Segmental dynamics of reactively prepared polystyrene blends: Unsaturated polyester resin versus high impact polystyrene

Segmental dynamics of two phase‐separated reactively prepared polystyrene blends namely unsaturated polyester resin (UPR) and high impact polystyrene (HIPS) was investigated by dynamic–mechanical spectroscopy and calorimetric studies. The results showed a thermorheologically simple behavior for the HIPS, which could be quantified based on the KWW function with β_KWW of 0.37. The UPR data, however, could not be evaluated using KWW function, even though lower β_KWW than the HIPS was expected for it. Furthermore, the α‐dispersion of the UPR was considerably broader while its fragility index was comparable with the HIPS. Nonetheless, segmental dynamics comparison based on normalized ΔC_p(T_g) by molecular weight of the structural units of the studied systems showed much greater differences. Accordingly, the UPR was both kinetically and thermodynamically more fragile than the HIPS. The higher fragility of the UPR could be attributed to its larger relative cooperativity size and topological constraints. Finally, enhanced contrast in dynamic fragilities of two studied systems could be achieved if similar overall and local compositions could be made experimentally. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

The Effect of Fullerene C60 and its Amine Derivative on the ZDDP Antioxidative Functionality

In this work we describe the effect of both fullerene and its oil-soluble amine derivative on antioxidative properties of ZDDP (zinc dialkyldithiophosphate, alky groups: isobutyl and isoamyl). An oxidation reaction in the presence of AIBN (as an initiator) was chosen as chemical probe to investigate mutual interaction of ZDDP with fullerene and its derivative. According to the experimental results, both fullerene C₆₀ and its amine derivative show more antioxidative properties than ZDDP. Experimentally, it is concluded that the presence of these species increase the effect of ZDDP as antioxidant. This effect could be experimentally described in terms of the metal center of ZDDP.     

Performance analysis of a passive cooling system using underground channel (Naghb)

The present study, aims at introducing and studying the effect of an old and specific type of house cooling system in Bam city. Primary of the system is similar to Baud-Geers (wind tower) but in the mentioned system, there is an additional channel connected to Baud-Geer which is called Naghb. Naghb in fact is an underneath channel that uses the ground humidity to cool the air. Baud-Geer input wind passes through the Naghb and evaporation cooling makes it cooler in the Naghb. Therefore, the cooling effect of Baud-Geer enhances. Unfortunately, all of Baud-Geers and Naghbs in Bam destroyed in the earthquake happened on December 26, 2003 and only ruins of them are left, hence in order to study Naghb performance in the present study, a one-dimensional model is presented and the conservation equations of energy, mass and momentum have been solved simultaneously. In order to evaluate the model, a simple experimental setup is made on the basis of real dimensions of Naghb. The model results reveal the ability of Naghb in cooling the air during hot and dry months in Bam.     

Skytherm: an approach to year-round thermal energy sufficient houses

The skytherm system, a roof covered with water filled plastic bags equipped with moveable insulation, is studied and a model is presented to predict its thermal behavior. A computer program is written to calculate hourly cooling and heating load requirements of a building and is validated by comparison with field data taken from an actual house in Shiraz, Iran. This program is then used to simulate metal and concrete skytherms. It is shown that for a 140.55 m² one story house, the skytherm system is capable of reducing heating demands by 86% and cooling loads by 52%.     

Microstructure and Multiwall Carbon Nanotube Partitioning in Polycarbonate/Acrylonitrile-Butadiene-Styrene/Multiwall Carbon Nanotube Nanocomposites

The multiwall carbon nanotube (MWNT) partitioning and its impact on morphology and electrical properties of Polycarbonate (PC)/Acrylonitrile-Butadiene-Styrene (ABS)/MWNT nanocomposites were studied. The rheological and TEM results indicated that the MWNT partitioning and state of dispersion of MWNT were determined by the affinity between MWNT and the blend components and MWNT concentration. In the PC/ABS (70/30: w/w)/2 wt.% MWNT sample the MWNTs were preferentially located in the ABS droplets and the interface due to the greater affinity between MWNT and ABS compared with PC. In the PC/ABS (30/70: w/w)/MWNT samples, however the MWNTs were mostly located in the ABS matrix.     

Site-specific atomic scale analysis of solute segregation to a coincidence site lattice grain boundary

A site-specific method for measuring solute segregation at grain boundaries in an Aluminum alloy is presented. A Σ7(Σ7=38°〈1 1 1〉) grain boundary (GB) in an aluminum alloy (Zr, Cu as main alloying elements) was evaluated using site-specific Local Electrode Atom Probe (LEAP). A sample containing a Σ7 GB was prepared by combining electron backscatter diffraction (EBSD) and focused ion beam (FIB) milling to locate the GB of interest and extract a specimen. Its composition was determined by LEAP, and compared to a general high angle GB (HAGB). Zr was the only alloying element present in the Σ7 GB, whereas the general HAGB contained both Cu and Zr. This site-specific LEAP method was found to be an accurate method for measuring GB segregation at specific GB misorientations. The method has advantages over other methods of measuring chemistry at GBs, such as spectroscopy, in that GB structure can be assessed in three dimensions.     

Environmental,technical and financial feasibility study of solar power plants by RETScreen,according to the targeting of energy subsidies in Iran

In this study, based on new electricity tariffs, three scenarios have been developed with The RETScreen International Photovoltaic Project Model, according to the targeting of energy subsidies in Iran. We have also dedicated one of our scenarios to the reduction of greenhouse gasses.In the first case the electricity price was set to 3.75 Cents/kWh (450 Rial/kWh) and no credit was assigned to the reduction of greenhouse gasses (GHG), therefore equity payback (Return positive cash flow) has been 12.1 year. In the second case the electricity price was set to 17.5 Cents/kWh, therefore equity payback (return positive cash flow) was 8 year. Finally in the last scenario by considering a credit to the reduction of greenhouse gasses and electricity price being 175 Cents/kWh and applying solar panels with high efficiency and suitable batteries (DOD = 60%), equity payback (return positive cash flow) reached within 6 years.