Solid-phase polymerization of maleic anhydride at high pressures

Abstract

Solid maleic anhydride undergoes spontaneous polymerization when it is heated to 100-170°0 at pressures above 20000 atm. On a pressure- temperature diagram, the regions of monomer stability and of polymerization are separated by a rather well-defined line, which possibly marks the occurrence of a physical polymorphic transition. The structure of the polymer is discussed. Efforts to polymerize some other 1,2-disubstituted ethylenes have been unsuccessful. The following substances were recovered unchanged after being heated to 160-180°0 at 30000-45000 atm: maleic acid, fumaric acid, crotonic acid, sorbic acid, coumarin, and trans-stilbene. The melting temperature of maleic anhydride has been measured to 3770 atm and the parameters in the Simon melting equation are reported.