Question

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Discuss the type of surface treatments that are applied to nanoclays in order to improve nanoclay dispersion in polymer matrices. What happens when untreated nanoclay is used to reinforce a polymer? What happens when a properly organically modified clay is used? List and discuss three techniques that are used to characterize the microstructure/nanostructure of nanoclay-filled polymers.

Answer 1

Solution:

1. Surface treatment given to nano clay:

There are major two treatment are given to the nano lay such as organic treatment and ion exchange method

a) Organic treatment: Modification of nanoclay surface through organic treatment provides a hydrophobic environment to the galleries of the nanoclay and that is responsible for enhancement of its compatibility with the polymer matrix.

b) Ion exchanage method: This is conventional modification method by using cationic salts such as alkyl ammonium or phosphonium salts. This modification process have some down sides such as low thermal stability of the cationic salts and the compounds are less readily intercalated in the polymer melts. Lower decomposition temperature 170-180˚C of alkyl ammonium salt confors that it is not suitable for the high temperature melt processing techniques

2. What happen when untreated nanoclay is used to reinforce a polymer?

Two crucial challenges may face when untreated nanoclay is used such as chemical compatibility between the polymer matrix and the nanofiller at the nanoscale and homogeneous dispersion of the nanofiller within the polymer matrix. The interfacial interaction between nanoclay fillers and polymer matrix, as well as the quality of nanoclay dispersion, has a significant influence on the performance of polymer/nanoclay composites. These intercorrelated features determine the polymer/nanoclay composites’ morphology and, thus, their final bulk properties such as strength, elastic modulus, thermal stability, heat distortion temperature, self-healing, shape memory abilities and gas barrier.

3. What happens when a properly organically modified clay is used?

Modifying the nanoclay surface through organic treatment will give a hydrophobic environment to the galleries of the nanoclay and enhance its compatibility with the polymer matrix.

4. List and discuss three techniques that are used to characterize the microstructure/nanostructure of nanoclay-filled polymers:

XRD: X-ray Diffraction (XRD) analysis was used to characterize the interlayer d-spacing of the nanoclay galleries and the dispersion of nanoclay in the polymer nanocomposite structure. Modified nanoclay, shows the increase in the d-spacing of the nanoclays which proves that the modification agent is successfully intercalated into the nanoclay galleries consequently pushing the nanoclay layers and confirms that modification process has taken place. This increase in the d spacing create the mesoporous structure of modified nanoclay.

SEM : The morphology of nano- clay and modified nano clay are analysed by means of FESEM.

TEM: The particle size of the modified nanoclay is generally evalutaed by TEM analysis to the nanostrucure property of modified clay.

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