فصلنامه مواد پیشرفته و پوشش های نوین
پیاپی 10 (پاییز 1393)

Microcapsules containing isophorene diisocyanate (IPDI) for use in self-healing polymers were successfully fabricated via interfacial polymerization of polyurethane (PU). The preparation of PU prepolymer and microencapsulation of IPDI healing agent was proved by Fourier Transform Infra-Red (FTIR) and Thermo-Gravimetric Analysis (TGA). Scanning Electron Microscope (SEM) was shown smooth spherical microcapsules of 1.5-2 μm with shell thickness of 200-300 nm in diameter was produced.

Hydrophilic silver nanoparticles synthesized by chemical reduction method and particle size distribution evaluated by dynamic light scattering. The results shows that nanoparticles were uniform and homogenous. Also، the surface modification of nanoparticles carried out and FTIR spectra was used to evaluate the modification. Furthermore، modified nanoparticles were disturbed in two different environments، which results from hydrophobic nanoparticles to the surface modification of oleic acid.

In this paper, polyamidoamine dendrimer of zero, first and second generation were synthesized via divergent method using ethylendiamine and methyl acrylate as starting materials and their application in modification of polyamide fibres to increase their dye ability were evaluated. For this purpose, the synthesized dendrimers were reacted with cyanuric chloride (2,4,6-trichlorotriazine) and obtained compounds introduced to the polyamide fibres structure through covalent bonds. These interpretations lead to increase the number of amino groups of these fibres. To confirm this, the modified polyamides were dyed with C.I acid orange 2 as a monosulphonic anionic dye in various concentrations. The results obtained from spectroscopic data of dyeing wastewaters and dyed fabrics indicate that the dye ability of modified fabric with second generation was improved more than 20 times. Furthermore, the major determinant of dye exhaustion appeared to be associated with the modification reaction condition and the generation of used dendrimers, not the dye concentration in dyeing process.

Inthis research، A380 and B390 aluminum alloys with lowest and highest silicon content were casted and coated by anodic oxidation (anodizing) method. The conditions of bath were adjusted 12% volume sulfuric acid، 2-4℃ temperature، 1. 2 A/dm2 current density and fixed time on20 and 60 min. So the effect of alloyon thickness، surface morphology and chemical composition of coating was studied. It is found that increase of silicon content leads to decrease rate of growth thickness and increase non-uniformity، which it has near linear depending to silicon content of alloy. As well as، surface microcracks increased by increasing of coating time andby increasing silicon content.

Thermal and structure stability control against variable temperature condition in space is very significant. The black polyurethane paints are widely used in order to protect of spacecraft surfaces versus this destructive factor. In this present work، black polyurethane thermal control paint has produced by methylenebis phenyl isocyanate، polypropylene glycol، polycaprolactone، various concentrations of carbon black pigment and various ratios of NCO/OH، then sprayed on 6061 aluminum substrate. The design of experiments was down with Taguchi method. The abrasion، adhesion، impact and bending tests were carried out on prepared paints. The results indicated that the coating made by polyester، ratio of NCO/OH equal to 1. 4 and 12 percentage of pigment had the highest abrasion resistance and the coating made by polyester، ratio of NCO/OH equal to 1. 8 and 10 percentage of pigment had the highest adhesion. Impact test and bending test of the paints showed high flexibility and impact resistance.

In this paper، modification of Chitosan as a biopolymer by Poly (amidoamine) (PAMAM) dendrimer G=-0. 5 was done. The prepared hybrid identified using infrared spectroscopy (FTIR). Then، nanoparticles of Chitosan-dendrimer hybrid were prepared by ionic gelation method using Sodium Tripolyphosphate (STPP) with average particle of 265 nm. Cotton fabric was finished by nanoparticles of Chitosan-dendrimer hybrid using pad-dry-cure method. The obtained results from Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) showed the grafting between nanoparticles of Chitosan-dendrimer hybrid and cotton fabric has been done successfully. Physical characteristics of finished cotton were tested، and the results showed the strength of finished cotton fabric was improved (~ 2147 gf/tex). Stiffness of finished cotton fabric was determined by measuring bending length in weft and warp direction did not change sensible in compared with cotton fabric (~0. 4 cm).

In this study، the sintering of alumina-mullite-zirconia composites using microwave heating has been examined. Raw materials were alumina and zircon powders which have been mixed uniformly using wet milling by a planetary mill and then pressed at 250 MPa pressure. Time of milling and time of sintering are of investigated parameters in this paper. In order to achieve sintering، prepared samples were heated at the temperatures of 1550°C for 60 and 90 minutes in a microwave oven. Density، porosity، three-point bending strength، hardness، microstructure and phase analysis of prepared samples were measured and compared with those samples sintered in conventional furnace. Results showed that using microwave sintering can economize time and cost; it can also yield to a high density، more tetragonal zirconia formation and extraordinary strength of alumina-mullite-zirconia composites.