Model-based characterization and enhancement of the through-thickness thermal conductivity of polymer composites using infrared camera

• An infrared camera combined with FEM to measure thermal conductivity is developed.
• Role of convective and conductive conditions on thermal transport is characterized.
• A conductive coating can augment the heat transfer across the thickness.

Improved out-of-plane thermal conductivity of fiber reinforced polymer (FRP) composite materials will enable light weight structures to integrate efficient thermal management. Heat extraction through its relative thin thickness direction can be improved by placing highly conducting material strategically and sparingly across the thickness. This paper combines an infrared camera temperature measurement system with a finite element method to investigate the natural convection influence on the effective thermal conductivity of such heterogeneous materials. Measurements of reference samples were conducted to validate the methodology. Effective conductivity of a PTFE matrix with embedded copper rods was characterized with one of its boundaries exposed to natural convection and the results were contrasted with the condition under which the specimen is placed between two conducting bars. Our method was extended to characterize the effective thermal conductivity of a heterogeneous 3D woven fabric structure embedded within a polymer matrix. A conductive coating layer was introduced and quantified to demonstrate the heat transfer enhancement.