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Nondestructive testing of defects in adhesive joints

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organoclay <strong>in</strong>to the blend matrix results <strong>in</strong> a remarkable <strong>in</strong>crease <strong>in</strong> the storage modulus over the entire<br />

<strong>in</strong>vestigated temperature range. The blend nanocomposites prepared us<strong>in</strong>g C30B organoclay displays<br />

optimum E’ as compared with the other blend nanocomposites<br />

Differential Scann<strong>in</strong>g Calorimetry (DSC)<br />

The DSC thermogram <strong>of</strong> virg<strong>in</strong> PTT, virg<strong>in</strong> m-LLDPE, 70PTT/30m-LLDPE blend and the blend<br />

nanocomposites is depicted <strong>in</strong> figure-4. Virg<strong>in</strong> PTT depicts a melt<strong>in</strong>g transition around 247.59 0 C with m-<br />

LLDPE at 127 0 C.The DSC scan <strong>of</strong> the blend reveals two dist<strong>in</strong>ct Tm which <strong>in</strong>dicates phase-separated<br />

morphology. Similar to the blend, the DSC curves <strong>of</strong> the blend nanocomposites also exhibited two<br />

dist<strong>in</strong>ct Tm’s confirm<strong>in</strong>g presence <strong>of</strong> a phase-separated morphology. However, <strong>in</strong>corporation <strong>of</strong><br />

organically modified nanoclays <strong>in</strong>creases the Tm <strong>of</strong> the PTT phase <strong>in</strong> blend matrix, while reduc<strong>in</strong>g the<br />

Tm <strong>of</strong> the m-LLDPE phase. This <strong>in</strong>dicates improved compatibility <strong>of</strong> nanoclay <strong>in</strong> the PTT matrix. The<br />

crystallization exotherms <strong>of</strong> virg<strong>in</strong> PTT, PTT/m-LLDPE blend and blend nanocomposite system is shown<br />

<strong>in</strong> figure-5. It is evident that the Tc <strong>of</strong> PTT matrix decreases from 175.47 0 C to 170.40 0 C with<br />

<strong>in</strong>corporation <strong>of</strong> m-LLDPE <strong>in</strong>dicat<strong>in</strong>g elastomeric effect due to amorphous nature and low spherulitic<br />

growth <strong>of</strong> m-LLDPE. However <strong>in</strong>corporation <strong>of</strong> nanoclay <strong>in</strong>creases the Tc <strong>of</strong> PTT phase <strong>in</strong> the blend<br />

matrix considerably <strong>in</strong>dicat<strong>in</strong>g heterogeneous nucleat<strong>in</strong>g effect.<br />

Thermo gravimetric analysis (TGA)<br />

Virg<strong>in</strong> PTT exhibits an <strong>in</strong>itial degradation temperature (Tid) <strong>of</strong> 352.12 0 C with f<strong>in</strong>al degradation<br />

temperature (Tfd) 503.47 0 C (Figure 6).Incorporation <strong>of</strong> m-LLDPE decreases Tid <strong>of</strong> matrix from 352.12 0 C<br />

to 345.97 0 C and Tfd <strong>of</strong> matrix from 503.47 0 C to 495.90 0 C.This is predom<strong>in</strong>antly attributed to lower<br />

degradation temperature <strong>of</strong> ethylene l<strong>in</strong>kage due to weak bond<strong>in</strong>g between them and presence <strong>of</strong> side<br />

cha<strong>in</strong> branch<strong>in</strong>g (5-10%) <strong>in</strong> m-LLDPE. Further addition <strong>of</strong> organoclays substantially <strong>in</strong>creases the<br />

thermal stability (Tid, Tfd) <strong>of</strong> the blend matrix. Blend nanocomposites with C20A organoclay has highest<br />

thermal stability due to higher modifier concentration and gallery spac<strong>in</strong>g.<br />

Conclusion<br />

The mechanical, thermal, crystallization and morphological characteristics <strong>of</strong> PTT/m-LLDPE blend and<br />

its nanocomposites prepared through batch mix<strong>in</strong>g process were <strong>in</strong>vestigated. The impact strength <strong>of</strong> PTT<br />

<strong>in</strong>creased up to 30 wt% load<strong>in</strong>g <strong>of</strong> m-LLDPE. The blend nanocomposites prepared us<strong>in</strong>g C30B shown<br />

maximum mechanical performance. XRD results showed <strong>in</strong>tercalated structure <strong>in</strong> the elastomer modified<br />

PTT organoclay nanocomposites DSC & DMA analysis revealed two phase morphology <strong>in</strong> the blend<br />

system. TGA thermograms <strong>in</strong>dicated <strong>in</strong>creased thermal stability <strong>of</strong> PTT matrix <strong>in</strong> the blends with the<br />

addition <strong>of</strong> nanoclays.<br />

References<br />

1. Mishra S.P.; Deopure L.; Polym.Bull; 1985:26:5.<br />

2. Yu Y.; Choi K. ; Polym. Eng. & Sci 1997: 37: 91.<br />

3. Nabisaheb D; Jog J.P., J. Polym. Sci: part-B: Polym Phy. 1999: 37: 2439.<br />

4. Avramova N. Polym 1995: 36: 801.<br />

5. Wfer J., M. US pat. 4,485,212 (1984)<br />

6. Pratt C.F., Phadke S.V., Olivier E., U.S.Pat. 4,965,111 (1990)<br />

7. Khatua B.B.; Lee D.J.; Kim H.Y.; Kim J.K.; Macromolecules 2004:37:2454-59.<br />

8. Ray S.S.; Bousm<strong>in</strong>a M.; Macromol. Rapid Commun., 2005:26:1639-46.<br />

9. Lim J.W.; Hassan A.; Rahmat A.R.; Wahit M.U. Polym Int 2006:55:204-15.

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