Assessment of the compatibility in hot melts by using different thermoanalytical methods. Ethylene/n-butyl acrylate (EBA) hot melts containing tackifiers of different nature

Abstract

Several thermoanalytical methods were used to assess the compatibility of EBA (copolymer of ethylene and n-butyl acrylate) hot melts containing tackifiers of different nature (pentaerythritol rosin ester, polyterpene resin, aliphatic hydrocarbon resin, aromatic hydrocarbon resin, and cycloaliphatic-aromatic hydrocarbon resin). The influence of the compatibility of EBA hot melts on their rheological, viscoelastic, and adhesion properties to polar (aluminum foil) and nonpolar (polypropylene film) substrates were analyzed. The viscosity and shear thinning at 160 °C of EBA hot melts varied significantly by changing the tackifier nature; however, at 180 °C all EBA hot melts showed similar viscosities and shear thinning was absent because of the rupture of physical interactions between their components. EBA copolymer showed broad tackifier compatibility, even though aliphatic and aromatic hydrocarbon resins were less compatible. Compatibility was assessed by softening point and cloud point measurement, and dynamical mechanical thermal analysis. The most compatible EBA hot melts were obtained with rosin ester, polyterpene and cycloaliphatic-aromatic hydrocarbon tackifiers and they showed the highest tack and adhesion. On the contrary, the less-compatible EBA hot melts were obtained with aromatic and aliphatic hydrocarbon tackifiers, and they showed the lowest adhesion. EBA containing aliphatic hydrocarbon tackifier was exceptional because of even being incompatible, it showed high tack.