Flame‐retardant expandable polystyrene foams coated with ethanediol‐modified melamine–formaldehyde resin and microencapsulated ammonium polyphosphate

Abstract

Melamine–formaldehyde resin was modified by ethylene glycol to decrease the amount of free formaldehyde and extend the storage time. The modified resin (EMF) was further used to prepare microencapsulated ammonium polyphosphate (MCAPP). The structures of both EMF and MCAPP were well characterized. Afterward, EMF and MCAPP were mixed and coated on the surface of pre‐expanded polystyrene particles to prepare flame‐retardant expandable polystyrene foams (EPS). Both water resistance and impact strength were enhanced by the presence of MCAPP, and the flammability of the samples was also significantly improved. For the sample containing 75 phr MCAPP, the limiting oxygen index value was increased to 31.4% with a V‐0 rating in the UL‐94 vertical burning test. Cone calorimeter tests showed that the peak heat release rate of the sample declined sharply to 172.7 kW/m2, which is 81.6% lower than that of neat EPS. The smoke production of EPS foams during combustion was suppressed by the presence of MCAPP, and the thermal stability was also improved. Scanning electron microscopy showed that the char layer of the flame‐retardant sample after combustion became compact with negligible voids or cracks, which could further form an isolation barrier to prevent both heat and flame transfer. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46471.

Preparation of halogen‐free flame‐retardant expandable polystyrene foam by suspension polymerization

“…Thermal degradation of pure PS beads mainly occurs between 350°C and 450°C, and the initial decomposition temperature is 365.48°C. The thermal degradation of PS is attributed to a free radical reaction mechanism . Random chain breaking occurs first, resulting in a decrease in molecular weight.…”

Poly (diallyldimethylammonium) and polyphosphate polyelectrolyte complexes as an all‐in‐one flame retardant for polypropylene

“…FTIR spectra of APP, PDDA and PAPP were shown in Figure . For APP and PAPP, the absorption bands of P═O, P─O, and P─O─P stretching vibration appeared at 1250 cm −1 , 1068 cm −1 , and 868 cm −1 , respectively . In the FTIR spectrum of APP, the peak at 3162 cm −1 , 3000 cm −1 , 2832 cm −1 and 1422 cm −1 were attributed to the typical absorption of NH 4 + , while PAPP didn't exist, indicating that there was almost no NH 4 + in PAPP.…”

Preparation and characterization of the halogen‐free, smoke suppression, organic–inorganic hybrid flame‐retardant expandable polystyrene materials

“…Therefore, the design and preparation of EPS materials with high flame-retardant efficiency have become the focus of research in this field. [2,3] Hamdani-Devarennes et al prepared flame-retardant EPS with water-based flameretardant coating based on nano boehmite and poly(vinyl alcohol). [4] The coated EPS exhibit better flame retardancy and their Euroclass fire ratings upgrade from "F" to "E." The flame tip never reaches 150 mm above the application point during the test and no burning drop is observed.…”

“…The LOI was 31.5% and their UL 94 rating is V-0. According to Zhang et al, [2] the modified resin and microencapsulated ammonium polyphosphate were mixed and coated on the surface of pre-expanded polystyrene particles to prepare flame-retardant EPS foams .The LOI value was increased to 31.4% and the peak heat release rate (PHRR) of the sample was declined to 172.7 kW/m 2 . However, they cannot give out a satisfactory result in flame-retardant effect and the release of free formaldehyde may cause environmental and health problems.…”