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Formation of the alpha and gamma polymorphs in random metallocene-propylene copolymers. Effect of concentration and type of comonomer

Formation of the alpha and gamma polymorphs in random metallocene-propylene copolymers. Effect of concentration and type of comonomer
Formation of the alpha and gamma polymorphs in random metallocene-propylene copolymers. Effect of concentration and type of comonomer
Four sets of random propylene-based copolymers with 1-10 mol % of ethylene, 1-butene, 1-hexene, or 1-octene as co-units, synthesized with the same metallocene catalyst, were investigated by differential scanning calorimetry and wide-angle X-ray scattering following rapid and isothermal crystallization. Parameters related to defect concentration, defect type, and microstructure and thermodynamic and kinetic factors were evaluated as to their role in developing the gamma polymorph. The effect of the comonomer in enhancing the fractional content of the gamma polymorph is akin to the role of defects in the homo-poly(propylene) chain. However, differences in the partitioning of the comonomer between the crystalline and noncrystalline regions leads to contents of the gamma phase that differ among the copolymers at any given crystallization temperature. Qualitatively, these differences can be used to assess the degree to which a counit participates in the crystallite. The experimental results suggest that there is no discrimination of the defects that enter the crystal lattice (stereo, regio, ethylene, or butylene units) between the alpha or gamma crystallites. The results with copolymers establish that the bases that lead to the formation of the gamma polymorph are the same for homo-poly(propylene) and its copolymers.
5623-5636
Hosier, I.L.
6a44329e-b742-44de-afa7-073f80a78e26
Alamo, R.G.
645b9a45-2766-424e-9509-37246e42942e
Esteso, P.
54a896ae-7a92-4736-9a93-5c880d83e0f2
Isasi, J.R.
84416781-32df-4231-a92d-dc5ce5dd324c
Mandelkern, L.
7bd8692b-597d-479b-931e-f6ddf6513c44
Hosier, I.L.
6a44329e-b742-44de-afa7-073f80a78e26
Alamo, R.G.
645b9a45-2766-424e-9509-37246e42942e
Esteso, P.
54a896ae-7a92-4736-9a93-5c880d83e0f2
Isasi, J.R.
84416781-32df-4231-a92d-dc5ce5dd324c
Mandelkern, L.
7bd8692b-597d-479b-931e-f6ddf6513c44

Hosier, I.L., Alamo, R.G., Esteso, P., Isasi, J.R. and Mandelkern, L. (2003) Formation of the alpha and gamma polymorphs in random metallocene-propylene copolymers. Effect of concentration and type of comonomer. Macromolecules, 36 (15), 5623-5636.

Record type: Article

Abstract

Four sets of random propylene-based copolymers with 1-10 mol % of ethylene, 1-butene, 1-hexene, or 1-octene as co-units, synthesized with the same metallocene catalyst, were investigated by differential scanning calorimetry and wide-angle X-ray scattering following rapid and isothermal crystallization. Parameters related to defect concentration, defect type, and microstructure and thermodynamic and kinetic factors were evaluated as to their role in developing the gamma polymorph. The effect of the comonomer in enhancing the fractional content of the gamma polymorph is akin to the role of defects in the homo-poly(propylene) chain. However, differences in the partitioning of the comonomer between the crystalline and noncrystalline regions leads to contents of the gamma phase that differ among the copolymers at any given crystallization temperature. Qualitatively, these differences can be used to assess the degree to which a counit participates in the crystallite. The experimental results suggest that there is no discrimination of the defects that enter the crystal lattice (stereo, regio, ethylene, or butylene units) between the alpha or gamma crystallites. The results with copolymers establish that the bases that lead to the formation of the gamma polymorph are the same for homo-poly(propylene) and its copolymers.

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Published date: July 2003
Organisations: Electronics & Computer Science, EEE

Identifiers

Local EPrints ID: 265718
URI: http://eprints.soton.ac.uk/id/eprint/265718
PURE UUID: 6ccbedd7-fc58-4ed8-ba50-a80202dacbdf
ORCID for I.L. Hosier: ORCID iD orcid.org/0000-0003-4365-9385

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Date deposited: 15 May 2008 09:52
Last modified: 25 Sep 2020 01:35

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