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Nondestructive testing of defects in adhesive joints

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CONCLUSION:<br />

1. Tetraglycidyl Diam<strong>in</strong>o Diphenyl Methane res<strong>in</strong> was synthesizes us<strong>in</strong>g 4, 4’-<br />

Diam<strong>in</strong>o Diphenyl Methane (DDM) and Epichlorohydr<strong>in</strong> (ECH) as raw materials<br />

2. Fourier Transform Infrared Spectroscopy (FTIR) was done and it was confirmed<br />

that the res<strong>in</strong> synthesized was TGDDM.<br />

3. Proton magnetic Resonance Spectroscopy and molecular 13 C NMR spectroscopy<br />

was done and it was confirmed that the res<strong>in</strong> synthesized was Tetraglycidyl ether <strong>of</strong><br />

Diam<strong>in</strong>o Diphenyl Methane (TGDDM)<br />

4. DSC curves shows exothermic peak for all the 3 systems. This may be due to the residual<br />

cure. So, post cure temperature is not sufficient. It is concluded that still higher temperature<br />

is required for post cure. From these results optimum cur<strong>in</strong>g procedures are proposed <strong>in</strong> this<br />

paper<br />

5. TGA curves show that 2 transitions are there for uncured TGDDM res<strong>in</strong> and<br />

TGDDM/DDM system. But there is only one transition was observed <strong>in</strong> TGDDM/DDS<br />

system. This is attributed to the complete condensation <strong>of</strong> aromatic r<strong>in</strong>gs occur dur<strong>in</strong>g DDS<br />

cur<strong>in</strong>g and it leads to stiff and tightly cross l<strong>in</strong>ked structure. It also gives the highest char<br />

yield at 750°C. So, it was <strong>in</strong>ferred that TGDDM/DDS system will have the excellent flame<br />

resistance.<br />

TGDDM/DDM system shows 2 transitions. This is due to the cyclization occurr<strong>in</strong>g dur<strong>in</strong>g<br />

cur<strong>in</strong>g and it retards cross l<strong>in</strong>k<strong>in</strong>g. This system has higher char yield at 750°C, so this<br />

system also has very good flame resistance.

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