Efficient Approach to Improving the Flame Retardancy of Poly(vinyl alcohol)/Clay Aerogels: Incorporating Piperazine-Modified Ammonium Polyphosphate

Abstract

Ammonium polyphosphates (APP) modified with piperazine (PA-APP) was used to improve the flame retardancy of poly(vinyl alcohol) (PVA)/montmorillonite (MMT) aerogels, which were prepared via an environmentally friendly freeze-drying method. The thermal stabilities of the samples were evaluated by thermogravimetric analysis (TG); the flammability behaviors of samples were investigated by limiting oxygen index (LOI), vertical burning test (UL-94) and cone calorimeter (CC) tests. TG test results showed that the 5% weight loss temperature (T5%) of PVA/MMT/PA-APP was 10 °C higher than that of PVA/MMT/APP. In combustion testing, all of PVA/MMT/PA-APP aerogels achieved V-0 ratings and have a higher LOI values than the unmodified PVA/MMT aerogel. Moreover, the aerogel with 1% PA-APP5, which means that the content of piperazine is 5% in PA-APP, decreased the cone calorimetry THR value to 5.71 MJ/m(2), and increased the char residue to 52%. The compressive modulus of PVA/MMT/PA-APP was increased by 93.4% compared with PVA/MMT/APP because of the increase in interfacial adhesion between matrix and PA-APP fillers. The densities of the PVA/MMT/PA-APP samples were slightly lower than those of the unmodified aerogels because of reduced shrinkage in the presence of PA-APP. All the tests results indicated that the incorporation of PA-APP not only improved the thermal stability and flame retardancy of aerogels but also maintained their mechanical properties.

Boron/nitrogen flame retardant additives cross‐linked cellulose nanofibril/montmorillonite aerogels toward super‐low flammability and improved mechanical properties

“…This fact suggested a synergistic effect between BA and MF on the flame retardant properties of CNF/MMT aerogels. The LOI value of the B/N FRA modified CNF‐based aerogels was much higher than those reported for flame retardant polymer‐based aerogels or foams, such as CNF/MoS 2 aerogel (LOI = 34.7%), PVA/MF aerogels (LOI = 36.5%), and PVA/MMT/APP (LOI = 42%) …”

“…The LOI values also increased with MF cross-linking; 58 and PVA/MMT/APP (LOI = 42%). 59 The combustion of representative aerogels was also studied through cone calorimetry tests, which could mimic the combustion behavior of a material in a real fire scenario. The heat release rate as a function of burning time is shown in Figure 9A.…”

Large-scale, thick, self-assembled, nacre-mimetic brick-walls as fire barrier coatings on textiles

“…6b–f) in accordance with TGA54. This thick protective solid char acts as a thermal barrier and lowers the formation of flammable volatiles, therefore, leading to the reduction in pkHRR and THR365459. Lower pkHRR is a desired parameter to exhibit efficient fire-retardancy in real fire situation as it retards or diminishes the self-propagation or spreading of the flame to other materials when the external flame or ignition source is removed39.…”

Polymer/Carbon-Based Hybrid Aerogels: Preparation, Properties and Applications

“…Preparation of polymer/clay aerogel materials through a freeze drying process was reported and intensively studied by Schiraldi and coworkers [17,36,37,215,216]. They fabricated low flammable aerogels based on renewable ammonium alginate and MMT clay through a simple, environmentally-friendly freeze-drying process [215].…”