Flame retardancy and thermal and mechanical performance of intercalated, layered double hydroxide composites of polyamide 11, aluminum phosphinate, and sulfamic acid

Abstract

Sulfamic acid-intercalated MgAl-layered double hydroxide (SA-LDH) was prepared and added with aluminum phosphinate (AlPi) into polyamide 11 (PA11). The results showed that AlPi/SA-LDH made a positive contribution to both flame retardancy and thermostability, and the effect was demonstrated with the limiting oxygen index (LOI), vertical burning tests (UL-94), cone calorimetry (CONE), and thermogravimetric analysis (TGA). The char morphologies were observed by SEM, and its chemical composition was investigated by Fourier transform infrared spectroscopy (FTIR). The decomposition mechanism was examined by TGA-FTIR. The results showed that the LOI of PA11 was only 23.0 and cannot pass any UL-94 rating. The addition of 20% AlPi increased the LOI to 31.5 and passed the UL-94 V-1 rating, and AlPi/SA-LDH 15%/5% increased the LOI to 32.4 and also passed the UL-94 V-1 rating. The CONE results revealed that 20% of either AlPi or AlPi/SA-LDH brought about a 30% decrease in the peak heat release rate (pHRR). The contribution of SA-LDH to flame behavior was especially reflected in the postponement of pHRR. SEM showed that the char morphologies became denser after SA-LDH incorporation. The improvement in thermal stability of the AlPi/SA-LDH combination was documented by TGA in both N 2 and air atmospheres. The mechanical performance deterioration caused by AlPi was partly improved by SA-LDH. The storage modulus (E 0 ) below the T g of AlPi/SA-LDH 15%/5% was about 300 MPa higher than with 20% AlPi. This was attributed to a compatibility improvement. The interaction forces among PA11, AlPi, and SA-LDH were probed by X-ray photoelectron spectrometry.

Sol–Gel Treatments to Flame Retard PA11/Flax Composites

“…The Figure 14 presents the different heat of release rate (HRR) curves obtained for each material, and Table 3 gives a mean value for each measurement using all the experiments performed for each composites, as well as the standard deviation associated with the measurements. generally appears at an additive level of 17-20 wt.% [29]. Considering that the present composites have 45 wt.% matrix content, the amount of AlPi versus PA11 is too low to be efficient.…”

“…The condensation level of the sol-gel obtained on the fibers has been investigated using 29 Si solid-state NMR. The measurements have been performed on a Bruker Avance II 400 at 19.6 MHz using a 7 mm probe, with 1 H− 29 Si cross-polarization (CP) and magic angle spinning (MAS) at a speed of 5 kHz.…”

“…To investigate the level of condensation of the sol-gel, 29 Si NMR was used. At the molecular level, solid-state 29 Si NMR allows the observation of connectivity and degree of condensation in solid siliceous materials. The silicone structure can be distinguished according to bridging oxygen number per silicone-oxygen tetrahedron.…”

“…The silicone structure can be distinguished according to bridging oxygen number per silicone-oxygen tetrahedron. Q 0 , Q 1 , Q 2 , Q 3 , and Q 4 notations used in 29 Si NMR spectroscopy are used for Si with four oxygens attached; the numbers 0-4 denote the number of 'Si' units attached through the oxygen to an individual silicon atom. Similarly, T 0 , T 1 , T 2 , and T 3 are used for Si with three oxygens attached; the numbers 0-3 denote the number of 'Si' units attached through the oxygen to an individual silicon atom (see Supplementary Materials for further details) [27].…”

Synergistic flame‐retardant effect of phosphaphenanthrene derivative and aluminum diethylphosphinate in glass fiber reinforced polyamide 66

“…AlPi is a favorable free‐halogen organic phosphorous FR . Many researches have revealed FR mechanism of AlPi, and it has been widely used in PA and other thermoplastics .…”