37results about How to "High weight average molecular weight" patented technology

A method of producing a stereocomplex polylactic acid having a high melting point and a high molecular weight, wherein only stereocomplex crystals are grown even when melting and crystallization are repeated. The method comprises the steps of: (1) obtaining a first polylactic acid by the ring-opening polymerization of a first lactide composed of lactic acid units of the same chirality; (2) obtaining a purified first polylactic acid by removing the lactide from the first polylactic acid in a molten state under reduced pressure; (3) obtaining a second polylactic acid by the ring-opening polymerization of a second lactide which differs from the first lactide in chirality in the presence of the purified first polylactic acid; and (4) obtaining a purified second polylactic acid by removing the lactide from the second polylactic acid in a molten state under reduced pressure.

The invention discloses a polyphenylene sulfide resin production process, which aims to a resin production method with good particle formation, high product yield, high solvent recovery rate, and reduced corrosion degree of a polymerization reaction device. The process adopts sodium sulfide containing a certain crystal water and p-dichlorobenzene as raw materials, and takes N-methylpyrrolidone asa solvent to synthesize the polyphenylene sulfide resin, and before a dehydration process, sodium sulfide and NMP raw materials are added to a dehydration system, a synthesis system is heated and dehydrated, after the dehydration is completed, p-dichlorobenzene and sodium sulfide are added in the synthesis system to carry out a condensation polymerization reaction to obtain the polyphenylene sulfide resin. The polyphenylene sulfide resin synthesized by the invention is widely used in the fields of aerospace, electronic machinery, petrochemical, food, light industry, thermal power generation, cement industry, steel manufacturing, environmental protection, textile industry and the like.

The invention relates to the field of papermaking and paper chemicals, aims to solve the problem that a paper used polyacrylamide dry strength additive, which has an efficient enhancement effect, and is good in adhesiveness, and environmentally friendly, is required to be prepared in the papermaking industry at present, and provides a preparation method of cross-linked polyacrylamide with high molecular weight and narrow distribution and application of the cross-linked polyacrylamide to papermaking. The cross-linked polyacrylamide prepared with the preparation method has higher weight-average molecular weight and narrower molecular distribution, and has the advantages of good enhancement effect, low loss of white water, good adhesiveness, less jello, environmental protection and the like. When the cross-linked polyacrylamide is applied to various fields, actual effective constituents are concentrated better, the operating barrier is reduced, and fewer side effects are caused.

Provided are: an alkaline water soluble resin; a method for producing an alkaline water soluble resin; and an emulsion polymer including an alkaline water soluble resin. The alkaline water soluble resin is produced by polymerizing a first monomer which includes one or more among an acrylic monomer, a methacrylic monomer, or a styrene-based monomer and does not have an allyl group, and a second monomer which has an allyl group.

The present invention relates to a copolymer including 20 to 65 wt% of units derived from an alkyl styrene-based monomer; 10 to 40 wt% of units derived from a (meth)acrylate-based monomer; and 20 to 40 wt% of units derived from an aromatic vinyl-based monomer, based on the total weight of the copolymer, wherein the residual monomer content is 780 ppm or less, and a method for preparing the same.

The present invention relates to the technical field of chemical extraction of active ingredients, in particular to an extraction process of polysaccharides in Hericium erinaceus spore powder, comprising the following steps: S1. The spore powder of Hericium erinaceus is broken to obtain the broken spore powder of Hericium erinaceus; S2. Broken Hericium erinaceus spore powder is mixed with mannitol solution according to the material-to-liquid ratio of 1g: (60-88) mL, and heat-treated for 45-70min to obtain a broken-wall Hericium erinaceus spore powder solution; S3. Broken Hericium erinaceus spore powder solution Introduce nitrogen gas into the spore powder solution, keep it for 12 minutes to half an hour under the pressure condition of 1-1.3MPa, and then quickly reduce the pressure to standard atmospheric pressure to obtain the crude polysaccharide extract; S4. Separating and concentrating the polysaccharide extract by alcohol precipitation and drying to obtain a polysaccharide extract. The process provided by the invention has high polysaccharide extraction yield, high weight-average molecular weight of the polysaccharide, low equipment requirements, and is suitable for large-scale industrial production.

The invention discloses a single metallocene compound, whose structure is shown in the formula I, wherein, X is selected from halogen atom, alkyl, alkyloxy and aryloxy; Cp' is selected from cyclopentadienyl without substituent group or with substituent group alkyl, indenyl without substituent group or with substituent group alkyl, and fluorenyl without substituent group or with substituent group alkyl. The single metallocene compound provided by the invention can be used for preparing polyolefin, especially preparing syndiotactic polystyrene with appropriate catalytic activity, and SPS in the polymer has a high proportion, thereby the compound has a wide application prospect.

The invention relates to a catalyst component and a catalyst for olefin polymerization and application of the catalyst to olefin homopolymerization and copolymerization. In the invention, an alpha-cyano ester succinate compound containing a specific structure is used as an internal electron donor, a magnesium chloride and silicon dioxide composite carrier is used, and the technical means are matched with each other for use, so that the polymerization activity of the catalyst is also kept while the grain form of the catalyst is improved. The catalyst is used for propylene polymerization; a polymerization product has a high isotactic index and high weight-average molecular weight; and polypropylene with wide molecular weight distribution is obtained. Compared with the conventional 2,3-dialkyl ester succinate compound, the alpha-cyano ester succinate compound has the advantages of high easiness in preparation and high contribution to industrial production.

The invention discloses a structural resin for high-speed offset printing ink and a preparation method thereof. The structural resin for high-speed offset printing ink has a weight-average molecular weight of more than 300,000, a high softening point, a small acid value, and a high viscosity , Low viscosity, suitable for high-speed offset printing ink. The preparation of the structural resin is as follows: input rosin, add fumaric acid at 190-210°C, react at 190-210°C, add pentaerythritol at 220-240°C, and react at 265-285°C to obtain rosin derivatives; octylphenol , Paraformaldehyde and triethylamine are kept warm at 90-95°C to obtain phenolic resin; mix rosin and rosin derivatives and heat up to 240-255°C, add phenolic resin to react to obtain rosin phenolic condensate, keep the temperature at 240-255°C, Add glycerin and silicon dioxide, and keep warm at 260-270°C to react to obtain the structural resin. The method is simple, the conditions are easy to control, and it can be produced industrially.

The invention relates to a rare earth catalyst and a controllable polymerization method for conjugated diene in an arene medium. A rare earth metal carboxylate-based composite catalyst is adopted for catalyzing conjugated diene polymerization in the arene medium under the protection of inert gas to prepare high molecular weight high cis polyconjugated diene rubber. The rare earth catalyst has high catalytic activity and high directional selectivity for polymerizing the conjugated diene in the arene medium, ensures that the monomer conversion rate of the conjugated diene is over 70 percent and even over 90 percent, the cis-content of constitutional units of the polyconjugated diene is over 97 percent and is over 99 percent particularly, the obtained polyconjugated diene has the weight-average molecular weight (Mw) of 2.0*10<5>-1.5*10<6>, and the content of vinylarene participating in copolymerization is less than 1 percent (mol) and even cannot be tested.

The invention provides a method for preparing aramid fiber nanofibers based on deprotonation of Kevlar, comprising: stirring and preprocessing a mixed system of aramid fiber, organic solvent and alkali to obtain aramid fiber dispersion; Proton donors and / or ionic reaction assistants are added to the aramid fiber dispersion to control the degree of deprotonation, thereby obtaining the aramid nanofiber colloidal dispersion. The present invention also provides the aramid nanofiber colloidal dispersion prepared by the method. The invention improves the nanometerization rate of aramid fibers (which can be within 1-4 hours) and the concentration of the reaction system (up to 4 wt% or more), and the prepared aramid nanofibers have uniform size and high stability (length 5-20 micron, 5-30 nanometers), large specific surface area and aspect ratio, and excellent high temperature resistance; the method has simple equipment and process, strong applicability, and solves the problems of long preparation period, low reaction concentration, low production efficiency, etc. High practical production and application value.

The invention belongs to the technical field of forest product chemical product manufacturing, and specifically relates to a rosin modified phenolic resin for a vacuum paint spraying high-grade coating and a preparation method of the rosin modified phenolic resin. The preparation method of the rosin modified phenolic resin for the vacuum paint spraying high-grade coating, provided by the invention, comprises the following steps: firstly reacting tert-octylphenol with formaldehyde in different proportions under sodium hydroxide to prepare phenolic resin with different dissolubility, carrying out esterification on rosin through pentaerythritol to obtain rosin resin, carrying out a synthetic reaction on phenolic resin and the rosin resin in different proportions, then adding an antioxidant and an anti-ultravoilet assistant, and then carrying out refining to obtain the rosin modified phenolic resin. According to the method, the rosin modified phenolic resin for the vacuum paint spraying high-grade coating is prepared by adopting a numerical control method, the condition is easy to control, the rosin modified phenolic resin with different softening points and different dissolubility canbe produced, the prepared rosin modified phenolic resin is excellent in performance, high in softening point, low in color and luster, small in acid value and high in viscosity, and has extremely high dissolubility and molecular weight, and the product quality is easy to control.