Professor
Jayaraman's research group at Michigan
State University is developing processing strategies,
flow models and design tools for shaping polymeric
materials into products for various industry sectors:
automotive, energy and building or construction.This research is
applied to develop processing strategies for polymer
composites, recycled polymers and polymer
nanocomposites to make foam core panels, multilayer
blown film, stronger light weight building materials
and porous plastic sheets. Dr. Jayaraman's research
interests and expertise are processing, rheology and
microstructure development in polymer materials.
Current Projects
Characterization and
Forming of Carbon-Fiber Composites with Mixed
Architecture
The objective of this project is to evaluate the
effect of varying estimates of friction between tool
and prepreg as well as inter-ply friction on the
predicted distortion in the compression molded
product, using forming simulations with finite
element software.
Dimensional Stability of Low-Cost
Thermoplastic Composite Molds This is a
collaborative project with ESI Inc. to
design and fabricate molds out of thermoplastic
composite and test them under compressive loads at
high temperatures in order to develop predictions
for performance of such molds.
Melt Rheology
of Polyolefin-Clay Nanocomposites with Coupling Agents Polymer nanocomposites with layered
silicates have two different types of interface
sites: edges with hydroxyl groups and gallery
faces with oxygen atoms. The polymer-particle
interface at either site may be strengthened by
silane coupling agents. Effects of reactive
coupling by the silane and a long chain polymeric
compatibilizer at different interface sites have
been investigated on the morphology and rheology
of polypropylene nanocomposites in the
melt-compounded state. In the illustration below,
two
different organoclays were used to obtain the
different coupling
effects. The
resulting state of dispersion and uniaxial
extensional viscosity behavior are shown in the
adjacent figure.
Reactive coupling at the interface produces finer
dispersions and strain hardening in uniaxial
extensional flow of polymer-layered silicate
nanocomposites; more so with both coupling at faces
and edges. Note that the
organoclays
used in the two cases are
different: the aspect ratio of
the organoclay is lower in the
second case -- hence the viscosity
level is lower in the
second case; however, the
extent of strain hardening however
is clearly higher when the
silane coupling is obtained at
both edges and faces.
Molding of Flexible and
Rigid Polypropylene Foams and TPO
foams with Nanostructured Additives
Foaming of linear polypropylene melts
with chemical blowing agents gives mean cell sizes
in the range of 37 to 150 microns when the linear PP
is compounded with nanoclay and coupling agents.
see
US Patent #9,279,046
High Performance Additives with
Nanoparticles for PolypropyleneFilm
New
masterbatch additives have been developed that may
be compounded with bulk polyolefins and used to
produce films with good tensile strength and tear
strength while also having much improved barrier
to water vapor.
These films were produced by two different
methods: (1) film blowing and (2)
equibiaxial stretching of extruded film.
see US
Patent #10,253,146
The Action of Lubricants and
Other Rheology Modifiers in Polymer
Compounds
Lubricants can be
effective in different ways: (a) by forming a wall
layer that is less viscous than the bulk and thus
producing apparent slip or (b) by reducing the
viscosity of the bulk. The presence of other
modifiers such as thickeners or interfacial agents
may affect the action of lubricants in the
formulation. This is being studied with polymer
composites and thermoplastic elastomer blends.