Proposed Work

Title: Effect of Nanoclay on Mechanical Behavior of Polymer Nanocomposites

1. Introduction

There is an increased interest in polymer nanocomposites using Nanoclay such as

Montmorillonite due to its high cation exchange capacity [1-2], large specific surface area,

swelling capacity, high platelet aspect ratio, ease of surface modification and have been

successfully used to improve the mechanical, thermal, barrier and fire retardant properties [3-

6]. These are considered for applications in a wide variety of areas, such as aerospace,

marine, electronics, sports goods, and automotive industries [8-10]. However,

nanocomposites do not always offer improved material properties over the conventional

composites. In fact, poorly dispersed nanocomposites result in degraded mechanical

properties [11-12].

In recent years, use of organoclays as precursors to nanocomposite formation has been

extended to various polymer systems including epoxy, vinylester, polyurethanes, polyimides

and polyesters. Among these vinylester based nanocomposites have significant importance

due to their wide range of applications owing to superior mechanical properties.

It also brings difficulties in dispersing the nanoparticles due to their strong interactions

among themselves. Due to these interlayer interactions, it is extremely difficult to disperse

nanoparticles uniformly, especially at higher particle loadings [13-15]. The organophilic

clays are not compatible with hydrophobic organic polymers as the spacing between the clay

sheets is extremely narrow and hence diffusion of polymer chains in the clay galleries is not

likely. This often leads to aggregation of clay particles, and the aggregated clay sheets act as

stress-concentration sites in the polymer matrix [16-17]. Melt intercalation is a simpler and

more economical technique than in-situ polymerization. Mixture of polymer and nanoclay

was heated above its glass transition temperature or melt temperature as a result of which the

polymer is penetrated in between the layered silicates. Ultrasonication for dispersion of

nanofillers in polymeric resins is widely reported. High shear forces during the dispersion

exfoliate the nanoclay by breaking the agglomerates. Extruders and three-roll mill or ball mill

are designed to achieve exfoliation of nanoclay through high shear forces by controlling

speed and temperature. Among the existing techniques, twin-screw extrusion may provide

some advantages over others due to its effective dispersion in twin screw extrusion.

Moreover, twin screw extrusion has to be performed within an appropriate and limited

window (temperature, shear, etc.). Under this circumstance, it becomes important to study

property changes in nanocomposites that result from partial exfoliation and how different

mixing combinations lead to varying degrees of exfoliation.

2. Project Objectives

The objective of the research was to examine the effect of nanoclay on the mechanical properties

of vinylester glass.

The specific objectives of the project were:

To prepare and optimize the mixing parameters of organo modified Montmorillonite in

polymeric resins using ultrasonication and twin screw extruder (Vinylester).

To prepare glass fibre reinforced nanoclay polymer composite laminates by hand layup

technique.

To evaluate the mechanical properties of organo modified nanoclay filled polymer GFRP

composite.

3. Project Methodology

The project methodology involved following steps:

Dispersion of 0 to 5wt% nanoclay into vinylester resin by ultrasonication followed by

twin screw extrusion.

Fabrication of nanoclay / vinylester / glass nanocomposites of 250 mm X 250 mm X 3

mm by wet hand lay-up technique.

Characterization of nanoclay/vinylester/glass specimens for tensile strength, flexural

strength and interlaminar shear strength.

Figure 1 Flow chart for Project Methodology

Dispersion of nanoclay in vinylester (ultrasonication and twin screw extrusion)

Fabrication of nanoclay / vinylester / glass nanocomposites by Hand

lay-up technique

Nanoclay / vinylester laminate

specimens (250 X 250 X 3) mm3

Characterization of the Flexural Strength and tensile,

Characterization of the ILSS

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