丁苯三嵌段共聚物/改性纳米层状白泥复合弹性体的力学性能

热塑性弹性体;混杂纳米复合材料;丁苯三嵌段共聚物/改性纳米层状白泥复合弹性体的力学性能     

白云母的剥片及粉碎技术

本文在分析白云母结构特点的基础上，阐述了白云母的剥片及粉碎技术，并介绍了所研制的研磨机及样品试验对比结果.     

Organothiol Monolayer Formation Directly on Muscovite Mica

Organothiol monolayers on metal substrates (Au, Ag, Cu) and their use in a wide variety of applications have been extensively studied. Here, the growth of layers of organothiols directly onto muscovite mica is demonstrated using a simple procedure. Atomic force microscopy, surface X‐ray diffraction, and vibrational sum‐frequency generation IR spectroscopy studies revealed that organothiols with various functional endgroups could be self‐assembled into (water) stable and adaptable ultra‐flat organothiol monolayers over homogenous areas as large as 1 cm². The strength of the mica–organothiol interactions could be tuned by exchanging the potassium surface ions for copper ions. Several of these organothiol monolayers were subsequently used as a template for calcite growth.     

Tailoring and investigation of surface chemical nature of virgin and ion beam modified muscovite mica

We report that the surface chemical properties of muscovite mica [KAl₂(Si₃Al)O₁₀(OH)₂] like important multi-elemental layered substrate can be precisely tailored by ion bombardment. The detailed X-ray photoelectron spectroscopic studies of a freshly cleaved as well as 12-keV Ar⁺ and N⁺ ion bombarded muscovite mica surfaces show immense changes of the surface composition due to preferential sputtering of different elements and the chemical reaction of implanted ions with the surface. We observe that the K atoms on the upper layer of mica surface are sputtered most during the N⁺ or Ar⁺ ions sputtering, and the negative aluminosilicate layer is exposed. Inactive Ar atoms are trapped, whereas chemically reactive N atoms form silicon nitride (Si₃N₄) and aluminum nitride (AlN) during implantation. On exposure to air after ion bombardment, the mica surface becomes more active to adsorb C than the virgin surface. The adsorbed C reacts with Si in the aluminosilicate layer and forms silicon carbide (SiC) for both Ar and N bombarded mica surfaces. Besides the surface chemical change, prolonged ion bombardment develops a periodic ripple like regular pattern on the surface.     

Effect of protein solution components in the adsorption of Herbaspirillum seropedicae GlnB protein on mica

The adsorption of proteins and its buffer solution on mica surfaces was investigated by atomic force microscopy (AFM). Different salt concentration of the Herbaspirillum seropedicae GlnB protein (GlnB-Hs) solution deposited on mica was investigated. This protein is a globular, soluble homotrimer (36 kDa), member of PII-like proteins family involved in signal transducing in prokaryote. Supramolecular structures were formed when this protein was deposited onto bare mica surface. The topographic AFM images of the GlnB-Hs films showed that at high salt concentration the supramolecular structures are spherical-like, instead of the typical doughnut-like shape for low salt concentration. AFM images of NaCl and Tris from the buffer solution showed structures with the same pattern as those observed for high salt protein solution, misleading the image interpretation. XPS experiments showed that GlnB protein film covers the mica surface without chemical reaction.     

Kinetics and mechanism of dehydration of kaolinite,muscovite and talc analyzed thermogravimetrically by the third-law method

Summary The third-law method has been applied to determine the enthalpies, Δ_rH_T⁰, for dehydration reactions of kaolinite, muscovite and talc. The Δ_rH_T⁰values measured in the equimolar (in high vacuum) and isobaric (in the presence of water vapour) modes (980±15, 3710±39 and 2793±34 kJ mol^-1, for kaolinite, muscovite and talc, respectively) practically coincide if to take into account the strong self-cooling effect in vacuum. This fact strongly supports the mechanism of dissociative evaporation of these compounds in accordance with the reactions (primary stages): Al₂O₃·2SiO₂·2H₂O(s)→Al₂O₃(g)↓+2SiO₂(g)↓+2H₂O(g); K₂O·3Al₂O₃·6SiO₂·2H₂O(s) →K₂O(g)↓+3Al₂O₃(g)↓+6SiO₂(g)↓+2H₂O(g) and 3MgO·4SiO₂·H₂O(s) →3MgO(g)↓+4SiO₂(g)↓+H₂O(g). The values of the Eparameter deduced from these data for equimolar and isobaric modes of dehydration are as follows: 196 and 327 kJ mol^-1for kaolinite, 309 and 371 kJ mol^-1for muscovite and 349 and 399 kJ mol^-1for talc. These values are in agreement with quite a few early results reported in the literature in 1960s.     

Dehydroxylation kinetic and exfoliation of large muscovite flakes

The thermal transformations of muscovite flakes are a key point in many applications because besides dehydroxylation a significant exfoliation process occurs. Dehydroxylation kinetic is experimented by isothermal TG analyses in the 700–850°C temperature range and described with the Avrami theory. Hydroxyl condensation predominates at the onset of the process, but water diffusion is the most important process when the transformed fraction is high. The progressive transition between the two transformation stages contrast with the more accentuated transition for a ground muscovite. The activation energy varies weakly (190–214 kJ mol⁻¹) in the whole transformation process that supports the co-existence of hydroxyl condensation and diffusion phenomena. Dehydroxylation kinetic increases strongly with temperature and decreases with the reaction advancement. Exfoliation is correlated with dehydroxylation kinetic and occurs in a narrow transformation and temperature ranges. An in-situ combination process of hydroxyls occurs and water vapor favors the layer expansion.     

Paradigms and Paradoxes:Estimation of the Enthalpies of Formation of Some Common,Solid-Phase Compounds of Considerable Theoretical Importance

The enthalpies of formation of the following solid-state species are estimated: calcium carbonate, muscovite, graphite, cellulose, and silicon, which, as found in chalk, slate, pencil lead, paper, and integrated circuits, are key reagents in numerous theoretical studies. Agreement between theory and experiment is within 40 kJ mol^–1.