Glass fiber reinforced PA6 composites with high strength and high flowability by hyperbranched polyesters

Abstract

Lightweighting of automotives is one of the efficient strategies to save energy and reduce CO2 emission and environmental pollution. Glass fiber reinforced polyamide composites (PA/GF) have accounted for about 20% of plastic composites for automotives, showing a large potential to replace metal materials. However, it is an imperative challenge to prepare high‐strength and rapid‐processing PA/GF composites due to poor compatibility between GF and PA. Here, we have synthesized amphiphilic hyperbranched polyesters (H24‐m) containing long aliphatic chains and hydroxyl groups by esterification between hydroxyl‐ended hyperbranched polyester (H24) and stearoyl chloride (SC), which are used to prepare high‐performance GF/PA6 composites. Influence factors on the mechanical properties and melt flow index (MFI) of PA6/GF composites have also been investigated, including GF content, H24‐50 content, esterification degree of H24, and the ratio of H24‐50 to carboxyl‐ended hyperbranched polymer (HyPer C100). The obtained C100/H24‐50/PA6/GF composites show simultaneously high strength, super toughness, high MFI, and high GF content of about 60 wt%. A dispersion‐bridging‐interfacial improvement mechanism has been discovered deeply by investigating crystal behavior, rheological behavior, hydrogen bond interaction, GF length variation, and the synergistic effect of amphiphilic hyperbranched polyester and HyPer C100. This work provides a simple approach to fabricating high‐performance GF/PA6 composites for extensive application in automotive parts, showing great prospects in the lightweight of automotives.