Effects of Zinc Borate on the Flame Retardancy Performance of Aluminum Diethylphosphinate in Polyamide-6 and its Composites

Polat Ö., Kaynak C.

INTERNATIONAL POLYMER PROCESSING, vol.34, pp.59-71, 2019 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 34
  • Publication Date: 2019
  • Doi Number: 10.3139/217.3579
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.59-71
  • Middle East Technical University Affiliated: Yes


In this study, the flame retardancy contribution of zinc borate when used together with a traditional flame retardant (aluminum diethylphosphinate compound) was investigated for neat polyamide-6 and for 15 wt% short glass fiber reinforced composite. Melt mixing with twin-screw extrusion was the compounding method while injection and compression molding were the shaping methods of specimens. Three different flammability tests (limiting oxygen index, UL-94 vertical burning, mass loss calorimetry) indicated that many flame retardancy parameters could be improved significantly by replacing a certain amount of aluminum diethylphosphinate with zinc borate. For example, using aluminum diethylphosphinate alone resulted in only 32% suppression in the value of the peak heat release rate for neat polyamide-6, while it was 82% (more than two-fold) when used together with zinc borate. It was revealed by evolved gas analyses, char analyses, x-ray diffraction and thermogravimetry that the main contribution of zinc borate to aluminum diethylphosphinate was in terms of a barrier mechanism via formation of additional boron phosphate inorganic content in the barrier layer.