The Experts below are selected from a list of 15102 Experts worldwide ranked by ideXlab platform
Chan Eon Park - One of the best experts on this subject based on the ideXlab platform.
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the effect of freon vapour on fracture behaviour of styrene acrylonitrile Copolymer i craze initiation behaviour
Polymer, 1998Co-Authors: Chan Eon ParkAbstract:Environmental stress cracking behaviour of polystyrene and Styrene-Acrylonitrile Copolymer (SAN) has been studied in Freon vapour in view of molecular weight and acrylonitrile content. The critical stress for craze or crack initiation was measured using three-point bending test and the surface damage was examined by scanning electron microscopy. The critical stress increased with an increase of acrylonitrile content in SAN Copolymer, which suggests that the craze initiation stress has a good correlation with the solubility parameter difference between the polymer and crazing agent. However, molecular weight did not have any significant effects on the critical stress for craze initiation. For homopolystyrene, relatively large-sized craze was developed in Freon vapour due to the increase of softened layer thickness in the developed craze wall. As acrylonitrile content increases the development of craze is suppressed.
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environmental stress cracking of rubber modified styrenic polymers in freon vapour
Polymer, 1997Co-Authors: Chan Eon ParkAbstract:Abstract The effects of incorporation of rubber particles on the environmental stress cracking (ESC) behaviour of rubber modified polystyrene (PS) and Styrene-Acrylonitrile Copolymer (SAN) in Freon vapour have been investigated in view of the rubbery particle size and rubber content. Core-shell particles such as poly( n -butyl acrylate) rubber core/PS or poly(methyl methacrylate) shell particles of 0.2–2 μm in rubbery core diameter were prepared, and these particles were incorporated into a PS or SAN matrix. The larger particles, about 1–2 μm, showed the higher ESC resistance for rubber modified PS, whereas for SAN alloys small particles around 300 nm were the most effective in ESC resistance. Microscopic examination on the Freon-exposed specimen surface revealed that the surface damage is well developed craze in homo PS, and the development of craze is suppressed with increasing rubber content. The yielded lines were observed in homo SAN, and they became vague and diffuse with increasing rubber content. From these results, it was concluded that the role of rubber particles in the ESC process of rubber modified styrenic polymers in Freon vapour is to promote surface plasticization and to suppress the development of local damage on the specimen surface. © 1997 Elsevier Science Ltd.
Donald R Paul - One of the best experts on this subject based on the ideXlab platform.
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poly styrene co acrylonitrile montmorillonite organoclay mixtures a model system for abs nanocomposites
Polymer, 2005Co-Authors: Holly A Stretz, Donald R Paul, Patrick E CassidyAbstract:Abstract Dispersion of clay particles in acrylonitrile–butadiene–styrene (ABS) and styrene–acrylonitrile Copolymer (SAN) nanocomposites with montmorillonite (MMT) have been compared to assess whether ABS/MMT nanocomposite behavior can be adequately modeled using the simpler SAN/MMT system. Electron microscopy photomicrographs show that clay particles in ABS/MMT composites reside in the SAN matrix phase and accumulate at the rubber particle surfaces. In mixtures of four organoclays with the two polymers, WAXS (wide angle X-ray scattering) peak height and shift in gallery height was the same for a given organoclay. Aspect ratios determined through image analysis were also the same in each polymer. Modulus enhancement as measured by an exfoliation efficiency index showed the same patterns for each organoclay in the two matrices, but the ABS/MMT composites had consistently lower efficiencies than in SAN/MMT composites. This trend is expected to be due to the variations in orientation of clay particles in ABS/MMT composites at the rubber particle surface. In summary, SAN/MMT composites represent a good model system for ABS/MMT.
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solid state nmr characterization and flammability of styrene acrylonitrile Copolymer montmorillonite nanocomposite
Polymer, 2004Co-Authors: Serge Bourbigot, David L Vanderhart, Jeffrey W Gilman, Severine Bellayer, Holly A Stretz, Donald R PaulAbstract:Abstract This work investigates the melt-processing of styrene–acrylonitrile Copolymer (SAN) with organo-modified montmorillonite (MMT) clays and the influence of the clay on mechanical properties and on fire performance of SAN. The nanodispersion of MMT is evaluated qualitatively by X-ray diffraction (XRD) and transmission electronic microscopy (TEM), and quantitatively by solid state nuclear magnetic resonance (NMR). SAN/MMT nanocomposites reveal an intermediate morphology, an intercalated structure with some exfoliation and with the presence of small tactoids, whatever the loading in MMT is. The polymer–clay interfacial area is estimated at 0.5 and the degree of homogeneity characterizing the distribution of MMT platelets is about 40%. The presence of clay in SAN-25 leads to a ‘filler effect’ increasing the stiffness but decreasing tensile strength of the nanocomposites. It also leads to a significant decrease of peak of heat release rate measured by mass loss calorimetry.
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reactive compatibilization of nylon 6 styrene acrylonitrile Copolymer blends part 1 phase inversion behavior
Polymer, 2000Co-Authors: N Kitayama, H Keskkula, Donald R PaulAbstract:Abstract The phase morphology and phase inversion behavior of nylon 6 (PA)/styrene–acrylonitrile (SAN) compatibilized blends have been studied using an imidized acrylic polymer (IA) and a styrene/acrylonitrile/maleic anhydride terpolymer (SANMA) as compatibilizers. PA/SAN blends can be considered as a simpler version of industrially important PA/ABS blends; therefore, this study is useful for the better understanding of the morphology development for PA/ABS blends with compatibilizers. Compared to binary blends of nylon 6 and SAN, addition of IA causes the phase inversion composition to shift to a higher nylon 6 volume fraction; whereas, addition of SANMA slightly changes the phase inversion composition to a lower nylon 6 volume fraction. The use of IA results in a significant increase of the nylon 6 phase viscosity due to the in situ formation of graft polymers during the melt processing; whereas, the addition of SANMA only slightly increases the nylon 6 phase viscosity. The significant change in the nylon 6 to SAN25 viscosity ratio due to the formation of PA–IA graft polymer may be partially responsible for the shift of the phase inversion composition observed as addition of IA. The method of the mixing also affects the phase inversion composition. The composition range where the nylon 6 forms a continuous phase extends to a lower nylon 6 volume fraction for blends mixed in an extruder compared to those prepared in a Brabender. The stabilization of blend morphology by formation of graft Copolymers was studied for compositions near phase inversion as well as at compositions away from this region. Accordingly, it has been shown that IA does not stabilize the morphology near the phase inversion composition, but it is very effective at compositions where either of the components forms a clearly defined dispersed phase. The factors affecting the critical composition where phase inversion occurs have been established.
R A Kudva - One of the best experts on this subject based on the ideXlab platform.
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compatibilization of nylon 6 abs blendsusing glycidyl methacrylate methyl methacrylate Copolymers
Polymer, 1998Co-Authors: R A KudvaAbstract:Abstract Blends of nylon 6 with acrylonitrile/butadiene/styrene (ABS) materials and with its styrene/acrylonitrile Copolymer (SAN) matrix were prepared using a series of glycidyl methacrylate/methyl methacrylate (GMA/MMA) Copolymers as compatibilizing agents. These Copolymers are miscible with SAN and the epoxide unit in GMA is capable of reacting with the polyamide end groups. This Copolymer thus has the potential to form graft Copolymers at the polyamide/SAN interface during melt processing. This study focuses on the effects of functionality and concentration of the compatibilizer on the rheological, morphological, and mechanical properties of these blends. In general, incorporation of this compatibilizer does not significantly improve the impact properties of nylon 6/ABS blends. In these blends, nylon 6 was always the continuous phase; TEM photomicrographs indicate that incorporation of the compatibilizer results in two distinct populations of ABS domains: large agglomerates, and small dispersed particles. The agglomerates become larger with increasing GMA content in the compatibilizer and result in a non-uniform distribution of rubber particles within the nylon 6 matrix. Torque rheometry was employed to identify the reaction mechanisms that may be responsible for the development of such morphologies. These experiments demonstrate that the cause of the poor ABS dispersion is the difunctionality of the nylon 6 end groups with respect to the epoxide group of GMA, which leads to cross-linking-type reactions.
N Kitayama - One of the best experts on this subject based on the ideXlab platform.
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reactive compatibilization of nylon 6 styrene acrylonitrile Copolymer blends part 1 phase inversion behavior
Polymer, 2000Co-Authors: N Kitayama, H Keskkula, Donald R PaulAbstract:Abstract The phase morphology and phase inversion behavior of nylon 6 (PA)/styrene–acrylonitrile (SAN) compatibilized blends have been studied using an imidized acrylic polymer (IA) and a styrene/acrylonitrile/maleic anhydride terpolymer (SANMA) as compatibilizers. PA/SAN blends can be considered as a simpler version of industrially important PA/ABS blends; therefore, this study is useful for the better understanding of the morphology development for PA/ABS blends with compatibilizers. Compared to binary blends of nylon 6 and SAN, addition of IA causes the phase inversion composition to shift to a higher nylon 6 volume fraction; whereas, addition of SANMA slightly changes the phase inversion composition to a lower nylon 6 volume fraction. The use of IA results in a significant increase of the nylon 6 phase viscosity due to the in situ formation of graft polymers during the melt processing; whereas, the addition of SANMA only slightly increases the nylon 6 phase viscosity. The significant change in the nylon 6 to SAN25 viscosity ratio due to the formation of PA–IA graft polymer may be partially responsible for the shift of the phase inversion composition observed as addition of IA. The method of the mixing also affects the phase inversion composition. The composition range where the nylon 6 forms a continuous phase extends to a lower nylon 6 volume fraction for blends mixed in an extruder compared to those prepared in a Brabender. The stabilization of blend morphology by formation of graft Copolymers was studied for compositions near phase inversion as well as at compositions away from this region. Accordingly, it has been shown that IA does not stabilize the morphology near the phase inversion composition, but it is very effective at compositions where either of the components forms a clearly defined dispersed phase. The factors affecting the critical composition where phase inversion occurs have been established.
Tarun K Maji - One of the best experts on this subject based on the ideXlab platform.
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chemical modification of simul wood with styrene acrylonitrile Copolymer and organically modified nanoclay
Wood Science and Technology, 2012Co-Authors: Rashmi R Devi, Tarun K MajiAbstract:Simul wood (Salmalia malabarica) was chemically modified by treatment with styrene–acrylonitrile Copolymer (SAN), glycidyl methacrylate (GMA), and organically modified nanoclay. The physical properties of wood polymer composites (WPC) were improved due to the addition of GMA and nanoclay. XRD analysis indicated a decrease in crystallinity in WPC. FTIR study confirmed the presence of clay in WPC. The presence of clay in cell lumen and cell wall was evidenced by SEM study. WPC containing lower percentage of clay showed better thermal stability compared to WPC loaded with higher percentage of clay.
