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Flame-Resistant Cellulose Fibers with Magnesium Hydroxide Prepared by Wet Electrospinning

Yingying ZhengVisiting Scholar

Department of Chemistry and Chemical Biology Rensselaer Polytechnic Institute, Troy, NY, USA

2013 Rensselaer Nanotechnology Center Research SymposiumWednesday, November 6, 2013

Robert J. Linhardt, Trevor J. Simmons, Jianjun Miao

Cellulose Fiber

Ease of thermal degradation, ignition and burning

Availability in vast quantitiesGood mechanical propertiesBiodegradabilityHydrophilicity…

Commonly Used Durable Flame Retardants

PEPBP

Halogen, Nitrogen, Organic-phosphorus compounds

React with the cellulosic fibre or form cross-linked structures on the fibre

-----W. Liu et al. Polymer Degradation and Stability 97 (2012) 2487

-----Z. Yang et al. Polymer Degradation and Stability 97 (2012) 2467

Fabrication of the Flame-Retarded Fibers of Cellulose—Wet Electrospinning

1. Coating of Cellulose with Mg(OH)2 (outside) 2. The mixture of the Cellulose and Mg(OH)2(inside)

3. Coating of the mixture of the Cellulose and Mg(OH)2 (inside & outside)

Standard Vortex Mixer

Ionic liquids

Fig. 1 TGA curves of cellulose under air and N2 atmosphere Fig. 2 TGA and DSCcurves of Nano Mg(OH)2

220-300OCMass loss:76%flame combustion

300-500OCMass loss:22%Smouldering phenomenon

Thermal Properties of Cellulose and Mg(OH)2

Fig.4 The XRD spectra of the cellulose fibers coated with nano Mg(OH)2

Fig.3 The ATR-FTIRspectra of the cellulose fibers with nano Mg(OH)2

Cellulose Coated with Mg(OH)2

Sample Tonset, ℃ Tmax,℃ Residue, wt%

Degradation of Cellulose

Degradation of Mg(OH)2

Degradation of Cellulose

Degradation of Mg(OH)2

Cellulose 239 302 0.39Coating1 254（15↑） 345（↑） 308（6↑） 358（↓） 34.4Coating2 276（37↑） 349（↑） 318（12↑） 360（↓） 31.3

Nano Mg(OH)2 339 364 66.9

Table 1 TGA and DTG data for Cellulose, Coating1, Coating2 and Nano Mg(OH)2 under air atmosphere

Fig. 5 TGA and DTG curves of Cellulose, Coating1, Coating2 and Nano Mg(OH)2 under air

atmosphere

The Flame Retardant Properties 1.1Coating(outside)

Sample Residue, wt% Content of Cellulose, wt%

Original rate, %/min

Final rate, %/min

Cellulose 0.39 100% 40.45 40.45Coating1 34.4 50.8% 8.15 16.04(↓)Coating2 31.3 53.8% 11.15 20.72(↓)

Nano Mg(OH)2 66.9 0 6.74 6.74

Table 2 Degradation rate for Cellulose, Coating1, Coating2 and Nano Mg(OH)2 under air atmosphere

Fig.6TGA and DTG curves of Cellulose, Coating1, Coating2 and Nano Mg(OH)2 under air atmosphere

Slower thermal degradation rate

Fig.7 FESEM images of electrospun fibers coated with Mg(OH)2

Lamellar-like

Coated completely

Table 3 TGA data and Degradation rate for Cellulose, Mixture(1:2), Mixture(1:1) and Nano Mg(OH)2 under air atmosphere

Sample Tonset, ℃ Tmax,℃ Residue, wt%

Content of Cellulose, wt%

Origin rate, %/min

Final rate,%/min

Degradation of Cellulose

Degradation of Mg(OH)2

Degradation of Cellulose

Degradation of Mg(OH)2

Cellulose 239 302 0.39 100% 40.45 40.45Mixture(1:2) 267（↑） 348（↑） 315（↑） 356（↓） 11.3 83.7% 27.3 32.62(↓)

Mixture(1:1) 271（↑） 349（↑） 314（↑） 361（↓） 30.5 55.0% 12.8 23.27(↓)

NanoMg(OH)2

339 364 66.9 0 6.74 6.74

Fig. 8 TGA and DTG curves of Cellulose, Mixture(1:2), Mixture(1:1) and Nano Mg(OH)2 under air atmosphere

1.2 Mixture (inside)The Flame Retardant Properties

Fig.9 FESEM images of electrospun fibers of 1:2 Mixture

1.3 Mixture &Coating (inside &outside)

Fig. 10 TGA curves of Cellulose, Coating ,Mixture, Mixture&Coating and Nano Mg(OH)2 under air atmosphere

The Flame Retardant Properties

Fig.11 FESEM images of electrospun fibers of Mixture&Coating

Flame Test

Sample Residue, wt% Content of Cellulose, wt% Quality of sample, needed for flame test(actual quality), mg

Cellulose 0.39 100% 100(30)

Coating1 34.4 50.8% 197

Coating2 31.3 53.8% 186(56)

Mixture(1:2) 11.3 83.7% 119(36)

Mixture(1:1) 30.5 55.0% 182

Mixture&Coating 28.1 58.6% 171(51)Nano Mg(OH)2 66.9 0 0

Table 4 Quality of sample needed for flame test(mg)

Mg(OH)2 (58) H2O + MgO(40)

Cellulose Coating 2

Mixture (1:2) Mixture &Coating

Flame Test

Conclusion

A novel nanofiber synthesis technique that embeds nanoparticles into the surface of wet electrospun cellulose fibers was reported.

Effective surface coating of cellulose fibers with Mg(OH)2improved the flame resistant performance greatly.

This wet electrospinning technique can also be applied to expand cotton fibers' application with different coating material, such as TiO2, Ag, etc.

Acknowledgement

• Prof. Robert J. Linhardt• Dr. Trevor J Simmons• Dr. Jianjun Miao• Dr. Guoyun Li