The micro-deformation processes of sealed low-density polyethylene/isotactic polybutene-1 (PE-LD/iPB-1 films with different contents of iPB-1 LIP to 20 m.-% (mass-percentage) were investigated in this study. The peel process was analyzed in detail using in situ peel test measurements with environmental scanning electron microscopy (ESEM). This method enables the direct correlation of recorded force-elongation data with observed structural phenomena. Thus, important parameters, e.g., the peel initiation value, could be determined directly from in situ measurements. The dependence of the peel properties on the iPB-1 content was analyzed and the correlation between micro-structure and performance of the peel process was clarified. Furthermore, the structural reason behind the dependence of the peel properties on the peel angle was identified. The crack propagation types interlaminar and translaminar were analyzed in detail with the ESEM. The translaminar crack propagation was further characterized using a tilted microscope stage with a mounted tensile tester. The direct contact of the electron beam with the non-conductive sample surface can cause beam damage. The beam damage, indicated by the absorbancy band at 965 cm(-1) in the infrared spectrum, was investigated in dependence on the total irradiation time. (C) 2008 Elsevier Ltd. All rights reserved.