Biological nano silica reinforced polymeric composites
tarafından
Ülker, Sevkan, author.
Başlık
:
Biological nano silica reinforced polymeric composites
Yazar
:
Ülker, Sevkan, author.
Yazar Ek Girişi
:
Ülker, Sevkan, author.
Fiziksel Tanımlama
:
xv, 151 leaves: charts;+ 1 computer laser optical disc.
Özet
:
The present thesis study focused on processing nano-silica powders of varying sizes and crystallinities through heat treatment (900–1200 °C), hydrofluoric acid leaching (1–7 N), and ball milling (1 h, 500 rpm) of natural diatom frustules. As-received frustules was composed of amorphous silica (88%) and quartz. The partially ordered crystalline low-quartz and/or precursor to low-cristobalite started to form at ~900 °C. As the heat treatment temperature increased, the crystallinity of the frustules increased from 9.3% at 25 °C to 46% at 1200 °C. Applying a ball milling reduced the mean particle sizes of the as-received and heat-treated frustules from 15.6–13.7 μm to 7.2-6.7 μm, respectively. Acid leaching of the as-received and heat-treated frustules resulted in a further increase in the crystallinity. Furthermore, ball milling applied after an acid leaching was very effective in reducing the particle size of the as-received and heat-treated frustules. The mean particle size of the acid-leached frustules decreased to 774-547 nm with a crystallinity varying between 12 and 48% after ball milling. A partially dissolved amorphous phase was observed in between crystalline silica grains after acid leaching, which resulted in a rapid fracture/separation of the frustules in ball milling. The prepared nano-silica powders were further used as a filler in an epoxy matrix. The tensile strength, fracture strain, and modulus of epoxy increased with increasing the volume percent of nano-silica up to 2%. The increase in the yield strength and elastic modulus was about 50% and 30% with the addition of 2 vol% frustules, respectively. The rule of mixtures showed a very good agreement with the experimental elastic modulus values and a numerical model of the tensile test in LS-DYNA agreed well with the experimental tensile stress-strain behavior. The microscopic observations showed the presence of nano-silica powder, proving an efficient load transfer from matrix to powders on the fracture surfaces, confirming a strong interface between silica powders and matrix.
Konu Başlığı
:
Polymeric composites
Nanocomposites (Materials)
Yazar Ek Girişi
:
Güden, Mustafa,
Akdoğan, Yaşar,
Tüzel Kişi Ek Girişi
:
İzmir Institute of Technology. Material Science and Engineering
Tek Biçim Eser Adı
:
Thesis (Doctoral)--İzmir Institute of Technology:Material Science and Engineering
İzmir Institute of Technology: Material Science and Engineering --Thesis (Doctoral).
Elektronik Erişim
:
Library | Materyal Türü | Demirbaş Numarası | Yer Numarası | Durumu/İade Tarihi |
---|
IYTE Library | Tez | T002641 | TA455.P58 U39 2022 | Tez Koleksiyonu |