摘要:
A lactide polymer composition combining compositional and purity limitations and catalyst optimization or addition of stabilizing agents resulting in a melt-stable polymer is disclosed. The melt-stable lactide polymer comprises a plurality of polylactide polymer chains, residual lactide in concentration of less than 2 percent and water in concentration of less than 1000 parts-per-million. A stabilizing agent in an amount sufficient to reduce depolymerization of the lactide polymer during melt-processing or alternatively, control of catalyst level at a molar ratio of monomer to catalyst greater than 3000:1 is also included in the melt-stable composition. A process for manufacture of a melt-stable lactide polymer composition includes polymerizing a lactide mixture and adding stabilizing agents sufficient to reduce depolymerization of the polylactide during melt-processing, followed by devolatilizing the polylactide to remove monomer and water.
摘要:
A vacuum dispensable silicone composition comprising (A) a polydiorganosiloxane containing an average of at least two silicon-bonded alkenyl groups per molecule; (B) an organopolysiloxane resin consisting essentially of (a) R.sup.3.sub.2 (CH.sub.2 .dbd.CH)SiO.sub.1/2 siloxane units, (b) R.sup.3.sub.3 SiO.sub.1/2 siloxane units, and (c) SiO.sub.4/2 siloxane units wherein each R.sup.3 is independently selected from the group consisting of monovalent hydrocarbon and monovalent halogenated hydrocarbon groups free of aliphatic unsaturation, the mole ratio of the combination of (a) and (b) units to (c) units is from 0.6 to 1.1, and the resin contains 1 to 5 percent by weight of vinyl groups; (C) an organohydrogenpolysiloxane having an average of at least three silicon-bonded hydrogen atoms per molecule in an amount sufficient to provide from one to three silicon-bonded hydrogen atoms per alkenyl group in components (A) and (B) combined; (D) an adhesion promoter in an amount sufficient to effect adhesion of the composition to a substrate; (E) a hydrosilylation catalyst; (F) a platinum catalyst inhibitor having a boiling point greater than 150 .degree. C. at 0.10 MPa in an amount sufficient to retard curing of the composition at ambient temperature; wherein the composition is substantially free of air.
摘要:
The present invention relates to thermoplastic polymer compounds comprising a blend of a chlorinated polyvinyl chloride and an impact modifier containing a polyorganosiloxane and polyalkyl(meth)acrylate. The novel thermoplastic compound has improved stability and toughness and exhibits a low rate of heat release.
摘要:
A photo-curable liquid silicone rubber composition is curable upon exposure to light into a cured product having a Shore A hardness of 20 to 60 and a light transmittance of at least 10% at a wall gage of 10 mm. The composition is suitable for forming a transparent templating mother mold which allows a photo-curable liquid resin cast therein to be cured with light transmitted by the mold wall.
摘要:
Polyarylene sulfide (PAS) is disclosed, of which extract with methylene chloride is in an amount of not more than 0.7% by weight, a melt viscosity V.sub.6 is 20 to 15,000 poises and a content of --SX groups is at least 15 micro moles/g, wherein X represents an alkali metal or a hydrogen atom. The PAS is prepared as follows: an alkali metal sulfide is reacted with a dihaloaromatic compound in an organic amide solvent, while a part of a gaseous phase in a reactor is condensed by cooling a gaseous phase part of the reactor to return the condensed liquid to a liquid phase; and the polyarylene sulfide thus prepared is washed with an organic solvent and then with water. The present invention also provides a composition comprising 100 parts by weight of (A) the aforesaid PAS and 0.01 to 5.0 parts by weight of (B) at least a silane compound selected from the group consisting of methacryloxysilane compounds, ureidosilane compounds and epoxy silane compounds.
摘要:
A method for preparing a room temperature curing organopolysiloxane composition having good working properties, which comprises (A) a diorganopolysiloxane having at least two hydroxyl groups bonded to silicon atoms in one molecule, (B) a thixotropy improver, (C) a finely divided silica powder, (D) at least one member selected from organosilanes having two or more ketoxime groups bonded to a silicon atom in one molecule and partial hydrolyzates thereof, (E) a curing catalyst for the condensation curing reaction between (A) and (D) components, and (F) an amine-based silane coupling agent for imparting adhesiveness to the composition, wherein the (A), (B) and (C) components are first mixed, with which the (D) and (E) components are further mixed, and the (F) component is finally added to and mixed with the resultant mixture.
摘要:
In a process for producing a vulcanizable rubber composition containing silica and having a low content of carbon black, at least a silica-based reinforcing filler and ad least a silane-based coupling agent are added to and intimately mixed with other ingredients of the composition in subsequent steps, at a temperature of from 165.degree. and 180.degree. C. and between 1100 and 160.degree. C. respectively. The rubber composition so obtained has an improved silica dispersion, constant physico-mechanical characteristics and a better drawability and is particularly suitable for the manufacture of treads for tires with low rolling resistance.
摘要:
A moisture-curable silicone composition is prepared from (A) an organopolysiloxane resin having hydrolyzable groups associated therewith, (B) a fluorosilicone resin having residual silanol groups associated therewith, (C) a hydrolyzable organosilane and (D) a cure accelerating catalyst. The cured composition of the invention in prepared by reacting the aforementioned components (A) through (D) in the presence of moisture and results in a material exhibiting superior oil- and water-repellent properties.
摘要:
Disclosed and claimed are cocoa extracts such as polyphenols or procyanidins, methods for preparing such extracts, as well as uses for them, especially as antineoplastic agents and antioxidants. Disclosed and claimed are antineoplastic compositions containing cocoa polyphenols or procyanidins and methods for treating patients employing the compositions. Additionally disclosed and claimed is a kit for treating a patient in need of treatment with an antineoplastic agent containing cocoa polyphenols or procyanidins as well as a lyophilized antineoplastic composition containing cocoa polyphenols or procyanidins. Further, disclosed and claimed is the use of the invention in antioxidant, preservative and topiosomerase-inhibiting compositions and methods.
摘要:
A highly productive, continuous method for the production of room-temperature-curable organopolysiloxane compositions is obtained by continuously feeding 100 parts by weight of a diorganopolysiloxane with a viscosity at 25.degree. C. of 0.1 to 500 Pa.s that contains at least 2 silicon-bonded hydroxyl groups or hydrolyzable groups in each molecule; 1 to 30 parts by weight of an organosilane that contains at least 2 silicon-bonded hydrolyzable groups in each molecule, or the partial hydrolysis condensate thereof; 1 to 200 parts by weight of an inorganic filler in powder form, and 0 to 10 parts by weight of a cure-accelerating catalyst into a continuous mixing apparatus having starting material feed openings installed at its top, a discharge opening installed at its bottom, and a rotating disk installed within a casing and are therein mixed by the rotation of the said rotating disk, and in that the resulting mixture is thereafter continuously introduced into a vacuum mechanism- equipped degassing apparatus in which the water fraction present in the said mixture is removed under reduced pressure.