Annealing treatment on waterborne polyurethane film-forming and structural features induced heat conduction performance in conductive adhesive

Thermal annealing treatment (60, 80, 100, 120 and 150 °C) on waterborne polyurethane (WPU) film-forming and further the structural features induced heat conduction behavior was investigated. It was found that the WPU films annealed at 100 °C or 120 °C showed a higher thermal conductivity than others, which was attributed to more ordered structural sequences as shown by x-ray diffraction (XRD) and differential scanning calorimetry (DSC). Combined with Fourier transform infra-red spectroscopy (FTIR), atomic force microscopy (AFM) and dynamic mechanical analysis (DMA), it is concluded that appropriate annealing can facilitate the creeping of polymer chains and further occurring rearrangement for forming ordered structural sequences. As concluded, annealing is an easy way of regulating morphological structures and further boosting microphase separation in engineering applications. Also for practical application in heat management domains, it is a good sign to see the WPU materials, such as conductive adhesive, with more ordered structural sequences (or high crystallinity) display a good heat transfer performance.