Correlation between morphological properties and thermal conductivity of injection-molded polyamide 46

Abstract

The morphology and thermal conductivity of injection-molded polyamide 46 (PA46) samples were investigated in this study. It was found that injection molding parameters had no influence on the thermal conductivity. This was attributed to the high crystallization speed and therefore imperfect crystal structure of PA46. By annealing of some samples at 260°C for 24 h the thermal conductivity was increased by 30%. Polarization light microscopy revealed only minor changes of the visible morphological structure for the as molded and annealed samples. For the investigation of the sample crystallinity via Raman spectroscopy an analysis method was established and the term “Raman crystallinity” is introduced as the intensity ratio of characteristic Raman bands. Via Raman crystallinity it was possible to distinguish between different mold temperatures and the annealed PA46 samples showed a significantly increased Raman crystallinity. Our results show that the thermal conductivity of PA46 primarily depends on the crystal structure on a length scale of crystallites. The size of the visible spherulite-like structures did not correlate with the change in thermal conductivity. A correlation of the Raman crystallinity with the thermal conductivity of PA46 was shown. POLYM. ENG. SCI., 55:2231–2236, 2015. © 2015 Society of Plastics Engineers