Mechanical properties of P(S-co-ITANA)/P(S-co-MANA), P(S-co-SSNA)/P(S-co-MANA), and P(S-co-ITANA)/P(S-co-SSNA) ionomer homoblends

摘要

Three different sets of styrene-based ionomer homoblends containing ca. 5 mol% af ionic repeat units, i.e. poly(styrene-co-sodium itaconale) [P(S-co-ITANa)]/ poly(styrene-co-sodium methacrylate) [P(S-coMANa)] ionomer blends, sodium oiiilfonated polystyrene [P(S-t0-SSNa)]/P(S-fo-MANa) ionomer blends, and P(S-co-ITANa)/P(S-eo-SSNa) ionomer blends, were prepared and their dynamic mechanical aroperties were investigated. It was observed that with increasing itaconate content in the blend of P(S-co-ITANa)/P(S-co-MANa) ionomers the multiple! of the P(S-co-VlANa) ionomer disrupted initially very rapidly, and ionic modulus of the blend .ncrcased drastically. In the case of P(S-co-ITANa)/P(S-co-SSNa) ionomer blends, igain, the ionic modulus increased significantly with increasing itaconate content. In these two ionomer blend systems, the itaconate, having two ionic groups per ionic repeat unit, influenced the properties of the blends more noticeably than the other, two ionic units, containing only one ionic group per ionic repeat unit. In the blend system of P(S-co-SSNa)/P(S-co-MANa), as expected, the cluster loss tangent peak shifted to higher temperature, ionic modulus decreased, but the ionic plateau extended more with increasing the ratio of the P(S-co-SSNa) content. However, it should be mentioned that when the ion contents of the methacrylate and sulfonate onomers increased to over 6 mol%, at which the cluster phase of the P(S-roMANa) onomers is known to become dominant, compared to the matrix phase, the three loss tangent peaks were observed, which implies that mcthacrylate-rich and sulfonate-ich phases exist together. This might be due to the fact that a copolymerization effect becomes stronger; that is, with increasing ion content the role of ionic units in oandom copolymer ionomers becomes more important, compared to the role of host ion-ionic units. As a concluding remark, the properties of these three ionomer blend iystems depend on the degree of clustering, type of ionic groups, and the number of onic groups per repeat unit.