Adam Ellis

The effect of build orientation and surface modification on mechanical properties of high speed sintered parts

High speed sintering is a novel additive manufacturing technology that uses inkjet printing and infra-red energy to selectively sinter polymeric powder. The research presented here investigates the effect of build orientation on dimensional accuracy, density, mechanical properties and surface roughness of high speed sintered parts. Tensile specimens were built through seven different angles between and including the XY (horizontal) and ZY (vertical) planes and analysed. The effect of the PUSh™ process was also investigated across this range of build orientations. The results show that build orientation does infuence the properties of the parts. A number of mechanical properties showed a relationship with build orientation. Density was seen to decrease as the angle increased from XY towards ZY. This increase in angle was shown to increase surface roughness while ultimate tensile strength and elongation at break decreased. At all build orientations, the PUSh™ process significantly reduces surface roughness, mildly increases part density and had a small effect on ultimate tensile strength whilst showing a small but consistent increase in elongation at break.

Bimolecular catalysis and turnover from a macromolecular host system.

The synthesis of a globular macromolecule and its application as a bimolecular catalyst are reported. The macromolecular structure supports (at least) two zinc-metalated porphyrin units, each capable of binding a single reactant. The proximity of the two bound reactants results in an increased local concentration, leading to a maximum 300-fold increase in the reaction rate. In contrast to other synthetic catalysts, where bidentate products inhibit further reactions, this macromolecular system allows the product to be displaced by the reactants leading to turnover and catalysis. We believe that this is due to the dynamics of the macromolecular host system, which maintains enough flexibility to adopt a favorable/reactive geometry, which allows the reactants to get close and react while possessing sufficient rigidity/poor geometry to reduce and disrupt any cooperative/inhibitive bidentate binding.