Polystyrene ionomer aqueous dispersion. I. Process and mechanism of the phase inversion of emulsification

Aqueous dispersions of lightly sulfonated polystyrene (SPS) that was neutralized by ammonia liquor were prepared. The variations of the conductivity and viscosity of SPS ionomer solution during the emulsification process and the effect of ionic contents on the phase inversion in the emulsification process were studied. The turning points in conductivity curve and the maximum viscosity were considered as the characters of phase inversion in the process of emulsification. The mechanism of phase inversion was inferred. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1671–1675, 1998     

Miscibility and mechanical properties of sulfonated polystyrene–polyurethane blends

A sulfonated polystyrene (SPS) and a polyurethane containing a tertiary amine group (NPU) were blended in solution. The effect of blend composition was studied in the blend of SPS with 9.83 mol % of sulfonation (SPS-9.83) and NPU with 33 mol % of MDEA (NPU-33). As the SPS concentration increases, a significant improvement of miscibility is observed. The tensile strength of the blends is greater than either pure NPU or SPS. A maximum strength and a maximum density occur at 50 wt % SPS. The stress–strain curve shows a well-defined yield when the SPS concentration in the blend is 30 or 50 wt %. The yield is more dramatic in the blend with 50 wt % SPS than that of 30 wt % SPS. At a lower SPS concentration, the blend behaves like a rubber, while a higher SPS concentration in the blend results in a brittle failure before yield. An increase in the sulfonation level of SPS in the SPS–NPU-33 (30/70) blends leads to an improved miscibility. A significant enhancement of tensile strength is observed as the sulfonation increases. A clear yield point on the stress–strain curves occurs when the sulfonation of SPS in the blend is 4.79 mol % or greater. Increasing the MDEA content of NPU up to 8.3 mol % can lead to an enhancement of tensile strength. A further increase in the MDEA content has little influence on the tensile strength, but a clear yield on the stress–strain curve occurs. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:2035–2045, 1998     

Sweet Potato Starch Microparticles as Controlled Drug Release Carriers: Preparation and In Vitro Drug Release

The aim of this study was to investigate the in vitro drug release behavior of sweet potato starch (SPS) microparticles intended for controlled drug delivery applications. Diclofenac sodium (DS) was used as a model drug candidate in the present study. SPS microparticles were prepared using a spray-drying technique by varying the polymer concentration and drug loading. The mean particles size of drug-loaded spray-dried SPS microparticles was between 10.3 and 13.1 µm. The mean particle size increased slightly with increase in the concentration of SPS. The mean particle size of spray-dried SPS microparticles increased from 10.3 to 13.1 µm when the concentration of SPS increased from 2 to 4% w/v. Under the current spray-drying conditions, the percentage yield of spray-dried SPS microparticles did not vary much among the various formulations and it was between 65.2 and 70.1%. The encapsulation efficiencies of SPS microparticles formulations was between 95.1–98.2%, suggesting good encapsulating ability of the SPS polymer by spary drying. Drug release from all the formulations of spray-dried SPS microparticles was controlled over period of 6 h. The cumulative amount of drug release from the spray-dried SPS microparticles decreased with an increase in the concentration of SPS, while it increases as the drug loading is increased. Release of the drug from spray-dried SPS microparticles followed Fick's law of diffusion since a good correlation coefficient (R²) was observed with the Higuchi plots (R² = 0.9928 to 0.9979).     

界面溶蚀法制备多孔磺化聚苯乙烯/壳聚糖微球及其Cr~(3+)吸附研究

采用固/液界面溶剂溶胀诱导相分离法,对磺化聚苯乙烯(SPS)和表面负载有生物相容性的壳聚糖(CS)的核壳型SPS/CS两种微球进行溶蚀,制备出具有多孔结构的SPS和SPS/CS微球。研究发现,溶剂类型和醇水比是影响多孔聚合物微球形态的主要因素。利用透射电镜(TEM)对多孔微球的结构进行表征,通过紫外可见分光光度计(UV-Vis)测定SPS/CS多孔微球在室温环境下对Cr3+的吸附行为。结果表明,界面溶蚀法可制备出形貌均一的多孔聚合物微球,其对Cr3+吸附量明显优于实心结构的微球。     

Electrochemical behaviour of steel in mortar and in simulated pore solutions: Analogies and differences

On evaluating the corrosion resistance of concrete, it is frequent to perform electrochemical tests in the so called simulated pore solutions (SPS) to replace tests performed in concrete specimens. Besides, to study the effect of the chloride content in concrete, chloride ions are added to the SPS. However, it is not obvious whether the SPS simulate the electrochemical behaviour of steel in concrete. Another concern is related to the relationship between the chloride content in concrete and the chloride content of a SPS. To investigate this issue a comparison between the polarization curves of steel in mortar and in SPS was performed. It was found that the SPS is not fully representative of the corrosion behaviour of steel in mortar but it yields conservative results. The relationship between the chloride content in mortar and in SPS that yields similar behaviour is not straightforward but depends on the electrochemical parameter considered.     

双组分溶剂型丙烯酸酯压敏胶的制备及应用

制备了一种双组分溶剂型丙烯酸酯压敏胶SPS01,它具有优良的初粘性和180°剥离强度,适中的黏度和较高的固含量、讨论了交联剂用量对其性能的影响．测试了用SPS01制备的双面胶粘带在钢板、玻璃、塑料和胶合板4种不同被粘表面的上180°剥离强度比较了SPS01与单组分压敏胶粘剂的应用特性及生产中的优缺点.     

Compatibilization by sulfonate ionomers in polyblends with thermotropic liquid crystalline polymers

It is shown by differential scanning calorimetry (DSC) measurements that lightly sulfonated polystyrene (SPS) is partially miscible with polysulfone (PSF), polycarbonate (PC), polyetherimide (PEI), and a thermotropic liquid crystalline polymer (LCP). Fourier transform infrared analysis confirms that the miscibility of SPS and PSF, and of SPS and PC, comes from the ion–dipole interaction between the sulfonate groups of SPS and the polar groups of PSF and PC, respectively. After the addition of SPS to LCP/PSF, LCP/PC, and LCP/PEI blends, this specific interaction leads to the compatibilization of SPS in these blends, which is revealed by inward glass transition temperature shifts of component polymers in DSC and dynamic mechanical analysis thermograms and by a much finer dispersion of the minor LCP phase in these matrix polymers. The utilization of SPS as the compatibilizer results in a stronger interfacial adhesion between LCP and matrix phases and improves the mechanical performances of LCP/PSF, LCP/PC, and LCP/PEI blends as well. Compared with ternary LCP/PSF, LCP/PC, and LCP/PEI blends with polystyrene as an inert third component, the ternary LCP/SPS/PSF, LCP/SPS/PC, and LCP/SPS/PEI blends have significantly enhanced tensile strengths and moduli, with acceptable processabilities at the same time. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:2141–2151, 1998     

磺化PS及其离聚物的合成及性能研究

用乙酸硫酸作为磺化试剂合成了一系列低磺化度磺化聚苯乙烯(SPS),并将其离子化得到锌、镧离聚物。考察了反应温度、磺化试剂用量对磺化反应的影响。同时通过溶解测试、热分析、红外光谱法研究了系列SPS及其离聚物的溶解性、玻璃化转变温度(t_g)值、热稳定性及吸水性。实验表明:随着反应温度的提高及磺化试剂用量的增加,产物磺化度有不同程度的增加;随磺化度提高,产物在非极性溶剂中溶解性下降,t_g值增大,吸水性提高,离聚物比相应磺化物具有更好的热稳定性。     

Synthesis of dense NiZn ferrites by spark plasma sintering

Dense NiZn ferrites were fabricated by spark plasma sintering (SPS) at 900 °C and 20 MPa in short periods. The powder was densified to 98% of the theoretical density by the SPS process. The SPS disks exhibited a higher saturation magnetization (Ms), up to 272 emu/cm³, than did the disks sintered by the conventional process. A higher coercivity (Hci) was obtained when the green bodies were sintered by the SPS process for 5 min. A modest holding time is essential to obtain fine grain and uniformity in the SPS process. Secondary crystallization, inhomogeneous microstructure and intragranular pores were found as a result of the rapid sintering and relatively longer holding time in the SPS process. Infrared (IR) spectra were also measured in the range from 350 to 700 cm⁻¹ to study the efforts of the SPS process on NiZn ferrites.     

A Screening Design Approach for the Understanding of Spark Plasma Sintering Parameters: A Case of Translucent Polycrystalline Undoped Alumina

An experimental screening design was used to evaluate the effects of spark plasma sintering (SPS) parameters such as heating rate, sintering temperature, dwell duration, and green-shaping processing on the relative density, grain size, and the optical properties of polycrystalline alumina (PCA). It is shown that heating rate and sintering temperature are the most critical factors for the densification of PCA during SPS. Green-shaping processing could prevent grain growth at low SPS sintering temperatures. No predominant SPS parameters are observed on the optical properties. Hence, the optical properties of PCA are controlled by microstructural evolution during the SPS process.     

Optimal multi‐period operational planning for steam power system in petrochemical enterprise with consideration of environmental costs in China

Steam power system (SPS) is a major source of both energy consumption and pollutants. In order to reduce the operational costs for petrochemical industry, the SPS should be operated under an optimal scheme. A SPS model is proposed to take into account the depreciation of equipments, changeover costs, and environmental costs. By applying an improved particle swarm optimisation (PSO) algorithm, the optimal operation scheme has been obtained. One example has been investigated to compare the different units and fuel selection in SPS and also the operation periods of SPS taking in account the power import/export policy and environmental cost.     

放电等离子烧结技术

放电等离子烧结(SPS)技术是一种快速、低温、节能和环保的材料制备新技术。综述了SPS在国内外的发展和应用,介绍了SPS技术的发展概况、原理、特点及在材料制备领域的应用,对SPS技术的发展前景进行了展望。     

Synthesis of AA‐based superabsorbent interpenetrated with sodium PVA sulfate

An interpenetrating network of acrylic acid (AA)‐based superabsorbents and sodium PVA sulfate (SPS) were prepared by copolymerizing AA and N,N′‐methylene bisacrylamide as a crosslinking monomer in a solution of SPS with KPS, a radical initiator. The SPS was prepared through the sulfation of the hydroxyl groups of PVA with DMF‐SO₃ complex in DMSO. The AA‐based superabsorbent interpenetrated with SPS (SA‐IP‐SPS) showed superior properties such as higher water and saline absorbency, absorbency under load (AUL), and water retention value (WRV) compared with AA‐based superabsorbent due to the interpenetrated SPS. The maximum water and saline absorbency of SA‐IP‐SPS was 1753 and 125.6 g/g, respectively. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2525–2532, 2000     

Architecture designs for extending thermal cycling lifetime of suspension plasma sprayed thermal barrier coatings

Suspension plasma spraying (SPS) as a relatively new spraying technology has great potential on depositing high performance thermal barrier coatings (TBCs). In some cases, however, columnar SPS TBCs show premature failure in thermal cycling test. To explain the reasons of such failure, a failure mechanism for columnar SPS TBCs was proposed in this work. The premature failure of TBCs might be related to the radial stresses in the vicinity of top coat/bond coat interface. These radial stresses were introduced by the thermal misfit and the roughness of bond coat. According to this mechanism, two architecture designs of SPS TBCs were applied to improve the thermal cycling lifetime. One was a double layered top coat design with a lamellar atmospheric plasma sprayed (APS) sub-layer and a columnar SPS top-layer. The other one was a low roughness bond coat design with a columnar SPS top coat deposited on a low roughness bond coat which was grinded before the spraying. With both designs, lifetimes of SPS TBCs were significantly extended. Especially, a lifetime even better than conventional APS TBCs was achieved with the double layered design.     

Rapid Grain Growth in 3Y‐TZP Nanoceramics by Pressure‐Assisted and Pressure‐Less SPS

Pressure‐less spark plasma sintering (SPS) is a new approach during which rapid densification of ceramic nanopowder green bodies is accompanied by rapid grain growth. Although the origin of this phenomenon has not yet been fully understood significant, difference in grain growth between pressure‐less and pressure‐assisted SPS was expected. In this work 3Y‐TZP nanopowder with average particle size of 12 nm was consolidated using two‐step approach: (1) at an intermediate temperature (600°C to 1000°C) SPS warm pressing followed by (2) high temperature (1400°C to 1600°C) pressure‐less SPS. The standard one step pressure‐assisted SPS experiments were quoted as references. Rapid grain growth was observed during both pressure‐less and standard SPS. The samples prepared by both approaches at the same sintering temperature (1400°C–1600°C) achieved identical grain size and grain size distribution, if large pores were eliminated in early stage by SPS warm pressing. The electric current, electromagnetic field, and mechanical pressure is proven to have a negligible direct influence on grain growth in 3Y‐TZP ceramics at temperatures above 1000°C under standard SPS conditions.     

Spark plasma sintering of structure-tailored ultrahigh-temperature components: First step to complex net shaping

The net-shaping capability in spark plasma sintering (SPS) of ultrahigh-temperature ceramics has been explored in this study. The annular or ring-like shape is considered here as the first step to a more complex geometry compared to a solid cylinder or disk. ZrC powders have been SPS processed in specially designed graphite tooling to achieve the annular shape geometry. Experimental runs have been carried out to determine the optimal processing parameters for producing highly dense ZrC specimens in this geometry. Finite-element modeling framework has been constructed to determine the internal stress evolution, as well as densification, during the SPS of the annular-shaped ZrC. The formulated processing schemes for ZrC have been adapted to process SiC/ZrB₂ composite powder with the purpose of making tooling components for SPS applications. The applicability of the obtained composite SPS tooling has been evaluated at high temperature and high pressure associated with SPS regimes.     

熔体旋甩法制备Sr_8Ga_（16）Ge_（30）笼合物的微结构及热电性能

将熔体旋甩法（MS）用于制备Ⅰ-型Sr8Ga16Ge30笼合物,研究了MS对Sr8Ga16Ge30笼合物微结构及热电性能的影响。结果表明,MS得到的Sr8Ga16Ge30薄带自由面晶粒尺寸随冷却速率的增加而减小,接触面未有明显结晶现象。薄带经SPS烧结得到的致密块体结构中存在大量精细的层状结构。与熔融＋SPS制备的试样相比,熔融＋MS＋SPS制备的Sr8Ga16Ge30试样的电导率变化不大,Seebeck系数增加,热导率显著降低,其中铜辊转速为4 000 r/min的Sr8Ga16Ge30试样的ZT值在800 K达到0.74,相对于熔融＋SPS试样提高了45%。     

A novel apatite-inspired Sr5(PO4)2SiO4 plasma-sprayed coating on Ti alloy promoting biomineralization,osteogenesis and angiogenesis

Osteoconductive, osteoinductive, anti-infection, and controlled ionic release properties are crucial for the long-term clinical success of orthopedic and dental metallic implants. In this study, we have successfully synthesized apatite chemical structure mimic Sr₅(PO₄)₂SiO₄ (SPS) nanopowder by sol-gel method to be used as a novel bioactive ceramics coatings on medical-grade titanium alloy by plasma-spray deposition technique. The deposited SPS coatings were analytically characterized by XRD and SEM-EDS analysis and confirmed that the coating possessed a pure crystalline phase of SPS without any other secondary phases, and exhibited a sharp needle-like morphology with the existence of Sr, P, O, Si elements. The cross-sectional view proved that the deposition of dense SPS layer with a thickness of 116 μm. The in vitro ionic dissolution behavior of SPS coatings was detected by ICP-OES analysis and confirmed their controlled releasing profile of ions such as Sr (120–55 ppm) and Si (0.14–9.86 ppm). In vitro biomineralization study demonstrated that the SPS coatings were remarkably encouraged the ball likes apatite crystals growth on their surface with a Ca/P ratio (1.677) similar to natural bone minerals. The SPS coatings exhibited notable cellular interactions with human umbilical card-derived mesenchymal stem cells (HUMSCs) in terms of cell proliferation, early-stage differentiation, and calcium nodule accumulation in ECM, also the osteogenic differentiation was found to be prominent for SPS coated Ti64 than sandblasted Ti64. Furthermore, the angiogenic property of SPS coated Ti64 was evaluated by Human umbilical vein endothelial cells (HUVECs) and confirmed their tremendous cell viability with non-toxicity and nominal angiogenic differentiation. Therefore, our study proved that the apatite-inspired SPS bioactive ceramics coatings could improve the biofunctional activities of orthopedic and dental implants for their better clinical success.     

Origin of the uniaxial magnetic anisotropy in cobalt ferrite induced by spark plasma sintering

Cobalt ferrite (CFO) is a promising candidate for magnetostrictive applications like actuators or sensors. We have recently shown that uniaxial magnetic anisotropy can be induced in CFO by reactive sintering using spark plasma sintering (SPS), which leads to an improvement of its magnetostrictive properties. However, the origin of the anisotropy and the formation mechanism remain unexplained so far. In this study, different SPS processes have been conducted to determine which parameter is responsible for the induced uniaxial anisotropy. We demonstrate that the magnetic anisotropy arises during the cooling step when done under SPS’s uniaxial compression. In addition, we also investigate the fundamental origin of the magnetic anisotropy induced during the SPS process. We show that the polycrystalline anisotropic cobalt ferrite obtained after SPS exhibits no texture. However, the SPS samples turn isotropic after being annealed in air at 400 °C/2 h, as shown by magnetic and magnetostrictive measurements. A change in ionic distribution after the annealing is also observed by Mössbauer spectroscopy. Our findings suggest that the induced magnetic anisotropy results from the ionic distribution of the Co²⁺ in the CFO’s spinel lattice, a mechanism previously observed in magnetic annealed CFO. This study advances the in-depth understanding of the relationship between SPS processing and magnetic properties of cobalt ferrite.     

Melt intercalation/exfoliation of polystyrene-sodium-montmorillonite nanocomposites using sulfonated polystyrene ionomer compatibilizers

Quaternary ammonium salts of sulfonated polystyrene (SPS) were used as compatibilizers for melt intercalation of PS and pristine Na-montmorillonite. Tetra-octyl ammonium SPS and tetra-decyl ammonium SPS ionomeric compatibilizers produced significant exfoliation and a homogeneous dispersion of the polymer-clay nanocomposites. Wide angle X-ray diffraction and transmission electron microscopy were primarily used to characterize the morphology of the nanocomposites. Image analysis was used to measure the percentage exfoliation. Exfoliation increased with the increasing length of the alkyl chain of the ammonium counter-ion of the SPS ionomer. The nanocomposites containing ionomers exhibited higher storage moduli compared to nanocomposites without the compatibilizer.