Flame Inhibition and Charring Effect of Aromatic Polyimide and Aluminum Diethylphosphinate in Polyamide 6

Abstract

An aromatic macromolecular polyimide (API) was synthesized and characterized, and used as a synergistic charring flame retardant in glass fiber reinforced polyamide 6 (GF/PA6). API and aluminum diethylphosphinate (ADP) exhibited better flame inhibition behavior and synergistic charring flame retardant behavior compared with ADP alone. The 5%API/7%ADP/GF/PA6 sample achieved the lower peak value of the heat release rate (pk-HRR) at 497 kW/m2 and produced higher residue yields of 36.1 wt.%, verifying that API and ADP have an outstanding synergistic effect on the barrier effect. The API/ADP system facilitated the formation of a carbonaceous, phosphorus and aluminum-containing compact char layer with increased barrier effect. FTIR spectra of the residue and real-time TGA-FTIR analysis on the evolved gases from PA6 composites revealed that API interacted with ADP/PA6 and locked in more P–O–C and P–O–Ar content, which is the main mechanism for improving flame inhibition and charring ability. In addition, the API/ADP system improved the mechanical properties and corrosion resistance of GF/PA6 composites compared to ADP alone.

Synthesis and Characterization of Aluminum 2-Carboxyethyl-Phenyl-Phosphinate and Its Flame-Retardant Application in Polyester

“…1 H solid-state NMR, 13 C solid-state NMR, 31 P solid-state NMR, and 27 Al solid-state NMR confirm the structure of CPA-Al, as in Figure 1. In Figure 1a, the chemical shift at 2.49 ppm was attributed to H atoms in ethyl group.…”

“…The chemical shift at 23.31 ppm in 31 P NMR was caused by the C-P-C. Combining the results of 1 H NMR, 13 C NMR, and 31 P NMR, a little of -COOH should react with Al 3+ , and Figure 2 shows the structure of the byproduct. Therefore, the shift at 36.27-37.94 was caused by the C-P-C bond, which was affected by the -COO-of by-product.…”

“…The 1 H nuclear magnetic resonance ( 1 H NMR), 13 C NMR, 27 Al NMR, and 31 P NMR data were obtained while using a Bruker 400 MHz WB Solid-State NMR Spectrometer (Karlsruhe, Germany).…”

“…In recent years, some researchers have been trying several kinds of flame retardants, such as brominated flame retardants [13], phosphorus-containing flame retardant [14,15], intumescent flame retardant [16,17], and nanometer flame retardant [18][19][20] to improve the flame retardancy of polyester textile. Some researchers have been trying to combine some known efficient phosphorus-based characteristic structures or functional groups, such as phosphonate and phosphinate [21][22][23][24], cyclotriphosphazene [25][26][27][28], and phosphinate-POSS [29,30] to prepare the flame-retardant polyester textile.…”

A Phosphorous‐Aluminium‐Nitride Synergistic Flame Retardant to Enhance Durability and Flame Retardancy of Cotton

“…Aluminium hydroxide (AH) and aluminium hypophosphite(AHP) as flame retardant are commonly used in plastic and fibers, such as polylactic acid, polypropylene, cellulose fibers, and so on . In addition to AHP and AH, aluminium‐containing compounds are also used as flame retardant for some special materials, like glass fiber, polyamide . For the flame retardant of cotton fabrics, the cotton fabric treated by AHP has a certain degree of flame retardancy, and whiteness also get improved .…”