Heating and Strain Sensing Elements Based on Segregated Polyethylene/Carbon Black Composites in Polymer Welded Joints

Area of Science:

• Materials Science
• Polymer Engineering
• Nanotechnology

Background:

• Real-time monitoring of welded joint quality is essential for industrial product reliability.
• Traditional methods relying on surface damage analysis are insufficient.
• Developing integrated sensing and heating elements in polymer joints is a key challenge.

Purpose of the Study:

• To investigate high-density polyethylene (HDPE)-based composites with varying carbon black (CB) content as integrated heating elements and strain sensors.
• To evaluate the impact of Joule heat generated during electrofusion welding on the structural and sensor properties of these composites.
• To determine the optimal CB content for balancing pyroresistive heating and strain sensing capabilities.

Main Methods:

• Fabrication of HDPE-CB composites with CB content ranging from 20 to 30 vol.%.
• Application of pyroresistive heating via Joule heat generation during simulated electrofusion welding.
• Analysis of changes in composite structure, crystallinity, and electrical conductivity post-welding.
• Correlation of CB content with electrical conductivity and pyroresistive/sensing performance.

Main Results:

• Joule heat generation during welding is dependent on nanocarbon content and influences polymer matrix crystallinity.
• Lower CB content composites showed decreased electrical conductivity due to conductive path disruption.
• Higher CB content composites exhibited increased electrical conductivity attributed to reduced particle-to-particle distances.
• A specific CB concentration was identified as optimal for pyroresistive and sensing properties.

Conclusions:

• HDPE-CB composites can function as effective heating elements and strain sensors in electrofusion welding.
• Welding-induced Joule heating significantly affects the microstructure and electrical properties of the composites.
• Careful control of carbon black content is critical for optimizing the performance of these smart polymer joints.