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Graphite-LDH hybrid supported zirconocene for ethylene polymerization: Influence of the support on the crystallization kinetics and thermal stability of polyethylene
https://orcid.org/0000-0002-2686-0231
https://orcid.org/0000-0002-6500-7532
Abstract A hybrid nanomaterial, low crystallinity graphite-layered double hydroxide, was used as a support for zirconocene catalyst. The hybrid nanomaterial graphite-NiAl layered double hydroxides (G/LDH) were synthesized by the co-precipitation method. The synthesized nanomaterial was used as a support for zirconocene catalyst. The polymerization reactions were carried out for ethylene polymerization. The synthesized polyethylene (PE) was analyzed by using differential scanning calorimetry (DSC), Crystallization analysis & fractionation (CRYSTAF), and thermogravimetric analysis for its thermal and microstructural characteristics. The crystallization kinetics were studied by the Ozawa and combined Ozawa and Avrami models. It was found that the presence of G/LDH from the catalyst support nucleated the PE crystallization and shifted the crystallization onset temperature to a higher value. However, the overall crystallization rate was slowed by the presence of the nanomaterial due to growth impingement. Moreover, the PE synthesized by G/LDH supported catalyst possessed higher thermal stability than PE synthesized by unsupported zirconocene catalyst. The integral isoconversional method was used to evaluate the activation energy of thermal degradation and crystallization kinetics. The degradation mechanism was validated by the application of the integral master plot technique. The degradation mechanism of neat PE resembled phase boundary controlled mechanism second and third-order, i.e. (R2, R3), while PE synthesized by G/LDH supported catalyst had a shift in degradation mechanism from (R2, R3) to a diffusion-limited mechanism at the later stages of degradation.
Highlights Polyethylene (PE) was synthesized by using low crystallinity graphite-NiAl LDH (G/LDH) supported zirconocene catalyst. The presence of G/LDH nucleated the PE crystallization and shifted the Tonset to a higher value. The degradation mechanism was studied; neat PE followed phase boundary-controlled mechanism (R2, R3). SZ-PE initially followed R2, R3 mechanism and then diffusion-limited mechanism at a higher temperature.
Graphite-LDH hybrid supported zirconocene for ethylene polymerization: Influence of the support on the crystallization kinetics and thermal stability of polyethylene
https://orcid.org/0000-0002-2686-0231
https://orcid.org/0000-0002-6500-7532
Abstract A hybrid nanomaterial, low crystallinity graphite-layered double hydroxide, was used as a support for zirconocene catalyst. The hybrid nanomaterial graphite-NiAl layered double hydroxides (G/LDH) were synthesized by the co-precipitation method. The synthesized nanomaterial was used as a support for zirconocene catalyst. The polymerization reactions were carried out for ethylene polymerization. The synthesized polyethylene (PE) was analyzed by using differential scanning calorimetry (DSC), Crystallization analysis & fractionation (CRYSTAF), and thermogravimetric analysis for its thermal and microstructural characteristics. The crystallization kinetics were studied by the Ozawa and combined Ozawa and Avrami models. It was found that the presence of G/LDH from the catalyst support nucleated the PE crystallization and shifted the crystallization onset temperature to a higher value. However, the overall crystallization rate was slowed by the presence of the nanomaterial due to growth impingement. Moreover, the PE synthesized by G/LDH supported catalyst possessed higher thermal stability than PE synthesized by unsupported zirconocene catalyst. The integral isoconversional method was used to evaluate the activation energy of thermal degradation and crystallization kinetics. The degradation mechanism was validated by the application of the integral master plot technique. The degradation mechanism of neat PE resembled phase boundary controlled mechanism second and third-order, i.e. (R2, R3), while PE synthesized by G/LDH supported catalyst had a shift in degradation mechanism from (R2, R3) to a diffusion-limited mechanism at the later stages of degradation.
Highlights Polyethylene (PE) was synthesized by using low crystallinity graphite-NiAl LDH (G/LDH) supported zirconocene catalyst. The presence of G/LDH nucleated the PE crystallization and shifted the Tonset to a higher value. The degradation mechanism was studied; neat PE followed phase boundary-controlled mechanism (R2, R3). SZ-PE initially followed R2, R3 mechanism and then diffusion-limited mechanism at a higher temperature.
Graphite-LDH hybrid supported zirconocene for ethylene polymerization: Influence of the support on the crystallization kinetics and thermal stability of polyethylene
https://orcid.org/0000-0002-2686-0231
https://orcid.org/0000-0002-6500-7532
Abstract A hybrid nanomaterial, low crystallinity graphite-layered double hydroxide, was used as a support for zirconocene catalyst. The hybrid nanomaterial graphite-NiAl layered double hydroxides (G/LDH) were synthesized by the co-precipitation method. The synthesized nanomaterial was used as a support for zirconocene catalyst. The polymerization reactions were carried out for ethylene polymerization. The synthesized polyethylene (PE) was analyzed by using differential scanning calorimetry (DSC), Crystallization analysis & fractionation (CRYSTAF), and thermogravimetric analysis for its thermal and microstructural characteristics. The crystallization kinetics were studied by the Ozawa and combined Ozawa and Avrami models. It was found that the presence of G/LDH from the catalyst support nucleated the PE crystallization and shifted the crystallization onset temperature to a higher value. However, the overall crystallization rate was slowed by the presence of the nanomaterial due to growth impingement. Moreover, the PE synthesized by G/LDH supported catalyst possessed higher thermal stability than PE synthesized by unsupported zirconocene catalyst. The integral isoconversional method was used to evaluate the activation energy of thermal degradation and crystallization kinetics. The degradation mechanism was validated by the application of the integral master plot technique. The degradation mechanism of neat PE resembled phase boundary controlled mechanism second and third-order, i.e. (R2, R3), while PE synthesized by G/LDH supported catalyst had a shift in degradation mechanism from (R2, R3) to a diffusion-limited mechanism at the later stages of degradation.
Highlights Polyethylene (PE) was synthesized by using low crystallinity graphite-NiAl LDH (G/LDH) supported zirconocene catalyst. The presence of G/LDH nucleated the PE crystallization and shifted the Tonset to a higher value. The degradation mechanism was studied; neat PE followed phase boundary-controlled mechanism (R2, R3). SZ-PE initially followed R2, R3 mechanism and then diffusion-limited mechanism at a higher temperature.
Graphite-LDH hybrid supported zirconocene for ethylene polymerization: Influence of the support on the crystallization kinetics and thermal stability of polyethylene
Shehzad, Farrukh (Autor:in) / Al-Harthi, Mamdouh A. (Autor:in)
Applied Clay Science ; 202
27.11.2020
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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