Abstract: A method for producing and preparing a steel bar for automotive bushings by means of an ecological and economical arc furnace is provided. The steer bar contains, in percentage by mass: 0.18-0.23% of C, 0.20-0.35% of Si, 0.42-0.60% of Mn, less than or equal to 0.015% of P, less than or equal to 0.010% of S, 0.82-1.00% of Cr, less than or equal to 0.25% of Ni, 0.41-0.53% of Mo, less than or equal to 0.15% of Cu, and the balance of Fe and inevitable impurities. By means of smelting in an ecological and economical arc furnace, LF refining, RH refining, continuous casting, a heating process and a rolling process, the method enables batch production of the steel bar for an automobile shaft sleeve by means of a continuous casting procedure using the ecological and economical arc furnace.

Abstract: A polylactide derivative according to the present invention is expressed by the following general formula (1) or general formula (2): In general formula (1), one of X1-X5 is an aldehyde group, one of the other four is an alkoxy group, and the other three are hydrogen atoms. In general formula (2), one of R1-R3 is selected from a chlorine atom, fluorine atom, aldehyde group, alkoxy group, alkyl group and ester, while the other two are selected from the chlorine atom, fluorine atom, aldehyde group, alkoxy group, alkyl group, ester, and hydrogen atom.

Abstract: A polylactide derivative according to the present invention is expressed by the following general formula (1) or general formula (2): In general formula (1), one of X1-X5 is an aldehyde group, one of the other four is an alkoxy group, and the other three are hydrogen atoms. In general formula (2), one of R1-R3 is selected from a chlorine atom, fluorine atom, aldehyde group, alkoxy group, alkyl group and ester, while the other two are selected from the chlorine atom, fluorine atom, aldehyde group, alkoxy group, alkyl group, ester, and hydrogen atom.