Some properties of styrene‐based ionomers II

Abstract

Some properties of styrene-based ionomers obtained from copolymers styrene (S) and acrylic acid (AA) or methacrylic acid (MA) obtained in emulsion containing alkali metal salts have been investigated. A study has been conducted to examine the influence of the acid content and nature (acrylic or methacrylic) and nature of alkali metal salt on the glass transition temperature, density, melt index, and activation energy of flow of the styrene-based ionomers.The present studies have indicated that the temperature of glass transition (T g ) of sodium ionomers increases as the sodium content rises, but the increase is lower than in the case of the ionomers based on copolymers obtained in bulk.The density of films rises with the content of alkali metal salt introduced to the polystyrene chain, and it is higher than in the case of the ionomers based on copolymers obtained in bulk containing almost the same content of alkali metal salts. Styrene ionomers containing alkali metal acrylates have higher densities than those containing alkali metal methacrylates. The melt index of the investigated ionomers depends on the amount and type of introduced acid and salt, as well as on the molecular weight of the initial copolymer.

Surface properties of ionomers based on styrene-b-acrylic acid copolymers obtained by copolymerization in emulsion

“…The photooxidation of these ionomers was more effective as well. The reason for such behaviour may be a different structure of both types of ionomers, and consequently some properties of them may vary [13][14][15][16]. In ionomers based on bulk copolymers aggregates, detected by SAXS method [13,14], were smaller than these observed in the case of ionomers obtained from emulsion copolymers.…”

“…This behaviour may result from the sample structures. It is known that the density of styrene copolymers obtained in bulk rose steadily when the content of acrylic acid introduced into polystyrene chain increased [15,16]. It is supposed that similar tendency may occur for copolymers obtained in emulsion.…”

“…The value of water contact angle is higher for S-b-ACs (9.7 mol%) than that for S-b-MCs (10 mol%), 85.18 and 64.58, respectively, which indicates that surface of S-b-ACs (9.7 mol%) is more hydrophobic than that of S-b-MCs (10 mol%). It was proved earlier that the size of clusters (ionic aggregates) is larger in acrylates than methacrylates [14,35] and the density of ionomer is higher for acrylates than for methacrylates [16]. That behaviour is explained by the presence of methyl group on a-carbon in methacrylate unit.…”

“…The density of these samples increases with increasing radii of cations except for ionomer containing lithium ions [16]. The density of this ionomer is higher than that of both initial copolymer and ionomers with Na + and K + ions.…”

“…It is worth comparing the surfaces of these two types of copolymers and ionomers, which because of different ways of formation, have different properties. It was indicated earlier that certain properties of ionomers based on copolymers obtained in bulk or in emulsion were different [12][13][14][15][16].…”