Correlation between thermal behavior of a sealant and heat sealing of polyolefin films

The correlation between melting behavior of a sealant and heat-sealing properties of multilayer polyolefin films was investigated. Different films with propylene-ethylene copolymers as sealant layer were produced via co-extrusion, and standard heat seal and hot tack measurements were performed. The sealing behavior was correlated with melting behavior of the sealant materials using successive self-nucleation and annealing thermal analysis (SSA-DSC). This technique enables solid-melt fractionation through different annealing temperatures, inducing crystallization of different polymer fractions at each temperature. Results demonstrated that heat seal and hot tack closely follow melting curves. A linear correlation was found between heat seal initiation temperature (HSIT taken at 4N/25.4 mm seal strength) and the temperature at which 40% of the polymer melted (using the SSA-DSC thermal fractionation method). This technique can be applied for predicting sealant properties of research materials, which are usually produced in small quantities.