Study on the optimization of the melt extrusion process for the preparation of T700/PPS prepregs for hydrogen pipelines and their NOL ring mechanical properties

To meet the demand for raw materials for high-performance thermoplastic composite materials for winding hydrogen pipelines, the problems existing in the hot melt extrusion process, such as insufficient and uneven resin impregnation, high porosity, and poor mechanical properties of the composite materials, were optimized. This paper studied the influence of key process parameters of the hot melt extrusion process on the quality of T700/PPS prepreg, designed single-factor experiments, used the response surface to analyze the influence of different process parameters (mold temperature, extrusion temperature, traction rate) in the hot melt extrusion process on the quality of prepreg (resin content, surface density), and explored the coupling effect among different process parameters. The T700/PPS prepreg prepared by the hot melt extrusion process was directly wound into NOL ring specimens using the in-situ consolidation winding process, and the interlayer shear strength and tensile strength of the thermoplastic composite material were tested. The results showed that the average surface density of the optimized prepreg was 339.95 g/m 2 , the resin content was 63.02 vol%, and the porosity was reduced from 12.5% before optimization to 1.5%. The average porosity of the NOL ring was 0.08%, the average ring tensile strength increased from 1541.54 MPa to 2212.31 MPa, and the average interlayer shear strength increased from 30.12 MPa to 50.18 MPa.