*1.3.1 Inorganic filling particles*

Fillers are often fine-grained nanometer- or micrometer-sized particles and fibers, which can be made of organic or inorganic materials. Generally, such particles and fibers are named as conventional sized fillers according to their size range. Composites formed by using these fillers are labeled as conventional sized filled composites, for example, nanocomposites and microcomposites. Recently, filler materials have been used to improve electrical, mechanical strength, and thermal properties [5]. Polymers are chosen in electrical engineering according to the required application, and their properties can be modified by adding inorganic fillers in it. The quantity of fillers in the base polymer matrix is still under question from the literature that which amount by weight is most suitable to improve the desired properties. Therefore, we only use very low filler quantity of nanoparticles into the base polyimide. The common used organic polymers and their derived inorganic fillers are shown in **Table 2** [6].


### **Table 2.**

*Organic and inorganic fillers and their chemical family.*
