ABSTRACT:The early stage of spinodal decomposition of partially miscible poly(methyl methacrylate)/poly(styrene-co-acrylonitrile) blend was studied by time-resolved synchrotron radiation small-angle X-ray scattering (SR-SAXS). Intensity change of a scattering peak corresponding to the concentration fluctuation was traced after rapid heating to the two-phase region from the miscible state. At the initial stage, the dominant phase size was kept constant on the order of tens of nanometers, and then, grew to the order of sub-microns during decomposition. The apparent diffusion constant was determined according to the Cahn-Hilliard theory.KEY WORDS Spinodal Decomposition / Polymer Blend / Poly(methyl methacrylate) / Poly(styrene-co-acrylonitrile) / Synchrotron Radiation-SAXS / Some investigations 1 -11 have been made on spinodal decompositon (SD) of partially miscible polymer blend systems out of interest in both basic research and industrial applications. Light scattering, electron microscopy etc. have played important roles in these investigations. Studies on the early stage of SD succeeded in verifying the application of the Cahn's theory 12 to polymer blends and also clarification of the mechanism of phase separation.The range of wavelength used in the light scattering experiments is limited so that we are not necessarily able to detect the dominant concentration fluctuation at the early stage SD. X-Rays are sometimes used as a light source to observe segmental order fluctuation. Though small-angle X-ray scattering (SAXS) is favorable from the point of detectable structural dimension, it generally requires long exposure time. So it is not suited for time-resolved measurements of structural change. As far as we know, only a few reports 13 -16 have been published on the application of SAXS for the dynamic study of phase separation of partially miscible blends. In these reports synchrotron radiation (SR) was used as the X-ray source because of its high flux, which is needed to perform time-resolved measurements. Phase separation phenomena were investigated for both upper critical solution temperature (UCST) type blends and lower critical solution temperature (LCST) type blends by time-resolved SR-SAXS: for the UCST type, low molecular weight polystyrene/polybutadiene blends, 13 and for the LCST type, polyt Present address:
ABSTRACT:Miscibility of binary blends of terpolymer of methyl methacrylate (MMA), acrylonitrile (AN) and styrene (MAS) and copolymer of St and AN (SAN), or MAS and PMMA was studied by light scattering experiments and optical microscope observation. Miscibility windows were calculated from solubility parameter on the basis of mean field approximations. The experimental results showed a good coincidence with the theoretical predictions of the miscibility window.KEY WORDS Miscibility/ Blend/ Styrene and Acrylonitrile / Poly(methyl methacrylate) / Terpolymer / Several studies 1 -4 were reported on the miscibility of blends of copolymer, poly(A-co-B) with homopolymer, poly(C). It is known from preceeding studies that the blend is miscibile only in certain restricted composition ranges of the copolymer. These are systems in which the component homopolymers corresponding to the constituents of the copolymer, e.g., poly(A) and poly(B), are not miscible with each other and neither with the homopolymer, poly(C), but when copolymerized there appears miscibility between copolymer and homopolymer. Mean field approximation by ten Brinke et al. 5 succeeded in explaining this behavior quantitatively.In this paper we investigated the miscibility of the blends of terpolymer of methyl methacrylate, acrylonitrile, and styrene (MAS) with copolymer of styrene and acrylontrile (SAN), and with homopolymer of methyl methacrylate (PMMA), and tried to apply the· mean field theory to the blends containing the terpolymer. EXPERIMENTALMAS was synthesized by a bulk and an emulsion polymerization in our laboratory. PMMA and SAN were commercial grades of Sumitomo Chemical Co., Ltd. and Sumitomo Naugatuck Co., Ltd., respectively. Details of the samples were shown in Table I.Compositions were determined by 13 C NMR and molecular weight of samples were determined by a size exclusion chromotography equipped with a refractometer and a UV meter as detectors. Blends were prepared by dissolving two polymers into 1,2-dichloroethane and casting onto a slide glass at ambient temperature. Concentration of solution was 2% by weight. For cloud point measurement, casted films were pressed at 135°C and annealed at 135°C further for 1 day. The sample thickness was 0.1 mm for MAS/PMMA blends and 0.5 mm for MAS/SAN blends.Both a Nikon Optiphotopol for the macroscopic observation and light scattering system equipped with a gonio-photometer (Optec Co., 643
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