Effects of welding procedures on mechanical and morphological properties of hot gas butt welded PE, PP, and PVC sheets

Abstract

Mechanical and morphological properties of hot gas butt welds on polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC) sheets for four different procedures, which are single and double V-welds with and without a welding shoe, were investigated. Besides, weldabilities of base materials were evaluated by rheological measurements. These revealed that weldabilities of PE and PP sheets were better than that of PVC. Welding energy (E w ), which is transferred onto weld surfaces, was calculated to evaluate weld quality. The results of tensile, impact, and bending tests indicated that the weld strengths of PVC sheets were lower than those of PE and PP sheets. When the welding shoe was used, weld strength increased significantly for each material because of the presence of sufficient welding pressure and the effective heating on surfaces. The best results were attained for the double V-welds with the welding shoe. Morphology of welded regions was evaluated by polarized light, stereo, and scanning electron microscopy. Polarized light microscopy studies indicated that the heat-affected zone (HAZ) consisted of welding rod core, molten zone, and deformed spherulitic zone, and the welding interface was indistinguishable from the base material when the welding pressure was enough. POLYM. ENG. SCI., 48:732-746, FIG. 3. Geometries of weld grooves (y-z plane). (a) Single V-weld groove. (b) Double V-weld groove. FIG. 4. A cross-sectional view of the welding jig. a The values of welding speed (S w ) were measured on one of the two seams. The true welding speed values of double V-welds (X-welds), which are shown in parentheses, are half because a double V-weld comprises two seams. b The values of welding energy (E w ) were calculated using the true welding speeds of corresponding double V-welds. FIG. 9. Stress-strain (r-e) curves for base and welded PE, PP, and PVC sheets with various welding procedures.

Polypropylene/date stone flour composites: Effects of filler contents and EBAGMA compatibilizer on morphology, thermal, and mechanical properties

“…From 240°C, the thermal degradation of cellulose takes place by hydration and depolymerization up to 360°C resulting in the formation of volatile products and char. The major weight loss in the temperature range of 360–500°C indicates the pyrolitic degradation of lignin involving the fragmentation of interunit linkages (releasing monomeric phenols into the vapor phase), decomposition and condensation of the aromatic rings 20, 21. Figure 4 shows the TGA thermograms of uncompatibilized PP/DSF composites recorded at various loading rates, i.e., 10, 20, 30, and 40 wt % compared to neat PP and DSF.…”

Soldagem Por Extrusão Em Chapas De Polietileno De Alta Densidade – Avaliação Sob Uma Perspectiva Naval

“…Então, consequentemente, esse é o foco da maioria dos trabalhos acadêmicos. Já foram feitos estudos para propriedades mecânicas em chapas de 3 mm de espessura soldadas por ar quente (hot gas welding) [5], porém fora da realidade das construções de embarcações, que utilizam chapas mais espessas (15 mm) e usam majoritariamente soldas por extrusão.…”

Welding methods for joining thermoplastic polymers for the hermetic enclosure of medical devices

“…The bond quality of hot-gas welds is dependent on welding speed, pressure, and gas temperature [44]. Balkan et al compared hot-gas butt welding of PE, PP and PVC [54]. The overall tensile strength of the PVC to PVC bond was found to be lower than the equivalent PE-PE and PP-PP bonds.…”

“…These unfused areas can act as notches and hence compromise the mechanical integrity of the bond. Additionally, both Potente et al and Balkan et al have highlighted the importance of applying pressure for transporting thermally damaged material out of the joining zone, and homogenising the material at the interface, and thus increasing the achievable weld strength [54,62]. However, increasing the pressure too much can cause a decrease in the molten-layer thickness and thus reduce the bond strength [44,62,67,68].…”