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The present may have been mere plastics, but the future will definitely be super plastics. Plastics are being treated with nanoparticles to create stronger, cleaner, more flame-resistant and high barrier plastics. Today we researchers are putting a new twist on the process, focusing on improving many of the plastics material properties.
Above figure will give you an idea about the scale of 'NANO' - and minuteness of what we are talking about.
Fillers are used in polymers for a variety of reasons:like improved mechanical properties, cost reduction, density control ,flame retardancy ,improved processing etc. The subject of hybrids based on layered inorganic compounds such as clays has been studied for a considerable time, but this area is enjoying a resurgence of interest and activity as a result of the exceptional properties which can be realised from materials such as nanocomposites.
Nanoclay (modified montmorillonite) is added to polyolefin by melt compounding .And effect of nanofiller was studied with comparatively lower clay loadings in to the polymer. Montmorillonite consists of agglomerate of staking/layers placed together. With the application of shear during compounding these lamina's gets separated. Here controlling nanoparticle dispersion is critical to obtain improvement in bulk properties. Structural characteristics were studied with XRD/DSC.Mechanical properties were found to be improved.
We tried two different grades of nanoclays- previously deagglomerated clay and pure clay.In comparing between these two, we tried with different amounts of loading and different processing routes.
Amount of compatibilizer found to give higher d-spacing and extent of clay separation and effectively improvement in mechanical properties.
In similar processing conditions previously deagglomerated clay shows better properties than pure clay. But for lower levels of addition pure clay does show bulk improvement in tensile as well as impact properties.
Pure clay uses alkyl ammonium treatment for compatibilization while deagglomerated clay uses onium ion (phosphonium) treatment. Though effect of different compatibilizers has not studied fully, this may affect final properties.
In between previously deagglomerated clay- dry blend and melt blended nanocomposite routes, its really tough choice purely because both blends show very much similarity in improvements. In case of dry blended nanocomposites, impact strength increase is much higher than that of melt blended nanocomposites (especially as the nanofiller content increases).But this occurs at the expense of loss in tensile properties.
In case of lower addition levels up to 5% clay by weight, both dry and melt melted route gave almost identical properties of modulus, tensile strength as well as impact so there is actually no need of extra compounding before moulding, However for increased levels of additions, Injection moulding process alone would not be sufficient for clay layers separation, hence compounding beforehand is recommended to achieve optimum properties with nanoclay.
Now further trials are going on with different preconditiong, screw geometries and processing parameters to study rhelogical properties.
Some of the Applications of this study can be found in following :-
Right now we are trying to implement nanoclay incorporation in biomedical devices. The work is in association with Boston Scientific Corp. And if succeded it will be first of its kind in catharters applications.
