Toughening microstructural features

There are stiU many unanswered questions as to why one LR additive more effectively toughens a particular resin than another LR additive. Microstructural features that may affect fracture behavior such as volume fraction, particle size and size distribution, particle-matrix adhesion, and the structure of dispersed phase are difficult to control independently. As a result, the importance of each has not been quantified. Nevertheless, significant improvements in the fracture toughness of rubber-modified UP and VE resins have been realized. 

Various ratio and distribution among the toughening zirconia polymorphs as result of the different sintering techniques could partially explain the obtained mechanical properties (Vickers hardness and fracture toughness by indentation). This assessment would be sustained by microstructural features analysis, XRD, far infrared and Raman spectra as follows. 

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