Flame Retarded Rigid Polyurethane Foams Composites Modified by Aluminum Diethylphosphinate and Expanded Graphite

Abstract

Rigid polyurethane foam (RPUF) was an organic porous material, which was applied in many fields for excellent thermal insulation and mechanical properties, especially in building insulation. However, the poor fire performance significantly suppresses its further application. In this work, aluminum diethylphosphinate (ADP) combined with expanded graphite (EG) to form a synergistic flame retarded system, which was introduced to fabricate flame retarded rigid polyurethane foam composites (FR-RPUF) by one-step water-blown method. Furthermore, thermal insulation, thermal stability, fire performance, and decomposition products of RPUF and FR-RPUF composites were systematically investigated. It was found that FR-RPUF composites possessed LOI of 25.9 vol% with V-1 rating in UL-94 test when 10 php of ADP and 20 php of EG were added, which were better than RPUF composites with ADP or EG added alone. MCC test showed that RPUF/ADP24/EG6 had the lowest PHRR value of 159.85 W/g, which was 52.01 W/g lower than that of pure RPUF. Gas phase products investigation implied that the combination of ADP and EG could decrease toxic and combustible gases intensities, thus significantly enhancing fire safety of FR-RPUF composites. SEM test indicated that ADP and EG promoted the formation of dense and continuous char residue, which significantly inhibited heat and substance transfer in combustion, thus significantly enhancing fire performance of FR-RPUF composites.

Bio-Based Rigid Polyurethane Foams Modified with Phosphorus Flame Retardants

“…By selecting the appropriate raw materials for the synthesis of polyurethane (PUR) foams, it is possible to obtain products with a wide range of properties [ 1 ]. These features, combined with good mechanical properties, make RPURF applicable in many branches of industry such as construction, automotive, transport, mainly as thermal insulations [ 2 , 3 , 4 , 5 ].…”

A liquid phosphorous flame retardant combined with expandable graphite or melamine in flexible polyurethane foam

“…This is because the synergistic effect was exerted by BDMPP and EG. The gluing effect of BDMPP strengthened the integrality and continuity of the EG char layer 32,33 …”

Investigating the Effect of Aluminum Diethylphosphinate on Thermal Stability, Flame Retardancy, and Mechanical Properties of Poly(butylene succinate)

“…Furthermore, they are environmentally friendly flame retardants because no harmful and toxic substances are released during combustion. Especially, aluminum diethylphosphinate (AlPi) is one of the most commonly used dialkylphosphinate salts, which has been widely added to improve the flame retardancy of polyethylene (PE), polyamide 6 (PA6), polyurethane (PU), polybutylece terephthalate (PBT), and epoxy resin (EP) (Ma et al, 2019;Oliwa et al, 2020;Pan et al, 2020;Hu et al, 2021;Liu et al, 2021). It is acceptant that AlPi can not only play a flame retardant role in the condensed phase to promote the formation of polymer carbon but also remove high energy active free radicals in the combustion zone (Liu et al, 2021).…”