Preparation and mechanism of polyurethane prepolymer and boric acid co‐modified phenolic foam composite: Mechanical properties, thermal stability, and flame retardant properties

Abstract

In this work, a new kind of co‐modified phenolic foam was synthesized with polyurethane prepolymer (PUP) and H3BO3 by a simple preparation method. Firstly, in order to determine the optimal amount of PUP, the effects of different PUP additions on the mechanical properties, foam microstructure, and pulverization rate of phenolic foam were investigated. Then H3BO3 was added to toughened phenolic foam, in order to reduce its fire hazard. The results showed that the mechanical properties of the PFPUP8 phenolic foam composite were the best when the PUP content was 8 wt%. It had a small and regular cell structure, and its pulverization ratio was reduced by 80% compared with that of pristine phenolic foam. Meanwhile, the flame retardant properties of PFPUP8 were improved in different degrees with an increase in the amount of H3BO3. Particularly, when the addition of H3BO3 was 10 wt%, the peak heat release rate, the total heat release, and the total smoke release values of PFPUP10B were decreased by 35.4%, 42.4%, and 45.2%, respectively, compared with those of PFPUP8. The value of the limit oxygen index was increased by 33.1%. Besides, the addition of H3BO3 had no adverse effect on the mechanical properties and pulverization ratio of PFPUP8. In addition, the specific mechanisms of toughening, flame retardant, and smoke suppression are also discussed in this paper on the basis of an investigation into the thermal properties of the toughened flame retardant foam composites by thermogravimetric analysis in N2 atmosphere.

Synthesis and characterization of polyethylene glycol-phenol-formaldehyde based polyurethane composite

“…In recent years, enhancement of the toughness of phenol foams has received tremendous attention because of its low strength, extreme brittleness and friability. Phenolic resins (PF) are toughened mainly using flexible polymers, such as polyurethane prepolymer 2 , cardanol 3,4 , polyether polyols 5,6 , epoxy 7 , rubber 8–10 . Besides, renewable biomass, such as tannin 11 , natural fibres 12,13 , have been also used to modify PF resin matrix.…”

Effective Halogen- and Phosphorus-Free Polyphenylene Ether Resin-Based Flame-Retardant Foam

“…As shown in Figure 8 B, there are two degradation peaks in the range of 350–650 °C. One is the decomposition of Tween 80 and curing agent at 350–500 °C, 32 and the other is mainly due to the decomposition of the SPF skeleton at 500–650 °C. Pure foam and modified foam exhibit similar degradation behavior in the range of 500–650 °C.…”

Preparation and characterization of polybenzoxazine foam with flame retardancy

“…It is worth noting that the compressive strength of polybenzoxazine foams with different contents of phenolic resin were apparently higher than the compressive strength of phenolic foam with 0.082 ± 0.003 MPa. [ 31 ]…”

“…contents of phenolic resin were apparently higher than the compressive strength of phenolic foam with 0.082 ± 0.003 MPa. [31] 3.6 | Flame retardancy properties…”