2results about How to "Low purity requirement" patented technology

This invention provides the application of a mixture of methylstyrene with high para-isomer content in the preparation of polystyrene substitute copolymers, belonging to the field of polymer material synthesis technology. This invention is the first to directly utilize a low-cost mixture of methylstyrene isomers to replace high-purity styrene. Through a "boiling-condensation" cycle in the fluidized bed polymerization process, efficient and constant-temperature heat dissipation is achieved, effectively overcoming the heat transfer difficulties and temperature runaway risks of traditional bulk polymerization. This facilitates control of the polymerization mechanism and yields random copolymers with a narrow molecular weight distribution and mechanical properties comparable to general-purpose polystyrene. This method is simple and controllable, significantly reduces raw material costs, and combines economic benefits with environmental value. The resulting copolymers can be used in general plastics, packaging materials, and other fields.

This invention discloses a method for preparing polyglycolic acid (PGA) and the PGA obtained by this method, relating to the field of PGA preparation technology. The method comprises: prepolymerizing glycolide in the presence of a catalyst to obtain a suspension; separating and removing insoluble matter from the suspension; and then performing a polymerization reaction to obtain the PGA. This invention uses low-purity glycolide as a raw material. After adding a catalyst, impurities undergo a certain degree of prepolymerization at a low temperature, allowing them to precipitate automatically. The precipitate is then separated and removed to obtain high-purity glycolide, which is then polymerized in situ at a higher temperature (retaining the initially added catalyst) to obtain high-molecular-weight PGA. This preparation method has low requirements for raw material purity, is simple and effective, and reduces the cost of PGA preparation to a certain extent.