抄録
Degradation of polyvinylpyrrolidone (PVP) by ball-milling in air in the presence of each of the seven kinds of organic powders and seven kinds of inorganic powders with Mohrse's hardness between 1 and 9 was investigated. The organic powders added to PVP were chloranil and Vitamin K3 (good electron accepters), phenothiazine (a good electron donor), acridine and methylene blue (good electron accepters and good electron donors at the same time), and p-hydroquinone and barbituric acid (poor electron donors and poor electron accepters as well). The rate of a decrease of molecular weight of PVP by ball-milling was represented by equation (1). [numerical formula] In case of the addition of organic powders, β was larger than 1.0 in the presence of poor electron donors, and approximately equal to 1.0 in the presence of good electron donors. In case of the addition of inorganic powders, β was between 0.4 and 1.9. In the presence of hard powders, ti was zero and β was large. In the presence of soft powders, β was small and ti was larger than zero. In case of the addition of p-hydroquinone, barbituric acid or hard inorganic powders other than silica sands and zinc oxide, the peak in the molecular weight distribution curve of PVP shifted from the molecular weight of approximately 106 to lower molecular weight with the lapse of ball-milling time. In case of the addition of the other powders, the original peak decreased and a new peak at molecular weight lower than that of the original peak increased by ball-milling.
