Showing papers on "Polystyrene published in 1988"
TL;DR: In this article, the surface structure and properties of miscible blends of polystyrene (PS) with polyvinyl methyl ether (PVME) have been studied as a function of the blend composition and constituent molecular weights.
Abstract: : The surface structure and properties of miscible blends of polystyrene (PS) with poly(vinyl methyl ether) (PVME) have been studied as a function of the blend composition and constituent molecular weights. The lower surface tension of the PVME compared to that of PS results in preferential adsorption of PVME at the surface. The surface PVME enrichment is characterized by measurements of the surface tension as a function of the temperature, accomplished with an automated pendant drop apparatus, and by x-ray photoelectron spectroscopy (XPS). Angle-dependent XPS has been used to determine the surface concentration profiles of the blend constituents.
247 citations
TL;DR: In this article, the authors explored phase continuity as a function of composition for three two-phase polymer blends produced by mixing in the melt: polystyrene/poly(methyl methacrylate), poly styrene/cis-polybutadiene, and poly(ethylene-propylene rubber).
Abstract: Phase continuity has been explored as a function of composition for three two-phase polymer blends produced by mixing in the melt: polystyrene/poly(methyl methacrylate), polystyrene/cis-polybutadiene, and poly(methyl methacrylate)/ethylene-propylene rubber. The condition for dual phase continuity Is the application of shear close to phase inversion and this can be predicted fairly accurately using the relation
where 1 and 2 are the blend components, η is viscosity, is the shear rate in the mixing device used to produce the blend and ϕ is volume fraction. The co-continuous materials, which we call Interpenetrating polymer blends (IPBs) are non-equilibrium structures and are subject to disruption by changes in flow regime.
177 citations
TL;DR: In this article, it was shown that transitions in micelle shape and mesophase type can occur by increasing the molecular weight of the homopolymer matrix, increasing the aggregating block molecular weight, or increasing the volume fraction of the copolymer.
Abstract: Blending of a block copolymer with a large amount of homopolymer can result in the formation of a micellar phase consisting of spherical domains of the aggregating copolymer block. We show that transitions in micelle shape and mesophase type($ can occur by increasing the molecular weight of the homopolymer matrix, by increasing the aggregating block molecular weight, or by increasing the volume fraction of the copolymer. The new morphologies include cylindrical micelles, vesicles, and lamellar type structures. These transitions can be understood in terms of the general rule of domain morphology as a function of relative microphase volume fractions put forth by Molaul for neat block copolymers and later extended by Sadron and Gallot2 to the case of block copolymers in preferential solvents.
155 citations
TL;DR: In this article, high-frequency dielectric response measurements were performed on three monodisperse polystyrene latices at varying electrolyte concentrations and compared with results obtained from microelectrophoresis.
151 citations
TL;DR: In this paper, it was shown that poly(4-vinylpyridine) is compatible with a copoly(styrene-4-hydroxystyrene) containing 50 mol% of 4-hydroxstyrene units over the entire range of blend composition.
139 citations
TL;DR: In this article, the thermal, dielectric, Theological, and mechanical properties of polyethylene terephthalate copolymers (PHB-PET) have been studied.
Abstract: We present a basic study of the thermal, dielectric, Theological, and mechanical properties of hydroxybenzoic acid-ethylene terephthalate copolymers (PHB-PET). It is argued that they have two-phase structures, one rich in ethylene terephthalate (PET) and one rich in hydroxybenzoic acid (PHB). Polystyrene (PS) is immiscible in 60% PHB-PET (60-PHB-PET) blends. Polycarbonate (PC) is partially miscible with the high PET phase of 60-PHB-PET. PET seems completely miscible with this high PET phase. Shear viscosity measurements on blends indicate that 60-PHB-PET gives rise to large reductions of viscosity. Extrudates and melt-spun fibers have been prepared. The phase morphologies of low PHB-PET blends as determined by scanning electron microscopy indicate ellipsoids or long fibrils of the, 60-PHB-PET in PS or PC matrices. High extrusion rates and melt spinning produce fibrillar structures. The mechanical properties of films, extrudates, and melt-spun fibers were studied. Blends with 10% 60-PHB-PET exhibited significant increases in Young's modulus and tensile strength.
115 citations
114 citations
TL;DR: In this paper, the authors obtained projections of a styrene-butadiene-styrene (SBS) copolymer (30 wt% styrene) at tilt angles ranging from −61.5° to +48.5 degrees in 5° increments.
112 citations
TL;DR: In this article, gas phase chemical modification (GCM) was applied to correlate the surface composition of NH3 plasma-treated polystyrene films with their cell-affinity, and the amount of primary-amine and that of carboxylic acid were directly determined by GCM.
Abstract: Gas phase chemical modification (GCM) is found to be more preferable as a pretreatment for the XPS surface analysis of polymer materials than the conventional liquid phase treatment because it can circumvent problems such as solvent contamination and swelling. We have tried the quantification of the surface composition successfully by estimating the yield of the reaction from model samples. GCM was then applied to correlate the surface composition of NH3 plasma-treated polystyrene films with their cell-affinity. The amount of primary-amine and that of carboxylic acid were directly determined by GCM. Although the amount of primary-amine, 15–20% of total nitrogen, did not depend on the treatment intensity, the total amine content for the treated samples increased with the plasma treatment intensity. The quantity of carboxylic acid generated was found to be very small. All treated samples had better cell-affinity than the control. The sample N2 (of medium treatment) showed the best cell-affinity. The most strongly treated sample N3, with larger amine content than N2, showed worse cell-affinity because of the interference by the sputtered SiO2 on the surface.
108 citations
TL;DR: In this paper, critical reflection experiments were performed for the interface between polystyrene and poly(methyl methacrylate) and it was shown that the interfacial mixing is not greater than 20 ± 5 A.
108 citations
TL;DR: Proprietes optiques des polymeres dopes avec des colorants (azoique, derive de l'aniline ou du stilbene) as mentioned in this paper.
Abstract: Proprietes optiques des polymeres dopes avec des colorants (azoique, derive de l'aniline ou du stilbene)
TL;DR: In this article, a discussion of linear organic polymers having fixed ionic sidechains of exclusively either positive or negative charges is presented, examples of which would include the ethylene-methacrylic acid copolymer salts, sulfonated polystyrene, and Nanon perfluorosulfonate salts.
Abstract: In general, ionomers are ion-containing polymers [1] which, in contrast to the traditional ion-exchange resins [2], are usually rendered insoluble through the presence of crystalline do-mains. This review will be confined to a discussion of linear organic polymers having fixed ionic sidechains of exclusively either positive or negative charges, examples of which would include the ethylene-methacrylic acid copolymer salts, sulfonated polystyrene, and Nanon perfluorosulfonate salts. More complicated systems, such as those containing zwitterion moieties, polysalts, halato-telechelics, or polyether-salt complexes, will not be of interest herein.
TL;DR: In this article, microscopical observations of the influence of these mechanisms on small particles near ultrasonically activated gas-filled micropores in thin plastic sheets were compared to approximate theoretical treatments of the particle behavior.
Abstract: Nonthermal bioeffects of ultrasound can be induced by the physical mechanisms of radiation force and acoustic microstreaming. In this study, microscopical observations of the influence of these mechanisms on small particles near ultrasonically activated gas‐filled micropores in thin plastic sheets were compared to approximate theoretical treatments of the particle behavior. The microstreaming flow was localized within a toroidal eddy around an active micropore, as indicated by isopycnic 1‐μm polystyrene spheres. The size of the flow pattern seemed to decrease slowly with increasing frequency in the range 0.7–3.5 MHz. Flow was radially inward along the surface, rather than outward as expected from the theory. All the particles tested, which included particles with density less than, equal to, or more than the medium, seemed to accumulate at the micropores. From the theory for the radiation force, the particles less dense than the medium were expected to be repulsed from the micropores. Therefore, the theories for these phenomena, at least to the level of approximation available, may not be completely adequate for the detailed analysis of these phenomena.
TL;DR: In this article, the etch rate of poly(ethylene terephthalate), polycarbonate, and polystyrene was measured as a function of the laser intensity, at 193 and 248 nm.
Abstract: We have developed a new technique to measure the etch rate of polymer films under the ablative photodecomposition condition obtained by absorption of the far‐UV radiation of the excimer laser. The technique is based on the use of a quartz‐crystal microbalance interfaced with a microcomputer. It has high accuracy (17 ng/cm2). Etch rates of poly(ethylene terephthalate), polycarbonate, and polystyrene were measured as a function of the laser intensity, at 193 and 248 nm. The etch rate in the region of the ablation threshold intensity is obtained precisely. A slow ablation regime between the threshold and the linear regime is evidenced. For polycarbonate and polystyrene, a reaction of the irradiated surface with molecular oxygen accelerates the ablation process at low fluence of the 248 nm radiation. The degradation reaction of poly(ethylene therephthalate) is monitored as a function of fluence by selective dissolution in acetone. A sudden increase of the degraded depth is seen at the transition between the t...
TL;DR: In this article, the Gordon-Taylor equation was analyzed and it was shown that the background is based on additivity, and the corresponding parameter K = ρ1 Δα2 / (ρ2 Δα1), however, may include also an interaction contribution if the quadratic concentration term is neglected in a virial-like extension of the glass transition temperature vs composition expression.
Abstract: An analysis of the Gordon-Taylor equation shows that its background is based on additivity. The corresponding parameter K = ρ1 Δα2 / (ρ2 Δα1), however, may include also an interaction contribution if the quadratic concentration term is neglected in a virial-like extension of the glass transition temperature vs. composition expression. Then K becomes a real fitting parameter. It is shown that a distinction of the two cases is possible by using the corresponding linearized form of the respective equations. The discussion of data of polystyrene/poly(2,6-dimethyl-1,4-phenylene oxide), styrene copolymers/poly(2,6-dimethyl-1,4-phenylene oxide) and poly(methyl vinyl ether)/polystyrene blends gives evidence for the decisive influence of the stiffer component on the glass transition behaviour of compatible polymer blends.
TL;DR: The first description of the separate identities of these two antibodies is described, separating anticardiolipin antibodies from lupus anticoagulant activity in the plasma of a patient with the l upus obstetric syndrome.
TL;DR: A plurifunctional metalorganic initiator is obtained upon reaction of potassium naphthalene with commercial divinylbenzene and the resulting polymeric core exhibits a number of metalorganic sites in a subsequent step, these sites initiate the polymerization of styrene to yield a star-shaped polymer as mentioned in this paper.
Abstract: A new method for the synthesis of compact, multifunctional star-shaped polystyrenes was designed A plurifunctional metalorganic initiator is obtained upon reaction of potassium naphthalene with commercial divinylbenzene The resulting polymeric “core” exhibits a number of metalorganic sites In a subsequent step, these sites initiate the polymerization of styrene to yield a star-shaped polymer High numbers of branches can be obtained, thus rendering these molecules extremely compact However, the major advantage of the “core first” method is that it allows functionalization of the branches at their outer end, thus providing the possibility of further reaction or selective adsorption This “core first” method was also applied to the preparation of star-block copolymers formed of a polystyrene block and a poly(ethylene oxide) block
TL;DR: Etude par calorimetrie differentielle dans la cis-decaline, transdecaline et chloro-1 decane as mentioned in this paper, dans l'a.
Abstract: Etude par calorimetrie differentielle dans la cis-decaline, trans-decaline et chloro-1 decane
TL;DR: In this paper, the ratio of rubber to polystyrene phase was kept constant at 1:4 by weight, and the concentration of reactive oxazoline groups in the polystyrenes phase was varied by mixing poly styrene (PS) with a copolymer of styrene and vinyl oxozoline (OPS), and the impact strength and ductility of the reactive blends were found to be up to 73% greater than those of the corresponding nonreactive blends.
Abstract: Acrylonitrile-butadiene rubber having carboxylic acid groups (XNBR) and polystyrene having oxazoline groups, were melt blended in a Rheomix mixer under optimized conditions, The ratio of rubber to polystyrene phase was kept constant at 1:4 by weight. The concentration of the reactive oxazoline groups in the polystyrene phase was varied by mixing polystyrene (PS) with a copolymer of styrene and vinyl oxazoline (OPS). A torque rise observed during blending was found to be related to the concentration of oxazoline-carboxylic acid pairs. This torque rise, and independently measured increases in viscosity, both indicate inter-polymer crosslinkihg. Scanning electron microscopy was used to observe the morphology of the blends. Improved rubber phase dispersion was observed with increasing oxazoline concentration. Instrumented impact strength measurements were made using an unnotched Charpy technique. The plastic yielding was then quantified with the use of a ductility ratio. The impact strengths and ductility of the reactive blends are found to be up to 73% greater than those of the corresponding non-reactive blends. Increasing the OPS concentration beyond 5% results in decreasing impact strength, for as the compatibility increases, the rubber particle size decreases below an effective size for rubber toughening. Similar impact improvement is observed when the major PS phase is substituted with high impact polystyrene (HIPS) containing some OPS.
TL;DR: Aromatisation d'un copolymere styrene/cyclohexadiene-1,3 puis traitement thermique qui decompose les sequences polystyrene conduisant a des films de poudres de PPP pur
Abstract: Aromatisation d'un copolymere styrene/cyclohexadiene-1,3 puis traitement thermique qui decompose les sequences polystyrene conduisant a des films de poudres de PPP pur
TL;DR: In this paper, the effect of supercritical ethane on the high pressure phase behavior of polystyrene-toluene system is experimentally investigated, and it is shown that adding 17.8 wt. % ethane to the polystylene solution lowers the temperature of the lower critical solution temperature (LCST) curve by 162°C.
Abstract: The effect of supercritical ethane on the high-pressure phase behavior of the polystyrene-toluene system is experimentally investigated. Adding 17.8 wt. % ethane to the polystyrene-toluene solution lowers the temperature of the lower critical solution temperature (LCST) curve by 162°C, 22.5 wt. % lowers the temperature of the curve by 231°C, and with 24.9 wt. % the curve is shifted to such low temperatures that it merges with the upper critical solution temperature curve. In practice this means that polymer solutions can be separated at lower temperatures where thermal degradation of the polymer is less. Also, more than 99 wt. % of the polystyrene is recovered in the polymer-rich phase after the solution phase splits. Patterson's corresponding states treatment is used to model the LCST data.