Effects of filler content and coupling agents on the mechanical properties and geometrical accuracy of selective laser sintered parts in glass bead-filled polyamide 12 composites

• Main Author: Mousah, Alkir
• Published: Cardiff University 2011
• Subjects: TS Manufactures
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.567123

Improvements in existing materials and the development of new materials for use in selective laser sintering are continually being pursued in the industrial and academic domains. This research will focus on the possibilities available for improving the mechanical properties and geometric accuracy of selective laser sintered parts produced from non-commercial polyamide 12 (PA12) composites. The specific material of interest is PA 12 filled with glass beads. This thesis describes a study of the relationship between filler particles, the polymer matrix and processing parameters and their influence on the mechanical properties and geometric accuracy of the composite. The aim of the study is to better understand the effect of coupling agents on the above mentioned properties as there is a lack of information in this area. Most of the experiments described in the thesis were performed with PA 12 filled with coated and uncoated glass beads. The production of test samples was carried out on a selective laser sintering machine (DTM Sinterstation 2000). Knowledge about different machine-material combinations has been extended by performing additional PA 12 composite experiments. The accessible information from PA 12 and glass-filled PA 12 (PA12/GF) manufacturer’s data was used as a reference in comparison and assessment of the results obtained from the new machine-material combinations. This research has shown that adding coated glass beads to PA 12 improves the tensile strength and elastic modulus but reduces the impact strength and ductility of the ii resulting material. Under suitable processing conditions, the geometrical accuracy of sintered parts also improves with the addition of glass beads. The work has also shown that good interfacial bonding between the polyamide matrix and the glass beads, particularly when a coupling agent is used, is a likely cause for the observed improvements.