Determination of Primary Relaxation Temperatures and Melting Points of Ethylene Vinyl Acetate Copolymers

The relationship between copolymer composition and transition temperatures was studied by means of differential scanning calorimetric analysis and dynamic mechanical spectroscopy. Six samples of ethylene vinyl acetate (EVA) copolymers containing from 5 to 40 mass per cent of vinyl acetate (VA) were studied. The differential scanning calorimetric analysis revealed that each EVA copolymer displays two endothermic peaks (Tm1 and Tm2 ) in the melting zone. Dynamic mechanical spectroscopy was used to determine the primary relaxation temperature (Tα ) for EVA copolymers. This latter characteristic is relatively insensitive to the level of vinyl acetate contained in the copolymer and is influenced by the pulsation frequency ω, also named the angular frequency.