In situ polymerization of polyamide 66 nanocomposites utilizing interfacial polycondensation. II. Sodium montmorillonite nanocomposites

Interfacial polycondensation (IPC) is used to generate polyamide 66 (PA66) nanocomposite using sodium montmorillonite (NaMMT), which offers better thermal stability than organically modified montmorillonite. Several approaches are used to obtain different levels of dispersion for studying the factors affecting dispersion of NaMMT layered‐silicates. These approaches include dispersing NaMMT in either aqueous media or in a compatible nonaqueous medium. Moreover, clay slurry was added to the reaction media separately or in combination with the aqueous hexamethylenediamine solution, which includes either excess amine or sodium carbonate as the by‐product scavenger, in order to study the effect of sequencing on the dispersion of NaMMT. Several characterization techniques including dynamic mechanical analysis, wide angle X‐ray diffraction, and transmission electron microscopy are used to examine the structure and relate it to the mechanical properties of the nanocomposites. Results show that in situ polymerization techniques predominantly give rise to hybrid exfoliated–intercalated NaMMT structure. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Optimization of municipal solid waste (MSW) disposal in Saudi Arabia

Municipal solid waste (MSW) mainly comprises organics, paper, glass, plastics, metals, wood, etc. Rapid industrialization, high population growth rate, and fast urbanization have resulted in increased levels of pollution and MSW in Saudi Arabia. The amount of waste has been steadily increasing due to increasing human population and urbanization. Recovery refers to materials removed from the waste stream for the purpose of recycling and/or composting. There are various options available to convert solid waste to energy. Mainly, the following types of technologies are available: (1) sanitary landfill, (2) incineration, (3) pyrolysis, (4) gasification, and (5) anaerobic digestion. An integrated MSW disposal policy comprises (1) reduction of MSW source, (2) reuse of MSW, (3) recycling of MSW, (4) landfill and gas-to-energy conversion, and (5) MSW-to-energy conversion. Traditionally, MSWs have been disposed in landfills. Landfill is the most inexpensive waste disposal option. The main MSW disposal policies and barriers have been concluded in this study.     

Effect of garlic powder on the performance,egg traits and blood parameters of laying hens

This study was conducted to investigate the effects of garlic powder on the performance, egg traits and blood parameters of laying hens. One hundred and sixty‐two SHSY‐type brown layers aged 21 weeks were chosen at random from a large flock. They were allocated to three dietary treatments. Each treatment comprised six replicates of nine layers in groups of three. The diets were supplemented with 0, 5 and 10 g kg^?1 garlic powder. The experimental period lasted 22 weeks. Garlic powder addition did not significantly affect body weight, egg production, feed consumption, feed efficiency, egg shell index, egg breaking strength, egg shell thickness, egg albumen index, egg yolk index, egg Haugh unit, egg yolk weight and serum protein concentration. Egg weight increased (P < 0.01) with garlic powder supplementation. There was a significant (P < 0.01) reduction in egg cholesterol concentration as mg g^?1 yolk when the dietary level of garlic powder was increased from 0 to 10 g kg^?1. Hen serum triglyceride (P < 0.05) and total cholesterol (P < 0.01) concentrations decreased with garlic powder supplementation. This study demonstrated that garlic powder addition increased egg weight and decreased egg yolk cholesterol concentration (mg g^?1 yolk) and serum triglyceride and cholesterol concentrations without adverse effects on performance and egg traits. Copyright © 2006 Society of Chemical Industry     

CATALYTIC CONVERSION OF RESIDUAL LIGNOCELLULOSIC MATERIALS TO AN ACETONE-SOLUBLE OIL

A study of the reaction involving the heating of air dried and ground lignocellulosic materials such as wheat straw, corn stover, tobacco stalk, tobacco leave and hazel nut shell suspended in water containing sodium carbonate catalyst at elevated temperatures and pressures in a 0.1 liter autoclave. They have been converted to acetone-soluble oil and water-soluble chemicals by being heated for 75 minutes. Within the ranges of the reaction parameters studied: amount of the catalyst (2.0-11.0 wt %), water-to-solid ratio (1:1-5:1) and temperature (518-573 K). Nominal reaction time was 75 min and particle size was 0.6 mm. The optimum ratio of water to solid was found 3:1. The yield of total acetone-solubles were about 50 % of dry and ashless tobacco stalk in the presence of 11 % catalyst of used sample.     

Studies on synthesis,characterization, and metal adsorption of mimosa and valonia tannin resins

A few thermosetting wood adhesive tannin resin system from formaldehyde reaction with both condensed and hydrolysable tannin has been developed. Polymerization of formaldehyde with mimosa tannin and valonia tannin was carried out at optimal conditions obtained from literature to establish the adhesive resin formulation. Formed reaction products were characterized by FTIR spectroscopy. The possible adsorption mechanisms for the adsorption of various metal ions onto tannin‐formaldehyde resins were proposed. Also, thermal analysis were studied and discussed by differential scanning calorimetry and thermogravimetry. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 786–797, 2006     

Design of a front-end integrated circuit for 3D acoustic imaging using 2D CMUT arrays

Integration of front-end electronics with 2D capacitive micromachined ultrasonic transducer (CMUT) arrays has been a challenging issue due to the small element size and large channel count. We present design and verification of a front-end drive-readout integrated circuit for 3D ultrasonic imaging using 2D CMUT arrays. The circuit cell dedicated to a single CMUT array element consists of a high-voltage pulser and a low-noise readout amplifier. To analyze the circuit cell together with the CMUT element, we developed an electrical CMUT model with parameters derived through finite element analysis, and performed both the pre- and postlayout verification. An experimental chip consisting of 4 X 4 array of the designed circuit cells, each cell occupying a 200 X 200 microm2 area, was formed for the initial test studies and scheduled for fabrication in 0.8 microm, 50 V CMOS technology. The designed circuit is suitable for integration with CMUT arrays through flip-chip bonding and the CMUT-on-CMOS process.     

Synthesis and proton conductivity studies of 5‐aminotetrazole‐doped sulfonated polymer electrolyte membranes

This work reports the preparation and characterization of a new anhydrous proton conducting membrane based on poly(vinyl alcohol) (PVA), sulfosuccinic acid (SSA), and 5‐aminotetrazole (ATet) at various stoichiometric ratios. The proton conductivities of membranes were investigated as a function of ATet composition, SSA composition, and temperature. New anhydrous proton conducting membranes were characterized by infrared spectra, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), methanol permeability, and impedance measurements for proton conductivity. TGA showed that the samples were thermally stable up to 150°C. DSC results illustrated the homogeneity of the materials. Mechanical analysis showed that the storage modulus of the PVA–SSA–ATet blend polymer membranes decreased with increasing ATet content. The membranes with higher tetrazole content, or higher acid doping level presented the higher proton conductivity. PVA–SSA–ATet4 can exhibit an anhydrous proton conductivity of 1.7 × 10⁻³ S/cm at 130°C and the proton conductivity increased with increasing temperature and acid doping level. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers