Dielectric constant at different frequencies (Hz)
The main function of an insulator is to insulate the current carrying
conductors from each other and from the ground, which requires
materials with very low dielectric constant. For rubber, the dielectric
constant increases with temperature due to change in intra and inter
molecular interactions. Therefore it is necessary to modify rubber to
thermally more stable by adding some ingredients or dynamic
vulcanization. The variation of dielectric constants of pure components
and the blends of NR/CS as a function of frequency is shown in
Fig. 5. It shows that the blend NR80CS20 exhibits the lower value; while
the chitosan exhibits the maximum value of dielectric constant. The
dielectric constant values of the blends decreased with increase in
frequency. The effect of blend composition on the dielectric constant
values is given in Table 2 for different frequencies. The table shows
that the dielectric constant of natural rubber is less at higher
frequencies. The blend NR85CS15 shows the least frequency dependent
and more stable. Above 20% chitosan in the blend, the dielectric
constant increased, which can be attributed to the change in overall
polarity of the system with the addition of chitosan.
Table 3 shows that the dielectric constant of blend after
vulcanization is more stable. The added dicumyl peroxide undergoes
cross-linking reaction in the rubber phase and the cross-links formed
at the interface decreases the free volume. The cross-linked structure
will avoid increase in free volume resulting in stable dielectric
properties. The effect of vulcanization on the dielectric constant for
the blend with 10% of chitosan is shown in Fig. 6. The dielectric
constant decreases by vulcanization and it is more stable than pure
blend at lower frequencies. The vulcanized NR90CS10 blend is more
stable than MA compatibilized NR90CS10 and the vulcanized blend is
frequency independent at lower frequencies.
In electrical applications, it is desirable to keep the electrical losses
to a minimum. Electrical losses indicate the inefficiency of an
insulator. Dissipation factor is a measure of the alternating current
electrical energy, which is converted to heat. This heat rises the
temperature and accelerates deterioration of the polymeric materials.
The loss factor values with frequency for the various blend compositions
Dielectric constant at different frequencies (Hz)The main function of an insulator is to insulate the current carryingconductors from each other and from the ground, which requiresmaterials with very low dielectric constant. For rubber, the dielectricconstant increases with temperature due to change in intra and intermolecular interactions. Therefore it is necessary to modify rubber tothermally more stable by adding some ingredients or dynamicvulcanization. The variation of dielectric constants of pure componentsand the blends of NR/CS as a function of frequency is shown inFig. 5. It shows that the blend NR80CS20 exhibits the lower value; whilethe chitosan exhibits the maximum value of dielectric constant. Thedielectric constant values of the blends decreased with increase infrequency. The effect of blend composition on the dielectric constantvalues is given in Table 2 for different frequencies. The table showsthat the dielectric constant of natural rubber is less at higherfrequencies. The blend NR85CS15 shows the least frequency dependentand more stable. Above 20% chitosan in the blend, the dielectricconstant increased, which can be attributed to the change in overallpolarity of the system with the addition of chitosan.Table 3 shows that the dielectric constant of blend aftervulcanization is more stable. The added dicumyl peroxide undergoescross-linking reaction in the rubber phase and the cross-links formedat the interface decreases the free volume. The cross-linked structurewill avoid increase in free volume resulting in stable dielectricproperties. The effect of vulcanization on the dielectric constant forthe blend with 10% of chitosan is shown in Fig. 6. The dielectricconstant decreases by vulcanization and it is more stable than pureblend at lower frequencies. The vulcanized NR90CS10 blend is morestable than MA compatibilized NR90CS10 and the vulcanized blend isfrequency independent at lower frequencies.In electrical applications, it is desirable to keep the electrical lossesto a minimum. Electrical losses indicate the inefficiency of aninsulator. Dissipation factor is a measure of the alternating currentelectrical energy, which is converted to heat. This heat rises thetemperature and accelerates deterioration of the polymeric materials.The loss factor values with frequency for the various blend compositions
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