**6. Results and discussion**

#### **6.1 Characterization and structural analysis by SEM**

**Figure 6**, uncoated PA 6,6 fabric (a); TPU-DMF coated PA 6,6 fabric (b); CBP-TPU-DMF coated PA-6,6 fabric (c); TVR-TPU-DMF coated PA-6,6 fabric (d); CBP-TVR-TPU-DMF coated PA-6,6 fabric (e); NA-TVR-TPU-DMF coated PA-6,6 fabric (f); NA-CBP-TVR-TPU-DMF coated PA-6,6 fabric (g); blended CBP in water (h); blended CBP after 24 hour precipitation (i); blended CBP after 48 hour precipitation (j); 3% TPU in DMF (k), 3% TPU in DMF after addition of five drop NA; 5% of 70% NA (l); solidification slice of TPU-DMF in the presence of NA (l); SEM magnification of CBP particle (m) and its color thresholding structure of CBP particle (n); particle size of CBP (o); SEM magnification of TVR particle (p) and its color thresholding image of particle size (q); SEM magnification of PA 6,6 uncoated fabric (r); TPU-DMF coated PA 6,6 fabric (s) and its color thresholding image to refine TPU-DMF on fabric surface (t); CBP-TPU-DMF coated PA-6,6 fabric (u) and its color thresholding image to signify TPU-DMF on fabric surface (v); TVR-TPU-DMF coated PA-6,6 fabric (w) and its color thresholding image to identify TPU-DMF on fabric surface (x); CBP-TVR-TPU-DMF coated PA-6,6 fabric (y) and its color thresholding image to signify TPU-DMF on fabric surface (z); NA-TPU-DMF coated PA-6,6 fabric (z1); NA-TVR-TPU-DMF coated PA-6,6 fabric (z2); NA-CBP-TVR-TPU-DMF coated PA-6,6 fabric (z3).

**Figure 6** (i, j), water medium diluted CBP has been shown to signify the dispersibility of raw CBP. 0.5gm CBP was blended (30 minutes) with 150 ml *Evaluation of Camouflage Coloration of Polyamide-6,6 Fabric by Comparing Simultaneous… DOI: http://dx.doi.org/10.5772/intechopen.101537*

**Figure 6.**

*Photograph of treated and untreated fabric (a-h), CBP and TPU-DMF derivative solution (i-l), SEM and color thresholding image of treated and untreated PA 6,6 fabric (m-z3).*

deionized water. The solution showed a precipitation/aggregation after keeping 24 and 48 hours in non-shaking condition. **Figure 6** (m) shows the structure of CBP. CBP particles are aggregated in different direction like a net structure which is demonstrated by red threshold, imageJ, **Figure 6** (n). The magnified cross section of CBP signifies the particle size, water insolubility, and randomly oriented microstructure of surface for diffuse reflection due to surface roughness, **Figure 6** (m-q). Particle size of CBP denotes the higher degree of cracking on CBP coated PA-6,6 fabric rather than TVR coated surface, **Figure 6** (u-x). The existing of CBP-TPU-DMF has been clearly identified on PA 6,6 coated fabric, **Figure 6** (u, v, z3). The cementing of CBP-TPU-DMF-PA-6,6 is higher in comparison with NA-CBP-TPU-PA-6,6. CBP-TPU formed a darker appearance due to higher prominence of black region on CBP-coated surface. CBP coating with TPU-DMF binder showed a crosslinking in CBP-TPU-DMF-PA-6,6. The functional group of CBP (-COOH) and the functional group of TPU (-NHCO) was formed a CBP-TPU matrix on the surface of PA-6,6 fabric. **Figure 6** (t, v, x, z, z1, z2, z3), TPU was visualized in SEM image as whitish color surface. The prominence of TPU was recorded as minor when it was formed matrix with CBP. TPU binder was almost uniformly distributed on PA-6,6 fabric surface, **Figure 6** (t-z, z3). TPU-CBP was implanted and well dispersed on

PA-6,6 surfaces. **Figure 6** (k, l), NA-TPU-DMF was also characterized in the presence of NA and TPU was showed freezing tendency. The application of TPU on PA-6,6 fabric was also confirmed by SEM, **Figure 6** (z1, z2).

## *6.1.1 Coupling of CM and SEM evidence of material suitability for visible-NIR camouflage*

**Figure 6** (o- z3) shows the evidence of almost suitability of CBP material. The simultaneous applications of NA-TPU-CBP-TVR on PA-6,6 fabric surface have been confirmed by SEM image. The structural representation and coupling with similar functional groups have been revealed with individual coupling reactions with PA-6,6 **Figures 7**–**12**. Oxidized and aqueous CBP have amide group. PA-6,6 has also similar group, thus it may create a coupling of CBP-PA-6,6. CBP has amine group and TVR has also amine group. There is a possibility of bonding between CBP-TVR. Similarly, CBP has carbonyl group and TPU has also carbonyl group, thus CBP-TPU moiety may form in CBP modified PA-6,6 fabric. Carbonyl carbon of CBP may be bonded with two hydrogen atoms of TPU. Hence there is possibility of cross-linking. TPU may be adsorbed by CBP and dispersed the carbon black due to its structural formation of steric hindrance.
