Interlayer destabilization process of natural and commercial bentonite incorporated Ethylene Vinyl Acetate (EVA) nanocomposite with hybrid silicate nanofillers
Natural and commercial bentonites can act as efficient fillers to reinforce a polymer matrix if their strong interlayer binding forces are weakened to reduce tactoid formation. In this research, interlayers destabilization process was applied to gain a loosely packed, swelled and disorganized clay...
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| Format: | Thesis |
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| Language: | English |
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| Online Access: | http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/78021/1/Page%201-24.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/78021/2/Full%20text.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/78021/3/Asfa.pdf |
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| Summary: | Natural and commercial bentonites can act as efficient fillers to reinforce a polymer matrix if their strong interlayer binding forces are weakened to reduce tactoid formation. In this research, interlayers destabilization process was applied to gain a
loosely packed, swelled and disorganized clay layered structure for better polymer intercalation and filler dispersion during the polymer/clay composite fabrication. Three different destabilization methods were applied to the natural and commercial bentonites and their effects on swelling and platelets ordering/stacking of the clays were observed. The pristine and destabilized natural and commercial bentonites were characterized and compared based on their chemical component (XRF), chemical structure (XRD and
FTIR) and morphology (FESEM). Chemical analysis revealed that mineralogical and
chemical compositions of both types of bentonite affect their structure and swelling
capability during the destabilization process. XRD results suggest that basal spacing
(d001) of both natural and commercial bentonites reduced when single destabilization
process (by salt addition) was applied but increased when destabilization was done by
the combination of pH control and salt addition processes. The increment of basal
spacing was seen to be ~0.04 nm for both natural and commercial bentonites showing
that the destabilization process through combination of pH control and salt addition is
more efficient in swelling both natural and commercial bentonite clays. This is
supported by FESEM analysis where smaller, more loosely packed and uniform
platelets were observed due to swelling and weakening of the interlayer binding forces
of both natural and commercial bentonite clays. The ‘destabilized’ bentonites were used
as co-nanofiller with the organically modified montmorillonite (OMMT) to form hybrid
silicate nanofillers for EVA copolymer matrix reinforcement. Results show that the
‘destabilized’ bentonite prepared by the combination of pH control and salt addition is
most efficient in reinforcing the EVA matrix when combined with the OMMT by
allowing 124.9% increment in tensile strength, 13.5% in elongation at break and
190.8% in toughness values. Furthermore, thermal stability of the EVA nanocomposite
was also improved. This could be related to the improved dispersion of bentonite upon
the destabilization process that allows greater matrix-filler interactions in the
nanocomposite system. In summary, destabilization process through pH control and salt
addition is the promising and practical technique to improve the dispersion of bentonite
throughout the polymer matrix. Without the use of expensive and toxic chemicals, it
can be adopted as a new approach to swell bentonite for more environmental friendly
nanocomposite technology. |
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