Diphase flame‐retardant effect of ammonium polyphosphate and dimethyl methyl phosphonate on polyisocyanurate‐polyurethane foam

Abstract

Building energy consumption is an important component in the total social energy consumption. How to reduce building energy consumption became an important issue in today's society. Therefore, building insulation materials, as a kind of effective energy saving method, has been widely used for the external walls. However, the occurrence of many building fires caused by the ignition of the flammable insulation materials has brought serious damage to people. Consequently, it is significant to develop insulation materials which possess high level of fire safety. The aim of this study was to develop high efficient phosphorus-based flame-retardant system for polyisocyanurate-polyurethane (PIR-PUR) foam. Ammonium polyphosphate (APP) was used as condensed phase flame retardant and dimethyl methylphosphonate (DMMP) were used as gas phase flame retardant for preparing flame-retardant PIR-PUR foam. The flame retardancy, thermal decomposition, and combustion behaviors of PIR-PUR foams were evaluated by limiting oxygen index (LOI) test, vertical burning test, thermogravimetric analysis, cone calorimeter test (Cone), and microscale combustion calorimeter test, respectively. The LOI results showed that the PIR-PUR sample simultaneously containing APP and DMMP possessed higher flame retardant efficiency, which indicated that APP and DMMP possessed synergistic flame-retardant effect in PIR-PUR foam. Cone results indicated that the presence of DMMP can delay the ignition of specimen and delay the time to reach the maximal peak heat release rate. Moreover, the mechanical performance and thermal insulating properties were evaluated, respectively. KEYWORDS combustion behavior, diphase flame-retardant effect, flame retardancy, PIR-PUR foam, thermal insulation

Bi‐phase flame‐retardant effect of dimethyl methylphosphonate and modified ammonium polyphosphate on rigid polyurethane foam

“…Comparing with the reactive flame retardant, the addition flame retardant is easier to prepare by physical methods and more cost‐favored. For example, ammonium polyphosphate (APP) as the representative of the addition flame retardant has been applied into polyurethane foam due to its high contents of phosphorus, smaller loadings, and low cost . However, the poor dispersibility and compatibility of APP negatively impact the property of RPUF .…”

“…In order to improve the LOI value of RPUF, it is necessary to combine MAPP with other flame retardants for enhancing the gas‐phase flame retardant effect in the earlier stage of combustion. Dimethyl methylphosphonate (DMMP) is a kind of liquid phosphorus‐containing flame retardant with high efficiency, which has been used in polyurethane foams by a lot of researchers . It is found that DMMP can release the PO·and PO 2 ·free radicals in the early stage due to the lower thermal degradation temperature .…”

“…For example, ammonium polyphosphate (APP) as the representative of the addition flame retardant has been applied into polyurethane foam due to its high contents of phosphorus, smaller loadings, and low cost. [13][14][15] However, the poor dispersibility and compatibility of APP negatively impact the property of RPUF. 16,17 Therefore, we designed a phosphorus-containing organosilicon compound (PCOC) for modification of APP (MAPP) and then gained improved dispersibility and flame-retardancy.…”

“…Dimethyl methylphosphonate (DMMP) is a kind of liquid phosphoruscontaining flame retardant with high efficiency, which has been used in polyurethane foams by a lot of researchers. 15,[19][20][21][22] It is found that DMMP can release the PO·and PO 2 ·free radicals in the early stage due to the lower thermal degradation temperature. 23 These kinds of free radicals can exert the quenching effect by capturing the H and HO·free radicals in the gas phase during combustion, which effectively improve the flame retardancy of RPUF in the early stage of combustion.…”

Improving the Flame Retardance of Polyisocyanurate Foams by Dibenzo[d,f][1,3,2]dioxaphosphepine 6-Oxide-Containing Additives

“…Derivative incorporating secondary amines yielded phosphonamidates that were applied as FR in polyurethanes [27]. Phosphonates with intermediate oxidation state of +III, e.g., diethyl ethylphosphonate (DEEP) and dimethyl phenylphosphonate (DMPP) have been established as halogen-free FRs for polyurethanes, polyesters, and polyamides [28]. In all cases, the P-containing compounds were applied as non-reactive FR.…”