Dataset Information

Preparation of High-Performance Polyethylene Nanocomposites with Oleic Acid-Siloxene-Supported Ziegler-Natta Catalysts.

ABSTRACT: The addition of two-dimensional inorganic nanomaterials can effectively enhance the properties of polyethylene (PE). In the present study, a series of high-performance PE/oleic acid (OA)-siloxene nanocomposites were prepared by in situ polymerization using OA-siloxene-supported Ziegler-Natta catalysts. Compared with the conventional Ziegler-Natta catalyst, the polymerization activity of the OA-siloxene-supported Ziegler-Natta catalyst was enhanced to 100 kg/mol-Ti•h, an increase of 56%. The OA-siloxene fillers exhibited excellent dispersion within the PE matrix through the in situ polymerization technique. Compared to pure PE, PE/OA-siloxene nanocomposites containing 1.13 wt% content of OA-siloxene showed 68.3 °C, 126%, 37%, and 46% enhancements in T_dmax, breaking strength, modulus, and elongation at break, respectively.

SUBMITTER: Yue H

PROVIDER: S-EPMC11314101 | biostudies-literature | 2024 Aug

REPOSITORIES: biostudies-literature

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Preparation of High-Performance Polyethylene Nanocomposites with Oleic Acid-Siloxene-Supported Ziegler-Natta Catalysts.

Yue Huan H Yan Xin X Huang Chenghan C Zhang Hexin H Yang Jianming J Fang Liang L Kim Hee-Seon HS

Molecules (Basel, Switzerland) 20240802 15

The addition of two-dimensional inorganic nanomaterials can effectively enhance the properties of polyethylene (PE). In the present study, a series of high-performance PE/oleic acid (OA)-siloxene nanocomposites were prepared by in situ polymerization using OA-siloxene-supported Ziegler-Natta catalysts. Compared with the conventional Ziegler-Natta catalyst, the polymerization activity of the OA-siloxene-supported Ziegler-Natta catalyst was enhanced to 100 kg/mol-Ti•h, an increase of 56%. The OA-s ...[more]

PMID: 39125068

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Project description:Olefin polymerization using Ziegler-Natta catalysts (ZNCs) is an important industrial process. Despite this, fundamental insight into the inner working mechanisms of these catalysts remains scarce. Here, we focus on the low-γ nuclei 25Mg and 35Cl for an in-depth solid-state NMR and density functional theory (DFT) study of the catalyst's MgCl2 support in binary adducts prepared by ball-milling. Besides the bare MgCl2 support and a MgCl2-TiCl4 adduct, samples containing donors that are part of the families of 2,2-dialkyl-1,3-dimethoxypropanes and phthalates used in fourth- and fifth-generation ZNCs are studied. DFT calculations indicate that the quadrupolar coupling parameters of the chlorines differ significantly between bulk and surface sites. As a result, the NMR visibility of the chlorine sites correlates with the particle size except for the adduct with 2,2-dimethyl-1,3-dimethoxypropane donor. The DFT calculations furthermore show that the surface sites are fairly insensitive to binding of different donor molecules, making it difficult to identify specific binding motives. The surface sites with large 35Cl NMR line widths can be observed using high radio frequency field strengths. For the 2,2-dimethyl-1,3-dimethoxypropane donor, we observe additional surface sites with intermediately high quadrupolar couplings, suggesting a different surface structure for this particular adduct compared to the other systems. For 25Mg, pronounced effects of donor binding on the quadrupole interaction parameters are observed, both computationally and experimentally. Again the adduct with the 2,2-dimethyl-1,3-dimethoxypropane donor shows a different behavior of the surface sites compared to the other adducts, which display more asymmetric coordinations of the surface Mg sites. Identifying specific binding motives by comparing 25Mg NMR results to DFT calculations also proves to be difficult, however. This is attributed to the existence of many defect structures caused by the ball-milling process. The existence of such defect structures both at the surface and in the interior of the MgCl2 particles is corroborated by NMR relaxation studies. Finally, we performed heteronuclear correlation experiments, which reveal interactions between the support and Mg-OH surface groups, but do not provide indications for donor-surface interactions.

Dataset Information

Preparation of High-Performance Polyethylene Nanocomposites with Oleic Acid-Siloxene-Supported Ziegler-Natta Catalysts.

Publications

Preparation of High-Performance Polyethylene Nanocomposites with Oleic Acid-Siloxene-Supported Ziegler-Natta Catalysts.

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