The influence of a polymeric nucleating additive on the crystallisation in glass fibre reinforced polyamide 6 composites

Short glass fibre reinforced polyamide 6 composites compounded with a polymeric nucleating additive based on polyamide 2.2 of different content (0, 0.1 and 0.2 wt%) and processed by injection moulding have been studied to characterise the additive effect on the crystallisation kinetics and morphology. Differential scanning calorimetrical and optical hot stage experiments have shown a significant increase in the overall crystallisation rate as well as the spherulitic growth, respectively with nucleating additive content. Additionally, the presence of glass fibres is proven to enhance crystallisation. Atomic force microscopy confirms the existence of a transcrystalline layer in the vicinity of the glass fibres. The nucleating additives have significantly decreased the spherulitic size from about 15 to 20 μm towards less than 5 μm, which leads to an improved fibre-to-matrix contact. Those morphological changes are seen as the reason for a strong increase in the Martens heat deflection temperature from 145 to 164 °C characterising an improved thermal stability.