tensile stress failing thereby the material film before the seal. Maximum tensile resistance was 1.6 ? 0.3 MPa, being this value closer to the maximum strength of TPS films determined by the
aforementioned tensile test (Table 1). The fact that both values were similar regardless different crosshead speed used in tensile tests is an indicative that TPS films material failed before the seal.
On the other hand, film juncture of TPS composite with 5% w/w talc nanoparticles failed before material breakage. This result is in accordance with TPS matrix reinforcement by talc addition,
demonstrated through tensile and quasi-static tests (Fig. 1 and Table 1). For these composite films the involved energy to cause adhesive-cohesive seal failure was 19.1 ?1.7 J/m. Moreover, average
thermo-sealing resistance of composite films was 1.7 ? 0.1 MPa. The fact that this value resulted significantly lower than the maximum tensile strength obtained by tensile tests (Table 1)
demonstrates that seal was less resistant than film material. In addition, talc incorporation to TPS matrix increased the resistance around 11% to cause specimen failure, regardless the breakage
mode. SEM observations of the seal zone of tested specimens were carried out in order to analyze if failure of TPS films with 5% w/w talc corresponded to an adhesive or a cohesive mode. Fig. 3
presents SEM micrographs corresponding to both films which were in contact before tensile tests. Fig. 3A and B are like specular images between them. When seal was opened, part of the material cor-
responding to one of the films was pulled out, causing a cohesive failure mode. Resulting hollows due to the material pulling are indicated with arrows in Fig. 3A. On the other hand, in Fig. 3B are