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Mechanical and thermal properties of potassium salts of poly(ethylene‐ co ‐ethylacrylate): Polyolefin ionomers in the absence of acid groups
Author(s) -
Aoyama Masataka,
Koda Tomonori,
Miyata Ken,
Nishio Taichi,
Nishioka Akihiro
Publication year - 2015
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.24023
Subject(s) - crystallinity , materials science , differential scanning calorimetry , ionomer , vicat softening point , chemical engineering , polymer chemistry , softening point , ionic bonding , dynamic mechanical analysis , thermal analysis , composite material , polymer , ion , organic chemistry , thermodynamics , chemistry , copolymer , thermal , engineering , physics
The thermal and mechanical properties of ionomers prepared by partial saponification of poly(ethylene‐ co ‐ethylacrylate) (EEA) with potassium were investigated by using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The Vicat softening temperature (VST) and bending modulus were also evaluated. Molecular design of the present EEA‐based ionomers eliminates acid groups, which affect ionic aggregates for conventional ionomers. The DSC results showed that the melting enthalpy and main crystallization temperature decreased as the ion content increased, whereas on the other hand, the crystal melting temperature at about 360 K did not depend on the ion content, and a secondary exothermal peak was observed in the cooling process. The variance of the VST increased as the crystallinity decreased. The temperature‐dependent curves of DMA data of the EEA‐based potassium ionomers with a higher ion content showed elastic plateau even at temperatures above their crystal melting points. Our results indicate the existence of strong cross‐linking mediated by ion aggregates. The quadratic increase of stiffness as a function of ion content, increasing VST with decreasing crystallinity, and elastic plateau of temperature‐dependent moduli above crystal melting temperature are significant characteristics of the EEA‐based potassium ionomers, which contain ionic aggregations without acid group presence. POLYM. ENG. SCI., 55:1843–1848, 2015. © 2014 Society of Plastics Engineers