Design and Application of Fire-Retardant Sweater Using Polyimide

Fabric for Fire Fighters

Jianjun Xia, Zhiming Bao and Hongyang Wang

Weijin South Road 110, Nankai District, Tianjin, China

Keywords: Auxiliary Equipment, Fire-Retardant Sweater, Polyimide Fabric, Fire Fighter, Warmth Retention.

Abstract: To protect fire fighters’ security in city and forest, the auxiliary equipment was studied. Firstly, the

traditional wool sweater and cotton-padded suit were reviewed. Secondly, series new fire-retardant sweaters

using polyimide fabric was designed for better warmth retention. Finally, different sweaters with short or

long polyimide villus were applied in different areas with relative clothing climate zones. The new

sweater’s parameters like fiber shedding should be examined in the future to ensure its actual effect during

the trail in the city and forest forces.

1 INTRODUCTION

Firefighters’ job is to extinguish city fires and forest

fires. The allocating numbers for city firefighters was

shown in Tab 1. To protect fire fighters, fire

protective clothing equipment was required. Current

aramid sweater had low warmth retention. And the

current cotton-padded suit created a lot of deleterious

smoke. So new fire-retardant sweater using

polyimide

was required with high warmth retention

and little smoke.

Theoretically, the outer equipment like fire

protective clothing could help people to keep his

safety from fire radiation and fire flame. However,

the fire fighters’ skin might be still burnt in large fire

scene in extreme circumstances using polyester

underwear or polyester sweater. Therefore,

protective auxiliary equipment like fire-retardant

underwear or sweater for fire fighters was also

necessary.

Table 1: Personal protective equipment’s allocating number for city fire fighters.

Name Fire service station class one Fire service station class two

Special fire service

station

Fire protective clothing for

firefi

hte

2 to 1 fireman 2 to 1 fireman 2 to 1 fireman

Protective gloves for firefighters 4 to 1 fireman 4 to 1 fireman 4 to 1 fireman

Adiabatic protective clothing for

firefi

hte

4 to 1 team 4 to 1 team 4 to 1 team

Chemical protective class two

ensemble for firefi

hters

6 to 1 station 4 to 1 station 1 to 1 station

Fire-retardant sweater - - 1 to 1 fireman

2 THE TRADITIONAL

PROTECTIVE AUXILIARY

EQUIPMENT FOR FIRE

FIGHTERS

There were generally two type forces including city

fire rescue and forest fire rescue. The main different

characters were as shown in Tab 2 below. Compared

with city fire, the forest fire were generally

happened on the site far away from city. Especially,

the small scale fire would be put off by forest ranger

in Forestry Bureau, people’s militia in country and

even local villager. The forest fire fighters would

Xia, J., Bao, Z. and Wang, H.

Design and Application of Fire-Retardant Sweater Using Polyimide Fabric for Fire Fighters.

DOI: 10.5220/0011898100003613

In Proceedings of the 2nd International Conference on New Media Development and Modernized Education (NMDME 2022), pages 68-72

ISBN: 978-989-758-630-9

 2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)

only put off the large scale fire. The whole fire

extinguishing process would last for a few days or

even a few weeks. Therefore, the fire fighters in

forest fire rescue force paid more attention on their

equipment’s warmth retention during their sleep in

the wild.

Table 2: The difference between forest fire fighters and city fire fighters

Parameter Forest fire fighter City fire fighter

Fire extinguishing place Forest or grassland far away from the city City building or chemical plant near city

Fire extinguishing time A few days or even a few weeks A few days

Work environment Complex field temperature like cold Complex field temperature like cold

Rest place Field camps Dormitory

Rest environment Might be cold with high humidity Comfortable

2.1 The Traditional Fire-Retardant

Sweater Using Wool as City Fire

Fighters Protective Auxiliary

Equipment

According to Firefighter Protective Auxiliary

Equipment Fire-Retardant Sweater XF 1274-2015,

the flame-retardant sweater was designed using

99.5% wool fiber and 0.5% polyester conductive

fiber. The relative standard didn’t make specific

request to wool fiber’s warmth retention as shown in

Tab 3. Then the experiments on fire-retardant

sweater were carried out to determine its warmth

retention.

Table 3: The requirements of fire-retardant sweater using wool

Parameter Data Testing method Note

Warmth retention Thermal resistance rating (100±10)% Gb 11048 Clause 6.2

Flame retardant LOI ≥ 28 GB 5454 Clause 6.3

Flame retardant Afterflame time ≤2 s no droplet GB 5455 Clause 6.3

Bursting strength Bursting strength ≥300 N GB 7742 Clause 6.11

Electrostaic property One sweater’s electricity≤0.6μC GB 19976 Clause 6.11

The thermal resistance can be defined as a

parameter to characterize clothing’s warmth

retention. To fire protective clothing with four

layers, the thermal resistance was about 0.0541

·K/W. To traditional wool sweater with one layer

as shown in Fig 1, the thermal resistance was only

0.0651 m

·K/W. Although this wool sweater was

fire retardant and had little smoke during its burning

process. Its low thermal resistance should be still

paid attention. This parameter thermal resistance for

wool sweater should be improved by modifying.

The new fabric material with lower thermal

conductivity should be introduced and the structure

of shorter villus of woolen fabric should be

modified.

Figure 1: The fire-retardant sweater using wool and cotton-padded suit using modacrylic fabric

2.2 The Traditional Fire-Retardant

Cotton-Padded Suit for Forest Fire

Fighter as Forest Fire Fighters

Protective Auxiliary Equipment

Before 2015, the fire retardant cotton-padded suit

were prepared for the forest fireman for cold sleep

in the field by introducing modacrylic fabric. This

material could be obtained by acrylonitrile and fire

retardant ethylene. This fabric’s prize was relative

low and most of the forest fire fighters were

equipped before 2015.

Design and Application of Fire-Retardant Sweater Using Polyimide Fabric for Fire Fighters

This fabric had good thermal resistance 0.202

·K/W, but its warmth retention would decrease to

0.108 m

·K/W gradually because of its

hygroscopicity in long time serving. Moreover, this

modacrylic fabric would generate more black

smoke. This deleterious HCN smoke would affect

fire fighters’ breathing. So the thermal resistance

for cotton-padded suit should be improved.

3 THE NEW FIRE-RETARDANT

SWEATER USING POLYIMIDE

FOR FIRE FIGHTER

To improve new sweater’s thermal resistance, the

different fire-retardant fabrics were considered to

take the place of wool fabric in sweater or

modacrylic fabric in cotton-padded suit. The

parameters of functional fabrics were as shown in

Tab 4.

Table 4: The parameters of functional fabric

Aramid PMIA Aramid PPTA Polysulfonamide PSA Polyimide PI

Density g/cm

1.38 1.45 1.40 1.41

Long time thermal stability °C 230 190 200 280

Short time thermal stability °C 260 260 290

＞300

Resistance to ultraviolet radiation heat Bad Bad Good Good

Moisture regain 4.5% 4.5% 6.3% 3.5%

The first functional fabric was aramid fiber

whose structure had at least 85% of the amide

linkages attached directly to two aromatic rings.

Then its short time thermal stability could reach

260°C with LOI 28. However, its heat thermal

conductivity could even reach 0.045 W/m·K.

Therefore, aramid fabric was not the suitable fabric

material to new sweater.

The second functional fabric was

polysulfonamide. This fabric could be prepared by

interfacial polymerization of polyethylenimine and

benzene-1,3-disulfonyl chloride. Then its short time

thermal stability could reach 290°C with LOI 33. Its

heat thermal conductivity could reach 0.033

W/m·K. Therefore, polysulfonamide fabric was the

suitable fabric material to new sweater.

The third funciton fabric was polyimide. The π-π

interactions between aromatic rings guarantee this

fabric’s thermal functions. Its short time thermal

stability could be higher than 300 °C with LOI 38.

Its heat thermal conductivity could reach 0.040

W/m·K. Therefore, polyimide fabric was also the

suitable fabric material to new sweater.

Considering the fabric’s mechanical property

and spinnability, polyimide was chosen to produce

new sweater. In addition, there was little balck

smoke during the polyimide fabric’s burning

process. According to polyimide villus’ length, there

were two types of fire-retardant sweaters.

3.1 Fire-Retardant Sweater with Long

Villus Using Polyimide

To polyimide sweater, there were two parts in the

clothing including ground yarn and veil yarn. The

ground yarn should had better bursting strength to

maintain the clothing’s elasticity. Then the flame

retardant polyester fabric with elastic strength was

introduced. The veil yarn should had better warmth

retention to guarantee the sweater’s thermal

property. Then the polyimide fabric and antistatic

polyester fabric were introduced.

One type clothing was the sweater with long

polyimide villus as shown in Fig 2. The long villus

could guarantee its thermal resistance to 0.201

·K/W. To keep the sweater’s antistatic property.

Not only the antistaic polyester fabrics were

introduced in the veil yarn with poylimide, but also

the antistatic polyester yarn and elastic polyester

filament were double twisted in the ground yarn.

Then this new sweater’s surface electricity could be

lower than 0.6 µC. The longer of the polyimide

villus, the easier losing of the fabric during the long

time serving. The fiber shedding was obvious.

NMDME 2022 - The International Conference on New Media Development and Modernized Education

Figure 2: The fire-retardant sweater using long polyimide villus and using short polyimide villus

3.2 Fire-Retardant Sweater with Short

Villus Using Polyimide

The other type clothing was the sweater with short

polyimide villus as shown in Fig 2. The veil yarn

were generally produced by polyimide fabric and fire

retardant viscose. The introduction of viscose could

be used to improve sweater’s skin affinity. Then the

whole sweater with short polyimide villus could

reach 0.132 m

·K/W. Compared with the veil yarn

using 98% polyimide fabric in the first type, the

second type sweater used only antistatic polyester in

the veil yarn except ground yarn. Then this new

sweater’s surface electricity could also be lower than

0.6 µC. Although this sweater with short polyimide

villus had lower warmth retention, the short villus

could be stable during the long time servicing.

4 APPLICATION OF NEW FIRE-

RETARDANT SWEATER

USING POLYIMIDE

According to The Requirements on Insulation of

Labour Protective Clothing in Cold Condition

GB13459, different areas with relative clothing

climate zones were as shown in Tab 5. Considering

the outer protective clothing and inner thickened

underwear, the sweaters with different length villus

were recommended with different retention. The

fire-retardant sweater’s trail in Heilongjiang’s city

firefighters and Sichuan’s forest firefighter were

shown in Fig 3.

Table 5: The climate zones in China

Climate zone Area Synthetic temperature Warmth retention

V Between Mohe and Harbin <-25°C 1.01 m

·K/W

IV Between Harbin and Zhangjiakou Between -15°C and -25°C 0.89 m

·K/W

III Between Zhangjiakou and Zhengzhou Between -5°C and -15°C 0.72 m

·K/W

II Between Zhengzhou and Fuzhou Between 5°C and -5°C 0.59 m

·K/W

I Between Fuzhou and Haikou >5°C 0.45 m

·K/W

For example, in the city of Altay with synthetic

temperature -21°C in IV climate zone, the required

warmth retention was 0.89 m

·K/W in static

condition. The forest firefighters or city firefighters’

fire protective clothing’s warmth retention was 0.05

·K/W. The thick underwear’s warmth retention

was 0.05 m

·K/W. Then the new sweater and thick

flocculus-padded suit with 0.60 m

·K/W should be

applied together in winter. The new sweater’s

warmth retention should be higher than 0.19

·K/W. Then the sweater should be with long

polyimide villus in the area between Zhangjiakou

and Mohe.

Figure 3: The fire-retardant sweater’s trail in

Heilongjiang’s city firefighters and Sichuan’s forest

firefighter

Design and Application of Fire-Retardant Sweater Using Polyimide Fabric for Fire Fighters

For example, in the city of Nanjing with

synthetic temperature -3.2°C in II climate zone, the

required warmth retention was 0.45 m

·K/W in

static condition. The forest firefighters or city

firefighters’ fire protective clothing’s warmth

retention was 0.05 m

·K/W. The thin underwear’s

warmth retention was 0.02 m

·K/W. Then the new

sweater and flocculus-padded suit with 0.25

·K/W should be applied together in winter. The

new sweater’s warmth retention should be higher

than 0.13 m

·K/W. Then the sweater with short

polyimide villus could be used in the area between

Haikou and Zhengzhou.

5 CONCLUSION

To keep forest and city fire fighters’ security, the

auxiliary equipment were studied on the base of

wool sweater and cotton-padded suit. The new fire

retardant sweater using polyimide were produced

with better warmth retention. New sweater with

long polyimide villus could be used in climate zone

V and IV with thick flocculus-padded suit. New

sweater with short polyimide villus could be used in

climate zone II and III with thin flocculus-padded

suit. The further study should focus on the actual

application of polyimide sweater in moving

condition instead of static condition. And the other

comfortable parameters including fiber shedding,

skin affinity and moisture regain should also be

studied.

ACKNOWLEDGEMENT

This paper was supported by Tianjin Fire Research

Institute Fundamental Research Funds Project No.

2020SJ13 Research and development of skin

friendly personal protective equipment for

firefighters, Project of Application Innovation of the

Fire Bureau No. 2020XFCX24 Research on

decontamination technology of fire fighting

protective equipment, China Fire Protection

Association Standard Project T/CFPA 010-2022

Firefighter protective auxiliary equipment-thermal

sweater.

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