Why does the hot melt glue stick to the object? That's because the hot melt zone is polymer.
Take our common Eva hot melt adhesive tape as an example. Eva hot melt adhesive tape is a vinyl acetate polymer. When the hot melt glue stick is applied to the surface of the adherend with a glue gun, the hot melt adhesive will penetrate into the surface of the adherend. When hot melt adhesive is used in China, the bonding is completed. This is the principle of thermosetting. When the surface polarity of the object is close to EVA, the object is easier to penetrate, that is, the bonding effect is better.
For example, polyethylene plastic, that is, polyethylene, is similar in polarity to EVA, so it is easy to bond. Polypropylene (PP) plastics, namely polypropylene (PP) and EVA (EVA), have the characteristics of different polarity, poor permeability, and poor bonding effect.