57results about How to "Molecular weight control" patented technology

The invention provides a continuous nylon polymerization method which comprises the following polymerization raw materials in parts by mass: 5-60 parts of polymerization monomer dibasic acid and / or dibasic acid ester, 3-50 parts of diamine and 10-90 parts of reactive dispersion medium polyamide. The polymerization step comprises the following steps: continuously adding the polymerization raw materials into a material mixing device in proportion, mixing and reacting the raw materials in the material mixing device to form a continuously conveyed melt, and reacting the uniformly dispersed melt ina subsequent polymerization device until the nylon is polymerized to reach the required molecular weight. The method is an efficient, green and environment-friendly nylon polymerization method.

The invention provides a method for synthesizing a polylactic acid which has no metallic residue and has controllable molecular weight. The method is as follows: a reaction solvent is added into lactide to prepare a lactide solution the mol concentration of which is between 0.5 and 1.5 M under the protection of inert gas, and an initiator and catalyst are added into the lactide solution in turn, and subjected to polymerization for 0.25 to 2 hours, wherein the mol ratio of the lactide to the initiator to the catalyst is 6-350 to 1 to 0.06-0.35; a terminator is added into the lactide solution, and subjected to termination reaction for 10 to 20 minutes, wherein the mol ratio of the initiator to the terminator is 1 to 1-5; and methanol is prepared, wherein the volume ratio of the reaction solution to the methanol is 1 to 10-20, the reaction solution is dripped into the methanol to form polylactic acid deposit, and the polylactic acid deposit is separated out, filtered, subjected to methanol washing for 2 to 3 times, and subjected to vacuum drying for 24 to 48 hours at a temperature of between 20 and 40 DEG C to obtain the product. The synthesis method can be performed under the condition of room temperature and normal pressure, has high product yield and simple technique, does not require the conditions of heating and decompression, is easy to operate, and can effectively control the molecular weight of the polylactic acid product; and the product has no metallic residue and can be used as a medical material.

The invention discloses a supported double-metal cyanide catalyst and a preparation method and application thereof. The supported double-metal cyanide catalyst uses hydrotalcite as the supporter, double-metal cyanide is supported on the supporter, and the supported double-metal cyanide catalyst uses polyethylene glycol as the chelating agent. The preparation method includes: using zinc chloride and metal cyanide as precursors, dripping the aqueous solution of central metal into a ligand substance solution for reaction, adding the supporter and the chelating agent at the same time, and performing centrifugal separating and drying to obtain the supported double-metal cyanide catalyst. The invention also provides a preparation method using the supported double-metal cyanide catalyst to prepare carbon dioxide-epoxide copolymer. Compared with same-type catalysts, the supported double-metal cyanide catalyst has the advantages that the catalyst is high in catalyzing activity and good in product selectivity; when the catalyst catalyzes carbon dioxide to have copolymerization reaction with epoxides, the carbonic ester unit content of the copolymerization product is high, the cyclic carbonate content of the copolymerization product is low, and the catalyst is high in actual application value and promising in market prospect.