We here demonstrate a novel experimental approach by which peel strength of heat-sealed polypropylene (PP) films can be improved by a tensile cyclic loading method, without using chemical adhesive materials. Laminated films of oriented polypropylene (OPP) and cast polypropylene films (CPP) were prepared using the dry lamination method. The tensile cyclic loadings were then applied to these films, and the influence of heat sealing conditions and tensile cyclic loading on the peel strength of the films were experimentally investigated using tensile tests, optical microscopic inspection, and micro Raman spectroscopy. As a result of the heat sealing, the peel strength was increased with increasing numbers of tensile cyclic loadings. It was noted with increasing number of cyclic loadings, the peel strength of the OPP/CPP films was enhanced and exhibited good durability after tensile cyclic loading. The result of micro-Raman spectra revealed the local variation in the heat-sealed edge part, and it was found that HWHM on line mapping correlated with the peel strength. (C) 2016 Elsevier B.V. All rights reserved.