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A. K. Samanta et al.
that is there will be a much higher effect obtained for using a suitable combination
of urea and AS than the use of AS individually and use of Urea individually. For
an increase in LOI value, this combination of urea and AS has a synergistic effect.
So, it may be mentioned here that both the chemicals are equally required to get the
optimum value of LOI and other response variables.
RSM contour plot in Fig. 3 shows that char length (one of the major second important criteria for the fire-retardant performance of textiles) is reduced by increasing
both the process variables (A) and (B) up to a certain dosages and then further
increases above a certain dosage level of these process variables. However, the effect
of variable (A), that is urea is found to be lower than the effect of variable (B), that
is, ammonium sulfamate.
Corresponding RSM equation 6 generated for predicting values of R2 (char length)
for specific dosages of urea (A) and ammonium sulfamate (B) indicate the negative
value of the coefficient for A and B and A
2 term, that is, both increase of A & B
cause a good reduction in char length but very high increase in A (Urea) did not show
much reduction in R2 (char length). Hence, it can be said that ammonium sulfamate
is much more important and is essentially required to reduce char length along with
urea. So, the determination of optimal values for the combination of ammonium
sulfamate and urea is essential in this treatment formulation.
RSM contour plot in Fig. 4 shows that loss in fabric tenacity of treated jute fabric
is increased with an increase in input variable B (ammonium sulfamate) to a large
extent than the effect of variable A, that is, urea. Increase in concentration of urea
has a minimum or very less effect on loss of fabric tenacity. Ammonium sulfamate
partially produces sulfamic acid and also use of MgCl 2 acidic catalyst causes an
acidic environment particularly during heating (at curing stage) and hence, there is
probable acidic degradation of jute cellulose/hemicelluloses chains, causing the said
loss in fabric tenacity, where acidic degradative action of cellulose chains is enhanced
due to use of pre-fixed small dosages of MgCl 2 catalyst used in all such fire-retardant
formulations used.
Corresponding RSM equation 7, generated for predicting resultant values of R3
(loss in tenacity) for specific dosages of Urea (A) and ammonium sulfamate (B) indicate the positive value of coefficient, for both variables A and B showing coefficient
of variable—B is higher than coefficient—A, that is it meant the effect of increase
of Ammonium sulfamate is much higher than the said effect of increase of variable
A, that is Urea. Hence, the dosages of AS is to be restricted to avoid higher loss in
fabric tenacity. So there is no question of using Urea and AS in a higher dosages as
understood from values of A
2 and B
2 terms.
Finally, the numerical optimization program was run in the design expert software
of UDQM model to evaluate the optimal parametric values which are correspondingly
represented in the three respective contour curves in plots given in Figs. 2, 3 and 4
presenting the above-stated results mentioned above for R1 (LOI), R2 (Char length)
and R3 (Loss of fabric tenacity), respectively.
A. K. Samanta et al.
that is there will be a much higher effect obtained for using a suitable combination
of urea and AS than the use of AS individually and use of Urea individually. For
an increase in LOI value, this combination of urea and AS has a synergistic effect.
So, it may be mentioned here that both the chemicals are equally required to get the
optimum value of LOI and other response variables.
RSM contour plot in Fig. 3 shows that char length (one of the major second important criteria for the fire-retardant performance of textiles) is reduced by increasing
both the process variables (A) and (B) up to a certain dosages and then further
increases above a certain dosage level of these process variables. However, the effect
of variable (A), that is urea is found to be lower than the effect of variable (B), that
is, ammonium sulfamate.
Corresponding RSM equation 6 generated for predicting values of R2 (char length)
for specific dosages of urea (A) and ammonium sulfamate (B) indicate the negative
value of the coefficient for A and B and A
2 term, that is, both increase of A & B
cause a good reduction in char length but very high increase in A (Urea) did not show
much reduction in R2 (char length). Hence, it can be said that ammonium sulfamate
is much more important and is essentially required to reduce char length along with
urea. So, the determination of optimal values for the combination of ammonium
sulfamate and urea is essential in this treatment formulation.
RSM contour plot in Fig. 4 shows that loss in fabric tenacity of treated jute fabric
is increased with an increase in input variable B (ammonium sulfamate) to a large
extent than the effect of variable A, that is, urea. Increase in concentration of urea
has a minimum or very less effect on loss of fabric tenacity. Ammonium sulfamate
partially produces sulfamic acid and also use of MgCl 2 acidic catalyst causes an
acidic environment particularly during heating (at curing stage) and hence, there is
probable acidic degradation of jute cellulose/hemicelluloses chains, causing the said
loss in fabric tenacity, where acidic degradative action of cellulose chains is enhanced
due to use of pre-fixed small dosages of MgCl 2 catalyst used in all such fire-retardant
formulations used.
Corresponding RSM equation 7, generated for predicting resultant values of R3
(loss in tenacity) for specific dosages of Urea (A) and ammonium sulfamate (B) indicate the positive value of coefficient, for both variables A and B showing coefficient
of variable—B is higher than coefficient—A, that is it meant the effect of increase
of Ammonium sulfamate is much higher than the said effect of increase of variable
A, that is Urea. Hence, the dosages of AS is to be restricted to avoid higher loss in
fabric tenacity. So there is no question of using Urea and AS in a higher dosages as
understood from values of A
2 and B
2 terms.
Finally, the numerical optimization program was run in the design expert software
of UDQM model to evaluate the optimal parametric values which are correspondingly
represented in the three respective contour curves in plots given in Figs. 2, 3 and 4
presenting the above-stated results mentioned above for R1 (LOI), R2 (Char length)
and R3 (Loss of fabric tenacity), respectively.