Nondestructive testing of defects in adhesive joints

INFERENCE:
1. Temperature at 10% weight loss is 157.4°C for uncured resin. This value increases by a
factor of 2 after curing. This value is comparable for both TGDDM/DDM system (251°C)
and TGDDM/TETA system (274.25°C).
2. Temperature at 10% weight loss is 305.89°C for TGDDM/DDS system. This means that
the cross linked network is very stiff and it has excellent flame resistance
3. Char yield at 200°C increases for the cured resin systems than the uncured resin system.
The values are almost the same for both TGDDM/DDM and TGDDM/DDS system. This
value is slightly less for TGDDM/TETA system
4. TGDDM/DDS system has the highest char yield at 400°C. there is drastic drop in char
yield for TGDDM/TETA system at 400 °C than 200°C
5. TGDDM/DDS system has the highest char yield even at 600°C. TGDDM/DDM and
TGDDM/TETA system have char yield lower than the uncured resin
6. Residues for all the above said systems were found at 750°C. TGDDM/DDS system has the
highest char yield. So, it is inferred from the result that TGDDM/DDS system has very
good flame resistance. If we add some flame retardants to this system we could achieve
excellent flame retardancy.
7. For TGDDM/DDM and TGDDM/TETA system Char yield at 750°C is less than the
uncured resin. Flame retardancy of the resin was affected by these curing agents.
8. But TGDDM/DDM system has the highest degradation temperature when compared to
other systems. So this system will offer high performance even at elevated temperatures.
9. TGDDM/DDM system does not have that much crosslink density as in the case of
TGDDM/DDS system. It is somewhat flexible, so this can be used for tooling applications
10. TGDDM/TETA system has first decomposition temperature at 284.78°C(Highest of all
systems compared). But the final decomposition point lies at a short interval of 100°C. This
system looses almost 75 % of the polymer between the primary and secondary onset
temperatures. So this is not suitable for high performance