Toughening of polymeric materials.

Model of Transformation Toughening in Brittle Materials

Assuming that the energy dissipation decreases inversely with distance from the crack tip, the increase in steady-state toughness of a transformation-toughened ceramic is estimated to be AJ = (AJ,/w) In (1 + w), where (i) AJo denotes the toughness increment which would be expected for a given zone height h , assuming full transformation throughout the zone, and (ii) w is a nondimensional parame...

Zirconia Toughening of Glass-ceramic Materials

A ceramic material suitable for packaging of large scale integrated circuit is produced by the process of forming a mixture of a powdered glass ceramic material which is a glassy precursor to cordierite ceramic material, formed by the steps which are as follows: a. Mix tetragonal phase material selected from the group consisting of zirconia or hafnia powder con taining a stabilizing oxide compo...

Toughening mechanisms in bioinspired multilayered materials.

Outstanding mechanical properties of biological multilayered materials are strongly influenced by nanoscale features in their structure. In this study, mechanical behaviour and toughening mechanisms of abalone nacre-inspired multilayered materials are explored. In nacre's structure, the organic matrix, pillars and the roughness of the aragonite platelets play important roles in its overall mech...

Polymeric triple-shape materials.

Shape-memory polymers represent a promising class of materials that can move from one shape to another in response to a stimulus such as heat. Thus far, these systems are dual-shape materials. Here, we report a triple-shape polymer able to change from a first shape (A) to a second shape (B) and from there to a third shape (C). Shapes B and C are recalled by subsequent temperature increases. Whe...

Polymeric Nanocomposite Materials