摘要:
L'invention a trait à une composition de caoutchouc diénique à base d'au moins (i) un élastomère diénique, (ii) une charge inorganique renforçante, (iii) un agent de couplage assurant la liaison entre la charge renforçante et l'élastomère, caractérisée en ce que ladite charge inorganique comprend au moins une silice possédant les caractéristiques suivantes: (a) une surface spécifique BET entre 45 et 400 m 2 /g et de préférence entre 50 et 300 m 2 /g; (b) une surface spécifique CTAB entre 40 et 380 m 2 /g et de préférence entre 45 et 280 m 2 /g; (c) une taille moyenne (en masse) de particules, notée dw, de 20 à 300 nm; et au moins une des caractéristiques suivantes de préférence deux et plus préférentiellement les trois: (d) une distribution de taille de particules telle que dw ≥ (16500/CTAB)-30; (e) une porosité vérifiant le critère L/IF ≥ -0,0025 CTAB + 0,85; (f) un taux de silanols par unité de surface, noté N SiOH/nm 2 , N SiOH/nm 2 ≤ -0,027 CTAB + 10,5. Ces silices sont susceptibles d'être obtenues selon un procédé de préparation original. L'invention concerne également l'utilisation de ces compositions de caoutchouc diénique pour la fabrication de pneumatiques ou de produits semi-finis destinés aux pneumatiques, ainsi que ces produits et pneumatiques.
摘要:
The invention relates to improved lithium intercalation compounds containing lithium manganese oxide, having a spinell structure and a special morphology for thin-film electrodes. The invention further relates to a method for the production of said compounds, electrodes produced from said compounds and secondary lithium batteries with lithium intercalation compounds containing lithium manganese oxide as an active material for the positive electrode, offering high energy and able to be produced in an inexpensive manner in addition to being ecologically friendly and safe.
摘要:
Amorphous precipitated silica which may be used to form battery separators of very low shrinkage is characterized by (a) a BET surface area in the range of from 60 to 200 m /g; (b) a CTAB surface area in the range of from 40 to 150 m /g; (c) a DBP oil absorption in the range of from to 180 to 300 cm /100g; (d) a mean ultimate particle size in the range of from 20 to 30 nm; (e) a total intruded volume in the range of from 2.5 to 4 cm /g; (f) an intruded volume in the range of from 0.3 to 1.2 cm /g for pores having diameters in the range of from 20 to 100 nm; and (g) a pore diameter at the maximum of the volume pore size distribution function in the range of from 30 to 200 nm.
摘要:
High performance activated clays suitable for bleaching oil are produced by mixing a clay mineral with a metal salt that is a Lewis acid. Mixtures of such metal salts can be used as well.
摘要:
A novel method for preparing precipitated silica having a good dispersibility and highly satisfactory reinforcing properties is disclosed. Novel precipitated silicas in the form of a powder, substantially spherical beads or granules are also disclosed. Said silicas are characterised in that they have a CTAB specific surface area of 90-250 m /g, a BET specific surface area of 90-250 m /g, a DOP oil absorption of less than 300 ml/100 g, and a zinc content of 1-5 wt %, and in that the number N of stearic acid molecules consumed per nm of the silica surface, when stearic acid is reacted with said silica in xylene for 2 hours at 120 DEG C, is at least 1. Furthermore, the use of said silicas as reinforcing fillers for elastomers, in particular for enhancing the rheological properties thereof, is disclosed.
摘要:
A novel method for preparing precipitated silica having a good dispersibility and highly satisfactory reinforcing properties is disclosed. Novel precipitated silicas in the form of a powder, substantially spherical beads or granules are also disclosed. Said silicas are characterised in that they have a CTAB specific surface area of 90-250 m /g, a DOP oil absorption of less than 300 ml/100 g, a pore distribution such that the pore volume consisting of pores with a diameter of 175-275 ANGSTROM is less than 50 % of the pore volume consisting of pores with a diameter of at most 400 ANGSTROM , and a zinc content of 1-5 wt %, and in that the number N of stearic acid molecules consumed per nm of the silica surface, when stearic acid is reacted with said silica in xylene for 2 hours at 120 DEG C, is of at least 1. Furthermore, the use of said silicas as reinforcing fillers for elastomers, in particular for enhancing the rheological properties thereof, is disclosed.
摘要:
Silicas in the form of powder and substantially spherical beads or granules are characterized by a CTAB specific surface of 140-240 m /g a high ultrasonic disaggregation factor, an average diameter, which is small after ultrasonic disaggregation, and optionally, a porous distribution, the porous volume formed by the pores with a diameter of 175 to 275 ANGSTROM being less than 50 % of the porous volume formed by the pores with diameters of 400 ANGSTROM or less. Said silicas may be used as reinforcing fillers for elastomers. The invention also concerns a method for preparing precipitated silica of the type comprising the reaction of an alkaline metal silicate M with an acidifying agent, resulting in a suspension of precipitated silica, and the separation and drying of said suspension, wherein precipitation is performed as follows; (i) an initial starter is formed comprising a portion of the total quantity of alkaline metal silicate M in the reaction, the silicate concentration (expressed in SiO2) in said starter being less than 20 g/l; (ii) an acidifying agent is added to said initial starter until at least 5 % of the quantity of M2O in said initial starter is neutralized; (iii) the acidifying agent and the remaining quantity of alkaline metal silicate M is added simultaneously so that the ratio of the quantity of added silicate (expressed as SiO2) to the quantity of silica in the initial starter (expressed as SiO2) is greater than 4 and at most 100.
摘要:
A method and system for synthesizing nanocrystalline material. A system includes a chamber (14), a nonconsumable cathode (20) shielded against chemical reaction by a working gas not including an oxidizing gas, but including an inert gas, a consumable anode (12) vaporizable by an arc formed between the cathode and the anode, and a nozzle (35) for injecting at least one of a quench and reaction gas in the boundaries of the arc.
摘要:
A process for making high porosity boehmite alumina comprising forming an aqueous dispersion of a boehmite alumina which has been obtained by hydrothermally treating an aqueous mixture of a precursor boehmite alumina at a pH of from about 5 to about 9 for a period of time sufficient to convert the greater portion of the precursor boehmite alumina to a colloidal sol, treating the dispersion of the hydrothermally treated alumina to form a viscous gel and subjecting the gel to sufficient shearing force for a sufficient period of time to increase the pore volume by at least 30 % and the median pore radius by at least 20 %.
摘要:
High-strength, non-agglomerated uniform porous microspheres of silica produced by spray drying a mixture comprising a colloidal silica sol and an additive selected from ammonium citrate or urea; an attrition resistant catalytic composite consisting essentially of metal crystallites such as palladium, platinum-palladium on said silica microsphere and method for preparing the same; and an improved process for making hydrogen peroxide from the direct combination of hydrogen and oxygen in the presence of said attrition resistant catalytic composite.