A calixarene derivative, 5,11,17,23-tetrakis (hydroxyl ethyl sulfonamide) calix [4]arene, was synthesized through a linear reaction from parent calix [4]arene. This sulfonamide calixarene derivative was used as a precursor to produce calixarene-polyurethane composite. Structural properties of calixarene-based synthesized precursors were studied using spectroscopic techniques such as 1 H-NMR, 13 C-NMR, and IR. Also, mechanical properties of produced polyurethane composite such as fracture elongation, modulus, and tensile strength were studied which indicated that these properties were deeply dependent upon calixarene ratio in composite. An increase in calixarene ratio resulted in a decrease the fracture elongation. In contrast, an increase in calixarene ratio caused a considerable decrease of modulus and tensile strength. The modulus and tensile strength were increased by 16.98 and 20 % as the calixarene/polyol ratio reached 3 %. Finally, TGA and DSC studies showed that calixarene ratio considerably enhanced the thermal stability of polyurethane.

Investigations were carried out to compare the effectiveness of compounds such as sodium nitrite, trisodium citrate (TSC) and TSC-zinc acetate to inhibit the corrosion of steel rebar in simulated concrete interstitial solution contaminated with chloride and to explain the mechanism of corrosion inhibition on reinforcing steel by these systems. Inhibition efficiency of these systems was studied by electrochemical techniques such as potentiodynamic polarization and half cell potential measurements. Electronic spectral studies of simulated pore solution and FT-IR spectral investigations of the film deposited on steel surface were carried out for understanding the mechanism of corrosion inhibition. Microscopic surface analysis was conducted to obtain the surface morphological behaviour of steel rebar. TSC alone was not exhibited good corrosion inhibition at very low and high concentrations according to electrochemical studies. However, in the presence of zinc acetate, corrosion protection efficiency of TSC increased appreciably. When comparing with sodium nitrite, TSC in the presence and absence of zinc acetate displayed good corrosion inhibition efficiency. Among a number of samples, TSC 100 ppm-zinc acetate 50 ppm combination showed maximum corrosion inhibition efficiency on steel rebar in simulated concrete interstitial solution.

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Zinc oxide (ZnO) and nano-zinc oxide (nZnO) were surface modified by polyethylene glycol (PEG) and poly propylene glycol (PPG). Modification of particles were controlled by transmission electron microscopy, Brunauer, Emmett, Teller specific surface area measurement, infrared (IR) spectroscopy, and differential scanning calorimetry. IR spectra were shown that the interactions between surface modifiers and particles are hydrogen bonding. Modified particles were applied as an activator in vulcanization of natural rubber/styrene butadiene rubber (NR/SBR) blend. Dispersion of modified particles in rubber matrix was investigated by scanning electron microscopy and shown good results. Blend properties were improved by using modified particles. These improvements were due to the better hydrophobicity of modified particles, which were more compatible with nonpolar rubber matrix and caused better participation in curing process. Modification by PEG and PPG were shown better compound properties for ZnO and nZnO, respectively. Application of ZnO-modified particles were presented better compound properties in comparison with nZnO-modified particles. It has confirmed more effective mixing of ZnO-modified particles in rubber matrix by using ordinary mixers.

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Thermal analysis provides a successful technique for the characterization and identification of rubber compounds. In this study, TGA (thermogravimetric analysis) and DTG (TGA derivative) profiles are used to predict and define the physico-mechanical properties of natural rubber — butadiene rubber (NR / BR) blends, using their thermal behaviors. DTG curves of vulcanizate showed that the initial degradation temperature of NR is lower than BR. According to TGA-DTG profiles we have demonstrated two useful factors, ΔTmax (Tmax BR100−Tmax BRX) and peak height ratio of NR-BR blends which are correlated with physico-mechanical properties of blends.

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Conformational diastereomers of 5-substituted-5H -6-chlorodibenzo[a,c]cycloheptene 1 are observed at room temperature in solution. Empirical force field and the AM1 semi-empirical quantum mechanics calculations indicate that the conformation of the cycloheptatriene ring in 1 is a boat (B) form. In the B form, the C-5 substituent can be oriented in equatorial (e) and axial (a) directions. The e-a interchange involves inversion of the biphenyl moiety in the range of 14.1-17.7 kcal mol Ϫ1 , determined by 1 H-NMR band shape analysis. The free energy difference between the e-a forms is not reproduced by the AM1 calculations. The e-a equilibrium in derivatives of 1 depend on the solvent polarity: for 1i the e-a ratio in CDCl 3 (28 : 72) changes to (55 : 45) in DMSO-d 6 .The conformational space of the flexible side chains in all mono-substituted compounds except 1k is searched by molecular mechanics and the AM1 semi-empirical method and the relative heats of formation of all rotamers are considered in estimation of the e-a ratio. Many of the rotamers show an internal hydrogen bond calculated by the AM1 method. The diethylamino derivative of 1 (1l) was found just in the e form. The preferred conformation of 1h in the solid state was found by X-ray crystallography of a single crystal to be e with a strong OH ؒ ؒ ؒ N internal hydrogen bond in the side chain. Dissolution of the 1h single crystals at low temperature and recording the 1 H-NMR spectrum at Ϫ60 ЊC show that assignment of the e form as the dominant one at room temperature for 1h is justified.