film with a thin layer of tin oxide (SnO₂) by liquid-phase deposition. Tin oxide was crystallized in solution and formed nanocrystal coatings on regenerated cellulose. The nanocrystalline layers did not exfoliate from cellulose. Transmission electron microscopy and energy dispersive x-ray spectroscopy suggest that SnO₂ was not only deposited over the cellulose surface, but also nucleated and grew inside the cellulose film. Current–voltage characteristics of the nanocomposite revealed that its electrical resistivity decreases with deposition time, with the lowest value obtained for 24 h of deposition. The cellulose–SnO₂ hybrid nanocomposite can be used for biodegradable and disposable chemical, humidity and biosensors.     

Role of zirconia filler on friction and dry sliding wear behaviour of bismaleimide nanocomposites

This paper discusses the friction and dry sliding wear behaviour of nano-zirconia (nano-ZrO₂) filled bismleimide (BMI) composites. Nano-ZrO₂ filled BMI composites, containing 0.5, 1, 5 and 10 wt.% were prepared using high shear mixer. The influence of these particles on the microhardness, friction and dry sliding wear behaviour were measured with microhardness tester and pin-on-disc wear apparatus. The experimental results indicated that the frictional coefficient and specific wear rate of BMI can be reduced at rather low concentration of nano-ZrO₂. The lowest specific wear rate of 4 × 10⁻⁶ mm³/Nm was observed for 5 wt.% nano-ZrO₂ filled composite which is decreased by 78% as compared to the neat BMI. The incorporation of nano-ZrO₂ particles leads to an increased hardness of BMI and wear performance of the composites shows good correlation with the hardness up to 5 wt.% of filler loading. The results have been supplemented with scanning electron micrographs to help understand the possible wear mechanisms.     

Development of microcontroller based thermogravimetric analyzer

Thermogravimetric analyzer (TGA) is an analytical technique extensively used to study the thermal decomposition of inorganic solids, their kinetics, reaction mechanisms, chemical property, structure of intermediate and final products and synthetic conditions. This paper reports the development of microcontroller based thermogravimetric analyzer. The TGA has been setup with additional features like controlled gas delivery system suitable for the study of decomposition (gas–solid interaction) in various atmospheres like air, oxygen, hydrogen, etc. The displacement of the spring in the system due to sample weight loss or gain on heating can be measured by using Infrared (IR) grating assembly and also by using cathetometer (least count is 0.001 cm).     

Flexible humidity and temperature sensor based on cellulose–polypyrrole nanocomposite

Recently, cellulose has been re-discovered as a smart material that can be used as sensor and actuator materials, which is termed as electro-active paper. In this work we demonstrate the application of cellulose as a flexible humidity and temperature sensor. Nanoscaled polypyrrole (PPy) as a humidity and temperature sensitive layer was introduced onto cellulose surface via in situ polymerization technique without disrupting cellulose structure. Atomic force microscopy, UV–visible spectroscopy, transmission electron microscopy and secondary ion mass spectroscopic analysis revealed the successful deposition of polypyrrole nanolayer onto cellulose surface, which is referred as a cellulose–PPy nanocomposite. Effect of polymerization time on sensing behavior of cellulose–PPy nanocomposite was investigated, experimental results revealed that cellulose–PPy nanocomposite with 16 h polymerization time suitable for suitable for humidity and temperature sensor.     

Fabrication,Physicochemical Characterizations and Electrical Conductivity Studies of Modified Carbon Nanofiber-Reinforced Epoxy Composites: Effect of 1-Butyl-3-Methylimidazolium Tetrafluoroborate Ionic Liquid

This study presents the fabrication of carbon nanofiber-reinforced epoxy nanocomposites using 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid as filler dispersant. FTIR and XRD measurements were utilized to assess structural attributes and crystallographic change in the composites. In addition, morphological studies were performed by field emission scanning electron microscope while the extent of miscibility between epoxy and IL was computed by Accelrys Materials Studio Software. The conductivity measurement was performed by two point impedance analyzer and result demonstrated increase in the electrical conductivity from ～10^?7 to ～10^?5?S?cm^?1 compared to pristine epoxy composite.     

Effect of poly(ethylene oxide)‐ poly(ethylene glycol) addition on actuation behavior of cellulose electroactive paper

This article reports the influence of poly(ethylene oxide)‐ poly(ethylene glycol) (PEO‐PEG) addition on its actuation behavior of cellulose electroactive paper. The actuator showed its maximum bending displacement of 5.0 mm with very low electrical power consumption (7 mW/mm) at an ambient condition. Increased displacement output and decreased electrical power consumption of the actuator might be due to the improved polymer chain flexibility and ion mobility. The ion migration effect might play a more important role in actuation principle. Present investigation reveals that cellulose/PEO‐PEG‐based EAPap actuators are suitable to construct an actuator working at normal ambient condition. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influence of silicon carbide filler on mechanical and dielectric properties of glass fabric reinforced epoxy composites

Fiber‐reinforced polymeric composites (FRPCs) have emerged as an important material for automotive, aerospace, and other engineering applications because of their light weight, design flexibility, ease of manufacturing, and improved mechanical performance. In this study, glass‐epoxy (G‐E) and silicon carbide filled glass‐epoxy (SiC‐G‐E) composite systems have been fabricated using hand lay‐up technique. The mechanical properties such as tensile strength, tensile modulus, elongation at break, flexural strength, and hardness have been investigated in accordance with ASTM standards. From the experimental investigations, it has been found that the tensile strength, flexural strength, and hardness of the glass reinforced epoxy composite increased with the inclusion of SiC filler. The results of the SiC (5 wt %)‐G‐E composite showed higher mechanical properties compared to G‐E system. The dielectric properties such as dielectric constant (permittivity), tan delta, dielectric loss, and AC conductivity of these composites have been evaluated. A drastic reduction in dielectric constant after incorporation of conducting SiC filler into epoxy composite has been observed. Scanning electron microscopy (SEM) photomicrographs of the fractured samples revealed various aspects of the fractured surfaces. The failure modes of the tensile fractured surfaces have also been reported. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009