Related Papers
علوم و تکنولوژی پلیمر
Effect of Rigid Polyurethane Foam Core Density on Flexural and Compressive Properties of Sandwich Panels with Glass/Epoxy Faces
2013 •
Jafar Eskandari Jam
Sandwich panels as composite materials have two external walls of either metallic or polymer type. The space between these walls is filled by hard foam or other materials and the thickness of different layers is based on the final application of the panel. In the present work, the extent of variation in core density of polyether urethane foam and subsequent flexural and compressive changes in sandwich panels with glass or epoxy face sheets are tested and investigated. A number of hard polyether urethane foams with different middle panel layers density 80-295 kg/m3 are designed to study the effect of foam density on mechanical properties including flexural and compressive properties. Flexural and compressive test resultsshow that increased core density leads to improved mechanical properties. The slope of the curve decreases beyond density of 235 kg/m3. The reason may be explained on the limitation of shear intensity in increasing the mechanical properties. In this respect an optimum...
Crystallinity Effect on Migration of Low Molecular Weight Substances from Hdpe Into Fatty Food
2005 •
Homayoun Moaddel
Drug Release Modeling from a Novel Temperature-Responsive Polymeric System
2007 •
mehrdad kokabi
علوم و تکنولوژی پلیمر
Fire Behavior of Rigid Polyurethane Foam and Metal Faced Polyurethane Sandwich Panels and Its Fire Hazard Assessment
2009 •
Taghi Akbari
Reaction to fire of fire-retarded rigid PUR foams and two types of metal faced rigid polyurethane foam core sandwich panel was evaluated by using cone calorimeter test method. The tests were carried out in various radiative heat fluxes from 15 to 75 kW/m2. The radiation rate effect on reaction to fire parameters, including time to ignition (TTI), peak of heat release rate (PRHR), total heat release (THR), average heat release rate (Av.RHR) and average heat of combustion (Av.EHC) was investigated. The phenomenon of char forming, when the foam is exposed to heat, leads to the formation of a protective layer on the surface of foam and hence no direct relation exists between Av.RHR and average specific mass loss rate (Av.Spec.MLR) of foam with increased radiation rate. In addition, the increased PRHR with foam density was also very smooth. The relation between TTI and heat flux was investigated for the foam and its corresponding correlation has been achieved with a specified density. Fi...
علوم و تکنولوژی پلیمر
Development of Braiding-Pultrusion Method and Investigation of Mechanical Properties of Composite Rods Produced by this Method
2013 •
Mojtaba Sadighi
In this research, a braiding-pultrusion production line is developed by modifying a conventional textile maypole braiding machine and adding it to a pultrusion line for production of braid-pultruded (BP) composite rods. In order to evaluate the mechanical properties of BP rods and study the effect of some braiding parameters, they were produced with different braid roving linear densities and braid angles. The results are also compared to those of unidirectional (UD) pultruded rods which were produced without braided fabric cover, but with the same fiber volume fraction and diameter.The results showed BP rods had higher shear modulus, but lower tensile modulus and flexural rigidity compared to UD rods. It was also concluded that increasing the braid roving linear density leads to an improvement in shear modulus, but a reduction in tensile modulus and flexural rigidity. Moreover, the highest shear modulus is observed in the rod with braid angle of 45o. Tensile modulus and flexural ri...
Design and Manufacture of Self-Wiping Extruder for the Reaction Extrusion of Melamine Formaldehyde
2004 •
mehrdad kokabi
Alignment of Electrospun Nanofibers and Prediction of Electrospinning Linear Speed Using a Rotating Jet
2009 •
Mehrdad Khamforoush
Science and …
Ethylene hom*opolymerization by Ziegler-Natta (TiCl4/MgCl2) Catalyst through Full Factorial Experimental Design
2009 •
SHOKOUFEH HAKIM
علوم و تکنولوژی پلیمر
Synthesis and Characterization of Organic-Inorganic Polyacrylate-Silica Nanocomposites
2007 •
Mohsen Mohseni
In this article, hybrid organic-inorganic materials were prepared by free radical copolymerization of 2-hydroxyethyl methacrylate (HEMA) and 3-methacryloxy-propyltrimethoxysilane (MPTMS) via sol-gel process. The methoxysilane-containing copolymer precursors were synthesized at different compositions. These copolymer precursors were then hydrolyzed and condensed to produce PHEMA-SiO2 nanocomposites. The samples were characterized by FTIR spectra and TGA thermograms. Optical properties and hardness were measured by visible spectroscopy and Shore D, respectively.Morphological characteristics were investigated with SEM images and finally the formation and distribution of nano SiO2 particles were characterized by AFM images. FTIR spectra showed the formation of silica bonds (Si-O-Si) and TGA thermograms showed high thermal resistance up to 340oC for hybrid samples. Also samples possessed very good transparency in visible avelength range. Microscopical images showed the existence and sui...
Chitosan Extraction by Fungi in Solid State Fermentation
2006 •
Soheila Yaghmaei
