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Zabihzadeh S.M.,Sari University of Agricultural Sciences and Natural Resources
BioResources | Year: 2010

The flexural properties of commercial bagasse-filled polyethylene (PE) and polypropylene (PP) composites were determined as a function of strain rate at room temperature. The applied strain rates were 1.5 ×10-4, 3.75×10-4, 7.5×10-4, and 1.5×10-3 s-1. The flexural modulus tended to increase linearly for the two types of composites with the logarithm of strain rate. The bending strength of polypropylene composite also behaved in a similar manner, but the polyethylene composite exhibited different behavior in which the MOR values of polyethylene composite didn't alter appreciably as a function of strain rate. The flexural response of a polypropylene-based composite was found to exhibit higher dependency on strain rate than a polyethylene-based composite. Water absorption of both composites followed the kinetics of a Fickian diffusion process. Water absorption and dimensional instability of PE-based composites were lower than those of PP-based composites. The highest swelling took place in the thickness of the samples, followed by the width and length, respectively. Source

Zabihzadeh S.M.,Sari University of Agricultural Sciences and Natural Resources
BioResources | Year: 2010

Composites of flour from different lignocellulosic sources with high-density polyethylene were prepared, and their water absorption and flexural properties were studied. Flour samples from loblolly pine, hybrid Euro-American poplar, and wheat straw were mixed with the polymer at 35 wt % lignocellulosics content and either zero or 2% compatibilizer. Water absorption tests were carried out on injection-molded specimens for temperatures of 30, 45, 60, and 75°C. Results indicated a significant difference among different lignocellulosic types, of which wheat straw composites exhibited the highest and the pine composites showed the lowest water absorption values. The composites with 2% MAPE showed lower water absorption compare to the composites without MAPE. This indicates that the compatibilizer plays an important role to repel the water molecules. For all four temperature conditions, rising temperature increased water absorption significantly. Composites with poplar had the highest flexural strength and modulus. Adding compatibilizer to the composites boosted the flexural properties by improving the adhesion between natural filler and the polymer matrix. Source

Kordkheili H.Y.,Islamic Azad University at Sari | Farsi M.,Islamic Azad University at Sari | Rezazadeh Z.,Sari University of Agricultural Sciences and Natural Resources
Composites Part B: Engineering | Year: 2013

The objective of this investigation was to evaluate physical, mechanical and morphological properties of experimental polymer type panels made from single-wall carbon nanotube (SWCNT) and wood flour. The composites with different SWCNTs (0, 1, 2, 3 phc) and maleic anhydride grafted polyethylene (MAPE) (0 and 3 phc) contents were mixed by melt compounding in an internal mixer and then the composites manufactured by injection molding method. The mass ratio of the wood flour to LDPE was 50/50 (w/w) in all compounds. Water absorption, thickness swelling, bending characteristics, impact strength and morphological properties of the manufactured composites were evaluated. Based on the findings in this work the water absorption and thickness swelling of the nanocomposites decreased with increasing with amount of the SWCNTs (from 1 to 3 phc) and MAPE (3 phc) in the panels. The mechanical properties of LDPE/wood-flour composites could be significantly enhanced with increased percentage of MAPE and SWCNTs content. Panels having 2 phc SWCNTs and 3 phc MAPE exhibited the highest impact strength value. Also Scanning Electron Microscope (SEM) micrographs showed that carbon nanotubes can fill the voids of wood plastic composites as well as addition of MAPE and SWCNTs enhanced interaction between the components. © 2012 Published by Elsevier Ltd. Source

Amirkolaie A.K.,Sari University of Agricultural Sciences and Natural Resources
Reviews in Aquaculture | Year: 2011

The discharge of waste from aquaculture operations can lead to eutrophication and destruction of natural ecosystem in receiving water body. A controlled waste production strategy is necessary to maintain sustainable aquaculture growth into the future. As feed is the major source of waste in aquaculture, the management of aquaculture waste should be approached through diet formulation or feeding strategies. Highly digestible diets have been introduced as a solution to reduce solid waste excretion. Further reductions in solid waste can be achieved through careful selection of feed ingredients and feed processing to improve nutrient availability. An increase in faeces consistency by diet manipulation can improve solid removal efficiency. This condition can reduce the proportion of solids in discharged water in the effluent and also improve farm water quality. A reduction in dissolved nitrogen waste can be achieved by ensuring a balance between protein and energy causing fish to use non-protein sources as energy. Phosphorous waste can be decreased through careful ingredient selection and proper processing to improve digestibility. A proper feed ration and feeding method for each species should be adopted because feed waste constitutes a large part of waste production. © 2011 Blackwell Publishing Asia Pty Ltd. Source

Zabihzadeh S.M.,Sari University of Agricultural Sciences and Natural Resources
Journal of Thermoplastic Composite Materials | Year: 2010

The thermal stability and the thermal expansion of wheat straw flour filled polypropylene and high density polyethylene composites were studied using thermogravimetric analysis and thermomechanical analysis. The results of this study showed that the thermal degradation and the thermal expansion of the composites were affected by plastic type and compatibilizer. The thermal stability of HDPE-based composites was found to be higher than that of PP-based ones. Adding compatibilizer to the composites boosted the thermal stability of agro-filler thermoplastic composites by improving the adhesion between wheat straw flour and the matrices. The thermal degradation activation energy of pure PP and HDPE was higher than that of the composites. The activation energy of compatibilized composites was slightly higher than uncompatibilized ones. TMA results indicated that wheat straw flour was a suitable material for decreasing the thermal expansion of the composites caused by cold and warm atmospheric changes. The thermal expansion of PP and wheat straw flour filled polypropylene composites was found to be lower than that of HDPE and HDPE-based composites. © 2010 The Author(s). Source

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