562results about How to "Reduce the degree of polymerization" patented technology

A process for making lyocell fibers including the steps of pulping raw material in a digester to provide an alkaline pulp, wherein the raw material includes sawdust in an amount greater than 0% up to 100%; contacting the alkaline pulp including cellulose and at least about 7% hemicellulose under alkaline conditions with an amount of an oxidant sufficient to reduce the average degree of polymerization of the cellulose to the range of from about 200 to about 1100 without substantially reducing the hemicellulose content or substantially increasing the copper number of the pulp; and forming fibers from the pulp.

Strands of molten polyethylene terephthalate (PET) from a PET polycondensation reactor are solidified, pelletized, and cooled only to a temperature in the range of 50° C. to a temperature near the polymer Tg by contact with water. The still hot pellets are conveyed, optionally followed by drying to remove water, to a PET crystallizer. By avoiding cooling the amorphous pellets to room temperature with water and cool air, significant savings of energy are realized.

A high pH and a low pH process for reducing the degree of polymerization of a pulp having a hemicellulose content of at least 7%. The high pH is greater than 8, and the low pH process is 2 to 8. The high pH process reduces the degree of polymerization without substantially increasing the copper number. The low pH process requires a subsequent treatment with alkali to reduce the copper number of the pulp to less than 2. The process can be practiced in pulp mills with a bleaching sequence having one or more E or D stages. At the end of the bleach sequence, a pulp having a degree of polymerization of 200 to 1100, a copper number of less than 2, and a hemicellulose content of at least 7% is provided. The pulp can be used to make lyocell fibers.

The invention relates to a production method for preparing a dissolving pulp by an oxygen-dissolving and continuous-cooking method, which applies the preparation of cotton linters in the production of viscose fibers in the textile industry, and the method comprises the following steps of: I. cotton linter pretreatments: including cotton linter loosening, cyclone separation and dust removal, feeding, two-roll grinding treatment, etc. to the cotton linters by a two-roll pulping machine; and II. oxygen dissolving and continuous cooking: a horizontal continuous cooking digester is adopted to realize the continuous, fast and low-pollution preparation of dissolving cotton pulp through the actions of high temperature, alkali, oxygen or hydrogen peroxide. The horizontal continuous cooking digester includes a pre-reaction bin, a two-roll gauge, a feeding screw, a T-shaped tube, a continuous-cooking tube and a cold discharge device. The method can effectively solve the problems of: cutting, tearing and cell primary wall breakage to the cotton linters by dry method after feed preparation, physical and chemical stripping to mass impurities in the cotton linters, fast accumulation reduction of the cotton linters in a continuous-cooking device and the purification of alpha cellulose under fast accumulation reduction, recycling of waste heat in the production link, and reduction of total amount of COD in a black liquor, and the method has advantages of even cooking and short cooking cycle.

A water-solible polymer dispersion, p process for producing the same and a method of use therefor. In particular, the water-soluble polymer dispersion is one comprising water-soluble polymer fine particles of 100 μm or less diameter having at least one ionic property selected from among cationic, amphoteric, nonionic and anionic properties together with a polyalkyleneimine and/or a product of polyalkyleneimine modification wherein according to necessity an appropriate amount of water-soluble inorganic salt is incorporated. The provided process enables easily performing the production in dispersed form by means of production facilities of low cost. The obtained water-soluble polymer dispersion is excellent in storage stability and exhibits satisfactory fluidity and solubility so as to enable use in papermaking raw material pretreatments added to papermaking raw materials prior to machine operation and also for enhancement of freeness, increase of sizing degree and enhancement yield. Further use can be found in incorporation in an organic sludge or paper mill sludge for flocculation and ensuing drainage.

The invention relates to a deodorant nitrogen-conserving conditioner. The using method comprises the following steps: evenly mixing pig manure and crushed straw or other crop straw in a ratio of 2-8:1, wherein the moisture content is between 60 and 65 percent; carrying out simple high-temperature composting by adding 25 to 40kg deodorant nitrogen-conserving conditioner in each 1,000kg compost rawmaterial; and adopting a pile-turning or a forced ventilation mode, wherein the temperature is not more than 70 DEG C during high-temperature composting. The deodorant nitrogen-conserving conditionercomprises 15 to 20kg calcium chloride, 10 to 15kg calcium superphosphate and 3 to 8kg zeolite. The compost becomes thoroughly decomposed after 30-day composting. The deodorant nitrogen-conserving conditioner is characterized in that: the conditioner can reduce odorous substances in the pig manure compost and ammonia volatilization and eliminates odour more than 10 days earlier; moreover, the conditioner increases the content of nitrogen nutrients in a compost product by over 20 percent and reduces nitrogen loss by over 70 percent in the composting process; and at the same time, the conditioner has the advantage of simple and easy operation and is suitable to be used in organic fertilizer factories and vast rural areas.

A catalytic system for cellulose acylation includes an adduct of sulfuric acid with N,N-dimethylacetamide, free sulfuric acid or free N,N-dimethylacetamide with the following mole ratio of the components: adduct:1.0; free sulfuric acid, max:0.49; or free N,N-dimethylacetamide, max:0.4. A process for producing such a catalytic system is based upon reacting sulfuric acid with N,N-dimethylacetamide in an anhydrous medium at a temperature of 0° C.-25° C. with the following mole weight ratio of the components: sulfuric acid:1.0; N,N-dimethylacetamide, max:1.4. A process for cellulose acylation in the presence of this catalytic system incorporates cellulose treatment with acetic acid followed by treatment of the resultant activated cellulose with a lower fatty acid anhydride at a temperature of 10° C.-90° C. in the presence of this catalytic system taken in an amount of 1.5-30.0 wt. % of the cellulose weight in terms of sulfuric acid, a weight ratio of the liquid phase and cellulose being 3-7:1, respectively.

A catalyst for producing a liquefied petroleum gas according to the present invention comprises a Pd-based methanol synthesis catalyst component and a β-zeolite catalyst component. It can be used in a reaction of carbon monoxide and hydrogen to give a hydrocarbon containing propane or butane as a main component, i.e., a liquefied petroleum gas, with high activity, high selectivity and high yield. Furthermore, the catalyst has a longer catalyst life with less deterioration.

The invention relates to a preparation method of a cellulose nanofiber. The method comprises the following steps: with wood fiber biomass as a raw material, presoaking, and carrying out steam explosion pretreatment; carrying out high-temperature hydro-thermal treatment on pretreated materials; hydrolyzing hemicellulose, and carrying out washing suction filtration to obtain hemicellulose hydrolysate and filter residues rich in lignin; putting the filter residues into a high-pressure reaction kettle, adding an ethylene glycol solution, heating and extracting the lignin from the residues with ethylene glycol; extracting and carrying out solid-liquid separation to obtain a lignin extract liquid and cellulose solid; carrying out enzymolysis on the cellulose solid with cellulase and removing an amorphous region of the cellulose to obtain cellulose crystal; and carrying out high-pressure homogenizing on the cellulose crystal to obtain a cellulose nanofiber product. The cellulose nanofiber prepared by the method has the advantages of nanoscale, large specific surface area, high activity and high security.

The invention discloses a method for separating and recovering waste cotton-polyester blended fabric under a subcritical water condition, and belongs to the field of resource recycling and reuse of waste fabric. Under the conditions that the mass fraction of hydrochloric acid is 0.5-2% and reaction temperature is 130-160DEG C, reaction is carried out for 3-5h, cotton fibers in the waste cotton-polyester blended fabric are decomposed into microcrystalline celluloses, but polyester fibers are not changed, and therefore, the polyester fibers and the microcrystalline celluloses are separated and recovered. The method is suitable for the cotton-polyester blended fabric formed at any ratio and has the advantages of simpleness in operation, short technological process, low energy consumption, light environment pollution and the like.

The invention discloses PVC (Polyvinyl Chloride) paste resin and a preparation method thereof, belonging to the technical field of polymer chemical industry. Weighted in 100 parts by weight of vinyl chloride, the PVC paste resin with the average grain diameter of 0.5-2mum, the average degree of polymerization of 1600-1900 and the paste viscosity of 1500-3500mPa.s is prepared from the following components: 70-120 parts of deionized water, 0.5-5 parts of mixed emulsifier, 0.005-0.02 part of oil-soluble compound initiating agent, 0.05-0.5 part of pH value regulator and 0-0.1 part of chain extender through microsuspension polymerization. The paste resin prepared according to the invention has the advantages of high degree of polymerization, low paste viscosity, rapidness in plasticization, good transparency and favorable defoaming performance.

The present invention features that PVA of polymerization degree 500-2000 and alcoholysis degree 75-99 mol% in 100 portions is mixed with solvent mixture of dimethyl sulfoxide and water in 200-400 portions, the mixture is stirred and heated to 80-120 deg.c at -0.01--0.08 MPa pressure in a stainless steel reactor for 3-4 hr to compound the spinning solution, and the spinning solution is filtered and defoamed and used in spinning to obtain water soluble PVA fiber after post-treatment. The PVA fiber has a water solving temperature of 10-90 deg.c, strength greater than 3.5 cN/dtex, monofilament length of 1.5-10 dtex, fracture elongation of 15-30%. It may be processed into top, which may further blended with wool top, cotton, top, etc. to produce fine yarn or hollow yarn, or cut into staple fiber for producing non-woven fabric, etc.

The invention discloses a preparation method of a nanometer stepped hole mordenite molecular sieve. The method comprises the following steps: dissolving sodium hydroxide in water and then adding a silicon source at room temperature to stir for 0.5-1.5 h to obtain alkaline silicon source solution; adding an aluminum source dissolved by using the water into the alkaline silicon source solution, stirring for 1 h at the room temperature to form uniform silicon and aluminum mixed solution, adding a mesoporous soft template (R) for 1 h, then adding a seed crystal (M) and stirring for 1 h to form a gel mixture, and then dynamically crystallizing at 100-180 DEG C for 12-96 h; cooling, performing extraction filtration and washing the product after crystallization until pH is about 7, drying at 100 DEG C for 12 h, roasting at the constant temperature of 110 DEG C for 3 h and then rising temperature to 500 DEG C to roast for 3 h to obtain a nanometer stepped hole mordenite product. The mordenite molecular sieve prepared by the invention has the typical nanometer stepped hole characteristic, and the hydrodealkylation performance of the Pt/MOR catalyst loaded with the sieve as a carrier is obviously improved.

The invention belongs to the technical field of material preparation and photocatalysis, and discloses a high-activity graphite-phase carbon nitride material and a preparation method thereof. The preparation method comprises the following steps: forming a self-generated gas atmosphere a gas generated from a precursor by pyrolysis in the high-temperature calcining process under the control on an inert gas, and guiding synthesis of a carbon nitride material, thereby obtaining a flaky porous graphite-phase carbon nitride material. According to the preparation method, after the inert gas is not introduced any longer, a self-generated gas generated from the precursor is relatively uniform at different parts, and the carbon nitride material prepared with the preparation method is uniform in morphology and relatively good in crystal form; due to the escape of the self-generated gas, the material is effectively pored, and thus the specific surface area and the active sites of the material are increased; due to the self-generated gas atmosphere, the polymerization degree of the precursor is reduced, and the obtained carbon nitride material has a relatively large amount of unpolymerized amino or imino groups. The preparation method disclosed by the invention is simple, efficient and low in cost, and the carbon nitride material prepared with the preparation method is excellent in photocatalysis activity and very good in practicability.

The invention relates to a method for preparing microcrystalline cellulose at low temperature. The method is characterized by comprising the following steps: (1) completely soaking the cellulose raw material in a soaking solvent, wherein the soaking solvent is water or an acid solution with mass percent concentration not over 15wt% or an oxide solution with mass percent concentration not over 5wt%; (2) freezing the cellulose raw material after the soaking treatment in the step (1), and grinding; (3) performing high-speed shear treatment on the cellulose powder obtained by the grinding in the step (2), and performing aftertreatment on the product after the high-speed shear treatment to obtain the microcrystalline cellulose. The method for preparing microcrystalline cellulose at low temperature provided by the invention can obtain microcrystalline cellulose with different polymerization degrees lower than 350 and relatively high crystallization degree; high-temperature treatment process can be avoided, the energy consumption is low, and the process is simple and green and environment-friendly.

The invention discloses an energy-saving and high-efficiency method for dying crude wood, comprising the following steps of: (1) selecting crude wood; (2) preparing a dye solution for dying; (3) dyeing the crude wood; and (4) drying the dyed crude wood and preparing dyed wood. The invention has the advantages that: firstly, in the process, fresh crude wood is used in the dyeing process so as to avoid energy source consumption due to dried dyeing and secondary drying; secondly, the granularity and the polymerization degree of dye molecules subjected to ultrasonic treatment are greatly reduced so as to be conductive for the dye molecules to enter inside the wood for deeply dyeing; thirdly, the dyed crude wood can be sawn into boards in different thicknesses according to requirements; fourthly, the wood subjected to dyeing treatment by using the process is uniform in colors inside and outside and retains natural structures and grains of the crude wood; and fifthly, the dyeing process is simple and easy to operate.

The present invention relates to a method for producing chemical fibre pulp by using plant fibre as raw material. Said method includes the following several steps: raw material treatment, making the treated raw material undergo the processes of rubbing and extruding, cooking, washing, removing sand and bleaching treatment. It is characterized by that in the preparation process of said chemical fibre pulp a screw extruding machine and a rubbing-extruding machine are adopted.