Sodium sulfonated poly(styrene-ethylene-butylene) random ionomers [P(SEB-co-SSNa)] were obtained by hydrogenation, sulfonation, and neutralization of styrene-butadiene copolymers containing 45 wt % styrene. The dynamic mechanical properties were measured as a function of temperature for ionomers of a wide range of ion contents. Most of the ionomers showed two glass transitions, as well as a well-developed ionic plateau region in the storage modulus between the two glass transitions. The loss tangent peak of the upper Tg appeared below the decomposition temperature of the polymer, which permitted its detailed analysis as a function of ion concentration. The results of this study are explained on the basis of a recent model of morphology of ionomers in the solid state (the EHM model) and compared with those of the styrene-sodium methacrylate copolymers [P(S-co-MANa)] and sodium sulfonated polystyrene [P(S-co-SSNa)]. Considerable similarities exist in the properties of the matrix phase in the P(SEB-co-SSNa) and P(S-co-MANa) ionomer systems, in spite of the differences in composition. The P(SEB-co-SSNa) and P(S-co-SSNa) ionomer systems show similarities in the properties of the cluster phases, which, however, differ from those in the P(S-co-MANa). A detailed analysis of the storage modulus and the loss tangent curves showed that the storage modulus in the ionic plateau region is controlled by a filler effect of the dispersed phase (cluster or matrix) when there is only one continuous phase in the system. The storage modulus changes according to the logarithmic mixing rule when both the matrix and cluster phases are cocontinuous. Also, percolation theory can be applied to the modulus values of the P(SEB-co-SSNa) ionomer system.

In fiber‐reinforced plastic materials, the fiber volume fraction is one of the most important parameters, and it strongly influences the composite properties. However, it is hard to improve impregnation and the fiber volume fraction in fiber‐reinforced thermoplastics because thermoplastic resins have high melt viscosities. This study explored a reformative solution impregnation method for molding fabric‐reinforced thermoplastic composites with a high fiber volume fraction. The fiber volume fraction was significantly increased, to 60%, which is equal to that of fiber‐reinforced thermosetting plastic materials. A comparison indicated that a fiber‐reinforced thermoplastic and a fiber‐reinforced thermosetting plastic with the same reinforcing fiber had similar tensile properties and that the proposed molding method is effective in thermoplastic composite manufacture. POLYM. COMPOS., 34:953–958, 2013. © 2013 Society of Plastics Engineers

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KEY WORDSMorphology 1 Small-Angle X-Ray Scattering I Ionomer I Styrene-Butadiene I Ionomer Peak I Hydrogenation I During the past three decades, extensive studies have been performed to improve our understanding of the morphology and properties of ionomers. It is generally accepted that ionic groups form aggregates, called multiplets. 1 The Eisenberg-Hird-Moore (EHM) model, a recent model of the morphology of random ionomers, postulates that polymer chains surrounding the multiplets undergo reduction in mobility. 2 At very low ion content, only multiplets are present. As the number density of the multiplets increases with ion content, the regions of restricted mobility start to overlap and form large contiguous regions of reduced mobility. When the dimensions of these regions exceed ca. 100 A, they are called clusters. 2 In this state, the ionomer exhibits two glass transitions: one for the matrix regions is found at lower temperatures, while that for the cluster regions is located at higher temperatures.In general, clustered ionomers exhibit small-angle peaks in small-angle X-ray scattering (SAXS) profiles. The poly(styrene-co-cesium methacrylate) ionomer containing ca. 7 mol% of ions exhibits the maximum in the SAXS peak at q=ca. 0.32A -1 (q=4nsin8fJ,, where e is half the scattering angle and Jc is the X-ray wavelength). 3 q corresponds to a Bragg spacing (dsragg) of ca. 20 A.Bragg spacing is thought to reflect the distance between multiplets. 4 • 5 The poly(styrene-co-cesium styrenesulfonate) ionomer (ca. 5 mol% of ions) shows the maximum of the SAXS peak at qmax=ca. 0.15A -1 (dsragg=ca. 42 A). 6 Another interpretation of the SAXS profile, the so-called core-shell model, has also been proposed. 7 The dynamic mechanical properties of sulfonated poly(styrene-co-ethylene-co-butylene) (SPSEB) random ionomers have been investigated. 8 Thus, as a follow-up work, the present study explores the morphology of the SPSEB ionomers. The comparison of the results obtained in this study with those from the sulfonated polystyrene ionomers is also made. Among the results obtained in the present study, the answers to the following two questions are of most importance; 1) what type of morphology does this ionomer system have? 2) what is the effect of the matrix Tg on the multiplet formation?t To whom correspondence should be addressed. EXPERIMENTAL Polymer SynthesisThe preparation and sulfonation of a hydrogenated poly(styrene-co-butadiene) random copolymers, i.e., poly(styrene-co-ethylene-co-butylene) (PSEB), are described elsewhere. 8 The PSEB copolymer is composed of 73 mol% of ethylene, 8 mol% of butylene, and 19 mol% of styrene. The polymer was sulfonated using a modification of the sulfonation method of Thaler. 9 The sulfonation level was determined by titration of the sulfonated PSEB (SPSEB) sample with standard methanolic NaOH to the phenolphthalein end point. Sample PreparationThe copolymers were dissolved in a mixture of xylenefl-butanol (3/1 vfv, for ionomers of low ion contents) or in a mixture of methanolftetrahyd...

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