Search

The impact of phosphorus-containing flame retardants (FR) on rigid polyisocyanurate (PIR) foams is studied by systematic variation of the chemical structure of the FR, including non-NCO-reactive and NCO-reactive dibenzo[d,f][1,3,2]dioxaphosphepine 6-oxide (BPPO)- and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-containing compounds, among them a number of compounds not reported so far. These PIR foams are compared with PIR foams without FR and with standard FRs with respect to foam properties, thermal decomposition, and fire behavior. Although BPPO and DOPO differ by just one oxygen atom, the impact on the FR properties is very significant: when the FR is a filler or a dangling (dead) end in the PIR polymer network, DOPO is more effective than BPPO. When the FR is a subunit of a diol and it is fully incorporated in the PIR network, BPPO delivers superior results. [ABSTRACT FROM AUTHOR]

In this paper, the role of trimerization in polyisocyanurate (PIR) foams and its impact on the physical properties and the fire behavior is discussed. The degree of trimerization was systematically varied using different catalyst concentrations. The enhanced formation of isocyanurate structures through higher catalyst concentrations leads to higher mechanical stability and improved fire behavior as measured by vertical flame spread according to DIN4102 and under forced flaming conditions in the cone calorimeter. A clear correlation between catalyst content, chemical structure of the foams (relative concentration of isocyanurate units representing crosslinking) and fire behavior is found. • A variety of halogen free, phosphorus-containing PIR foams with different amounts of catalyst was successfully prepared. • The influence of catalyst concentration on isocyanurate content, foam properties, and flame-retarding properties was verified. • Higher catalyst contents yielded higher isocyanurate contents and caused higher compression strength. • Higher isocyanurate contents in these foams yielded better flame retarding properties. [ABSTRACT FROM AUTHOR]

A series of new flame retardants (FR) based on dibenzo[d,f][1,3,2]dioxaphosphepine 6-oxide (BPPO) incorporating acrylates and benzoquinone were developed previously. In this study, we examine the fire behavior of the new flame retardants in polyisocyanurate (PIR) foams. The foam characteristics, thermal decomposition, and fire behavior are investigated. The fire properties of the foams containing BPPO-based derivatives were found to depend on the chemical structure of the substituents. We also compare our results to state-of-the-art non-halogenated FR such as triphenylphosphate and chemically similar phosphinate, i.e. 9,10-dihydro-9-oxa-10- phosphaphenanthrene-10-oxide (DOPO), based derivatives to discuss the role of the phosphorus oxidation state. [ABSTRACT FROM AUTHOR]