Effects of a vanadium post-metallocene catalyst-induced polymer backbone inhomogeneity on UV oxidative degradation of the resulting polyethylene film

Handle URI:
http://hdl.handle.net/10754/594071
Title:
Effects of a vanadium post-metallocene catalyst-induced polymer backbone inhomogeneity on UV oxidative degradation of the resulting polyethylene film
Authors:
Atiqullah, M.; Winston, M. S.; Bercaw, J. E.; Hussain, I.; Fazal, A.; Al-Harthi, M. A.; Emwas, A. H M; Khan, M. J.; Hossaen, A.
Abstract:
A Group 5 post-metallocene precatalyst, (ONO)VCl(THF) 2 (ONO = a bis(phenolate)pyridine LX 2 pincer ligand), activated with modified methylaluminoxane (MMAO-3A) produced a linear ethylene homopolymer (nm-HomoPE)and an unusual inhomogeneous copolymer (nm-CopolyPE) with 1-hexene having very low backbone unsaturation. The nm-CopolyPE inhomogeneity was reflected in the distributions of short chain branches, 1-hexene composition, and methylene sequence length. The 1-hexene incorporation into the polyethylene backbone strongly depended on the molecular weight of the growing polymer chain. (ONO)VCl(THF) 2, because of site diversity and easier removal of a tertiary (vs. a secondary) hydrogen, produced a skewed short chain branching (SCB) profile, incorporating 1-hexene more efficiently in the low molecular weight region than in the high molecular weight region. The significant decrease in molecular weight by 1-hexene showed that the (ONO)VCl(THF) 2 catalytic sites were also highly responsive to chain-transfer directly to 1-hexene itself, producing vinyl and trans-vinylene termini. Subsequently, the effect of backbone inhomogeneity on the UV oxidative degradation of films made from both polyethylenes was investigated. The major functional group accumulated in the branched nm-CopolyPE film was carbonyl followed by carboxyl, then vinyl/ester, whereas that in the linear nm-HomoPE film was carboxyl. However, (carbonyl, carboxyl, vinyl, and ester) nm-CopolyPE film >> (carboxyl) nm-HomoPE film). The distributions of the tertiary C-H sites and methylene sequence length in the branched nm-CopolyPE film enhanced abstraction of H, decomposition of hydroperoxide group ROOH, and generation of carbonyl compounds as compared with those in the linear nm-HomoPE film. This clearly establishes the role played by the backbone inhomogeneity. The effect of short chain branches and sequence length distributions on peak melting temperature T pm, and most probably lamellar thickness L o, was modeled from a nanoscopic viewpoint. The accumulation of the above oxygenated functionalities and its effect on % crystallinity are explained considering polyethylene UV autooxidation mechanism, and Norrish I and Norrish II chain scissions. © 2012 Elsevier Ltd. All rights reserved.
KAUST Department:
KAUST Center In Development at KFUPM; Imaging and Characterization Core Lab
Citation:
Atiqullah M, Winston MS, Bercaw JE, Hussain I, Fazal A, et al. (2012) Effects of a vanadium post-metallocene catalyst-induced polymer backbone inhomogeneity on UV oxidative degradation of the resulting polyethylene film. Polymer Degradation and Stability 97: 1164–1177. Available: http://dx.doi.org/10.1016/j.polymdegradstab.2012.03.042.
Publisher:
Elsevier BV
Journal:
Polymer Degradation and Stability
Issue Date:
Jul-2012
DOI:
10.1016/j.polymdegradstab.2012.03.042
Type:
Article
ISSN:
0141-3910
Sponsors:
The authors thank the King Abdullah University of Science & Technology (KAUST) Center-in-Development for Transformative Research in Petrochemicals and Polymers, established at King Fahd University of Petroleum & Minerals (KFUPM), Dhahran, Saudi Arabia for supporting this research. The technical assistances provided by the Department of Chemistry and Chemical Engineering at California Institute of Technology (Caltech), Pasadena, USA; the King Fahd University of Petroleum & Minerals (KFUPM) Center of Refining & Petrochemicals (CRP) at the Research Institute, the Center of Research Excellence in Petroleum Refining & Petrochemicals (CoRE-PRP), and the Department of Chemical Engineering; Polymer Char, Spain; and KAUST are also gratefully acknowledged. The authors also thank Jubail United Petrochemical Company for donating 1-hexene.
Appears in Collections:
Articles; Advanced Nanofabrication, Imaging and Characterization Core Lab

Full metadata record

DC FieldValue Language
dc.contributor.authorAtiqullah, M.en
dc.contributor.authorWinston, M. S.en
dc.contributor.authorBercaw, J. E.en
dc.contributor.authorHussain, I.en
dc.contributor.authorFazal, A.en
dc.contributor.authorAl-Harthi, M. A.en
dc.contributor.authorEmwas, A. H Men
dc.contributor.authorKhan, M. J.en
dc.contributor.authorHossaen, A.en
dc.date.accessioned2016-01-19T13:20:52Zen
dc.date.available2016-01-19T13:20:52Zen
dc.date.issued2012-07en
dc.identifier.citationAtiqullah M, Winston MS, Bercaw JE, Hussain I, Fazal A, et al. (2012) Effects of a vanadium post-metallocene catalyst-induced polymer backbone inhomogeneity on UV oxidative degradation of the resulting polyethylene film. Polymer Degradation and Stability 97: 1164–1177. Available: http://dx.doi.org/10.1016/j.polymdegradstab.2012.03.042.en
dc.identifier.issn0141-3910en
dc.identifier.doi10.1016/j.polymdegradstab.2012.03.042en
dc.identifier.urihttp://hdl.handle.net/10754/594071en
dc.description.abstractA Group 5 post-metallocene precatalyst, (ONO)VCl(THF) 2 (ONO = a bis(phenolate)pyridine LX 2 pincer ligand), activated with modified methylaluminoxane (MMAO-3A) produced a linear ethylene homopolymer (nm-HomoPE)and an unusual inhomogeneous copolymer (nm-CopolyPE) with 1-hexene having very low backbone unsaturation. The nm-CopolyPE inhomogeneity was reflected in the distributions of short chain branches, 1-hexene composition, and methylene sequence length. The 1-hexene incorporation into the polyethylene backbone strongly depended on the molecular weight of the growing polymer chain. (ONO)VCl(THF) 2, because of site diversity and easier removal of a tertiary (vs. a secondary) hydrogen, produced a skewed short chain branching (SCB) profile, incorporating 1-hexene more efficiently in the low molecular weight region than in the high molecular weight region. The significant decrease in molecular weight by 1-hexene showed that the (ONO)VCl(THF) 2 catalytic sites were also highly responsive to chain-transfer directly to 1-hexene itself, producing vinyl and trans-vinylene termini. Subsequently, the effect of backbone inhomogeneity on the UV oxidative degradation of films made from both polyethylenes was investigated. The major functional group accumulated in the branched nm-CopolyPE film was carbonyl followed by carboxyl, then vinyl/ester, whereas that in the linear nm-HomoPE film was carboxyl. However, (carbonyl, carboxyl, vinyl, and ester) nm-CopolyPE film >> (carboxyl) nm-HomoPE film). The distributions of the tertiary C-H sites and methylene sequence length in the branched nm-CopolyPE film enhanced abstraction of H, decomposition of hydroperoxide group ROOH, and generation of carbonyl compounds as compared with those in the linear nm-HomoPE film. This clearly establishes the role played by the backbone inhomogeneity. The effect of short chain branches and sequence length distributions on peak melting temperature T pm, and most probably lamellar thickness L o, was modeled from a nanoscopic viewpoint. The accumulation of the above oxygenated functionalities and its effect on % crystallinity are explained considering polyethylene UV autooxidation mechanism, and Norrish I and Norrish II chain scissions. © 2012 Elsevier Ltd. All rights reserved.en
dc.description.sponsorshipThe authors thank the King Abdullah University of Science & Technology (KAUST) Center-in-Development for Transformative Research in Petrochemicals and Polymers, established at King Fahd University of Petroleum & Minerals (KFUPM), Dhahran, Saudi Arabia for supporting this research. The technical assistances provided by the Department of Chemistry and Chemical Engineering at California Institute of Technology (Caltech), Pasadena, USA; the King Fahd University of Petroleum & Minerals (KFUPM) Center of Refining & Petrochemicals (CRP) at the Research Institute, the Center of Research Excellence in Petroleum Refining & Petrochemicals (CoRE-PRP), and the Department of Chemical Engineering; Polymer Char, Spain; and KAUST are also gratefully acknowledged. The authors also thank Jubail United Petrochemical Company for donating 1-hexene.en
dc.publisherElsevier BVen
dc.subjectPolyethyleneen
dc.subjectPost-metallocene catalysten
dc.subjectShort chain branchen
dc.subjectUV oxidative degradationen
dc.titleEffects of a vanadium post-metallocene catalyst-induced polymer backbone inhomogeneity on UV oxidative degradation of the resulting polyethylene filmen
dc.typeArticleen
dc.contributor.departmentKAUST Center In Development at KFUPMen
dc.contributor.departmentImaging and Characterization Core Laben
dc.identifier.journalPolymer Degradation and Stabilityen
dc.contributor.institutionCenter for Refining and Petrochemicals (CRP), Research Institute, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabiaen
dc.contributor.institutionCenter of Research Excellence in Petroleum Refining and Petrochemicals (CoRE-PRP), King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabiaen
dc.contributor.institutionDepartment of Chemistry and Chemical Engineering, California Institute of Technology (Caltech), 1200 E. California Blvd., Pasadena, United Statesen
dc.contributor.institutionDepartment of Chemical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabiaen
kaust.authorAtiqullah, M.en
kaust.authorHussain, I.en
kaust.authorHossaen, A.en
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