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NMR Characterization of Vis‐Broken Heterophasic Ethylene−Propylene Copolymers
Author(s) -
Matthews Megan,
Magagula Sifiso,
Reenen Albert
Publication year - 2020
Publication title -
macromolecular reaction engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.37
H-Index - 32
eISSN - 1862-8338
pISSN - 1862-832X
DOI - 10.1002/mren.202000039
Subject(s) - ethylene , copolymer , tacticity , ethylene propylene rubber , materials science , polymer chemistry , peroxide , polypropylene , carbon 13 nmr , polymer , catalysis , chemistry , organic chemistry , polymerization , composite material
Solution 13 C nuclear magnetic resonance (NMR) is used in conjunction with in situ solid‐state NMR to determine the effect of peroxide treatment on the chemical structure and morphology of ethylene−propylene copolymers. The copolymers contain increasing quantities of ethylene with the lowest ethylene content corresponding to pure isotactic polypropylene. The vis‐breaking of heterophasic ethylene‐propylene copolymers (HEPCs) is found to be influenced by the homogeneity of the chain sequences. The in situ vis‐breaking in solid‐state NMR reveals significant changes in mobility of the crystalline domains and the formation of a disordered crystal phase within the α structure is observed. Both solution and solid‐state NMR experiments confirm the greater sensitivity of copolymers containing short ethylene sequences to peroxide degradation. It is proposed that longer chain ethylene sequences resist chemical changes and provide some degree of protection from degradation as a result of the reactivity of the ethylene units.