Micromechanical effect of layered silicates of the second generation: a novel nanofiller to increase stiffness and toughness of PMMA
In this thesis a new generation of layered silicates was used for modification of PMMA with the goal to reach a maximum in stiffness-toughness-balance without sacrificing tensile strength and processability. Additionally, the micromechanical effect of these novel nanofillers has been evaluated using fracture surface analysis and structure-property-relationships have been established. To highlight the better performance of the novel nanofiller compared to conventionally used layered silicates, a commercially available system based on surface-modified Bentone has been used as benchmark material and the properties of its nanocomposites have also been analyzed in detail. Finally, a deep understanding about the extent of influence of various filler properties on nanocomposite properties was generated.
The newly developed PMMA nanocomposites based on layered silicates of the second generation show a unique stiffness-toughness balance. The huge lateral extension and the resulting low particle densities in combination with high aspect ratio and high intrinsic stiffness make the layered silicates a high performance nanofiller.
The conventionally used layered silicates lead only to an increase of stiffness at the cost of strength and fracture toughness reflecting the results from literature. In terms of fracture toughness, the conventionally nanofillers are not effective as their lateral extension is too small to promote any additional toughening mechanism. On the contrary, the layered silicates of the second generation lead to the occurrence of additional energy dissipating mechanisms like crack pinning or crack deflection and this to a significant increase of fracture toughness.
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Free keywords:
PMMA, nanofiller, layered silicates, clay, nanocomposite, morphology, fracture toughness
Institute / chair:
Lehrstuhl für Polymere Werkstoffe der Universität Bayreuth
Language:
German
Technical consultant for expert services:
Prof. Dr.-Ing. Volker Altstädt,
Prof. Josef Breu
Publication year:
2018
Provider:
Wissenschaftlicher Arbeitskreis Kunststofftechnik (WAK) / Kunststoffe.de
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