Nanjing, China – Castor oil has been used by a team of scientists to make ultra-strong, solvent-free thermally conductive PU adhesives. The group at the Chinese Academy of Sciences’ Institute of Engineering Thermophysics in Nanjing say they have potential for heat management in electronic devices.
Thermal conductivity is becoming increasingly important with the growing trend towards the miniaturisation and lightweighting of electronic devices. The scientists used a castor oil-based PU as the matrix and alumina as a thermal conductive filler, with the aim of making environmentally friendly thermally conductive structural adhesives.
The adhesive made with a 49.3% hard segment content was effective as an adhesive, with a tensile stress of 8.6MPa, an elongation at break of 21%, and good lap shear strength to substrates ranging from glass and steel to aluminium.
Importantly, the thermal conductive pathways in composites that included 75% alumina filler by weight gave a thermal conductivity of 1.23Wm–1K–1. This is nearly five times higher than the PU alone, which would be ineffective for imparting heat dissipation properties in electronic devices.
The work has been published in the journal Industrial Crops and Products.