Construction of Synergistic and Efficient Flame-Retardant Polyamide 6 Composites by Incorporating Aluminum Diethylphosphinate and Fly Ash

Ruiping Wang, Chuang He, Shuo Zhang, Miaojun Xu^*, Zhuo Wang, Xiaoli Li^*, Bin Tao, Suliang Gao, Bin Li^*
Heilongjiang Key Laboratory of Molecular Design and Preparation of Flame Retarded Materials, College of Chemistry, Chemical Engineering and Resource Utilization, Northeast Forestry University, Harbin, 150040, China
* Corresponding Author: Miaojun Xu. Email: email ; Xiaoli Li. Email: email ; Bin Li. Email: email
(This article belongs to the Special Issue: Polymer-based Functional Composite Materials: Cutting-edge Advances and Innovative Applications)

Journal of Polymer Materials https://doi.org/10.32604/jpm.2025.073108

Received 10 September 2025; Accepted 11 November 2025; Published online 03 December 2025

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Abstract

The fabrication of highly flame-retardant polyamide 6 (PA6) composites is of great significance for expanding their practical applications. Herein, a new flame-retardant system (ADP/FA) was developed by combining aluminum diethylphosphinate (ADP) with excellent flame retardancy and fly ash (FA), an economical and environmentally friendly industrial waste. Due to the synergistic flame-retardant effect of ADP/FA in the condensed phase and gas phase, the PA6 composite containing only 11 wt% of ADP/FA (mass ratio 93:7) obtained vertical burning (UL-94) tests V-0 rating with a limiting oxygen index (LOI) of 30.9%. To obtain the same flame-retardant level of PA6/ADP/FA-3, the loading amount of ADP alone was required 14 wt%. Compared with the PA6/ADP, the introduction of FA not only reduced the amount of flame retardant added but also inhibited the formation of molten droplets during combustion, greatly enhancing the fire safety of the PA6 composites. The flame-retardant performance of the ADP/FA system is superior to that of most current ADP-based synergistic strategies. In the meantime, the introduction of FA also significantly reduced the high smoke release caused by ADP flame retardant. The peak smoke production rate (pSPR) of the PA6 composite, from 0.221 m²·s⁻¹ (PA6/ADP) to 0.116 m²·s⁻¹, represents a 47.5% decrease. This work provides a feasible solution for fabricating PA6 composites with excellent flame retardancy.