Hot-melt adhesive properties of EVA/aromatic hydrocarbon resin blend

A series of ethylene vinyl acetate copolymers (EVAs) were blended with aromatic hydrocarbon resins for use as hot-melt adhesives. The glass transition temperature, viscoelastic properties, melt viscosity, crystallinity and adhesion properties of the EVA/aromatic hydrocarbon resin system were determined as a function of the softening point of the aromatic hydrocarbon resin, the blend ratio of the two components and the vinyl acetate content of EVAs. Most blends showed a glass transition temperature at about -25degreesC and a melting peak between 30degreesC and 100degreesC. The peaks of loss modulus increased with increasing softening point of the aromatic hydrocarbon resin. The melt viscosity of the blends decreased with increasing temperature. Also, the melt viscosity increased with increasing softening point, but decreased with increasing aromatic hydrocarbon resin and vinyl acetate content. Increasing the softening point of the aromatic hydrocarbon resins, in cases of the same blend ratio, increased the crystallinity, while the addition of aromatic hydrocarbon resin decreased the crystallinity. Also, increasing the vinyl acetate content decreased the crystallinity of the blend, due to a decrease in the crystalline region of ethylene. The lap-shear strength increased with increasing softening point of the aromatic hydrocarbon resin. The lap-shear strength also increased with increasing concentration of aromatic hydrocarbon resin, until it reaches a maximum value. (C) 2003 Elsevier Ltd. All rights reserved.