A halogen-free phosphorus-containing triol named phosphoryltrimethanol (PTMA) was synthesized and used as a cross-linking agent and a reactive-type flame retardant to prepare inherently flame-retardant flexible polyurethane foam (FPUF). Incorporation of a low content (7.8 wt %) of PTMA into the polyurethane chains can increase the flame retardance of FPUF because of good char formation. The residual chars and evolved gases of PTMA-cross-linked FPUFs were analyzed by SEM, FTIR spectroscopy, inductively coupled plasma-atomic emission spectrometry (ICP-AES), energy-dispersive X-ray (EDX) spectroscopy, and thermogravimetric analysis (TGA) coupled with FTIR spectroscopy. The results indicated that more than 60% of the phosphorus in PTMA-cross-linked FPUF was decomposed into polyphosphoric acid or its derivatives and retained in the char residue. This shows that PTMA mainly played a role in the condensed phase of flame-retardant FPUF. Based on the results, a possible thermal degradation mechanism of PTMA-cross-linked FPUF is proposed.

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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.

Biocomposite of wood flour (WF)/polypropylene (PP) composite (WPC) is not easily flame-retarded because of the different flame retardant mechanisms of PP and WF. In order to improve the flame retardancy of WPC, a single flame retardant of ammonium polyphosphate (APP) modified via ion exchange reaction with ethanolamine, which is named as ETA-APP, was used to prepare flame-retardant WPC. The flammability was investigated by limiting oxygen index (LOI), UL-94 vertical burning test, and cone calorimeter. The results show the flame retardant properties of the flame-retardant WPC are improved greatly. The limiting oxygen index is 43.0%, which is increased by 71.6% compared with that of WPC with the same content of APP. And the vertical burning test can pass UL-94 V-0 rating. The results of cone calorimeter test show that the heat release rate (HRR) and total heat release (THR) of the WPC with ETA-APP are decreased in comparison with WPC/APP. The flame-retardant mechanism of WPC/ETA-APP system was investigated by thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). It is found that the hydroamine groups and phosphate acid in ETA-APP might promote the etherification and dehydration reactions in WPC/ETA-APP, which facilitated the formation of stabile char residue of WPC. Consequently, the flame-retardant efficiency is improved greatly. The flexural properties of WPC/30 wt % ETA-APP increase a lot in comparison with WPC/30 wt % APP, which is because of the better compatibility of ETA-APP with WF.

An effective flame retardant and smoke suppression oligomer, poly(melamine-ethoxyphosphinyl-diisocyanate) (PMPC), was successfully synthesized. The chemical structure was characterized by Fourier transform infrared (FTIR), 1H nuclear magnetic resonance (1H NMR), and 31P nuclear magnetic resonance (31P NMR) spectroscopies. PMPC was used alone as the flame retardant for epoxy resins (EP). The results showed that PMPC endowed EP with good flame retardancy. The limiting oxygen index (LOI) value of a EP/PMPC system containing 20 wt % PMPC increased to 28.0%, and can achieve a UL-94 V-0 rating. The cone calorimeter data showed that the heat release rate (HRR) and total heat release (THR) were considerably reduced with the addition of PMPC, and the smoke production rate (SPR), total smoke production (TSP), and carbon monoxide production (COP) were also reduced. Moreover, the thermal degradation behavior of PMPC and the flame-retardant mode of the EP systems were also investigated.