*5.4.2.3 Raman imaging and Spectrum of multiple washed sample at 60°C*

In **Figure 23** the scanning position, image A shows the PCM in the web and on the fibre, however the dept. profiling of the Raman image B only exhibits 3 wavelengths in the spectrum identified as hexadecane, octadecane and the acrylic resin, represented by the colours: red, blue, and green. It can be understood that due to multiple laundering, and rupture of the PCM microcapsules, tetradecane content has evaporated at wash temperature 60°C.

**Figure 24** illustrates the Raman spectrum of the washed sample at 60°C, the Raman shift, intensity, peak width, and shape is different to the unwashed sample

#### **Figure 23.**

*Raman scan position of washed sample at 60°C (left: Image a); Raman scan depth of washed sample at 60°C (right: Image B).*

#### **Figure 24.**

*Raman spectrum of washed sample at 60°C.*

#### *The Effect of Laundering on the Physical and Thermal Properties of Phase Change Textile… DOI: http://dx.doi.org/10.5772/intechopen.105064*

and the washed samples at 30°C and 40°C, the chemical composition, crystal size, molecular chain length and morphology vary for different areas of the samples.

It is evident that the washed sample at 60°C show a Raman peak with a wider width and thus indicates a lower degree of crystallinity, which possibly means that the latent heat effectiveness of the PCM has reduced. It is also apparent that the intensity and polarisation of the Raman peaks have changed compared to the unwashed sample, which means the crystallinity and orientation of the PCM has changed due to loss of thermoregulating content, and therefore validate that crystallinity is a structural arrangement in the material and can be calculated from the DSC analysis.

### **6. Conclusions**

The main objective of this study was to investigate the effect of multiple laundering at different wash temperatures, on the thermal and physical related properties, as measured by TGA, DSC, SEM and Raman, of a non-woven textile fabric containing PCM.

Thermal degradation as determined by TGA thermograms was found to be higher at a wash temperature of 60°C relative to that of a wash temperature at 30°C, the mass loss being 4.6% more at 60°C than at 30°C. This was asserted to physical changes such as size and shape of the PCM microcapsules as evident in SEM images. The SEM images showed broken and collapsed PCM microcapsules in the web and around the fibre, indicating evaporation of the thermoregulating content of the PCM.

It was found that the heat capacity of the sample washed at 60°C was much lower than that of the unwashed sample, the difference being approximately 50% in terms of the latent heat capacity as determined by DSC thermograms. This implies that the latent heat effectiveness of the PCM has decreased significantly. The physical properties of the PCM such as the intermolecular interaction, the intensity and width of peaks, polarisation, degree of crystallinity and the orientation changed as illustrated in the Raman analysis.

It can be concluded that the multiple laundering of textiles which contain PCM causes damage to the PCM capsules, causing the thermoregulating effectiveness to be reduced as confirmed by the results from the analytical techniques. In addition, the results also indicate that reducing the wash temperature and improving the design and formation method of the PCM microcapsules can extend the usable life and value of a textile containing PCMs.

*Phase Change Materials - Technology and Applications*
