33results about How to "Molecular weight distribution index is small" patented technology

The invention relates to a method for preparing micromolecule pectin, belonging to the production technology of macromolecule pectin. The invention provides a method for preparing micromolecule pectin of which the weight-average molecular weight is 10000-30000, the micromolecule pectin is obtained by degrading natural pectin in an acid solution system at the temperature of 55-110DEG C, and the acid solution system is methanoic acid, acetic acid, sulfuric acid or hydrochloric acid aqueous solution. The reaction yield can be 5-30%, the pectin esterification degree is not lowered, and the structure of branched chain heteropolysaccharide is not changed; and the obtained pectin degree of index (PDI) is controlled to 1.6-2.5, i.e. the molecular weight distribution index is lower. The pectin of which the molecular weight is 10000-30000 can serve as a carrier for the in-vivo kidney to excrete and can serve as a polymer drug carrier for intravenous injection.

The invention provides a preparation method of medical biodegradable polymer material polylactate geycollic acid (PLGA). A mass polymerization method is adopted for manufacturing the polylactate geycollic acid (PLGA), the production technology is simple, conditions needed by the reaction are low, the reaction speed is high, and the reaction time is short; a catalytic system adopting an organic metal compound as a main catalyst and adopting a substance containing reactive hydrogen as an initiator is adopted as an efficient catalytic system, the reaction time is shorter compared with a single catalyst, the weight-average molecular weight of the product is adjustable, the lowest molecular weight distribution index can reach 1.40, the catalytic activity is high, and the PLGA is non-toxic basically; the reaction product is precipitated three times, unreacted monomers and low-molecular-weight by-products can be removed, the molecular weight distribution index is lowered, and the product purity is improved.

A fractionators narrowing polyester polyol molecular weight distribution is disclosed. A wastewater collection tank (7) is installed adjacent to a polyester reaction vessel (2), also a reflux pipe is connected between the upper end of the polyester reaction vessel (2) and the lower end of a dephlegmator (4), the reflux-pipe segment is provided with a U-shaped pipe (5), the communication bottom end of the U-shaped pipe (5) is connected with the wastewater collection tank (7), and the bottom of a condenser is connected with the wastewater collection tank (7); the dephlegmator (4) is connected with the condenser (6), the polyester reaction vessel (2) is connected with the dephlegmator (4), a return valve is arranged at the pipeline connecting the U-shaped pipe (5) with the polyester reaction vessel (2). The product quality is improved, alcohol removal labor hour is saved, the processing time of 6 KL of the raw material is shortened within 1 h from original 3-5 h, micromolecule alcohols are rapidly efficiently removed, polyester polyol molecular weight distribution is properly narrowed, and the molecular weight distribution index is relatively small. The cobalt-platinum colour is relatively low, and the acid value is relatively low and is within 0.1 mg KOH / g.

The invention relates to the field of olefin polymerization, and particularly provides polypropylene, a preparation method and applications thereof, wherein the polypropylene has a melt flow index MFRof more than 30 g / 10 min, has an isotactic index of 96-99.5 wt%, and has a molecular weight distribution index MW / Mn of 3-5.5. The preparation method comprises: polymerizing propylene in the presenceof a catalyst under an olefin polymerization condition to obtain a polypropylene product, wherein the catalyst contains a catalyst component, an alkyl aluminum compound, and optionally an external electron donor, the catalyst component contains the product obtained by carrying out a reaction on a magnesium source, a titanium source and an internal electron donor, the internal electron donor contains a phosphate compound and a diether compound, and the phosphorus content (calculated as the phosphorus element) in the catalyst component is not more than 0.06 wt%. According to the present invention, the polypropylene integrates characteristics of high isotactic index, high melt flow index and narrow molecular weight distribution.

The invention discloses a reversible addition-fragmentation chain transfer free radical polymerization method, wherein characterized in that, microwave radiation heating can be used for polymerization, and it is possible not to use initiating agent . The invention can greatly increase polymerization speed, andconveniently control molecular weight of polymerization product.