Abstract: In this work， a split molding process involving injection molding， extrusion， and welding was proposed to effectively reduce the molding difficulty of the inner liner of type-IV hydrogen storage bottle. A hot-melt welding experiment was conducted to evaluate the effects of heating temperature， welding time， and unit area welding pressure on the quality of the welding line of the samples. The tensile and impact properties of the samples on the welding line were measured， and the microstructure of the fracture surface of the welding line was investigated using scanning electron microscopy. The results indicated that the plastic fracture was the main form for weld failure， and the tensile strength on the weld line was essentially the same as that of the base material. Furthermore， the impact strength became higher. The experiments also identified the optimal welding process parameters as a heating temperature of 240 ℃， a welding time of 60 s， and a unit area welding pressure of 0.10 N/mm2. Under this process condition， the optimal mechanical properties were obtained for the welding line.

Key words: IV hydrogen storage bottle, hot-melt welding, single-factor experiment, mechanical property testing, scanning electron microscopy analysis