Preparation and performance study of waterproof and breathable layer of alginate/aramid-based fabrics and flame-retardant multilayer combination

Figures & data

Table 1. Basic properties of waterproof and breathable layers.

Material	Organizational structure	Thicknesses (mm)	Surface density (g/m^2)
Waterproof and breathable layer B1	Aramid nonwoven + PTFE membrane	1.021	173.78
Waterproof and breathable layer B2	Alginate 1/Aramid 4 blended nonwoven + PTFE membrane	0.895	150.67
Waterproof and breathable layer B3	Alginate 5/Aramid 5 blended nonwoven + PTFE membrane	0.601	119.70
Waterproof and breathable layer B4	Alginate 4/Aramid 1 blended nonwoven + PTFE membrane	0.603	156.74
Waterproof and breathable layer B5	Alginate nonwoven + PTFE membrane	0.957	115.82

Table 2. Basic fabric specification information.

Material	Fabric composition	Organizational structure	Color	Thickness/(mm)	Surface density (g/m^2)
Flame-retardant outer layer A	93% Nomex+5% Kevlar+2% AS	Twill	Sapphire blue	0.44	217.6
Waterproof and breathable layer B2	100g 20% alginate + 80% aramid + PTFE membrane	Needle-punched nonwovens PTFE membrane	White	–	–
Waterproof and breathable layer B3	100g 50% aramid + 50% alginate + 50% aramid + PTFE film	Needle-punched nonwovens PTFE membrane	White	–	–
Waterproof and breathable layer B4	100g 80% alginate + 20% aramid + PTFE membrane	Needle-punched nonwovens PTFE membrane	White	–	–
Waterproof and breathable layer B6	70g80% Nomex+20% Kevlar+PTFE membrane	Hot press nonwoven PTFE film	White laminated surface, yellowish base cloth	0.61	103.5
Heat insulating layer C	70g80% Nomex+20% Kevlar	Hot press nonwovens	Yellowish	0.77	103.5
Comfort level D	50% Nomex + 50% VicoseFR	Twill	Pallid gray	0.32	128.5

Figure 1. Preparation of the flame-retardant multilayer fabric.

Table 3. Multi-layer fabric combinations for firefighting clothing.

Fabric combination	Combinatorial approach	Thickness (mm)	Grammage (g/m2)
1	A+B2+C+D	2.49	523
2	A+B3+C+D	2.12	512
3	A+B4+C+D	2.16	508
4	A+B6+C+D	2.19	540
5	A+C+D	1.54	432

Figure 2. Scanning electron micrographs of aramid nonwovens (a1,a2), calcium alginate nonwovens (e1, e2) and alginate/aramid blended nonwovens (b1,b2: alginate 1/aramid 4; c1,c2: alginate 5/aramid 5; d1,d2: alginate 4/aramid 1) at different magnifications (x500,x2000).

Table 4. Air and moisture permeability data for fabrics.

Material	Air permeability (mm/s)	Moisture permeability (g/m^2·24h)
B1	5.47	4978.66
B2	4.12	6091.14
B3	3.86	5815.41
B4	4.30	6019.53
B5	2.78	3316.75
(an official) standard	-	5000.00

Table 5. Fabric moisture permeability ANOVA.

	SS	DF	MS	F	Sig
Intergroup analysis	21054081.494	4	5263520.373	3.174	0.063
Intragroup analysis	16581153.471	10	1658115.347
Total	37635234.965	14

Table 6. Thermal stability of breathable waterproofing layers.

Material	Dimensional change rate
	Transversal	Vertical	Synthesized
B1	−1.38%	−0.97%	−2.34%
B2	−2.10%	−1.93%	−4.00%
B3	−3.48%	−3.68%	−7.05%
B4	−3.24%	−2.91%	−6.05%
B5	−3.88%	−4.44%	−8.18%

Table 7. Fabric limiting oxygen index.

Material	Limiting oxygen index (%)
B1	31.7
B2	34.4
B3	37.1
B4	38.7
B5	40.3

Figure 3. Waterproof breathable layer (a) TG curve under nitrogen atmosphere; (b) DTG curve under nitrogen atmosphere.

Figure 4. Waterproof and breathable layer (a) TG curve under air atmosphere; (b) DTG curve under air atmosphere.

Table 8. Thermogravimetric test data under nitrogen atmosphere for waterproof and breathable layers (where T_n is in ℃; R_n is in %/℃).

	T5%	T10%	Tmax1	Rmax1	Tmax2	Rmax2	Tmax3	Rmax3	Residual 700℃(%)
Alginate + PTFE membrane	60.10	93.85	69.42	0.15	255.87	0.49	540.51	0.56	8.82
Alginate 4/Aramid 1 + PTFE membrane	64.51	114.76	258.37	0.25	489.43	0.26	554.63	0.38	8.94
Alginate 5/Aramid 5+PTFE membrane	106.46	257.79	272.49	0.12	450.84	0.41	560.45	0.27	18.61
Alginate 1/Aramid 4 + PTFE membrane	253.97	332.92	440.28	0.30	553.41	0.20	-	-	32.66
Aramid + PTFE membrane	265.11	374.74	450.01	0.21	612.15	0.54	-	-	0.34

Table 9. Thermogravimetric test data under air atmosphere for waterproof and breathable layers (where T_n is in ℃; R_n is in %/℃).

	T5%	T10%	Tmax1	Rmax1	Tmax2	Rmax2	Tmax3	Rmax3	Residual 700℃ (%)
Alginate + PTFE membrane	65.31	114.70	254.94	0.39	436.66	0.19	558.80	0.28	10.37
Alginate 4/Aramid 1+PTFE membrane	71.55	177.03	264.3	0.25	459.08	0.22	557.55	0.32	13.28
Alginate 5/Aramid 5+PTFE membrane	125.06	270.96	529.57	0.60	-	-	-	-	6.94
Alginate 1/Aramid 4 + PTFE membrane	247.95	276.42	206.41	0.14	534.26	0.67	-	-	11.63
Aramid + PTFE membrane	123.29	352.13	552.89	0.79	-	-	-	-	3.55

Table 10. TOPSIS evaluation results.

I J	Positive ideal solution	Negative ideal solution	Final Score	Arrange in order
B1	47.151	69.293	0.595	4
B2	6.055	115.639	0.95	2
B3	12.039	104.256	0.896	3
B4	3.597	112.838	0.969	1
B5	115.632	8.6	0.069	5

Table 11. Air and moisture permeability data for multi-layer fabric systems.

Fabric combination	Air permeability (mm/s)	WVT (g/m^2·24h)
1	4.12	3954.77
2	3.86	4153.78
3	4.3	5420.78
4	3.15	6002.54
5	11.9	6913.05

Table 12. Water-vapour transmission rate of multilayer fabric systems.

Material	WVT（g/m2·24h）average value	Standard Deviation	Fabric combination	WVT（g/m2·24h）average value	Standard Deviation
A	5142.33	379.25	1	3954.77	210.20
B	5080.99	215.07	2	4153.78	688.71
C	5332.01	166.47	3	5420.78	883.36
D	4640.64	828.48	4	6002.54	705.58
			5	6913.05	741.43

Figure 5. Surface of multi-fabric system for thermal protection testing.

Table 13. TPP test results for multi-layer fabric systems.

Fabric combination	Second-degree burn time (s)	Burn temperature (℃)	Final heat flux (kw/m^2)	TPP (cal/cm^2)
1	23.85	39.75	12.68	47.7
2	24.25	37.55	12.81	48.5
3	26.1	40.05	12.95	52.2
4	18.4	40.95	11.69	36.8
5	18.15	45.35	11.68	36.3

Table 14. Cone calorimetric test data for multi-layer fabric systems.

Fabric combination	p-HRR	Tp-HRR	Av-HRR	TII	MARHE	FIGRA	p-SPR	TSP	p-COP	p-CO P2	THR	Residue
1	123	20	18.40	11	62.52	6.15	0.041	4.78	0.00444	0.09147	7.33	22.94
2	159	20	19.46	13	64.31	7.95	0.057	3.63	0.00532	0.11133	7.55	23.91
3	144	20	18.73	15	61.53	7.20	0.054	7.70	0.00398	0.12471	6.87	27.23
4	149	20	17.59	12	74.41	7.45	0.059	1.75	0.00420	0.10268	6.99	19.81

Figure 6. Heat release rate, total heat release, smoke release rate, total smoke release for tested combinations.