Synthesis and characterization of cardo-based phosphorous–containing flame-retardant aromatic polyesters

Abstract

Phosphorous-containing cardo polyesters were synthesized by interfacial polycondensation of phenylphosphonic dichloride with various bisphenols using a phase-transfer catalyst at ambient temperature. The structure of the synthesized polymers was confirmed using Fourier transform infrared and proton, carbon 13, and phosphorous 31 nuclear magnetic resonance spectroscopic techniques. The thermal properties of the polymers were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry under nitrogen atmosphere. All the polyesters showed high thermal stability, the maximum decomposition temperature being in the range of 475–523°C. The TGA data showed that all the synthesized phosphorous-containing polyesters produce high char yield at 700°C due to the presence of phosphorous atom in the polymer chain and hence have good flame-retardant properties. The synthesized phosphorus-containing polyesters have tensile strength in the range of 38.2–48 MPa, and the percentage of elongation at breaks of 3.3–16.8. The flame retardancy of all synthesized polymers was investigated by limiting oxygen index (LOI) and vertical burning (UL-94) tests. The results showed that the synthesized polymers have excellent flame retardancy, that is, the polymer samples achieved an increased UL-94 rating and the LOI values were in the range of 28.5–34. Broido model has been used to study the thermal degradation kinetic parameters.

Synthesis, characterization and thermal degradation kinetics of azomethine-based halogen-free flame-retardant polyphosphonates

“…This may be attributed to the presence of methoxy group which need higher energy for Ar–O–C bond cleavage. 45 Among the blended epoxy thermosets, (CR + 1% P1) shows higher E a than (CR + 9% P1). This observation reveals that the incorporation of higher amount of synthetic polymer into thermoset leads to higher plasticization, which reduces the thermal stability.…”

Enhanced Fire Safety of Rigid Polyurethane Foam via Synergistic Effect of Phosphorus/Nitrogen Compounds and Expandable Graphite

“…The UL-94 vertical burning test is a universal measurement to assess the combustion property of polymeric materials [ 43 , 44 , 45 ]. The results of the UL-94 vertical burning test for RPUF and its composites are summarized in Figure 2 and Table 2 .…”