Engineering and Technology Journal

Abstract

Dielectric constant (εr ) and dielectric strength (Ebr) of composite materials that
consist of Novolak reinforced with glass fiber, Novolak reinforced with asbestos
fiber and Novolak reinforced with (60%) ratio of glass fiber and asbestos have
been Studied. The specimens were made in different ratios of
Hexamethylenetetramine (HMTA) content of (10%) and (14%), Then a study
was made on influence of (HMTA) on dielectric constant (εr ) and dielectric
strength ( Ebr) of these speciments. It was found that permittivity (εr ) and
dielectric strength (Ebr) for composite materials are dependent matrix the types
and properties of reinforcing materials.
Then relation between dielectric constant (ε
r) and frequency and temperature
and percentage moisture absorption was studied. It was found that dielectric
constant increases when the temperature and percentage moisture absorption
increase, whereas dielectric constant (ε
r) is dependent on capacity of composite
materials.