Phosphorus intercalation of halloysite nanotubes for enhanced fire properties of polyamide 6

Abstract

The fire performance of polyamide 6 (PA6) blended with phenyl phosphonic acid functionalized halloysite nanotubes (PPA-HNTs) is evaluated in order to determine if there is any fire performance gains over the unmodified composite. In the continuing search for safe halogen-free fire retardants for polymers, and the desire to more fully capture the advantages of nano-materials, this research seeks to utilize any synergy which might result in improved fire performance of PA6, via the known advantages offered by nano particles and phosphorus-based compounds. HNTs offer the ability for functionalization by exchange at their hydroxyl sites, while PPA can readily attach at these sites because of its acidity. In this context, the nanotubes act as a carrier for the acid within the polyamide polymeric matrix because it is readily intercalated and functionalized with the acid. The intercalated nano particles are added to the polyamide via melt extrusion and then analyzed using thermal analysis and cone calorimetry. The key finding from this work is that functionalization of HNTs with PPA, followed by blending into PA6 results in a significant improvement in fire performance by altering the combustion dynamics of the polymer. This work proposes a new synergistic fire retardant system for polyamides utilising relatively safe and inexpensive components. More broadly, the concept of using a carrier such as HNTs, which is so easily functionalized, can be applied to other thermoplastic materials, and other additives, for improvements in material properties other than fire.

Preparation of biodegradable poly(butylene succinate)/halloysite nanotube nanocomposite foams using supercritical CO2 as blowing agent

“…Due to a high length-to-diameter ratio and a low hydroxyl functional group density on the surface, HNT can disperse uniformly in a polymer matrix [33,34]. It has been emerged as the additive in polymers to improve their mechanical properties and thermal properties [35][36][37][38]. As reported in our previous study [39], the addition of HNT can improve the strength and the modulus of PBS simultaneously without much loss of ductility.…”

Fabrication and origin of new flame retarding bismaleimide resin system with low dielectric constant and loss based on microencapsulated hexaphenoxycyclotriphosphazene in low phosphorus content

“…The parameters related to heat release rate, including HRR, PHRR and THE, represent the burning intensity of a sample in the conditions of CONE tests [46]. Fig.…”

The effect of charge on the release kinetics from polysaccharide–nanoclay composites

“…HNT are generally well tolerated by cells (Vergaro et al 2010;Verma et al 2012;Zhao et al 2013) and have the quality to expose two differently reactive surfaces (inner Al-OH and outer Si-OH, Fig. 1) to the environment, thus paving the way to a whole range of asymmetric functionalization strategies (Yuan et al 2008;Chao et al 2013;Marney et al 2012;Massaro et al 2014;Arcudi et al 2014). The presence of a hollow lumen with nanometric size suggests the use of HNT as nanoreactors, nanotemplates, or sorbents for contaminants (Du et al 2010), and HNT may also be exploited for the loading and release of chemicals and drugs (Price et al 2001;Ward et al 2010;Shchukin and Möhwald 2011).…”