Suppression of Smoldering of Calcium Alginate Flame-Retardant Paper by Flame-Retardant Polyamide-66

• Main Authors: Kai Xu, Xing Tian, Ying Cao, Yaqi He, Yanzhi Xia, Fengyu Quan
• Format: Article
• Language: English
• Published: MDPI AG 2021-01-01
• Series: Polymers
• Subjects: calcium alginate fiber; flame retardant polyamide-66 fiber; blending; flame-retardant paper; smoldering; flame retardancy
• Online Access: https://www.mdpi.com/2073-4360/13/3/430

Calcium alginate (Ca-Alg) fibers are renewable fibers obtained from the ocean with essential flame retardancy, which have recently been applied as components of flame-retardant paper. However, the application of Ca-Alg fibers is limited because of their tendency to smolder. Therefore, composites papers were fabricated by blending using flame-retardant polyamide-66 (FR-PA), with a 5 wt% content of phosphorous flame retardant, which will form molten carbon during combustion. When the FR-PA content is 30% of the composite paper, FR-PA forms a compact carbon layer on the surface of the Ca-Alg fibers during combustion, which isolates the mass/heat transfer and effectively suppresses the smoldering of Ca-Alg. This consists of a condensed flame retardant mechanism. Furthermore, the combustion and thermal degradation behavior of paper were analyzed by cone calorimetry (CONE), TG and TG-IR. Ca-Alg in the composite paper decomposed and released CO₂ before ignition, which delayed the ignition time. Simultaneously, the FR-PA contained in the composite paper effectively inhibited the combustion of volatile combustibles in the gas phase. Overall, FR-PA and Ca-Alg improve the thermal stability of the composite paper in different temperature regions under air atmosphere. Ca-Alg reduces the formation of aromatic products and NH₃ in the composite paper under N₂ atmosphere. Ca-Alg-based paper with excellent flame retardancy was successfully prepared.