Fire performance of charring closed‐cell polymeric insulation materials: Polyisocyanurate and phenolic foam

Abstract

Summary Results are presented from 2 series of ad hoc experimental programmes using the cone calorimeter to investigate the burning behaviour of charring closed‐cell polymeric insulation materials, specifically polyisocyanurate (PIR) and phenolic (PF) foams. These insulation materials are widely used in the construction industry due to their relatively low thermal conductivity. However, they are combustible in nature; therefore, their fire performance needs to be carefully studied, and characterisation of their thermal degradation and burning behaviour is required in support of performance‐based approaches for fire safety design. The first series of experiments was used to examine the flaming and smouldering of the char from PIR and PF. The peak heat release rate per unit area was within the range of 120 to 170 kW/m2 for PIR and 80 to 140 kW/m2 for PF. The effective heat of combustion during flaming was within the range of 13 to 16 kJ/g for PIR and around 16 kJ/g for PF, while the CO/CO2 ratio was within 0.05 to 0.10 for PIR and 0.025 to 0.05 for PF. The second experimental programme served to map the thermal degradation processes of pyrolysis and oxidation in relation to temperature measurements within the solid phase under constant levels of nominal irradiation. Both programmes showed that surface regression due to smouldering was more significant for PF than PIR under the same heat exposure conditions, essentially because of the different degree of overlap in pyrolysis and oxidation reactions. The smouldering of the char was found to self‐extinguish after removal of the external heat source.

Phenolic Resin Foam Composites Reinforced by Acetylated Poplar Fiber with High Mechanical Properties, Low Pulverization Ratio, and Good Thermal Insulation and Flame Retardant Performance

“…It has a uniform closed pore structure, low thermal conductivity, and good thermal insulation performance, and is therefore better than PS and PU. Even in the event of a fire, phenolic foam shows no dripping and less smoking, and the char layer formed on its surface can protect the internal structure [5,6]. Phenolic foam is a thermal insulation composite with great development potential; it is known as a third-generation emerging thermal insulation composite, and is widely used in various thermal insulation pipelines [7], transportation [8], and flowers [9].…”

Fire performance of closed‐cell charring insulation materials in plasterboard‐insulation assemblies

“…However, in the presence of oxygen, foam B presents a worse behaviour as the pyrolysis and oxidation reactions are in the same temperature domain, as shown in the differential thermogravimetric (DTG) curves presented in Figure 2. This performance, which was further discussed elsewhere, 14 indicates that the char from foam A is expected to play a more effective role than the char from foam B protecting the virgin material.…”

“…12,14 Noting the concerns regarding a potential inadequate extrapolation of the fire performance of these specific products to the performance of generic material groups, 23 the polyisocyanurate and phenolic foam used within this work are hereafter denoted as foams A and B, respectively. 12,14 Noting the concerns regarding a potential inadequate extrapolation of the fire performance of these specific products to the performance of generic material groups, 23 the polyisocyanurate and phenolic foam used within this work are hereafter denoted as foams A and B, respectively.…”

“…The types of charring insulation material studied were specifically a commercial rigid closed-cell polyisocyanurate foam and a commercial rigid closed-cell phenolic foam, identical to the materials characterised in previous studies. 12,14 Noting the concerns regarding a potential inadequate extrapolation of the fire performance of these specific products to the performance of generic material groups, 23…”

“…Further work was developed to study the pyrolysis and smouldering processes of these foams in relation to temperature measurements within the solid phase under constant levels of nominal irradiation. 14 The fire performance was found to be strongly determined by their closed-cell structure and charring behaviour, ie, they present resistance to gas diffusion through the porous media and are characterised by leaving a carbonaceous residue (char) after pyrolysis. The former limits the smouldering behaviour, while the latter reduces the net heat flux delivered to the pyrolysis zone and, therefore, the release of flammable gases and resulting heat release rate.…”