فهرست مطالب raouf alizadeh

This study quantitatively estimated heavy metals as cadmium, lead, chromium and nickel (Cd, Pb, Cr and Ni) using flame atomic absorption spectrometry (FAAS) in ten lipstick products sold by local markets in Sari, Mazandaran State, Iran. All the samples were digested in HNO3 and HClO4 and then evaluated for heavy metal contents. All the concentrations are mean value of triplicate experiments for each sample. Analysis of variance (ANOVA) and Tukey post-hoc tests were used to determine significant variations in heavy metal contents and p

Cure kinetics of the reaction of diglycidyl ether of a bisphenol-A based epoxy resin(DGEBA) with aromatic diamines, such as 3,6-diaminocarbazole (DAC) and N´-[7-(acetyl-4-aminoanilino)-9,9-dioctylfluoren-2-yl]-N´-4-aminophenyl acetamide (ADOAc) as curing agents have been studied by using non-isothermal differential scanningcalorimetry (DSC). DAC was prepared according to literature and ADOAc was preparedvia the reaction of 2,7-dibromo-9,9-dioctylfluorene with 4-aminoacetanilide in thepresence of 10 mol% CuI and 20 mol% N,N''-dimethylethylene diamine(DMEDA) ascatalysts and K2CO3 as a base. The parameters of non-isothermal curing kinetics, activation energy (Ea), pre-exponential factor (A) and rate constant (k) were obtainedaccording to Kissinger, Ozawa, and iso-conversion equations. The activation energy(Ea) values for DGEBA/DAC and DGEBA/ADOAc systems obtained by Kissingermethod are 88.11 and 59.50 kJ/mol, by Ozawa method are 90.75 and 64.15 kJ/mol andby iso-conversion equation are 91.45 and 65.49 kJ/mol, respectively. The values of preexponential factors (A) obtained for DGEBA/DAC and DGEBA/ADOAc systems are1.29×1010 and 9.03×105 s-1 with rate constants (K) of 0.90 and 0.12 s-1, respectively.The results show that DGEBA/ADOAc system has lower Ea and K values than theDGEBA/DAC system. The exothermic curing thermograms of DGEBA with ADOAc aremuch broader than the curing exothermic peak of DGEBA with DAC. At 300ºC bothcured systems start to lose weight and the final weight loss is higher for DGEBA/ADOAc system.