2024-03-29T02:40:17Z
http://poj.ippi.ac.ir/?_action=export&rf=summon&issue=349
Polyolefins Journal
Polyolefins J
2322-2212
2322-2212
2015
2
2
Editor-in-Chief's Notes
Editor-in-chief's note
2015
06
01
http://poj.ippi.ac.ir/article_1242_a97cabaa66eb1fa5f05ef2d8b2c787b5.pdf
Polyolefins Journal
Polyolefins J
2322-2212
2322-2212
2015
2
2
Addition of a second alcohol in magnesium ethoxide synthesis as a way to vary the pore architecture of Ziegler-Natta catalysts
Toshiaki
Funako
Patchanee
Chammingkwan
Toshiaki
Taniike
Minoru
Terano
In Ziegler-Natta olefin polymerization, the pore architecture of catalysts plays a crucial role in catalytic performances and polymer properties. While the type of preparation routes (such as chemical reaction and solution precipitation) greatly affects the catalyst pore architecture as a result of different solidification mechanisms, the modification of the pore architecture within a given route has been hardly achieved. In this study, we propose a simple way to vary the pore architecture of Mg(OEt)2-based Ziegler-Natta catalysts by the addition of a second alcohol. It was found that the addition of a second alcohol during Mg(OEt)2 synthesis affected not only the morphology of Mg(OEt)2 macroparticles but also the shape of building units. The degree of alternation was found to be sensitive to the molecular structure of a second alcohol. Noticeable influences were observed in the case of branched alcohols, where the transformation of plate-like building units to cylindrical ones led to the generation of totally different pore size distributions of resultant catalysts.
Ziegler-Natta catalysts
pore architecture
magnesium alkoxide
2015
06
01
65
71
http://poj.ippi.ac.ir/article_1131_d3206454629de1a26c280525c722d0fe.pdf
Polyolefins Journal
Polyolefins J
2322-2212
2322-2212
2015
2
2
Study of Ziegler-Natta/(2-PhInd)2ZrCl2 hybrid catalysts performance in slurry propylene polymerization
Gholam-Reza
Nejabat
Mehdi
Nekoomanesh
Hassan
Arabi
Hamid
Salehi-Mobarakeh
Gholam-Hossein
Zohuri
Mohammad-Mahdi
Mortazavi
Saeid
Ahmadjo
Stephen
Miller
Several types of hybrid catalysts are made through mixing of 4th generation Ziegler-Natta (ZN) and (2-PhInd)2ZrCl2 metallocene catalysts using triethylaluminum (TEA) as coupling agent. Response surface methodology (RSM) is used to evaluate the interactive effects of different parameters including amounts of metallocene and TEA and temperature on metallocene loading. Analyzing the amounts of Al and Zr elements in the hybrid catalysts through ICP-OES and EDXA reveals that temperature plays a crucial role on anchoring of the metallocene catalyst on ZN while TEA has the least determining effect. The ICP analysis shows that as the concentration of Al goes up in the hybrid catalyst the concentration of Zr passes a maximum, while EDXA shows a direct relationship between the Al and Zr contents. Using triisobutylaluminum (TIBA) and methylaluminoxane (MAO) as the coupling agents, almost similar metallocene loadings are observed. Finally, the performance of hybrid catalysts is investigated in propylene polymerization and the obtained polymers are characterized using DSC and DMTA through which the presence of two types of polymers in the final product are confirmed.
Hybrid catalysts
Ziegler-Natta
metallocene
Surface and bulk analysis
Polypropylene
2015
06
01
73
87
http://poj.ippi.ac.ir/article_1145_37a49082a2bc170a27aa700414df433d.pdf
Polyolefins Journal
Polyolefins J
2322-2212
2322-2212
2015
2
2
Reaction dynamics during the testing of polymerization catalyst
Nickolay
Ostrovskii
Ladislav
Fekete
The olefins polymerization process in a slurry reactor is discussed. The reaction rate dynamics was analyzed and the contributions of feed flow, gas-liquid mass transfer, polymerization reaction, and catalyst deactivation were estimated. The propylene solubility in a solvent mixture “heptane” was calculated using Soave-Redlich-Kwong equation of state. These data were then approximated by Henry-like equation and the results were verified in experiments. The influence of propylene dissolving in ”heptane which was examined in special experiments without catalyst has provided the independent estimation of gas-liquid mass transfer coefficient. It has been shown that the reaction rate during the first 20-30 min of test is much lower (or higher) than total monomer consumption, depending on reactant addition sequence. The method of kinetic experiments interpretation and corresponding mathematical model are proposed. The method enables to estimate the kinetic parameter of monomer dissolution, the reaction rate constant of polymerization, as well as the parameters of active centers transformation – activation, deactivation and self-regeneration. An adequacy of model was proved by the description of experiments at two different pressures but with the same parameters values.
reaction dynamics
Propylene polymerization
catalyst testing
2015
06
01
89
97
http://poj.ippi.ac.ir/article_1156_db0223822d19c4f83ce3ec734497799d.pdf
Polyolefins Journal
Polyolefins J
2322-2212
2322-2212
2015
2
2
An investigation on non-isothermal crystallization behavior and morphology of polyamide 6/ poly(ethylene-co-1-butene)-graft-maleic anhydride/organoclay nanocomposites
Sepideh
Gomari
Ismaeil
Ghasemi
Mohammad
Karrabi
Hamed
Azizi
Nanocomposites based on polyamide 6 (PA6) and poly(ethylene-co-1-butene)-graft-maleic anhydride (EB-g- MAH) blends have been prepared via melt mixing. The effect of blend ratio and organoclay concentration on the crystallization and melting behavior of specimens were studied. Three types of commercial organo-modified clay (Cloisite 30B, Cloisite 15A and Cloisite 20A) were employed to assess the importance of the nanoclay polarity and gallery distance. The crystallization behavior was investigated using differential scanning calorimetry (DSC) and wide angle X-ray diffraction spectroscopy (WAXD). The strong interactions between amine end groups of PA6 and maleic anhydride groups of EB-g-MAH led to complete inhibition of EB-g-MAH crystallization according to the DSC results. A transformation from the α form to the γ form crystals of PA6, induced by both organoclays and EB-g-MAH, was monitored by WAXD and DSC. Small angle X-ray scattering (SAXS) was used to evaluate the morphology of nanocomposites. Moreover, transmission electron microscopy (TEM) was conducted to determine the location of organoclays and indicated that the organoclays mainly present in the PA6 matrix and rarely distribute in the EB-g-MAH phase in the case of low polarity organoclays. It was also evidenced that the organoclay with the most affinity to PA6 (Cloisite 30B) had the largest effect on the thermal and crystallization behavior of this phase in the blend.
polyamide 6
polyolefin elastomer
organoclay
crystallization
morphology
2015
06
01
99
108
http://poj.ippi.ac.ir/article_1164_c767bdf98fc8d9d7579c4ad1e3193b12.pdf
Polyolefins Journal
Polyolefins J
2322-2212
2322-2212
2015
2
2
The effect of high-energy electron beam on drawn and undrawn high density polyethylene fibers
Jalil
Morshedian
Yousef
Jahani
Farshad
Sharbafian
Foroogh Sadat
Zarei
HDPE monofilaments were obtained using different extruders and drawn by post-extruder equipments. After solidification, drawn and undrawn monofilaments (draw ratio 7:1) were irradiated with 10 MeV electron beams in air at room temperature at 25, 50, 75, 100 and 125 kGy dose ranges to induce a network structure. HDPE crosslinking was studied on the basis of gel content measurements. The fibers were examined by differential scanning calorimetry (DSC) and measurements of mechanical properties.It was noted that gel fraction increased with irradiation dose up to 75 kGy and showed a significant increase with draw ratio, but at higher doses remained without considerable change. Melting temperature of drawn fiber increased with raising irradiation dose but decreased in undrawn sample. Also a bimodal endotherm peak was observed for drawn polyethylene irradiated in air.The changes in melting temperature and appearance of bimodal endotherm were related to the radiation chemistry of polyethylene in the presence of oxygen and interlamellar interactions. Heat of fusion and degree of crystallinity slightly increased for undrawn and drawn samples but, heat of crystallization was reduced by increasing irradiation dose due to increase the degree of crosslinking. Results of mechanical properties reveal that no significant changes seen in Young’s modulus by increasing irradiation dose. As a result of oxidative degradation happened by presence the oxygen molecules during the irradiation process, tensile properties of irradiated fibers decreased but elongation at yield for undrawn and elongation at break for drawn fibers boosted by increasing irradiation dose up to 125 kGy.
polyethylene fiber
electron beam
crosslinking
draw ratio
2015
06
01
109
119
http://poj.ippi.ac.ir/article_1166_d88807ea89141051ba9f28c4a2fe7465.pdf
Polyolefins Journal
Polyolefins J
2322-2212
2322-2212
2015
2
2
Mathematical modeling the effect of catalyst initial shape and the crack pattern in olefin copolymerization
Marzieh
Nouri
Mahmoud
Parvazinia
Hassan
Arabi
Mohsen
Najafi
A two-dimensional (2D) single particle model for the copolymerization of propylene-ethylene with heterogeneous Ziegler-Natta catalyst is developed. The model accounts for the effects of the initial shape of the catalyst and carck/ pore patterns on the copolymer composition, polymerization rate and the average molecular weight properties. The spherical and oblate ellipsoidal shapes of catalyst particle and four different pattern distributions of cracks and pores in a growing particle are studied in this simulation. It is assumed that the diffusion coefficient of monomers in the cracks/pores is 10 times higher than the compact zone of the particle.In other word, the cracks are distinguished from parts with higher monomer diffusion coefficient.The dynamic 2D monomer diffusion-reaction equation is solved together with a two-site catalyst kinetic mechanism using the finite element method. Simulation results indicate that the initial shape of catalyst changes the average copolymer composition only in the early stage of polymerization, but the crack/pore patterns in the growing particle have a strong impact on the copolymer composition in the polymer particles due to the change ofmass transfer limitations.
single particle
modelling
finite element method
polyolefin
copolymerization
2015
06
01
121
133
http://poj.ippi.ac.ir/article_1165_b2df56b622f083cfcc23024846130f45.pdf