Ethoxide Type Research Articles

Bi‐supported Ziegler–Natta TiCl4/MCM‐41/MgCl2 (ethoxide type) catalyst preparation and comprehensive investigations of produced polyethylene characteristics

ABSTRACTBi‐supported Ziegler–Natta catalysts (TiCl4/MCM‐41/MgCl2 (ethoxide type)) were synthesized to improve the morphology and the properties of polyethylene. The morphology control is a crucial issue in polymerization process, while tailoring the properties of polymers is needed for specific applications. The catalysts were synthesized in different ratios of two supports with impregnation method. The polymerization process was carried out in atmospheric slurry reactor. The catalysts were characterized with scanning electron microscopy ‐ energy dispersive X‐ray spectroscopy (SEM–EDX), inductively coupled plasma, Fourier transform infrared spectrometry (FTIR), and Brunauer‐Emmett‐Teller (BET) methods. The polymers were analyzed with scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry, FTIR, and tensile‐strength analyses. Ubbelohde viscometer and frequency sweep measurements showed that the synthesized polymers are ultra‐high‐molecular‐weight polyethylene. Mechanical properties of polymers showed higher Young's modulus in samples containing MCM‐41, having higher thermal stability supported by TGA analysis. SEM images of bi‐supported catalyst showed a controlled spherical morphology with uniform size distribution. SEM analysis support that the polymers replicate their morphology from catalyst, improving their morphology comparing to MgCl2‐supported catalyst. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48553.

Preparation of ultra‐high‐molecular‐weight polyethylene and its morphological study with a heterogeneous Ziegler–Natta catalyst

AbstractUltra‐high‐molecular‐weight polyethylene (PE) with viscosity‐average molecular weight (Mv) of 3.1 × 106 to 5.2 × 106 was prepared with a heterogeneous Ziegler–Natta MgCl2 (ethoxide type)/TiCl4/triethylaluminum catalyst system under controlled conditions. The optimum activity of the catalyst was obtained at a [Al]/[Ti] molar ratio of 61 : 1 and a polymerization temperature of 60°C, whereas the activity of the catalyst increased with monomer pressure and decreased with hydrogen concentration. The titanium content of the catalyst was 2.4 wt %. The rate/time profile of the catalyst was a decay type with a short acceleration period. Mv of the PE obtained decreased with increasing hydrogen concentration and polymerization temperature. The effect of stirrer speeds from 100 to 400 rpm did not so much affect the catalyst activity; however, dramatic effects were observed on the morphology of the polymer particles obtained. A stirrer speed of 200 rpm produced PE with a uniform globulelike morphological growth on the polymer particles. The particle size distributions of the polymer samples were determined and were between 14 and 67 μm. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Effect of halocarbon promoters on polyethylene properties using MgCl2 (ethoxide type)/TiCl4/AlEt3/H2 catalyst system

AbstractIn our previous study we found that addition of proper amount of halocarbons (HC) including chlorocyclohexane (CHC), chlorocyclopentane (CHP), butylchloride (BC), 1,4‐dichlorobutane (DCB), and chloroform (C) to the MgCl2 (Ethoxide type)/TiCl4/AlEt3 catalytic system leads to a strong productivity improvement. In this study, the effect of these halocarbons on the properties of resulting polymers was investigated using H2 as chain transfer agent at optimum HC/Ti molar ratio. The nature of halocarbon compound had a strong effect on polymer properties as well as on development of polymerization activity. Effect of halocarbon promoters on the polymer melt flow index (MFI), melt flow ratio (MFR), particle size distribution (PSD), bulk density, wax amount, crystallinity, and thermal properties of the polymers were studied. Results showed that, in the presence of halocarbons, polyethylenes with higher MFI and bulk density, broader MFR and lower wax amount have been obtained. Also, sieve analysis showed that, in the presence of halocarbons as promoter, polymers had better particle size distribution (PSD). DSC analysis showed that the Tm of PEs prepared with the different promoters were in the region commonly reported for HDPE and was not affected substantially by halocarbons, but, the crystallinity of the polymers has been improved using halocarbon promoters. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Synthesizing UHMWPE Using Ziegler‐Natta Catalyst System of MgCl2(ethoxide type)/ TiCl4/tri‐isobutylaluminum

AbstractSummery: A Ziegler‐Natta catalyst of MgCl2 (ethoxide type)/TiCl4 has been synthesized. In order to obtain ultra high molecular weight polyethylene (UHMWPE) tri‐isobutylaluminum which is less active to chain transfer was used as cocatalyst. Slurry polymerization was carried out for the polymerization of ethylene while, dilute solution viscometry was performed for the viscosity average molecular weight (Mv) measurement. The effect of [Al]/[Ti] molar ratio, temperature, monomer pressure and polymerization time on the Mv and productivity of the catalyst have been investigated. The results showed increasing [Al]/[Ti] ratio in the range of 78–117, decreased the Mv of the obtained polymer from 7.8 × 106 to 3.7 × 106 however, further increase of the ratio, resulted in decreased of by much slower rate up to [Al]/[Ti] = 588. The higher pressure in the range of 1–7 bars showed the higher the Mv of the polymer obtained, while increasing temperature in the range of 50 to 90 °C decreased the Mv from 9.3 × 106 to 3.7 × 106. The Mv rapidly increase with polymerization time in the first 15 minutes of the reaction, this increase was slowly up to the end of the reaction (120 min). Increasing [Al]/[Ti] ratio raised productivity of the catalyst in the range studied. Rising reaction temperature from 50 to 75 °C increased the productivity of the catalyst however, further increase in the temperature up to the 90 °C decreased activity of the catalyst. Monomer pressure in the range 1 to 7 bars yields higher productivity of the catalyst. Also by varying polymerization conditions synthesizing of UHMWPE with Mv in the range of 3 × 106 to 9 × 106 was feasible.

Investigation of properties of polyethylene/clay nanocomposites prepared by new in situ Ziegler–Natta catalyst

This paper is devoted to investigation of morphological and physical–mechanical properties of polyethylene (PE)/clay nanocomposites prepared via in situ polymerization method using bi-supported Ziegler–Natta catalyst. Bentonite type clay and MgCl 2 (ethoxide type) were used as the support of TiCl 4. Catalyst support and polymerization process have been done in slurry phase using Triisobutylaluminum as the co-catalyst. The microstructure of the nanocomposites was examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD and TEM indicated that almost fully exfoliated PE/clay nanocomposites were produced successfully using this method. According to permeability measurements, it was found that oxygen permeability values of the nanocomposite samples prepared with in situ polymerization method were dropped more than 200% introducing only 1 wt% clay to polymeric matrix. Differential scanning calorimetry (DSC) results indicated that the crystallization temperatures of samples are significantly higher than that of virgin PE. Moderate thermal stability enhancement of in situ polymerized nanocomposites was confirmed using thermogravimetric analysis (TGA).The storage modulus, Young’s modulus and tensile strength of prepared samples were increased where the toughness was declined slightly. It seems that good dispersion and exfoliation of clay during polymerization should be responsible to get more effective reinforcing properties for clay in this method comparing to melt blending method for preparation of polyethylene nanocomposites.

Comparative study of propylene polymerization using monosupported and bisupported titanium‐based Ziegler–Natta catalysts

AbstractHeterogeneous Ziegler–Natta systems—MgCl2 (ethoxide type)/TiCl4/di‐n‐butyl phthalate (DNBP)/triethylaluminum (TEA)/dimethoxymethylcyclohexylsilane (DMMCHS) and SiO2/MgCl2 (ethoxide type)/TiCl4/DNBP/TEA/DMMCHS—were studied for the polymerization of propylene. The slurry polymerization of propylene was carried out with the catalyst systems in n‐heptane. Both systems performed with optimum activity at a particular [Al]/[DMMCHS]/[Ti] molar ratio. The ratio to reach the highest activity was much lower for the bisupported catalyst system. The productivity of the bisupported catalyst was higher than that of the monosupported one. Polypropylene of a high isotacticity index (II; >96%) was obtained with both systems and did not significantly change with an increasing [Al]/[DMMCHS]/[Ti] molar ratio. The addition of hydrogen as a chain‐transfer agent reduced II of the polymers obtained with both systems. The effect of the polymerization temperature (40–75°C) on the viscosity‐average molecular weight (Mv) and II showed a decrease in both cases. The bisupported catalyst system produced a polymer with higher Mv. The effect of temperature on II was similar for both the monosupported and bisupported systems. A monomer pressure of 2.02 × 105 to 0.8 × 106 Pa increased Mv of the obtained polymer. II of the polymer slightly decreased with increasing monomer pressure. The titanium content of the catalyst was 1.70 and 3.55% for the monosupported and bisupported systems, respectively. The surface area of the bisupported catalyst was higher than that of the monosupported catalyst. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2220–2226, 2006

Polymerization of propylene using MgCl2 (ethoxide type)/TiCl4/diether heterogeneous Ziegler–Natta catalyst

AbstractHeterogeneous Ziegler–Natta catalyst of MgCl2 (ethoxide type)/TiCl4/diether was prepared. 2,2‐Diisobutyl‐1,3‐dimethoxy propane (DiBDMP), diether, was used as internal donor. Slurry polymerization of propylene was carried out using the catalyst in dry heptane while triethylaluminium (TEA) was used as co‐catalyst. The co‐catalyst effects, such as catalyst molar ratio, polymerization temperature, H2 pressure, external donor, triisobutylaluminium (TiBA) and monomer pressure, on the activity of the catalyst and isotacticity index (II) of the polymers obtained were studied. Rate of polymerization versus polymerization time is of a decay type with no acceleration period. There are an optimum Al/Ti molar ratio and temperature to obtain the highest activity of the catalyst. The maximum activity was obtained at 60 °C. Increasing the monomer pressure to 1 010 000 Pa linearly increased the activity of the catalyst. Addition of hydrogen to 151 500 Pa pressure increased activity of the catalyst from 2.25 to 5.45 kg polypropylene (PP) (g cat)−1 h−1 using 505 000 Pa pressure of monomer. The II decreased with increasing Al/Ti ratio, monomer pressure, hydrogen pressure and increased with increasing temperature to 60 °C, following with decrease as the temperature increases. Productivity of 11.55 kg (PP) (g cat)−1 h−1 was obtained at 1 010 000 Pa pressure of monomer and temperature of 60 °C. Addition of methyl p‐toluate (MPT) and dimethoxymethyl cyclohexyl silane (DMMCHS) as external donors decreased the activity of the catalyst sharply, while the II slightly increased. Some studies of the catalyst structure and morphology of the polymer were carried out using FTIR, X‐ray fluorescence, scanning electron microscopy and Brunauer–Emmett–Teller techniques. Copyright © 2005 Society of Chemical Industry

Low Cis Polymerization of Butadiene Using TiCl4 and Bisupported with SiO2/MgCl2(Ethoxide Type)/TiCl4 Catalysts

Abstract To obtain low cis polymer of butadiene (PBR), heterogenous and homogeneous Ziegler-Natta catalyst of TiCl4 were used. SiO2 and Mg(OEt)2 were used as supports for the heterogenous catalyst, while TiCl2 was used as a soluble catalyst. Triisobutylaluminium (TIBA) was used as a cocatalyst. Optimum molar ratio of Al/Ti = 1.5 : 1 and Al:Ti = 13 : 1 were obtained for TiCl4/TIBA and SiO2/MgCl2 (ethoxide type)/TiCl4/TIBA catalyst systems, respectively, regarding productivity of the catalysts. Effect of the temperature of 25–65 °C on polymerization was studied for the bisupport one; while for the TiCl4 temperature control was difficult. This could be due to the obtained high gel content of polymer. The highest yield of PBR was obtained at 55 °C using the bisupported catalyst. Addition of H2 as a chain transfer agent decreased cis%, gel content and the yield of polymer obtained. Increasing polymerization temperature when H2 was used was negligible, which had an affect on the gel content of the polymer. Productivity of the bisupported catalyst was higher than the TiCl4 catalyst itself and the polymerization temperature was under control as well. Polymer with cis content of 4 to 65% was obtained using different catalyst and different polymerization conditions.

Polymerization of propylene using the high‐activity Ziegler–Natta catalyst system SiO2/MgCl2 (ethoxide type)/TiCl4/Di‐n‐butyl phthalate/triethylaluminum/dimethoxy methyl cyclohexyl silane

AbstractThe bisupported Ziegler–Natta catalyst system SiO2/MgCl2 (ethoxide type)/TiCl4/di‐n‐butyl phthalate/triethylaluminum (TEA)/dimethoxy methyl cyclohexyl silane (DMMCHS) was prepared. TEA and di‐n‐butyl phthalate were used as a cocatalyst and an internal donor, respectively. DMMCHS was used as an external donor. The slurry polymerization of propylene was studied with the catalyst system in n‐heptane from 45 to 70°C. The effects of the TEA and H2 concentrations, temperature, and monomer pressure on the polymerization were investigated. The optimum productivity was obtained at [Al]/[DMMCHS]/[Ti] = 61.7:6.2:1 (mol/mol/mol). The highest activity of the catalyst was obtained at 60°C. Increasing the H2 concentration to 100 mL/L increased the productivity of the catalyst, but a further increase in H2 reduced the activity of the catalyst. Increasing the propylene pressure from 1 to 7 bar significantly increased the polymer yield. The isotacticity index (II) decreased with increasing TEA, but the H2 concentration, temperature, and monomer pressure did not have a significant effect on the II value. The viscosity‐average molecular weight decreased with increasing temperature and with the addition of H2. Three catalysts with different Mg/Si molar ratios were studied under the optimum conditions. The catalyst with a Mg/Si molar ratio of approximately 0.93 showed the highest activity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1177–1181, 2003

Copolymerization of ethylene/propylene elastomer using high‐activity Ziegler–Natta catalyst system of MgCl2 (ethoxide type)/EB/PDMS/TiCl4/PMT

AbstractA high‐activity Ziegler–Natta catalyst of TiCl4‐supported MgCl2 (ethoxide type) was prepared. Ethyl benzoate (EB) and polydimethylsiloxane (PDMS) were used as internal donors, while p‐methyl toluate (MPT) and triethylaluminum (TEA) were used as the external donor and cocatalyst, respectively. Suspension copolymerization of ethylene–propylene (EPM) was carried out in n‐heptane using the catalyst system. The relative pressures of 1.5 : 1 and 2 : 1 atmosphere of propylene‐to‐ethylene (PP/PE) gave a polymer with elastomeric properties. The relative pressure of propylene‐to‐ethylene higher and lower than the above values, however, gave a homopolymer or copolymer without elastomeric properties. The effect of the TEA concentration, H2 concentration, temperature, and pressure of PP/PE on the yield of the polymer obtained was investigated. The effects of these factors on the glass transition temperature (Tg) and ethylene content of the polymer were studied. The content of ethylene in EPM was determined using the FTIR technique. The molar ratio of Al : MPT : Ti = 355 : 107 : 1 gave a polymer with an ethylene content of about 32%. However, a ratio lower than AL : MPT : Ti = 355 : 107 : 1 did not give a good elastomeric polymer. The highest productivity of the catalyst was obtained at a molar ratio of AL : MPT : Ti = 355 : 107 : 1. Increasing the temperature from 45 to 70°C caused a slight increase of Et % content and a decrease of the Tg of the copolymer obtained, while the highest productivity of the catalyst was obtained at 55°C with good elastomeric properties using an AL : MPT : Ti = 497 : 107 : 1 molar ratio. Increasing the pressure of propylene from 1.5 to 2.5 atm caused a sharp decrease in the Tg and ethylene content of the polymer. When the ethylene content in the copolymer was increased, the Tg value had a tendency to be closer to the polyethylene Tg. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 785–790, 2002; DOI 10.1002/app.10330