Experimental and numerical analyses of the thermoplastic pultrusion of large structural profiles

The selection of optimal process conditions is very important for the production of large pultruded thermoplastic profiles. This study investigates the influence of pulling speed on the temperature distribution and consolidation of glass fiber/polypropylene (GF/PP) preconsolidated tapes during thermoplastic pultrusion. For this purpose, several pultruded thermoplastic profiles with a cross-section of 75 mm x 3.5 mm were produced at various pulling speeds, and their cross-sections were studied under a microscope. In addition, a 3D numerical model was developed to analyze the influence of the pulling speed on the temperature distribution and to predict the consolidation of the tapes. Full consolidation of the tapes was observed in the profiles produced at a pulling speed of 0.2 m/min. The profiles produced at a pulling speed of 0.4 m/min contained unconsolidated tape, which resulted in reduced flexural, tensile, and compressive strengths by as much as 43%, 15%, and 23%, respectively. The results of the simulations and microscopic investigations show that the GF/PP tapes consolidate at temperatures above the Vicat softening temperature. Finally, a GF/PP tube with dimensions of 50 mm x 40 mm x 5 mm was produced using the optimum pulling speed and temperature determined using the developed 3D model. These results provide valuable insight into the design of thermoplastic pultrusion regimes.