Effect of Allyl Modified/Silane Modified Multiwalled Carbon Nano Tubes on the Electrical Properties of Unsaturated Polyester Resin Composites

Swain, Sarojini,Sharma, Ram Avatar,Patil, Sandip,Bhattacharya, Subhendu,Gadiyaram, Srinivasa Pavan,Chaudhari, Lokesh The Korean Institute of Electrical and Electronic 2012 Transactions on Electrical and Electronic Material Vol.13 No.6

Considering the properties of the carbon nano tubes (CNT), their inclusion into the polymer matrix vastly increases the properties of the resultant composite. However, this is not the case due to the poor interfacial adhesion of the CNT and the polymer matrix. The present approach focuses on increasing the interaction between the polymer matrix and the CNT through the chemical modification of the CNT resulting in allyl ester functionalized carbon nanotubes (ACNT) and silane functionalized carbon nano tubes (SCNT) which are capable of reacting with the polymer matrix during the curing reaction. The addition of ACNT/SCNT into unsaturated polyester resin (UPR) resulted in the improvement of the electrical properties of resulted nanocomposites in comparison to the CNT. The surface resistivity, volume resistivity, dielectric strength, dry arc resistivity, and the comparative tracking index of the nanocomposites were significantly improved in comparison to CNT. The chemical modification of CNT was confirmed via spectroscopy.

Effects of Nano-silica/Nano-alumina on Mechanical and Physical Properties of Polyurethane Composites and Coatings

Sarojini Swain,Ram Avatar Sharma,Subhendu Bhattacharya,Lokesh Chaudhary 한국전기전자재료학회 2013 Transactions on Electrical and Electronic Material Vol.14 No.1

The present approach shows the use of nano-silica / nano-alumina in polyurethane (PU) matrix, which lead to significant improvements in the mechanical and thermal properties of the nano-composite. It is observed that with incorporation of 1% of nano-alumina into the PU matrix, there is an improvement in the tensile strength of around 50%, and for nano-silica the improvement is around 41%, at the same concentration. The morphological data shows that above 3% of the nano particles there are agglomerations in the nanocomposite. Again with the absorption of moisture, there is a decrease in the thermal and mechanical properties of the PU resin, but in this research work it is observed that with the incorporation of the nano particles, in the presence of absorbed moisture there is an improvement in mechanical and thermal properties of the composite, over that of the PU matrix.

Effect of Allyl Modified/Silane Modified Multiwalled Carbon Nano Tubes on the Electrical Properties of Unsaturated Polyester Resin Composites

Sarojini Swain,Ram Avatar Sharma,Sandip Patil,Subhendu Bhattacharya,Srinivasa Pavan Gadiyaram,Lokesh Chaudhari 한국전기전자재료학회 2012 Transactions on Electrical and Electronic Material Vol.13 No.6

Considering the properties of the carbon nano tubes (CNT), their inclusion into the polymer matrix vastly increases the properties of the resultant composite. However, this is not the case due to the poor interfacial adhesion of the CNT and the polymer matrix. The present approach focuses on increasing the interaction between the polymer matrix and the CNT through the chemical modification of the CNT resulting in allyl ester functionalized carbon nanotubes (ACNT)and silane functionalized carbon nano tubes (SCNT) which are capable of reacting with the polymer matrix during the curing reaction. The addition of ACNT/SCNT into unsaturated polyester resin (UPR) resulted in the improvement of the electrical properties of resulted nanocomposites in comparison to the CNT. The surface resistivity, volume resistivity, dielectric strength, dry arc resistivity, and the comparative tracking index of the nanocomposites were significantly improved in comparison to CNT. The chemical modification of CNT was confirmed via spectroscopy.

Synthesis and Characterization of Graphene Based Unsaturated Polyester Resin Composites

Sarojini Swain 한국전기전자재료학회 2013 Transactions on Electrical and Electronic Material Vol.14 No.2

Graphene-based polymer nanocomposites are very promising candidates for new high-performance materials that offer improved mechanical, barrier, thermal and electrical properties. Herein, an approach is presented to improve the mechanical, thermal and electrical properties of unsaturated polyester resin (UPR) by using graphene nano sheets (GNS).The extent of dispersion of GNS into the polymer matrix was also observed by using the scanning electron microscopy (SEM) which indicated homogeneous dispersion of GNS through the UPR matrix and strong interfacial adhesion between the GNS and UPR matrix were achieved in the UPR composite, which enhanced the mechanical properties. The tensile strength of the nanocomposites improved at a tune of 52% at a GNS concentration of 0.05%. Again the flexural strength also increased around 92% at a GNS concentration of 0.05%. Similarly the thermal properties and the electrical properties for the nanocomposites were also improved as evidenced from the differential scanning caloriemetry (DSC) and dielectric strength measurement.

Effects of Nano-silica/Nano-alumina on Mechanical and Physical Properties of Polyurethane Composites and Coatings

Swain, Sarojini,Sharma, Ram Avatar,Bhattacharya, Subhendu,Chaudhary, Lokesh The Korean Institute of Electrical and Electronic 2013 Transactions on Electrical and Electronic Material Vol.14 No.1

The present approach shows the use of nano-silica/nano-alumina in polyurethane (PU) matrix, which lead to significant improvements in the mechanical and thermal properties of the nano-composite. It is observed that with incorporation of 1% of nano-alumina into the PU matrix, there is an improvement in the tensile strength of around 50%, and for nano-silica the improvement is around 41%, at the same concentration. The morphological data shows that above 3% of the nano particles there are agglomerations in the nanocomposite. Again with the absorption of moisture, there is a decrease in the thermal and mechanical properties of the PU resin, but in this research work it is observed that with the incorporation of the nano particles, in the presence of absorbed moisture there is an improvement in mechanical and thermal properties of the composite, over that of the PU matrix.

Synthesis and Characterization of Graphene Based Unsaturated Polyester Resin Composites

Swain, Sarojini The Korean Institute of Electrical and Electronic 2013 Transactions on Electrical and Electronic Material Vol.14 No.2

Graphene-based polymer nanocomposites are very promising candidates for new high-performance materials that offer improved mechanical, barrier, thermal and electrical properties. Herein, an approach is presented to improve the mechanical, thermal and electrical properties of unsaturated polyester resin (UPR) by using graphene nano sheets (GNS). The extent of dispersion of GNS into the polymer matrix was also observed by using the scanning electron microscopy (SEM) which indicated homogeneous dispersion of GNS through the UPR matrix and strong interfacial adhesion between the GNS and UPR matrix were achieved in the UPR composite, which enhanced the mechanical properties. The tensile strength of the nanocomposites improved at a tune of 52% at a GNS concentration of 0.05%. Again the flexural strength also increased around 92% at a GNS concentration of 0.05%. Similarly the thermal properties and the electrical properties for the nanocomposites were also improved as evidenced from the differential scanning caloriemetry (DSC) and dielectric strength measurement.

Synthesis and Characterization of Carbon Micro Tubes Based Unsaturated Polyester Resin Composites

Ram Avatar Sharma,Sarojini Swain,Tripti Sharma 한국전기전자재료학회 2013 Transactions on Electrical and Electronic Material Vol.14 No.5

In this paper, the thermal diffusivity of composites comprising hollow carbon microtube (CMT) filler and unsaturated polyester resin (UPR) have been investigated. The thermal diffusivity of the CMT-UPR composites was increased to 4.056 W/m K at 50 wt% filler loading after reaching a minimum value of about 0.210 W/m K at 1 wt%. At higher filler loading, the mechanical and electrical properties of composites are typically changed. Therefore, the properties of CMT-UPR composites were determined using ASTM methods. The surface and volume-resistivity reach minimum values of 107 Ohm/sq and 108 Ohm-cm at 50 wt%, and maximum values of 1017 Ohm/sq and 1015 Ohm-cm for neat UPR. The distribution of CMTs in the UPR matrix was analyzed by scanning electron microscope (SEM). The thermal behavior of the CMT-UPR composites was determined by differential scanning calorimeter (DSC) and thermal gravimetric analysis (TGA).

Process Modeling and Optimization Studies in Drying of Current Transformers

Bhattacharya, Subhendu,D'Melo, Dawid,Chaudhari, Lokesh,Sharma, Ram Avatar,Swain, Sarojini The Korean Institute of Electrical and Electronic 2012 Transactions on Electrical and Electronic Material Vol.13 No.6

The vacuum drying process for drying of paper in current transformers was modeled with an aim to develop an understanding of the drying mechanism involved and also to predict the water collection rates. A molecular as well as macroscopic approach was adopted for the prediction of drying rate. Ficks law of diffusion was adopted for the prediction of drying rates at macroscopic levels. A steady state and dynamic mass transfer simulation was performed. The bulk diffusion coefficient was calculated using weight loss experiments. The accuracy of the solution was a strong function of the relation developed to determine the equilibrium moisture content. The actually observed diffusion constant was also important to predict the plant water removal rate. Thermo gravimetric studies helped in calculating the diffusion constant. In addition, simulation studies revealed the formation of perpetual moisture traps (loops) inside the CT. These loops can only be broken by changing the temperature or pressure of the system. The change in temperature or pressure changes the kinetic or potential energy of the effusing vapor resulting in breaking of the loop. The cycle was developed based on this mechanism. Additionally, simulation studies also revealed that the actual mechanism of moisture diffusion in CT's is by surface jumps initiated by surface diffusion balanced against the surrounding pressure. Every subsequent step in the cycle was to break such loops. The effect of change in drying time on the electrical properties of the insulation was also assessed. The measurement of capacitance at the rated voltage and one third of the rated voltage demonstrated that the capacitance change is within the acceptance limit. Hence, the new cycle does not affect the electrical performance of the CT.

Effect of Nano/micro Silica on Electrical Property of Unsaturated Polyester Resin Composites

Sharma, Ram Avatar,D'Melo, Dawid,Bhattacharya, Subhendu,Chaudhari, Lokesh,Swain, Sarojini The Korean Institute of Electrical and Electronic 2012 Transactions on Electrical and Electronic Material Vol.13 No.1

The addition of nano/micro silica into unsaturated polyester resin (UPR) results in the improvement of the electrical properties of Silica-UPR composites. The surface, volume resistivity, dielectric strength, dissipation factor and dry arc resistivity of nano silica-UPR composites were found to improve significantly. The effects of the nano and micro fillers in UPR have been evaluated. They are presented in this paper. To evaluate the electrical properties of the nano & micro composites, all the measurements were done as per the prescribed methods in ASTM. It was observed that the addition of nano silica improves the electrical properties as compared to micro silica. The better dispersion of silica particles in unsaturated polyester resin enhances the electrical properties of silica-UPR composites.

Process Modeling and Optimization Studies in Drying of Current Transformers

Subhendu Bhattacharya,Dawid DMelo,Lokesh Chaudhari,Ram Avatar Sharma,Sarojini Swain 한국전기전자재료학회 2012 Transactions on Electrical and Electronic Material Vol.13 No.6

The vacuum drying process for drying of paper in current transformers was modeled with an aim to develop an understanding of the drying mechanism involved and also to predict the water collection rates . A molecular as well as macroscopic approach was adopted for the prediction of drying rate. Ficks law of diffusion was adopted for the prediction of drying rates at macroscopic levels. A steady state and dynamic mass transfer simulation was performed. The bulk diffusion coefficient was calculated using weight loss experiments. The accuracy of the solution was a strong function of the relation developed to determine the equilibrium moisture content. The actually observed diffusion constant was also important to predict the plant water removal rate. Thermo gravimetric studies helped in calculating the diffusion constant. In addition, simulation studies revealed the formation of perpetual moisture traps (loops)inside the CT. These loops can only be broken by changing the temperature or pressure of the system. The change in temperature or pressure changes the kinetic or potential energy of the effusing vapor resulting in breaking of the loop. The cycle was developed based on this mechanism. Additionally, simulation studies also revealed that the actual mechanism of moisture diffusion in CT’s is by surface jumps initiated by surface diffusion balanced against the surrounding pressure. Every subsequent step in the cycle was to break such loops. The effect of change in drying time on the electrical properties of the insulation was also assessed. The measurement of capacitance at the rated voltage and one third of the rated voltage demonstrated that the capacitance change is within the acceptance limit. Hence,the new cycle does not affect the electrical performance of the CT.