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Sunil K. Narayanankutty, Ph.D

Research Areas

The current research areas are:

  • Conducting Polymers
  • Nano Composites
  • Short Fiber-Elastomer Composites
  • Polymer Recycling
  • Fracture Mechanics
  • Novel Compounding Ingredients
  • Low Formaldehyde PF Resins

Conducting Polymers Aniline based conducting polymers are synthesised and its use as potential coating agent for Nylon fibers are being explored. The fiber surface is properly conditoned for better adhesion of the polyaniline synthesised and the conductivity of the fibers is improved ten times.

Nano Composites Nano size slilca is pepared by sol -gel method and characterised. The prepared slical is then used as one of the components of a dry bonding agent in short Nylon fiber - elastomer composites. the prepared silica is also used as filler in these composites. Significant improvement in properties can be achieved.  

Short Nylon Fiber-Elastomer Composites: The work focuses on the optimization of short fiber content, methods of processing and development of suitable interfacial boding agent for composites based on short Nylon fiber and elastomers such as NR, SBR, NBR and CR.  The fibers are preferentially oriented in one direction by proper selection of the processing conditions so that the properties could be maximized in that direction.  For further improvement of the performance of the composite, interfacial bonding agents were designed and tested.  Strong fiber-matrix interface is a critical requirement for better stress transfer to the fiber and thus improve the composite properties. The mechanical, thermal and rheological properties of the composites are being investigated.

Polymer Recycling:   The work is a systematic study of the suitability of Reclaimed rubber as a substitute for rubber hydrocarbon and reinforcing fillers in rubber composites.  Reclaiming is a process by which worn out and discarded tyres are converted to a reusable form after removing the metallic and fibrous components.  The reclaim usually contains good amount of fillers and roughly fifty percent of rubber hydrocarbon, apart from other ingredients like activators, curatives and plasticizer.  Blends of this reclaimed rubber with other rubbers in both natural rubber and synthetic rubbers were prepared and the properties were evaluated to optimise the blend composition and processing conditions.  The blends were then further modified by surface modification of the components and also by using coupling agents, both of which have been found to be beneficial.  

Composites based on reclaimed rubber:  The work is to utilize the reclaimed rubber and also the short fibers in rubber compounds as cheap ingredients to reduce cost without much compromising the properties.  Short fibers are obtained usually as rejects or waste  from the textile industry.  These were   chopped to required length  used as cheap filler.  One attraction of short fibers is that they  can be processed on conventional rubber processing equipment.  Short fibers are also used in rubber compounds  for obtaining an isotropic mechanical properties.  The blends of rubbers with reclaimed rubber have been found to have good mechanical properties compared to the gum compound.  These were compounded with short fibers to get the composite with fibers aligned in one direction.  These composite showed improved performance in terms of mechanical properties.  For fiber- rubber composites,  a stronger interface is very importance because of non-matching extensibility of the components.  Hence in the composite many interfacial bonding agents and coupling agents  have been tried and, grafting of Maleic anhydride was found to be the most promising. The thermal degradation studies also showed improved performance of the composite prepared  

Fracture mechanics and fracture properties:   The ultimate properties of a material depend on the mode of failure of the matrix under stress and the theories of fracture mechanics have been able to predict with reasonable accuracy the matrix properties under applied strain.  The strain energy density values, indicative of the energy spent in the process of fracture is a function of the level of reinforcement  brought about by a filler.  This work is an attempt to correlate the reinforcing  effect of various fillers as determined  by fracture mechanic studies with the results from other methods such as Dynamic Mechanical Analysis, swelling and probably by IR.  The dynamic mechanical properties of a composite is determined by the viscoelastic properties characteristics of the matrix material which is modulated by the type and quantity of the fillers used and also  by the extent of interaction between the filler and the matrix.  The swelling  studies and the IR study are  also expected to give insight in to the type  of  interaction  at the interface.  This work is in progress  

Natural oils in rubber compounding:   This work is aimed at finding possible application of natural oil as multipurpose  ingredient  in rubber compounds.  India produces a variety of vegetable oils which can be utilized for this purpose.  Of all the oils coconut oils, palm oil, gingelly oil, castor oil and punnal oil have special significance in the local context and is available in large quantities.  Conventionally petroleum based oils and synthetic esters are being used as plasticizer/ processing aid in rubber formulations to improve properties and also as cheapening agent.  Substituting these mineral oils in rubber compounds with natural oils can not only reduce the consumption  of non renewable source of energy, but can also cheapen the  product without compromising properties.  Being natural products, the use of these oils is expected to give improved processability.  The presence of natural fatty acids in these oils also expected to reduce the requirement of stearic acid in the rubber compounds.   This work is in progress.  We have evaluated quite a few vegetable oils in different elastomers and the results are encouraging.

Low Formaldehyde PF Resin: The free formaldehyde in PF resin is increasingly being looked at as a potential health hazard. The formaldehyde vapour in the processing centres is to be reduced to within limits. The work in this direction has just begun. The optimization and calibration procedures are being standardised.