Halogen Free flame retardant rigid polyurethane foam with a novel phosphorus−nitrogen intumescent flame retardant

Abstract

A novel phosphorous-nitrogen containing intumescent flame retardant, toluidine spirocyclic pentaerythritol bisphosphonate (TSPB), was synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR). Flame retardant rigid polyurethane foams (TSPB-RPUF) were prepared by using TSPB. The flame retardancy of TSPB on rigid polyurethane foams (RPUF) was investigated by the limiting oxygen index (LOI), vertical burning test, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and FTIR. The results showed TSPB exhibited better compatibility with RPUF and lesser negative influence on the mechanical properties of TSPB-RPUF. When the content of TSPB was 30 pph, the LOI of TSPB-RPUF could reach 26.5%, and a UL-94 V-0 rating was achieved. Furthermore, the TSPB-RPUF exhibited an outstanding water resistance that it could still obtain a V-0 rating after water soaking. TGA showed the charring ability of RPUF was relatively poor, However, the residual weight of TSPB-RPUF was improved greatly. SEM and FTIR indicated the intumescent chars formed from TSPB-RPUF were compact and smooth, which was a critical factor for protecting the substrate material from burning. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39581.

Investigating the influence of conduit residues on polyurethane plates

“…These results confirm those from the microstructural analysis that identified the existence of closed-cell structures in the composites [3,4,27,28,31,49] . The existence of closed cells in the composite is particularly important for materials to be used as thermal insulation, given that conductivity occurs by radiation, which is hampered regardless of the cellular size [20] .…”

“…Figure 5 shows images of PU (5A and 5B) and images of PU containing 20% conduit residue (5C and 5D). There is no certified or standard micrograph for PU foams, given that they vary with the type and percentage of their components [3,4,27,28,31,49] . Therefore, the PU sample used as reference was prepared under the same conditions of the composite.…”

“…There was a PVC dispersion in PU, and the interaction between the polymers occured at the interfacial level. There were hard PVC particles in the PU foam, which led to foam contraction [31,49] . Cell growth was hampered by the incorporation of the conduit as it can be seen by comparing 5A (PU) with 5C (PU/PVC), at a 15-fold magnification, and 5B (PU) with 5D (PU/PVC), at a 30-fold magnification.…”

“…These behaviors are due to the optimal level of compatibility reached between the components, which indicates that PVC has contributed to the mechanical reinforcement of PU/PVC composites, because PVC presented a uniform distribution in the PU matrix, as well as good interfacial interaction between the polymers [31,49] . The addition of PVC to the PU matrix causes two opposite intermolecular effects.…”

Rigid and steric hindering bisphosphate flame retardants for polycarbonate

“…SPCP was synthesized according to the procedure reported in the literature [20,21]. A 500 ml three-neck round bottom glass flask equipped with a temperature controller, magnetic stirrer and a reflux condenser was charged with 84.50 g (0.55 mol) of phosphorus oxychloride and 6.70 g (0.050 mol) of pentaerythritol.…”