Mechanical Enhancement and Strain Sensing of Electrofusion Joint With Carbon-Fiber-Reinforced Polyethylene

Electrofusion (EF) technology is widely used for connecting plastic pipes or composite pipes. For these pipes used in natural gas transportation and nuclear power plant, the higher and higher operation pressure makes the strength of EF joint a limitation in the pressure pipeline systems. In this paper, high density polyethylene (HDPE) filled with different contents of short-cut carbon fiber (CF) was prepared by melt mixing and injection molding. Scanning electron microscopy imagines indicated a good dispersion of CF in HDPE matrix. Experiments were carried out to evaluate the mechanical and electrical properties of the HDPE-CF composite. The addition of CF improved the elastic modulus and yield stress of the composite compared with neat HDPE. The enhanced mechanical properties of HDPE-CF composite can improve the strength of EF joints, and bursting tests revealed a burst pressure of 8.11 MPa, which is 41.8% higher than that of neat HDPE EF joint. Based on the improved electrical conductivity, the electrical resistance of EF joint induced by the strain under internal pressure can be monitored for structural health monitoring of the pipeline. Thus, the combination of mechanical enhancement and strain sensing of EF joint with carbon-fiber-reinforced polyethylene can improve the strength and reliability of pressure pipeline.