Abstract
With the continually rising material requirements for polymeric insulation materials in thermal and especially electrical applications, the enhancement of existing materials is necessary. Especially for enhancing the material’s thermal performance an increase of heat transfer or the material’s softening temperature is unavoidable. A recent and possible approach nowadays for achieving such required properties enhancements is the use of nanoscaled fillers. These are intended to influence the thermal conductivity and the thermo-mechanical and electrical performance of the material positively. The main focus of this work was to increase the performance of existing materials for electrical applications respectively the development of new materials. The nanoparticle types that were used in this work for property enhancement are commercially good available systems like non-modified silica- and aluminum oxide particles as well as surface-modified silica particles. The characterization and development of the used epoxy-anhydride systems is performed from molecular scale up to application properties. At the molecular scale level a brief description of the chemical cross linking reaction (and impact factors on this) including activation energy evaluation via dynamic scanning calorimetry is given. It was shown that the cross linking process of the zincsalt-accelerated system is heavily influenced through the use of aluminum oxide nanoparticles. These influences are generally not found in literature. For the purpose of sample preparation the process of sample moulding is described featuring the particle compounding process and a quantitative analysis of the particle distribution. In that case the modified silica particles showed the best distribution. The manufactured samples were thermally and thermo-mechanically characterized using steady thermal conductivity measurements as well as dynamic mechanical analysis (DMA) as a function of particle content. Once again, an influence of the aluminum oxide particles on the glass transition temperature is shown. In case of mechanical investigations, the nanocomposites were tested using 3-point bending-, impact strength- and fracture mechanic tests. For the purpose of industrial applicability of these developed materials profiles of fiber reinforced nanocomposites were produced via pultrusion process including a following characterization. The results showed an increase in thermal performance as well as the general applicability in large scale processes. In addition to the material development of nanocomposites a practical scenario of an industrially usable recycling process of fiber reinforced composites is presented. It describes the possibility of reusing production waste in a running production process. The development and implementation of this procedure was carried out in two steps. First, a study of waste filler content (up to 50 m% content of production waste) in an epoxy anhydride system was accomplished to define the maximum manageable content. The characterization methods of the resulting composites included thermo-mechanical methods (DMA) as well as mechanical methods (3-point bending- and impact tests). In the second step fiber reinforced composites were successfully produced (with a filler content of 15 m%) via pultrusion process.
Translated title of the contribution | Microstructure optimization and structure property relationships of thermoset nanocomposites |
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Original language | German |
Qualification | Dr.mont. |
Supervisors/Advisors |
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Publication status | Published - 2017 |
Bibliographical note
embargoed until nullKeywords
- plastic
- thermoset
- nanoparticles
- silicondioxide
- aluminiumoxide
- recycling
- DMA
- DSC
- thermal conductivity
- 3-point bending
- impact properties
- fracture mechanics