Observation of bimodal polyethylene derived from TiO2-supported zirconocene/MAO catalyst during polymerization of ethylene and ethylene/1-hexene

Jongsomjit, Bunjerd; Ngamposri, Sutti; Praserthdam, Piyasan

doi:10.1007/s10562-007-9132-7

Cited by 8 publications

(3 citation statements)

References 21 publications

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“…However, by a heterogeneous catalytic system, only one catalyst fixed on the certain support (filler) can generate dual active sites due to the heterogeneity of the support. As observed by our previous work [8] using micro-TiO2 as a support for zirconocene/MAO catalyst, it also found that this catalytic support can produce a bimodal MWD polymer. For further study in production of bimodal MWD polymer here, the TiO2 in nanometer scale (nano-TiO2) was used instead for gaining an advantage of nanotechnology to the resulting product, along with its modification by gallium (Ga) and zirconium (Zr), which have been proven previously as a good modifier in the catalytic system [9,10].…”

Section: Introductionsupporting

confidence: 79%

Observation of Bimodal LLDPE/TiO2 Nanocomposites Produced by in Situ Polymerization with Zirconocene/MMAO Catalysts via Ga Modification on TiO2 Nanofiller

Chaichana¹,

Pathomsap²,

Shiono³

et al. 2013

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Nano-TiO 2 and its modification with gallium (nano-TiO 2-Ga) and zirconium (nano-TiO 2-Zr) were used here as nanofillers in production of linear low-density polyethylene (LLDPE). The nanoparticles were immobilized by modified-methyl aluminoxane (MMAO) to be a catalytic filler prior to introducing into the in situ polymerization of ethylene and 1-hexene using zirconocene catalyst, and consequently produced LLDPE/TiO 2 nanocomposites. It was found that the modified nano-TiO 2 by Ga and Zr can hold more amount of MMAO on the surface than the unmodified one. This is because the modified particles have a stronger interaction between MMAO and the surface, as observed by thermal gravimetric analysis (TGA). However, the stronger interaction leads to lower catalytic activities for the polymerization systems. Observing from the molecular weight distribution (MWD) of the resulting products, it was found that the modified nano-TiO 2 with Ga can produce the LLDPE/TiO 2 nanocomposites with bimodal MWD. This result was due to the heterogeneity of the surface after modification, which can generate the multiple active sites for the catalyst, leading to multimodal properties of the polymer.

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Section: Introductionsupporting

confidence: 79%

Observation of Bimodal LLDPE/TiO2 Nanocomposites Produced by in Situ Polymerization with Zirconocene/MMAO Catalysts via Ga Modification on TiO2 Nanofiller

Chaichana¹,

Pathomsap²,

Shiono³

et al. 2013

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“…However, the homogeneous liquid phase reaction of metallocene is lack of morphology control. Therefore, the supported catalytic system (heterogeneous system), which can improve this problem, has been developed [1]. It has been reported that many inorganic supports such as SiO 2 , Al 2 O 3 and MgCl 2 have been extensively studied.…”

Section: Introductionmentioning

confidence: 99%

A Comparative Study of in situ and ex situ Impregnation for LLDPE/Silica Composites Production

Chaichana¹,

Shiono²,

Praserthdam³

et al. 2012

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Abstract. The two different kinds of impregnation (in situ and ex situ) were used in the heterogeneous copolymerization of ethylene and 1-hexene for production of LLDPE/silica composite. For the ex situ impregnation, MMAO cocatalyst was immobilized firmly onto the silica support through washing and drying step before introducing the powder of MMAO/silica support into the copolymerization system. For the in situ impregnation, MMAO was only contacted with silica support for the short period of time before bringing all of the slurry of MMAO/silica support into the copolymerization system. By comparing the catalytic activity between two methods, it was found that the in situ impregnation provided the higher one beneficial from the lower interaction between MMAO and silica due to lower contacting time. The lower interaction enhanced the reactivity of MMAO toward zirconocene catalyst during activation process thus leading to the higher catalytic activity. The said interaction can be proven by thermal gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) analysis. In addition, the obtained polymers were further characterized by means of scanning electron microscopy (SEM), 13 C-NMR spectroscopy (NMR) and differential scanning calorimetry (DSC).

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“…Furthermore, it has been perceived that active center distribution also has a strong effect on MWD of polymer. It means that the surface structure of MgCl 2 affects on MWD, which influences the physical and mechanical properties, and processability of polymer 2,14 . Up to this point, it can be said that the controlling of polymer properties can be done by the modification of MgCl 2 and the addition of hydrogen.…”

Section: Chapter I Introductionmentioning

confidence: 99%

Effect of hydrogen on Ziegler - Natta catalysts prepared by different methods for ethylene polymerization

Niyomthai

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This study focuses on effect of hydrogen on Ziegler-Natta (ZN) catalyst system for ethylene polymerization. The study was divided into four parts. Regarding to the first part, two types of ZN catalysts, TiCl4/MgCl2/THF (ZN-THF) and TiCl4/MgCl2•6EtOH (ZN-EtOH) catalysts, were compared. The results showed that ZN-EtOH had better active center distribution than that of ZN-THF. As a result, ZN-EtOH could retard the effect of hydrogen and showed higher activity than ZN-THF. According to higher hydrogen response of ZN-THF, ZN-THF system was selected to study in the second and the third parts with Lewis acid modification in order to improve the catalytic performance. AlCl3 and FeCl2 were employed in the second part. FeCl2 showed higher efficiency to remove the remaining THF in MgCl2 structure and provided better hydrogen response than AlCl3. For the third part, ZnCl2, mixed ZnCl2 with AlCl3 and mixed ZnCl2 with FeCl2 were studied in ZN-THF system. The results showed that ZnCl2 acted as a poison to catalyst resulting to the reduction of activity. The addition of the second Lewis acid could improve the activity; however, activity was still slightly lower than undoped ZnCl2 catalyst. For the last part, effect of alkoxysilanes as external donor on 2 types of the commercial catalysts, TiCl4/MgCl2•nEtOH and TiCl4/phthalate type/MgCl2, was investigated. Cyclohexylmethyldimethoxysilane could decrease activity more than dimethoxydimethylsilane did and provide higher hydrogen sensitivity as well.

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Observation of bimodal polyethylene derived from TiO2-supported zirconocene/MAO catalyst during polymerization of ethylene and ethylene/1-hexene

Cited by 8 publications

References 21 publications

Observation of Bimodal LLDPE/TiO2 Nanocomposites Produced by in Situ Polymerization with Zirconocene/MMAO Catalysts via Ga Modification on TiO2 Nanofiller

Observation of Bimodal LLDPE/TiO2 Nanocomposites Produced by in Situ Polymerization with Zirconocene/MMAO Catalysts via Ga Modification on TiO2 Nanofiller

A Comparative Study of in situ and ex situ Impregnation for LLDPE/Silica Composites Production

Effect of hydrogen on Ziegler - Natta catalysts prepared by different methods for ethylene polymerization

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