Influence of Ball-Milling Atmosphere on Decrease of Molecular Weight of Polyvinylpyrrolidone Powders

概要

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The rate of a decrease of mean molecular weight and molecular weight distribution of polyvinylpyrrolidone (PVP) powders changed by ball-milling in nitrogen, air or oxygen were investigated, and influence of a ball-milling atmosphere on the probability in which a PVP molecule was broken in a unit time and molecular size distribution of the polymers formed by the break of a PVP molecule in a unit time was discussed. If the function representing the probability in which a PVP molecule was cut off in a unit time, S (M), was proportional to (M-M_∞)^α, α was considered to be between 1.0 and 1.5,and to be 1.0 for the case of ball-milling in nitrogen of air and to be larger than 1.0 for the case of ball-milling in oxygen. It was considered to be much probable that a PVP molecule with molecular weight of 1.6×10^6 was broken both at the center and at the molecular weight between 6×10^3 and 1.1×10^4 from the end of a main chain by ball-milling in nitrogen, and at the molecular weight of 3.6×10^4 from the end by ball-milling in air or oxygen. It seemed to be possible that a PVP molecule with molecular weight of 1.6×10^6 was broken at the molecular weight between 5.0×10^4 and 3.7×10^5 from the end by ball-milling in oxygen.
公益社団法人日本薬学会の論文
1972-07-25