Nanofillers can be used to enhance the thermal conductivity of commercially available SLA resins.

Abstract

Stereolithography (SLA) is a form of 3D printing technology used for the production parts and patterns in a layer by layer fashion. Traditionally, 3D printing has been used for the manufacture of prototypes, however it is increasingly being used for the production of parts in small volumes. However, there are limited materials that can be used to produce parts using this process and they commonly need additional processes to produce a finished part. Additionally, 3D printing is time-consuming and is currently not suitable for the large scale production of low-cost parts.

Injection moulding, on the other hand, is a process where molten polymer is forced into a cooled metal mould, which solidifies the polymer into the shape of the mould. However, set up costs for injection moulding are prohibitively high for short production or pilot runs due to the cost of the metal mould. Hence, there is a lot of interest in a hybrid system which uses 3D printing to produce the tools for use in Injection moulding. However, recent work in AIT has shown that the 3D printed inserts are prone to wear and breakdown due to the high pressures and temperatures involved in injection moulding. As such, the current study aims to develop reinforced thermally conductive polymer resins for use in 3D printing of tooling. Initial trials include the incorporation of a range of nanofillers including silver, copper, halloysite and other nanoclays. These fillers were added to a photopolymer resin, cured and characterised in terms of thermal conductivity, mechanical properties, contact angle, hardness and scanning electron microscopy. Initial results indicate that the incorporation of conductive copper and silver nanoparticles does not have a significant effect on thermal conductivity.

Conversely, the incorporation of Halloysite nanoclay loading at 3 wt% significantly increased the thermal conductivity of the resin to 0.721 w/mk from 0.681 w/mk for the cured neat resin. These results indicate that nanofiller can be used to increase the thermal conductivity of commercially available SLA resins. However further work is needed before these materials are a viable alternative to metal tooling in injection moulding applications.