Dynamic mechanical properties of aromatic,aliphatic, and partially fluorinated epoxy resins

The α, β, and γ transitions at temperatures between ?200 and +100°C. of crosslinked aromatic and aliphatic epoxy polymers were determined from damping and shear modulus data, and compared with their fluorine containing analogs. Loci of segmental relaxation are suggested at various temperatures, and similarities between aliphatic and fluorocarbon segments, and polyethylene and polytetrafluoroethylene are discussed. Two systems of structurally similar monomers 2,2,3,3,4,4-hexafluoropentane diglycidyl ether-1,5 and 1,4-butane diglycidyl ether, and 2,2-bis(4-glycidyl phenyl ether)hexafluoropropane and 2,2-bis(4-glycidyl phenyl ether) propane were polymerized with the aid of two diamine curing agents, namely, ethylenediamine and m-xylylenediamine. Polymers of the aromatic diepoxides showed transitions with peaks at ?56°C. and above +70°C. Three main peaks were registered for the aliphatic and fluorocarbon diepoxides: at ?125 and at ?100°C., at ?56°C., and at 0°C. It is suggested that the T_g is affected by an interdependence of relaxation of all components of the polymer main chain.