Acrylamide was polymerized at 40 and 80 degrees C in presence of 4,4"-azobis-4cyanovaleric acid by radical polymerization, to high conversions. The polyacrylamides were isolated by precipitation in methanol. After drying, the limiting viscosity numbers, [eta], and apparent molecular weights of polyacrylamides were determined viscometrically by several empirical equations, in distilled water and also by GPC. The dependence of limiting viscosity number on percentage conversion is discussed, and the significance of polymer branching at 40 and 80 degrees C is assessed.

The final crystalline phase in poly (vinylidene flouride), PVDF, films mainly reflects the polymer structural arrangement or chain conformation during film formation. In this study, the intrinsic viscosity of PVDF solution or even the zero-shear-rate viscosity in polymer melt were used as indications of polymer hydrodynamic chain volume to predict the possible formation of all trans plannar zigzag conformation (b phase crystal). The studies on intrinsic viscosity of each diluted solution were carried out in Ubbelohde viscometer at temperature range of 25-100oC using two individual solvents with different polarities namely, dimethyl acetamide and cyclohexanone. In contrast to solvent polarity, the solution temperature showed negative effect in the degree of hydrodynamic chain volume. This behaviour maybe attributed to higher thermodynamic stability of gauche state rather than trans state in PVDF chains at higher crystallization temperatures. In this regard, through a temperature rise from 25oC to 100oC, the PVDF hydrodynamic chain volume experienced a reduction of about 38% and 25% in dimethyl acetamide and cyclohexanone, respectively. The further reduction of PVDF hydrodynamic chain volume in dimethyl acetamide solution may be referred to higher polymer chain mobility and reduced solvent polarity at higher temperatures. Using zero-shear rate viscosity, the increase in melt temperature showed reduction of about 87% in hydrodynamic chain volume. The temperature dependence of PVDF chain dimension in solution and melt state show a similar trend. These findings are in agreement with the previous results about the unhelpful effect of crystalization temperature in favor of b phase crystal formation in PVDF.

Molecular characterization of three grades of polyethylene, synthesized by Iranian Petrochemical Industries, was performed by dilute solution viscometry, viscometry at zero shear rate and melt flow index measurements. The results show that for molecular weight measurement with dilute solution viscometry, a threshold elution time of the solvent of 100 s is necessary. Also, the method by which the polymer solution is prepared may affect the value obtained for the average molecular weight. To prevent the molecular weight decrease due to degradation during sample preparation and experimental tests, the residence time of the solution at high temperature should be maintained as short as possible. On the other hand, the molecular weight distribution calculated, based on its relationship with zero shear viscosity and M v, showed comparable agreement with MFI10/MFI2.16 for some of the samples.    

Background and Aim Tamoxifen is a group of drugs of selective estrogen receptor modulators, and is one of the drugs effective in the prevention and treatment of some cancers (such as breast cancer). In this study, the interaction of tamoxifen with DNA is investigated experimentally. Also, the electronic structure (at atomic scale) of the molecular system of tamoxifen was theoretically investigated, using atom in molecule (AIM) theory. Methods & Materials First, in the experimental section of this study, the interaction of Tamoxifen with DNA were investigated by UV-ViS technique and hydrodynamic method (Viscometry). In addition, the analysis of the experimental results shows the obvious effect of concentration on the mechanism of how the tamoxifen molecule binds to DNA. Then, in the theoretical part of this research, using computational biophysical chemistry methods, some properties of tamoxifen molecular system, such as electronic Density of States (DOS), boundary orbital’, s energy (HOMO/LUMO), Electrostatic Potential Energy (EPS) and electronic contour maps of the electron density and its Laplacian, will be calculated. Ethical Considerations This article is a meta-analysis with animal sample. Results Result of the UV-ViS spectroscopy technique and viscometry indicated hyperchromism and hypochromism effect. In addition, the result were depend on the concentration of the drug and affected the kind of binding of Tamoxifen to DNA. the analysis of computational studies on the drug tamoxifen suggests that the mechanism of the local charge/energy distribution in the molecular system of tamoxifen plays an important role in how this drug binds to DNA. Conclusion Based on the experimental results of UV-ViS technique and viscometry, as well as the electronic/vibrational properties of the tamoxifen molecular system, it was defined that the Tamoxifen interacts significantly with all the binding sites of DNA.