ESR Studies on Fracture Mechanism of Solid Polymers Induced by Mechanical Fracture

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We speculated that a mehcano anion and a mechano cation were produced by a heterolytic carbon-carbon bond scission due to the mechanical fracture of solid polymer.The production of the mechano anions was assigned by a detection of tetracyano ethylene anion radical (TCNE^<・^^->) from polymers fractured with TCNE in vacuo in the dark at 77 K using ESR method. The mechano anions were obtained from polytetrafluoroethylene (PTFE), polyethylene (PE), polypropylene (PP), and polyvinylidenefluouride (PVDF).The yields of the mechano anions (ratios of the heterolytic carbon-carbon bond scission) were obtained as PTFE (16 %), PE (27 %), PP(37 %), and PVDF (85 %)The production of PVDF mechano cation was assigned by the detection of polyisobutylvinylether (PIBVE) produced by a cationic polymerization on isobutylvinylether (IBVE) initiated by PVDF mechano cation. The molecular weights of PIBVE were obtained as Mw=6.2 X 10^4, Mn=2.3 X 10^4.We concluded that the mechano anions and the mechano cations were produced by the homolytic carbon-carbon bond scission of polymer main chain due to mechanical fracture of solid polymers, and the ionic yield was affected by a polarity of the carbon-carbon bond due to an electron affinity of substitution groups attached to the polymer chain.