Macrostructural changes of polymer replicated open cell cordierite based foams upon sintering

Abstract

The goal of this work was to clarify the macrostructural changes that take place upon sintering of open cell cordierite based foams. A methodology, based on optical image analysis, was developed to assess the structure of open-cell foams, which allowed evaluating the macrostructure of both cordierite based foams obtained by the replication process and their polymeric templates. The parameters used to describe the structures were the size of the cell and the window, the window shape factor, the strut thickness and the volume fraction of the material. The experimental evidence gathered opened the way to understand the physical/chemical transformations involved in the polymer burnout and the ceramic sintering processes, as well as their influence on the ceramic final structure. The observed trends provide guidance for tailoring 'replicated' cordierite based foams, in view of the required application.     

Nonsingular Data Transformations: Definition, Validity, and Applications

This paper describes a unifying framework for nonsingular data transformations. It shows that a wide class of existing transformations may be expressed in this framework, allowing compound transformations to be performed in one step. Validity conditions for such transformations are developed as is the form of the transformed program and data. Constructive algorithms to generate data transformations for different applications are described and applied to example programs. It is shown that they can have a significant impact on program performance and may be used in situations where traditional loop transformations are inappropriate.     

Fracture behaviour of high impact polystyrene Influence of particle morphology

Abstract

The mechanical behaviour of high impact polystyrene has been examined with special attention to the influence of particle size and morphology. Video extensometry was used to follow the volume strain kinetics during tensile drawing and also to make direct observations of crack initiation in compact tension experiments at moderate rates. Materials incorporating composite particles with either small capsule (0.3 µm) or large salami (>1 µm) structures have been considered, as well as blends combining both morphologies. In the particular case of blends, a marked synergistic behaviour was achieved under impact conditions. Plasticity and fracture results, as well as morphological observations, suggest that the ability of the salami particles to stabilise the crazes initiated by the small capsules plays a key role, even at small volume fractions of salami particles.