PSI - Issue 14

P R Krishna Mohan et al. / Procedia Structural Integrity 14 (2019) 176–183 P R Krishna Mohan/ StructuralIntegrity Procedia 00 (2018) 000–000

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Fig.3. 90° composite failed specimen: (a) Force-Displacement plot; Microscopic Images (b) In front view (c) In side view

Fig.4. [±45] S composite: (a) Load-displacement plot; Microscopic Images (b) In front view (c) In side view

4.4. Fiber and void volume fraction TGA analysis for prepreg sheet non-vacuum and vacuum B-staged at room temperature, and the 0° laminate is carried out to obtain the information about the content of the fiber in the material. The density of the carbon fiber and the matrix are 1.81 g/cc and 1.22 g/cc, respectively taken from Vishnu (2016).There is a significant increase in the volume fraction of the fiber of the prepreg sheet from the previous results. The fiber volume fraction for non vacuum and vacuum prepreg sheet is similar as shown in Table 2.

Table 2.Fiber and void volume fraction Sample

Volume fraction of fibre (vf)%

Void volume fraction (vv)%

Old Prepreg sheet [11] Vacuum prepreg sheet Non-Vacuum Prepreg sheet

26.99

- - -

33 33 45

0 ◦ Laminate vacuum

1.29

4.5. FTIR Results

From the test conducted, it was seen that there are no functional groups induced on the fibers when fibers are exposed to air for a long time after plasma treatment. However, Fig. 5 shows a significant amount of functional groups produced on the fibers that are desirable to increase the wettability. According to the literature, the sample should be kept in the vacuum chamber right after plasma treatment, and the plasma effect lasts only for 20 minutes, and this is the reason for the noticeable traces of functional groups found in the second treated sample. However, this restriction is not much of help as the sample will be exposed for about one hour during the manufacturing of prepregs. Therefore, an effort to introduce the vacuum environment into the system is the future scope of this work.