A lot of plastic laminated films are used in our surroundings, so the welding of the films is essential processing technology. We paid attention to the relation between mechanical properties and the degree of crystallization of polymer, and measured the degree of crystallization of the film in the heat-sealing site. As a result of comparing it with mechanical properties, we found that in the case of CPP (Casted Polypropylene), which has a lot of the side chains, mechanical properties and the degree of crystallization of films are almost linked. However, in the case of HDPE (High Density Polyethylene), which has a little the side chain, these relationship are not linked.
