This document discusses the application of layered and non-layered nanoparticles in polymer modification. It describes how grafting polymers onto nanoparticle surfaces via irradiation can improve dispersion in polymers and enhance mechanical properties even at low filler loading. Methods for preparing polypropylene and epoxy nanocomposites are outlined. FTIR analysis shows grafted polymers chemically bond to nanoparticle surfaces. Tensile tests show grafted silica nanoparticles simultaneously increase modulus, strength and elongation of polypropylene. Layered nanoparticles also improve various thermal, barrier and mechanical properties when incorporated into polymers.

1. APPLICATION OF LAYERED AND NON-LAYERED
NANO/MICRO PARTICLES IN
POLYMER MODIFICATION
ARJUN K GOPI
2ND M.Sc BPS
CBPST, KOCHI

2. POLYMER MODIFICATION
 The modification of polymers is interdisciplinary in nature cutting across traditional
boundaries of chemistry, biochemistry, medicine, physics, biology and materials science and
engineering.
 Because of this interdisciplinary nature, persons involved with polymer modification should
be broadly trained to permit the best application of revealed information.
 Polymer modifications are intended to impute different, typically desired properties to the
new modified material--properties such as enhanced thermal stability; multiphase physical
responses; biological resistance, compatibility or degradability; impact response; flexibility;
rigidity; etc.

3. Advantages of polymer modification:-
1. The application of experimental design, statistical design to allow rapid
experimental testing of polymers.
2. Advances in the thermodynamics of polymers and the thermodynamics of
miscibility.
3. The development of predictive capacity of polymer properties and behaviour
based on field models of molecular interactions.
4. Development of the theory controlling the processing of polymers.
5. Modeling of the polymeric solid.
6. New methods to form polymers including coextrusion, pultrusion, and
production with internal reinforcement.

4. APPLICATION OF NON-LAYERED NANO-PARTICLES IN
POLYMER MODIFICATION
INTRODUCTION
Polymer nano composite can be considered as an important category of
organic-inorganic hybrid materials, in which inorganic nanoscale building
blocks(e.g., nanoparticles, nanotubes, or nanometer thick sheets) are dispersed
in an organic polymer matrix.
When compered to conventional composite based on micrometer-sixed fillers,
the interfase between the filler particles and matrix in a polymer nanocomposite
constitutes a much greater area within the bulk material, and hence influence
the composites’s properties to a much greater extent, even at a rather low filler
loading.

5. Currently numerous producers for the preparation of polymer nanocomposite have been
proposed, using the following approaches:-
1. Direct incorporation of nanoscale building blocks into a polymer melt or solution.
2. In-situ generation of nanoscale building blocks in polymer matrix.
3. Polymerization of monomers in he presence of nanoscale building blocks.
4. A combination of polymerization and formation of nanoscale building blocks.
The key issue of these techniques is that the geometry , spatial distribution, and volume content
of nano fillers must be effectively controlled through adjusting the preparation conditions so as
to ensure the structural requirements of nanocomposites stated above.
• Its noteworthy that the problem with dispersive mixing is that the nano particles commercially
available usually exist in the form of agglomerates, which are difficult to disconnect by limited
shear force during mixing.The latter will maintain their friable structure in the composite and
can hardly provide property improvements at all.
• Nanoparticles can be pretreated by irradiation to introduce grafting polymers onto their
surface not only outside but also inside the particle agglomerates.

6. • The surface of the nanoparticles will also become “hydrocarbonated” due to an increased
hydrophobicity resulting from the grafting polymer.
• This is beneficial for the filler/matrix miscibility and hence for the ultimate properties.
• In case of a thermosetting matrix polymer, the grafted nanoparticles will keep their more
stationary suspended state due to the interaction between the grafting polymer and matrix.
• After curing such a miture , the filler/matrix adhesion would also be substantially enhanced by
chain entanglement and/or chemical bonding between the grafting polymer and the matrix
material.
• Lets discuss about Application of silica nanoparticles in the modification of polypropylene and
epoxy resin.

7. Application of silica nanoparticles in
the modification of polypropylene
and epoxy resin.

8. Preparation of PP-Based nanocomposites and their characterization
• PP-based nanocomposites were reoared by tumble mixing the preweighed quantities of PP
and grafted fillers, followed by compounding this mixture on lab scale single screw extruder.
• Temperature : 200⁰C And screw RPM 25
• The specimens for mechanical tests were machined from compression molded
plates(65X45X3 mm3) of extrudates.
• The filler volume fractions could be computed from the known weights of the polymer matrix,
The fillers and the polymer introduced by irradiation.
• The reinforcing efficiency of the nanoparticles agglomerates was assessed by measuring of the
Young’s modulus , tensile yield strength and impact strength.
• Tensile test is carried out on dumbbell shaped specimens by UTM at a crosshead speed of
10mm/min.
• The fractured surfaces were observed by SEM.
• And XJJ-5 Tester was used for unnotched charpy impact strength measurements.

9. Preparation of epoxy-Based nanoparticles and their characterization
• Epoxy-based nanoparticles were prepared by mixing the preweighed quantities of epoxy and
grafted fillers at 80⁰C with stirring for 2h and sonication for 1h.
• Then the mixture was heated to 130⁰C and the curing agent DDS was added under stirring for
10min.(for curing the composites, the following procedures was carried out step by step: 3h at
100⁰C, 2h at 140⁰C,2h at 180⁰C, and 2h at 200⁰C.
• The curing behaviour of the epoxy and its composites was examined by DSC at a heating rate
of 2⁰C/min.
• Unlubricated sliding wear tests were carried out on a block on ring apparatus under a pressure
of 3MPA and a constant velocity of 0.4m/s.
• The specific wear rates were calculated from weight measurements of the specimens before
and after the actual steady test period.
• The morphologies of the worn surfaces were observed with SEM.

10. Effect of Irradiation grafting polymerization on the nanoparticles
• In order to establish the effect of modified nano-silica on the mechanical behaviour of PP
composites, the variation in the chemical structure of the particles should be known at the
very beginning of the discussion.
• FTIR spectra of untreated and treated nano-silica are shown Below:-

11. • To eliminate the influence of homopolymers, both polystyrene-grafted nano-Sio₂(Sio₂-g-PS)
and poly(ethyl acrylate)-grafted nano-Sio₂(Sio₂-g-PEA) used for the FTIR examinations were
separated from the homopolymers in advance.
• Compared to the spectrum of Sio₂ as-received, the adsorptions at 690, 1460, 2960 cm⁻ⁱ
appearing in the spectrum of Sio₂-g-PS represent the bending mode of C-H in benzene rings
and the stretching ,odes of C-C and C-H , respectively.
• In addition the band at 1725 cm⁻ⁱ in the spectrum of Sio₂-g-PEA indicates the existence of
carbonyl groups.
• These bands prove that PS and PEA have been chemically bonded to the nano-silica during the
irradiation polymerization.

12. Tensile Properties
Typical tensile stress strain curves of neat PP and its filled versions are Shown Below:-

13. • As Expected both a reinforcing and a toughening effect of the nanoparticles on the polymeric
matrix were fully brought into play.
• That is a structural weakness, that would have been expected from the agglomerating
behaviour of the nanoparticles, could be fully eliminate by the grafting of macro molecular
chains onto the individual particles.
CONCLUSION
• The modification of nanosilica by means of grafting polymerization helps to impart a balanced
performance of the composites.
• The addition of grafted silica nanoparticles into PP can bring in both reinforcing and
toughening effects at rather low filler contents.
• Such a simultaneous improvement in modulus, strength, and elongation to break is hard to
observe in conventional micron sixed particulate composites.
• Grafting polymerization onto nanosilica can also increase the interfacial interaction between
the particles and epoxy matrix through chemical bonding.

14. APPLICATION OF LAYERED NANO-PARTICLES IN
POLYMER MODIFICATION
INTRODUCTION
 Manufacturers fill polymers with particles in order to improve the stiffness and the toughness
of the materials, to enhance their barrier properties, to enhance their resistance to fire and
ignition or simply to reduce cost. Addition of particulate fillers sometimes imparts drawbacks
to the resulting composites such as brittleness or opacity.
 Nanocomposites are a new class of composites, that are particle-filled polymers for which at
least one dimension of the dispersed particles is in the nanometer range.One can distinguish
three types of nanocomposites, depending on how many dimensions of the dispersed
particles are in the nanometer range. When the three dimensions are in the order of
nanometers, we are dealing with isodimensional nanoparticles, such as spherical silica
nanoparticles obtained by in situ sol-gel methods or by polymerization promoted directly from
their surface

15. Nanocomposite preparation
• In situ intercalative polymerization: In this technique, the layered silicate is swollen within the
liquid monomer (or a monomer solution) so as the polymer formation can occur in between the
intercalated sheets. Polymerization can be initiated either by heat or radiation, by the diffusion
of a suitable initiator or by an organic initiator or catalyst fixed through cationic exchange inside
the interlayer before the swelling step by the monomer.
• . In a typical synthesis, the modified montmorillonite (12-Mont) was mixed with the monomer
in a mortar. A small amount of 6-aminocaproic acid was added as a polymerization accelerator
when the relative amount of 12-Mont used was smaller than 8 wt.% (relative to 12-Mont). The
mixture was heated first at 100⁰C for 30 min then at 2508C for 6 h. The cooled and solidified
product was crushed, washed with water at 80⁰C, and then dried.

16. PROPERTIES
Layered silicate nanofillers have proved to trigger a tremendous properties improvement of the
polymers in which they are dispersed. Amongst those properties, unexpected large increase in
moduli (tensile or Young's modulus and flexural modulus) of nanocomposites at filler contents
sometimes as low as 1 wt.% has drawn a lot of attention.
Thermal stability and fire retardancy through char formation are other interesting and widely
searched properties displayed by nanocomposites. Those new materials have also been studied
and applied for their superior barrier properties against gas and vapor transmission. Finally,
depending on the type of polymeric materials, they can also display interesting properties in the
frame of ionic conductivity or thermal expansion control.

17. CONCLUSION
The large array of improved thermo-mechanical properties attained at very filler content
(5 wt.% or less) together with the ease of production through simple processes such as melt
intercalation, directly applicable by extrusion or injection molding make layered silicate-based
nanocomposites a very promising new class of materials.
They are already commercially available and applied in car and food packaging industries.
Undoubtedly, the unique combination of their key properties and potentially low production
costs paves the way to much broader range of applications.
Furthermore, the quite low filler level required to display sizeable properties enhancement
makes them competitive with other materials.