Very good in flame retardency

1. Development
in flame
retardant
finishing of
textiles
SUBMITTED TO- DR SUPRIYO
CHAKRABORTY
SUBMITTED BY- RISHABH SINGH

2. Index
 Introduction
 Mechanism of flame retardancy
 Traditional flame retardants
 Nano finishes
 Conclusion

3. Thermal transition
of the most
commonly used
fibers

4. Mechanism of pyrolysis of cellulose
 Pyrolysis of cellulose at higher temperatures
gives three types of products:
 a gaseous fraction containing gases like
methane, carbon monoxide, carbon dioxide,
etc., a tar or heavy oil fraction containing
volatile species, and a char fraction.
 Laevoglucosan(1,6-anhydro-glucopyranose)
is considered to be a major product in the tar.

5. Flame retardant strategies
1. Removal of heat
2.Enhancement of decomposition
temperature
3.Decreased formation of flammable
volatiles, increase in char
4.Decreased access to oxygen or flame
dilution
5.Interference with flame chemistry
and/or increase in fuel ignition
temperature (Tc): Combustion as a feedback mechanism

6. Flame retardant mechanism of
vapor phase
 Most antimony-halogen systems
comprise trioxide and bromine
containing organic molecules such as
decarbodiphenyl oxide (DBDPO) or
hexabromocyclododecane (HBCD).
 On heating, these release HBr and
also Br radicals which interfere with
the flame chemistry by the following
general scheme Where R ,CH2, H and
OH radicals are part of the flame
oxidative chain reaction that
consumes (RCH3) and oxygen.

7. Flame retardant mechanism of
condensed phase
 Most phosphorus and nitrogen containing
retardants, when present in cellulose
decrease volatile formation and catalyze
char formation.
 The first reaction prevents formation of
levaglucosm, the precursor of flammable
volatile formation and ensures that the
competing char formation reaction is now
the favored pyrolysis route

8. Silicon containing
Nano-coating by layer-
by-layer assembly
With 15 bilayer nano-coatings (15.5%
weight increased), the coated T/C
blends achieved self-extinguishing
and got away from scaffolding effect
in vertical flame test.
And showed a little delay of
ignition and a strong decrease of
heat release during cone calorimetry
test, indicating excellent flame
retardance of the treated fabrics.
The nano-coating had both gaseous and
condensed-phase flame-retardant activity,
which was further confirmed by the results of
char analysis and thermogravimetric
analysis/infrared spectrometry
. Layer-by-layer assembly

9. Flame retardancy of silk
fabric by nano-TiO2
 The FT-IR analyses demonstrate that
PA could act as a catalyst of ester
crosslinking between BTCA and silk
fiber. These multiple interactions
among PA, TiO2, BTCA and silk fiber
contributed to the good washing
durability of the treated silk fabric .
 The thermogravimetry and pyrolysis
combustion flow calorimetry
revealed that a significant
condensed-phase FR mechanism of
the treated silk fabric took place due
to the great char forming ability
caused by PA and TiO2
Clearly, the pHRR of the silk fabrics treated with PA/BTCA and PA/TiO2/BTCA
was much lower than that of the untreated silk. The pHRR of the control
sample was 144.8 W/g.
As for the PA/BTCA and PA/TiO2/BTCA treatments, the pHRR decreased to
102.6 and 63.3 W/g, which was 29.1% and 56.3% reduction, respectively.
The PA/TiO2/BTCA treatment had higher efficiency on improving the flame
retardancy of silk than the PA/BTCA treatment.
HRR curves of the silk fabrics treated with PA/BTCA and
PA/TiO2/BTCA.

10. Nano zinc as a flame retardant
 SA and BTCA are environment-friendly compounds used for the finishing of
cellulosic fabrics.
 The effect of two different carboxylic acid agents (SA and BTCA) together
with SHP as catalyst and nano ZnO as a novel flame retardant for cotton and
cotton/polyester fabrics was investigated.
 Nano ZnO is an effective compound in increasing the char formation.
 Also, the presence of phosphorus deposited on the SHP treated samples is the
most effective parameter in the char forming and decreasing the flammability
of the treated fabrics.
 Totally, the performed treatment helps to form more nonflammable char
residue and increases char formation after heating in addition to the
improvement of the UV-protection property

11. Effect of curing temperature on flammability of cotton and cotton/polyester
fabrics treated by polycarboxylic acids

12. Flame retardant effect by
nano micro silica-based
sols
 These sols prepare as required
nanoscale and nano-micro
gradient requirement (1.0-100.0
nm/1.0-100.0 μm).
 Expectingly, these sizes will
have a positive impact on the
flame-retardant effect of late
modified flame retardants.
By Fourier transform infrared spectroscopy (FTIR), it is known the nano-
micro modified sols are thermally condensed and subsequently coated and
attached to the surface of the fabric substrate to form a carbonaceous
compound similar to the protective layer, which acts as a physical barrier.
This physical barrier can isolate the heat and oxygen to prevent the fabric
from further thermal decomposition and delay subsequent combustion
Schematic for preparation of fabrics finished by Hybrid Nano-
Micro Silica-based Sols

13. Conclusion
 Coating durability is major issue to be addressed. These coatings are
being deposited on substrates that will undergo significant wear-and-
tear, so the coatings must be able to survive and remain effective.
 Applicable substrates have expanded from textiles to foam to bulk
polymers and even nanoparticles.
 The unique ability to deposit materials in nanolayers has allowed
conventional chemistries to be adapted into submicron coatings that
are positioned to directly interact with the polymer/ flame interface.
 This multilayer deposition also facilitates the incorporation of multiple
FR mechanisms simultaneously, which may allow for the discovery of
new synergies.

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