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SynopsisAbout 40 epoxide-mine network polymers with glass transition temperatures ranging from 0 to 232°C were investigated, about one-third being reported for the first time. The glaw transition temperature T ' , of the corresponding linear copolymers was first calculated by use of an additivity law whose physical validity was carefully checked. Then the contribution of crosslink mers was determined, and various physical and empirical approaches of the effect of crosslinking on TR were compared. The results gave evidence in favor of the DiMardo approach. A predictive relationship based on these considerations is proposed.DGEBA-DDM epoxide-amine series5 (see below for the designating code). It has been shown however that eq. (1) cannot be applied to systems of high crosslink density such as polye~ters,~ a t least because the "copolymer effect" of the crosslinking species cannot be neglected. In this case free volume7 or more general considerations5 would lead to where x , is a parameter characterizing the network composition (segments,

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Tetraglycidyl 4,4'-diaminodiphenylmethane (TGDDM) undergoes homopolymerization on heating. lntramolecular reactions which compete with crosslinking favor the formation of cyclic structures with increasing thermal and fire resistance of the resin, whereas physical mechanical properties tend to decrease.The mechanism of thermal decomposition of TGDDM is studied by thermogravimety, differential scanning calorimetry and thermal volatilization analysis with characterization of volatiles evolved and residue left. Thermal degradation of poly-(TGDDM) starts at 260°C with elimination of water from secondary alcoholic groups which is a typical pathway for epoxy resin degradation. Resulting unsaturations weaken bonds in the &position and provoke the first chain breaking at allyl-amine and allyl-ether bonds. With increasing temperature, saturated alkyl-ether bonds and alkyl carboncarbon bonds are broken first, followed by the most stable alkyl-ayl bonds at T>365"C. The combustion performance of TGDDM is discussed on the basis of the thermal degradation behavior.