Fire, thermal and mechanical properties of TPE composites with systems containing piperazine pyrophosphate (PAPP), melamine phosphate (MPP) and titanium dioxide (TiO₂)

Abstract

A novel synergistic flame retardant system containing piperazine pyrophosphate (PAPP) synthesised by polycondensation, melamine phosphate (MPP) and titanium dioxide (TiO 2 ) was applied to the thermoplastic elastomer (TPE). The char residues of TPE/PAPP/MPP/TiO 2 composites were 23.5 wt-% in N 2 and 17.3 wt-% in air. Meanwhile, the as-obtained composites showed enhanced flame retarding properties including high limit oxygen index (LOI) valuing (37.8 vol.-%) and UL-94 V-0 rating. TGA results indicated that the fire retardant systems significantly altered the initial decomposition temperature (5-20°C) and resulted in the formation of increased residues (23.5 wt-% in N 2 and 17.36 wt-% in air). In addition, the scanning electron microscope (SEM) test and gas analysis proved that char formation was significantly accelerated in this system. Non-combustible gases like ammonia and carbon dioxide could dilute the concentration of combustible gas, and result in the fuel reduction action as the minor. The heat and smoke release behaviours were also measured by cone calorimeter. The tensile strength, elongation at break and notch impact strength of the FR-TPE composite increased by further substituting a portion of the PAPP with MPP and TiO 2 . The flame retarding mechanism of this system was also studied by SEM-EDX.

Improvement of Flame Retardancy and Antidripping Properties of Intumescent Polybutylene Succinate Combining Piperazine Pyrophosphate and Zinc Borate

“…9 After combustion, the top and bottom chars of PBS/PAPP20% show similar broad bands at around 128 ppm, corresponding to the aromatic and/or polyaromatic species owing to the cyclization process. 39 With the partial substitution of PAPP with 5 wt % zinc borate, the 13 C NMR spectrum of unburned PBS/PAPP15%/ZnB5% presents similar signals to that of unburned PBS/PAPP20%. It is interesting to note that the 13 C NMR spectra of top and bottom chars of PBS/PAPP15%/ZnB5% after the MLCC test show different resonance bands.…”

“…To further analyze the formation of new species during combustion, solid-state NMR spectra of the top and bottom chars of PBS/PAPP20% and PBS/ PAPP15%/ZnB5% were analyzed. As shown in Figure 6, the 13 C NMR spectrum of raw PAPP shows a single peak at around 40.9 ppm, which is assigned to carbon in the piperazine structure. This signal is also detected in the unburned PBS/ PAPP20% formulation.…”

“…3.3.2. 13 C NMR Analysis. ATR-FTIR spectra provided some information regarding the structures of char; however, they were not enough to fully characterize the formation and evolution of special species.…”

“…13 C NMR and 31 P NMR experiments were acquired with a Bruker Avance II 400 spectrometer (9.4 T). 13 C NMR spectra were collected at 100.6 MHz with a probe head of 4 mm, a spinning frequency of 12.5 kHz, and a recycle delay of 5 s. The 1 H decoupling and 1 H− 13 C crosspolarization (CP) MAS NMR spectra were obtained with a scan number of 1024. The 13 C chemical shifts were assigned to tetramethylsilane at 0 ppm.…”

Flame retardancy of biodegradable polylactic acid with piperazine pyrophosphate and melamine cyanurate as flame retardant

“…During combustion, PAPP was decomposed into phosphoric acid and other phosphorus-containing derivatives, which led to the carbonization of PLA. 57 Meanwhile, the piperazine unit in PAPP decomposed into vinylidene group and underwent cross-linking and charring process, which can promote the carbonization of PLA. 58 A part of triazine unit in MCA together with the phosphorus generated from PAPP retained in the carbon residue to enhance the stability of carbon residue and form the compact and continuous carbon layer.…”