Rigid Polyurethane Foams Containing Modified Ammonium Polyphosphate Having Outstanding Charring Ability and Increased Flame Retardancy

Abstract

Ammonium polyphosphate (APP) with different polymerization degrees were modified by a novel phosphorus-containing organosilicon compound (PCOC), and the products obtained were coded as MAPP-30 and MAPP-1000. Then they were applied to prepare flame-retardant rigid polyurethane foam (RPUF) separately. The impact of modified APP (MAPP) on the flame-retardant properties of RPUF was investigated by the limited oxygen index (LOI) test, horizontal burning test, and cone calorimeter test. The morphologies of the char residues were observed by SEM. Furthermore, the mechanical properties of RPUF composites were measured by the compressive strength test. The results showed that whether the degree of polymerization of MAPP is 30 or 1000, they both had greater charring ability and better flame-retardant properties than unmodified APP. The residual char yield of RPUF/MAPP-30 (37.3%) and RPUF/MAPP-1000 (36.5%) were both significantly higher than RPUF/APP-30 (22.8%) and RPUF/APP-1000 (24.9%). The peak heat release rate value of RPUF/MAPP-30 was 29.9% lower than that of RPUF/APP-30, and the drop of RPUF/MAPP-1000 was 50.9% compared to RPUF/APP-1000. Moreover, the total heat release of RPUF/MAPP-1000 (9.7 MJ/m2) was much lower than that of RPUF/MAPP-30 (11.3 MJ/m2). In summary, MAPP-1000 has the best flame-retardant properties among all RPUF composites. In addition, the results also showed that flame-retardant performance and the mechanical properties dramatically decreased with the increase in the addition of MAPP-1000, and the RPUF composite had the best comprehensive performance with 20% content of MAPP-1000.

Elaboration of Thermally Performing Polyurethane Foams, Based on Biopolyols, with Thermal Insulating Applications

“…From Figure 4 a, different parameters were determined to assess further the thermal performance of the formulations, and these are gathered in Table 6 . The onset temperature of degradation (T 5% ) did not show large differences between the formulations, except for the case of F_APP, for which the temperature was slightly higher and within the typical range for APP [ 74 ]. In fact, this formulation was the one that displayed the best thermal parameters.…”

Effect of microencapsulation flame retardant on flame retardancy and mechanical properties of rigid polyurethane foams

“…When the deformation degree exceeded 10%, the growth rate of foam compressive strength slowed down in the "platform" stage. 8,[56][57][58] When the deformation reached 40%, the foam gradually exceeded the tolerance limit, the cell wall deformed and even the foam collapsed. The stress-strain curve raised almost linearly.…”

Balanced Thermal Insulation, Flame-Retardant and Mechanical Properties of PU Foam Constructed via Cost-Effective EG/APP/SA Ternary Synergistic Modification

“…Different methods have been reported to improve the flammability of RPUF such as halogenated flame-retardants [15], phosphorous flame-retardants [16,17], graphite [18], aluminum hydroxide [19], expandable graphite (EG) [20], melamine [21], coating [22,23] and other additive flame-retardants [13,24]. However, a high loading amount is often needed in order to achieve satisfactory flame-retardant effects, which leads to a decrease in the mechanical properties of the RPUF and increases the risk of secondary damage caused by the detachment of the building external wall [25][26][27]. There is a significant synergistic flame-retardant effect where excessive amounts of EG can be effectively avoided through the use of EG in combination with phosphorus/nitrogen-based flame-retardants, while the resulting mechanical and thermal insulation properties are significantly reduced compared to neat RPUF [25,[28][29][30][31][32][33][34].…”