Running head: FLAME RETARDANT FOR HOUSEHOLD COUCHES

Flame Retardant for Household Couches:

Coating Foam Inside Couches with a Mixture of Wheat Gluten, Reax 88B and Glycerol to

Prevent Spread of Fire

Douglas Fox, Anh Do

American University – College of Art and Science

FLAME RETARDANT FOR HOUSEHOLD COUCHES 2

Abstract

The purpose of this research is to find a cheaper, yet more effective mixture to coat the foam

inside couches with for flame retardant purpose. This research uses wheat gluten and

lignosulfonate as primary flame retardants and focuses on adding other ingredients into the

mixture to both maintain the flame retardant property, minimize the stiffness of the coated foam

and prevent wheat gluten and lignosulfonate from leaving the coated foam. The best mixture

contains 80% of wheat gluten, 10% of lignosulfonate, and 10% of glycerol, the chosen

plasticizer. A very small amount of tannic acid is also present to prevent molding. This mixture

dries up and forms a flexible film that does not break easily even when folded up. The foam

samples coated with the mixture only experience a slight increase in stiffness. Only 10% of the

total lignosulfonate leaves the sample film after being soaked in water for one day.

FLAME RETARDANT FOR HOUSEHOLD COUCHES 3

Introduction

Research has shown that couches and sofas pose the greatest fire hazard among all the household

furniture. It only takes 1.5 minutes for a non-flame retarded sofa to be burned down and 4.5

minutes for the flame to spread to the entire room. One of the best ways to prevent fire damage

from burning couches from happening is to increase the flame retardant property of the foams or

fillings inside the couches. This research aims at creating a better flame retardant mixture to coat

couch fillings. The mixture must be cheap and easy to make, yet slows down or prevent burning

effectively. After coating, the foam’s softness must not be significantly affected, there must not

be any mold or similar health hazard associating with the coating and the coating mixture must

not easily come off from the foam sample in case water is spilled on the couch.

Previous research has confirmed the excellent fire retardant property of wheat gluten (WG) and

lignosulfonate (Reax 88B). However, coating foam with just WG is inefficient because WG is

hydrophobic, making it unable to fully dissolve in water. After coating and letting the foam

sample dry, the WG forms clumps on the surface and inside the foam sample that do not only

come off the sample easily, but also make the foam significantly harder. On the other hand, Reax

88B dissolves easily in water. Although this makes it easier to coat foam with Reax 88B, the

coating mixture will likely come off if water is spilled on the sample.

Since the flame retardants mentioned above have properties that can be compensated by one

another, mixing the two chemicals together may produce a better coating mixture. The goal of

the experiments is to find the other ingredients to add into WG and Reax 88B to create a new

mixture that meet all the aforementioned criteria.

FLAME RETARDANT FOR HOUSEHOLD COUCHES 4

Materials and Methods

The ingredients and their respective functions

Ingredients Purposes

Wheat Gluten Hydrophobic flame retardant

Water (H2O) Dissolve wheat gluten

Sodium Sulfite (Na2SO3) Make WG grains bond together and form a

coherent structure in water

Ethanol (CH3COOH) Break down WG’s hydrophobic clumps in

solution

Ammonium Hydroxide (NH4OH) Increase dispersion, make WG mixture

dissolve more easily in solution

Sodium Lignosulfonate – Reax 88B Flame retardant

Tannic Acid (C76H52O46) Prevent formation of molds

Glycerol (C3H8O3) Possible Plasticizer

1-Octanol Possible Plasticizer

Polydimethylsiloxane Possible Plasticizer

Table 1: Ingredients in the mixture and their respective functions

Procedure

In all samples, mix a consistent amount of 2.0000 g of WG with 14 ml of H2O and 0.0200 g of

Na2SO3. The mixture is stirred for 10 to 15 minutes, then decanted and washed again with water

to remove excessive Na2SO3.

FLAME RETARDANT FOR HOUSEHOLD COUCHES 5

Add 14 ml of NH4OH and 9 ml of Ethanol to the solid. Stir again and heat to 85oC. 0.25 g (10%)

of Reax 88B is then added in, followed by 0.01 g of Tannic Acid.

Add 0.2500 g of plasticizer to the mixture. Each sample only has one plasticizer.

Preparation to test the solubility of the sample: Put 0.5000 g of the sample into a tube.

Pour in 10 ml of distilled water. Gently disturbed the tubes overnight. Test the solution to

see which chemical dissolves in water.

Preparation to test the flexibility and flame retardant property of the sample: Pour the

final mixture to a dish and kept to dry in to fume hood. After three to five days, remove

the dried film from the dish.

Preparation to test the softness and flame retardant property of the coated foam: Coat the

foam with the mixture having the most flexible film by soaking the foam pieces in the

mixture until the weights of the pieces of foam increase to four times. Keep the foam

samples in the fume hood to dry.

FLAME RETARDANT FOR HOUSEHOLD COUCHES 6

Results and Discussion

The sample films have similar flame retardant property, with or without plasticizer.

As expected, no molds are formed in any of the samples thanks to the presence of tannic acid.

For all the sample films, about 10% of the Reax 88B put in the mixture dissolves upon soaking

in water. This corresponds to about 1% of the coating mixture. However, Reax 88B has a dark

brown color. When water is spilled on a couch whose filling is coated with this mixture, it is

possible that the cover of the couch will turn brownish yellow. This is undesirable since it

directly affects the aesthetic property of the couch over time. Further research must be conducted

to further prevent Reax 88B from leaving the dried sample mixture.

Without plasticizer, the dried sample was extremely brittle that it was hard to remove it from the

dish without breaking. With 10% of 1-octanol and polydimethylsiloxane (equivalent to 0.2500

g), the dried sample can be removed from the dish as a whole, but still break upon folding. With

10% of glycerol, the dried sample was the most flexible, allowing removal as a whole from the

dish as well as folding. The flame retardant property of the films was similar. Under a direct

flame, the films formed good char layers that range from 21.4% to 25.4% (See Appendix A); the

films were caught on fire but the flame was extinguished almost immediately.

The mixture of 80% WG, 10% Reax 88B and 10% Glycerol was chosen for coating. The coated

pieces of foam established very good flame retardant property with 9.3% to 10% of char

formation, reducing the heat release by about 20% (See Appendix A). After drying, the foam

hardened negligibly and there was no visible sign that the coated layer can be removed

physically from the foam samples. Further research should be conducted to increase the

flexibility of the sample film while maintaining the flame retardant property.

FLAME RETARDANT FOR HOUSEHOLD COUCHES 7

References

Blomfeldt, Thomas., Johansson, E., Holgate, T., Hedenqvist, M., Nilsson, F., &Xu, J. (2012,

February 14). Thermal Conductivity and Combustion Properties of Wheat Gluten Foams.

ACS Applied Materials & Interfaces (ACS Publications), 4, 1629−1635 Retrieved

December 10, 2015, from http://pubs.acs.org/doi/abs/10.1021/am2017877

Fire Safety. (n.d.). Retrieved December 10, 2015, from

http://www.cefic-efra.com/index.php/furniture-a-textile/fire-safety

Kitabatake, N., Murakami, T., & Tani, F. (2015). Dispersion in the Presence of Acetic Acid or

Ammonia Confers Gliadin-Like Characteristics to the Glutenin in Wheat Gluten. Journal

of Food Science, 80(2), 269-278. Retrieved December 10, 2015, from doi:10.1111/1750-

3841.12757

Pope, Penny M., Sean O'Bannon, and Steven R. Pope (1992). U.S. Patent No. 5,112,533 A.

Washington DC: U.S

FLAME RETARDANT FOR HOUSEHOLD COUCHES 8

Appendix A: Flame retardant property of samples and coated foam

Sample THR (kJ/g) HRC

(J/g·K)

Tpeak (°C) char (wt

%)

*THRrel

(kJ/g)

WG film #1 11.7 101 296 / 352 25.1 15.6

WG film #2 12.1 107 351 22.9 15.7

WG film #3 11.2 101 307 / 349 25.4 15.0

WG film #4 12.3 116 354 21.4 15.6

Uncoated foam 25.5 518 286 / 395 0 25.5

Coated foam #1 21.1 397 251 / 424 9.3 23.3

Coated foam #2 21.4 366 292 / 424 10.0 23.8

* - THR relative to amount of material actually consumed = THR / (1 – char fraction)

Table 2: Data and analysis for the samples and coated foam

THR is total heat released. It describes the total amount of fuel added to a fire. HRC is the heat

release capacity. It relates to the maximum heat release rate, or peak temperature of a fire. Char

is produced when some of the material is left unburned. The relative heat released is the heat

released scaled by the amount actually burned. It is related to the heat capacity of the material.

Although the peak heat release rate is often cited as one of the most important factors in a fire,

this actually correlates more closely to the THR in MCC experiments. This is due to the small

size of sample used here.

100 200 300 400 500 600 7000

20

40

60

80

100

120

140

WG #1WG #2WG #3WG #4

Temperature (°C)

Heat

Rel

ease

Rat

e (W

/g)

100 200 300 400 500 600 700

0

50

100

150

200

250

300

350

400PUFPUF + WGPUF + WG

Temperature (°C)

Heat

Rel

ease

Rat

e (W

/g)

Figure 1: Heat release rate for the samples and the coated foam

FLAME RETARDANT FOR HOUSEHOLD COUCHES 9

All films produce about the same amount of heat. This is clearer when comparing the relative

total heat released. Only film #3 is different, and its combustion was erratic (greater error in this

data point). Coating polyurethane foam with these formulations reduces both the heat released

and the peak heat released by 20%. The 2nd coating used performed slightly better, as evident by

both the shift in temperature of the earliest event and the reduction in the maximum heat

released. Note that in the foam profiles, the first peak represents depolymerization and

combustion of the isocyanate monomer, while the second peak represents the evaporation and

combustion of the remaining polyol that comprises the polyurethane. This indicates that the

coating reduces the depolymerization (lower peak heat release rate), producing a protective char

that inhibits polyol decomposition (higher temperature of 2nd peak). The first effect is more

significant in these systems and other coatings we have used. The second effect is seen in almost

all of our coatings.