ポリアクリロニトリルの熱的挙動と重合因子との関連
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概要
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Synopsis Relation between the thermal behavior of polyacrylonitrile and the polymerization factors has been studied in detail by means of differential thermal analysis, viscosity measuement, ultraviolet and infrared spectroscopies. General dependence of the exothermic peak temperature (T_) of the polymer on the polymerization methods was reconfirmed. That is, an aqueous redox slurry polymer had higher T_ (285 - 300℃) and polymers prepared in homogeneous solution and in buik did lower one (250- 275℃). The effect of end groups was studied quantitatively. Under the controlled conditions (i.e., in aq. solution system), the presence of N,N-dimethylformamide or isopropyl alcohol, and activator (NaHSO_3) give rise to polymers with a lower (-250℃) and higher T_(-300℃), respectively. Such a large dispersion of T_ (250-300℃) can be explained inclusively in terms of a single reaction factor, namely, chain transfer mechanism. The role of NaHSO_3 during the polymerization was examined. It was realized that a certain secondary reaction (i.e., chain branch formation) caused by the propagating chain end radical was restrained effectively by the strong and rapid chain transfer reaction to the activator. in the discussion of the inhibition effect of NaHSO_3 on branch formation, the existence of two different kinds of polymer radicals and the importance of polarity of them were emphasized. Characterization of the type of branch was made. It was found that a predominant branching occurs preferentially on polymer backbone (i.e., main chain branching.) The optimum polymerization conditions, under which the polymers with the highest thermal property (i.e., the least branched polymers) are obtained, were established empirically, within a limited experimental range, for aq. heterogeneous system.
- 山形大学の論文
- 1980-01-21