Bulk Polymerization of Butyraldehyde under High Pressure

Abstract

DPPH, radical scavenger, was found to catalyze the polymerization of butyraldehyde under high pressure. The resulting polymer has polyacetal structure and depolymerizes t6 original monomer at the normal condition. The bulk polymerization of this monomer by DPPH cathlyst was studied at 5600-8240 kg/cm2 and 7-34oC, This polymerization reaction has a saturation yield wbich depends on the reaction pressure and temperature. The ceiling temperature derived from the extrapolation to zero yield on the plots of the saturation yield vs. temperature at the constant pressure increases with the pressure as giving 12 at 5500kg/cm2 and36 at 8240 kg/cm2.
The thermodynamic quantities accompanying the polymerization were estimated from the Clausiu.s-Clapeyron equation, measuring dV, volume change accempanying the polymerizatiori and using the pressure coeflicient of the ceiling temperature, The heat of polymerization, H, was-63 kcal/mol at 7000 kg/cm2 and the corresponding entropy chenge, Sp*, was -21 e.u.
Extrapolation to atmospheric pressure gives a ceiling temperature of -53 C, JHe*=-4.2kcal/mol and tSo =-19 e.u.