Abstract
Modern day energy codes are driving the design and multi-layered configuration of exterior wall systems with significant emphasis on achieving high performance insulation towards improving energy performance of building envelopes. Use of highly insulating polyisocyanurate (PIR) based insulation materials enhanced with eco-friendly lamellar inorganic fillers contributes to meeting energy performance requirements, environmental challenges and cost reduction without undue compromise of the overall building fire safety. Towards that end, the aim of the current work is to assess the fire behaviour of PIR foams enhanced with lamellar inorganic smart fillers, namely Layered Double Hydroxides (LDHs) and ZrP. Experimental results indicate that fire reaction properties and thermal stability of foam samples enhanced with three types of lamellar inorganic smart fillers are evaluated using cone calorimeter (CC) and thermogravimetric (TGA) analysis. The initial degradation temperature of PIR-layered filler samples increases compared with neat PIR foam, indicating that incorporation of flame retardants decelerates the degradation of PIR foam and as result increases the thermal stability of PIR foam. Thermal decomposition of the PIR samples occurs in two distinct stages associated with the degradation of the urethane-urea linkages of the hard segment, releasing low calorific capacity products and the degradation of polyol derived products with higher calorific capacity than those derived from isocyanate. Increasing the filler content results in increased char formation and decreased peak Heat Release rates (HRR).
Highlights
Modern day energy codes are driving the design and multi-layered configuration of exterior wall systems with significant emphasis on achieving high performance insulation towards improving energy performance of building envelopes
Numerous studies [1,2,3] have established that thermal decomposition of polymeric foams, in both inert and oxygen atmospheres, is a complex process consisting of numerous decomposition pathways that strongly depend on the reactivity of organic compounds employed in its synthesis
The X-ray diffraction (XRD) spectra of PIR-ZrP3, compared to those of neat PIR indicate that ZrP layer has been exfoliated in the matrix as a great amount of polymers has entered into the gallery space separating ZrP layer during in situ intercalation polymerization process
Summary
Modern day energy codes are driving the design and multi-layered configuration of exterior wall systems with significant emphasis on achieving high performance insulation towards improving energy performance of building envelopes. Most commonly used insulation materials include polymers such as extruded polystyrene, expanded polystyrene, polyurethane foam (PUF) and polyisocyanurate (PIR) with or without flame retardants [1]. PIR foams are part of the polyurethane (PUR) rigid foam family and their main characteristic is that they contain a high percentage of cyclic isocyanurate chemical linkages and use of polyester polyol instead of the standard polyether polyol used in PUR’s. PIR are based on the reaction of polycyclotrimerization of diisocyanates or isocyanate terminated prepolymers to form triazine-trione ring structured isocyanurate rings [4] that, from the thermodynamic point of view, are more thermally stable than urethane bonds found in PUR foams as it dissociates at approximately 200oC as opposed to 350oC for polyisocyanurates [5]
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