A systematic series of flexible polyurethane foams (FPUF) with different concentrations of flame retardants, bis([dimethoxyphosphoryl]methyl) phenyl phosphate (BDMPP), and melamine (MA) or expandable graphite (EG) was prepared. The mechanical properties of the FPUFs were evaluated by a universal testing machine. The pyrolysis behaviors and the evolved gas analysis were done by thermogravimetric analysis (TGA) and TGA coupled with Fourier‐transform infrared (TG‐FTIR), respectively. The fire behaviors were studied by limiting oxygen index (LOI), UL 94 test for horizontal burning of cellular materials (UL 94 HBF), and cone calorimeter measurement. Scanning electronic microscopy (SEM) was used to examine the cellular structure's morphology and the postfire char residue of the FPUFs. LOI and UL 94 HBF tests of all the flame retarded samples show improved flame retardancy. BDMPP plays an essential role in the gas phase because it significantly reduces the effective heat of combustion (EHC). This study highlights the synergistic effect caused by the combination of BDMPP and EG. The measured char yield from TGA is greater than the sum of individual effects. No dripping phenomenon occurs during burning for FPUF‐BDMPP‐EGs, as demonstrated by the result of the UL 94 HBF test. EG performs excellently on smoke suppression during burning, as evident in the result of the cone calorimeter test. MA reduces the peak heat release rate (pHRR) significantly. The synergistic effect of the combination of BDMPP and EG as well as MA offers an approach to enhance flame retardancy and smoke suppression.
A series of flexible polyurethane foams (FPUFs) were
prepared with
single and different combinations of flame retardants and additives.
Expandable graphite (EG), phosphorous polyol (OP), copper (II) oxide
(CuO), and/or castor oil (CAS) were added to FPUF during the foam
preparation in a one-step process. The purpose of the study is to
evaluate the synergistic effects of the flame retardants, additives,
and the presence of bio-based content on the mechanical properties,
flame retardancy, and smoke behavior of FPUFs. The combination of
10 wt % EG and 5 wt % OP in FPUF significantly improves the char yield.
In the cone calorimeter experiment, the char yield is nearly three
times higher than that with 10 wt % EG alone. The smoke behavior is
additionally evaluated in a smoke density chamber (SDC). Comparing
the samples with a single flame retardant, 10 wt % EG in FPUF considerably
reduces the amount of smoke released and the emission of toxic gases.
Replacing the amount of 10 wt % polyether polyol in FPUF with CAS
maintains the physical and mechanical properties and fire behavior
and enhances the bio-based content. The presence of 0.1 wt % CuO in
FPUF effectively reduces the emission of hydrogen cyanide. As a result,
this study proposes a multicomponent flame retardant strategy for
FPUF to enhance the biomass content and address the weaknesses in
flame retardancy, smoke, and toxic gas emissions. A starting point
is disclosed for future product development.
Due to the high flammability and smoke toxicity of polyurethane foams (PUFs) during burning, distinct efficient combinations of flame retardants are demanded to improve the fire safety of PUFs in practical applications. This feature article focuses on one of the most impressive halogen-free combinations in PUFs: expandable graphite (EG) and phosphorus-based flame retardants (P-FRs). The synergistic effect of EG and P-FRs mainly superimposes the two modes of action, charring and maintaining a thermally insulating residue morphology, to bring effective flame retardancy to PUFs. Specific interactions between EG and P-FRs, including the agglutination of the fire residue consisting of expanded-graphite worms, yields an outstanding synergistic effect, making this approach the latest champion to fulfill the demanding requirements for flame-retarded PUFs. Current and future topics such as the increasing use of renewable feedstock are also discussed in this article.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.