Abstract: The present invention relates to the technical field of the production of polylactic acid, and in particular to a production method for preparing polylactic acid by means of a ring-opening polymerization method, and a prepolymer mixture and the polylactic acid. The production method comprises: (1) enabling an initiator, a catalyst and a monomer I to be in contact in a production device to undergo a ring-opening polymerization reaction, so as to generate a prepolymer mixture containing a polylactic acid prepolymer; and (2) enabling the prepolymer mixture and a monomer II to be in contact with one another to undergo a reaction, so as to generate a high molecular weight polylactic acid. The monomer I and the monomer II are the same or are different, and each independently comprises lactide. The production method provided by the present invention can reduce the fluctuation in the feeding quality of the initiator and the catalyst, and can improve the production stability during the production process.

Abstract: Disclosed in the present invention are ABS rubber powder with a low impurity content, a preparation method therefor, and an ABS resin. The ABS rubber powder is treated by using the following steps: washing the ABS rubber powder with a washing solution I, and monitoring the content of soluble organic carbon in the ABS rubber powder until the content of soluble organic carbon in the ABS rubber powder is less than or equal to 9000 ppm, so as to obtain the ABS rubber powder with the low impurity content. In the present invention, by controlling the content of soluble organic carbon or the contents of soluble organic carbon and iron ions in the ABS powder, the ABS resin with a low yellow index of less than or equal to 18 is obtained.

Abstract: Substituted phenacyl molecules are provided and employed to create molecules and polymers/copolymers that exhibit photoresponsiveness. In some instances, the substituted phenacyl molecule is incorporated into the polymer/copolymer backbone, and photoirradiation of the polymer/copolymer causes the substituted phenacyl group to break down and the polymer/copolymer to undergo degradation. In other instances, the substituted phenacyl molecules extend as a side chain from the polymer/copolymer backbone. In yet other instances the substituted phenacyl molecules extend as a side chain from the polymer/copolymer backbone, and a drug or polymer additive is linked to the photoresponsive substituted phenacyl group such that photoirradiation releases the drug or additive. In yet other embodiments the substituted phenacyl molecules extend as a side chain from the polymer/copolymer backbone, and serve to link the polymer/copolymer to another polymer/copolymer backbone, and photoirradiation breaks the links.

Abstract: Substituted phenacyl molecules are provided and employed to create molecules and polymers/copolymers that exhibit photoresponsiveness. In some instances, the substituted phenacyl molecule is incorporated into the polymer/copolymer backbone, and photoirradiation of the polymer/copolymer causes the substituted phenacyl group to break down and the polymer/copolymer to undergo degradation. In other instances, the substituted phenacyl molecules extend as a side chain from the polymer/copolymer backbone. In yet other instances the substituted phenacyl molecules extend as a side chain from the polymer/copolymer backbone, and a drug or polymer additive is linked to the photoresponsive substituted phenacyl group such that photoirradiation releases the drug or additive. In yet other embodiments the substituted phenacyl molecules extend as a side chain from the polymer/copolymer backbone, and serve to link the polymer/copolymer to another polymer/copolymer backbone, and photoirradiation breaks the links.