Application of metallic phytates to poly(vinyl chloride) as efficient biobased phosphorous flame retardants

Abstract

Simple, direct precipitation was used to synthesize green, renewable, biobased flame retardants. Copper phytate (Cu–Phyt), zinc phytate, aluminum phytate, and tin phytate (Sn–Phyt) were synthesized. Thermogravimetric analysis performed in N2 revealed that the metallic phytate (M–Phyt, where M is Cu, Zn, Al, or Sn) salts showed good charring. The limiting oxygen index (LOI), cone calorimetry (CONE) test data, tensile strength, and impact toughness were measured for flexible poly(vinyl chloride) (PVC) containing 15 wt % M–Phyt salts. The PVC/Sn–Phyt LOI rose from 24.9 to 30.3%, and the PVC/Sn–Phyt mechanical properties were on par with those of the pure PVC. The CONE test results indicate that PVC/Cu–Phyt showed the lowest total smoke production (TSP) and peak heat‐release rate (pHRR) among the samples. The TSP and pHRR of PVC/Cu–Phyt were 15.77 m2 and 181.77 kW/m2, respectively, 62.63 and 44.48% lower than those of the neat PVC. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46601.

Bio‐based Mg(OH)2@M‐Phyt: improving the flame‐retardant and mechanical properties of flexible poly(vinyl chloride)

“…The crystallinity of MH decreased after M‐Phyt modification and the position of the diffraction peak did not change, indicating that the coated layer on the surface of MH was amorphous. Previous work has confirmed that M‐Phyt is an amorphous compound . The combination of XRD pattern and SEM and TEM images proved that M‐Phyt was successfully coated on the surface of MH.…”

“…PVC burnt vigorously within 250 s after ignition and its HRR value reached a maximum burning intensity of 329.67 kW m −2 after 55 s. All the flame retardants reduced the HRR of the PVC composites. PVC/MH had two obvious HRR peaks and the second peak was higher than the first, which indicated that the char residue formed in the early stage of combustion was not stable after adding MH, and the char residue will burn further with increase of the radiation time . In comparison, PVC/MH@M‐Phyt had two lower gentle peaks, which prolonged the combustion time to about 400 s. These are mainly attributed to the presence of a number of P elements in M‐Phyt, which have a catalytic effect on the degradation of PVC and lead to carbon crosslinking to a char layer at an early stage of combustion .…”

“…The char layer and Mg–O compounds formed are the barrier to heat and oxygen . At the same time, P elements and M 2+ (Zn 2+ and Cu 2+ ) can catalyze the thermal degradation of PVC to generate HCl and lead to carbon crosslinking to the char layer in the early stage of combustion. Above all, the flame‐retardant and smoke suppression mechanism of MH@Zn‐Phyt involves a combination of gas phase and condensed phase as summarized in Fig.…”

“…Previous work has confirmed that M-Phyt is an amorphous compound. 22 The combination of XRD pattern and SEM and TEM images proved that M-Phyt was successfully coated on the surface of MH.…”

“…It is widely used for sensors, 19 sewage treatment, removal of heavy metals 20 and so on. Additionally, metallic phytate salt (M-Phyt) is anticipated to be a highly efficient flame retardant for its excellent charring property, 21 which has been proved in our previous work 22 and by others. 23 MH is the most abundant inorganic flame retardant and many modified MHs have been produced to be used as flame retardants.…”