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

Abstract

Three different sets of styrene-based ionomer homoblends containing ca. 5 mol% of ionic repeat units, i.e. poly(styrene-co-sodium itaconate) [P(S-co-ITANa)]/ poly(styrene-co-sodium methacrylate) [P(S-co-MANa)] ionomer blends, sodium sulfonated polystyrene [P(S-co-SSNa)]/P(S-co-MANa) ionomer blends, and P(S-co-ITANa)/P(S-co-SSNa) ionomer blends, were prepared and their dynamic mechanical properties were investigated. It was observed that with increasing itaconate content in the blend of P(S-co-ITANa)/P(S-co-MANa) ionomers the multiplet of the P(S-co-MANa) ionomer disrupted initially very rapidly, and ionic modulus of the blend increased drastically. In the case of P(S-co-ITANa)/P(S-co-SSNa) ionomer blends, again, 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 ionomers increased to over 6 mol%, at which the cluster phase of the P(S-co-MANa) ionomers is known to become dominant, compared to the matrix phase, the three loss tangent peaks were observed, which implies that methacrylate-rich and sulfonaterich 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 random copolymer ionomers becomes more important, compared to the role of host non-ionic units. As a concluding remark, the properties of these three ionomer blend systems depend on the degree of clustering, type of ionic groups, and the number of ionic groups per repeat unit.

First sources in infrared light: stars, supernovae and miniquasars

“…Note that the supernova spectrum of a Pop III star is highly uncertain in terms of spectral shape at the UV end, and more numerical models are needed to further address the extent to which supernovae may be an important source of ionizing photons. A more likely scenario involving Pop III supernovae is the one described in Oh et al (2003), where the blast wave propagates to the dense ionized IGM and heats the electrons to a substantial temperature which subsequently cools via inverse Compton scattering off of the cosmic microwave background, similar to the same effect related to hot electrons in galaxy clusters (the Sunyaev-Zel'dovich effect; Sunyaev & Zel'dovich 1980).…”

“…The formation of such massive stars in the early Universe has many important cosmological implications (e.g. Carr, Bond & Arnett 1984;Oh, Cooray & Kamionkowski 2003;Yoshida, Bromm & Hernquist 2004). Because radiation below the Lyman limit is absorbed by neutral hydrogen, luminous sources at redshifts of 10 E-mail: asante@caltech.edu and higher are generally seen only in the near-IR band.…”

Effects of dust grains on early galaxy evolution

“…This can directly constrain the abundance of metals formed in the early epoch of galaxy evolution. [Oh (2002) have also proposed to probe high‐redshift intergalactic medium metallicity by metal absorption lines.] In order to detect the stellar light from the high‐redshift Universe, observations by the Next Generation Space Telescope 2 ( NGST ) in the near‐infrared (NIR) will be particularly suitable.…”

The effect of cluster magnetic field on the Sunyaev-Zel'dovich power spectrum

“…Supernova remnants generated by first stars cool mainly through Compton scattering over CMB photons. The high efficiency of such energy injection into the CMB could introduce a SZ effect comparable to that of low-redshift gas (Oh, Cooray & Kamionkowski 2003).…”