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Here, it is aimed to clarify the structure‐performance relationship in MgCl2 based Ziegler Natta catalysts toward ethylene polymerizations. In this regard, 11 different adduct precursors were prepared through industrially appreciated melt quenching method employing various: (i) reaction times for dissolving magnesium chloride inside ethanol; (ii) ethanol/MgCl2 molar ratios in the feed; (iii) heating rates during thermal dealcoholation; (iv) N2 flows during thermal dealcoholation and (v) alcohol content after thermal dealcoholation. Among the studied parameters, heating rate and N2 flow during thermal dealcoholation have the most pronounced effect on the porosity and particle size of the resulted adducts. Related Ziegler Natta catalysts were subsequently employed in ethylene polymerizations. According to the kinetic curves, catalyst productivity and form of kinetic curve (as decay or build‐up type) can be precisely tailored by proper choosing of the mentioned variables during adduct synthesis. Microstructure analysis of the prepared polyethylenes reveals that alcohol content in the final adduct has the most significant effect on the H2 response, in terms of molar mass and its distribution, of the related Ziegler Natta catalysts. The overall results help polyethylene producers in choosing proper reaction conditions during adduct synthesis for the production of different polymer grades, when productivity or H2 response is targeted. [ABSTRACT FROM AUTHOR]

In this article, polymerization of 1-hexene with FeCl3-doped Mg(OET)2/TiCl4/electron donor (ED) catalytic system is presented. For this purpose, first a number of TiCl4catalysts supported on Mg(OEt)2and Fe-doped Mg(OEt)2supports were prepared with ethylbenzoate or dibutylphthalate as the internal EDs. After successive catalysts synthesis, they were employed in 1-hexene polymerization using cyclohexyl methyl dimethoxysilane as external ED as well as without it. The catalysts activity and molecular weight distribution (MWD) of poly 1-hexenes (PHs) were influenced strongly by both FeCl3doping and donor presence so that a remarkable increase in the catalyst activity was seen in doped catalysts. Deconvolution of MWD curves revealed that increase in the type of active centers by introducing FeCl3into the support should be responsible for the broadening of MWD of PHs.13CNMR analysis indicated that while isotacticity does not change considerably by Fe doping, EDs increase its amount as high as 8–21%. Second, the stereoselective behavior of active Ti species in doped and undoped catalysts was fully explored by molecular modeling using density functional theory (DFT) method. Finally, with the aid of rheological measurements, the processability of polymers were evaluated and then the gel permeation chromatography (GPC) results were approved through the values obtained from model fitting as well as changes in moduli crossover modulus. [ABSTRACT FROM PUBLISHER]

A nitratecitrate gel was prepared from metallic nitrates and citric acid by solgel process and was further used to synthesize Ni0.5Zn0.5Fe2O4 nanocrystalline powder by auto-combustion. Then, two novel 15 and 35% (w/w) magnetic Ni0.5Zn0.5Fe2O4 containing polyaniline nanocomposites, named as PANI-Ni15 and PANI-Ni35, respectively, were prepared via in-situ polymerization of aniline in an aqueous solution containing proper amount of Ni0.5Zn0.5Fe2O4 magnetic powder. The incorporation of the nanopowders to PANI matrix was confirmed by X-ray diffraction (XRD), IR and SEM. Synthesized PANI-NiZn ferrite composite particles were subsequently added to an epoxy resin matrix to produce related nanocomposites. The morphological properties of these nanocomposite materials were investigated by SEM and TEM. The electromagnetic-absorbing properties were studied by measuring the reflection loss in the frequency range of 8.0 to 12.0 GHz. Results showed the reflection loss of the PANI-Ni35 composite is higher than pure polyaniline and PANI-Ni15. The good reflection loss of the nanocomposites suggests their potential applicability as radar absorber. [ABSTRACT FROM AUTHOR]