Thermal-expansion and fracture toughness properties of parts made from liquid crystal stereolithography resins
✍ Scribed by Jill S Ullett; Tia Benson-Tolle; John W Schultz; R.P Chartoff
- Book ID
- 104314268
- Publisher
- Elsevier Science
- Year
- 1999
- Weight
- 247 KB
- Volume
- 20
- Category
- Article
- ISSN
- 0261-3069
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✦ Synopsis
Stereolithography is a layered manufacturing technique that uses a laser to selectively polymerize a thermosetting resin to form complex three-dimensional parts. This rapid prototyping technique has evolved over the years from a model maker to a rapid fabrication technique for soft-tooling and parts for in-service testing. With this evolution in applications has come increased Ž . demand for high-performance resins. Liquid crystal LC resins can be processed by stereolithography methods to provide parts with superior and in some cases unique properties compared with conventional resins. LC resins consist of rod-like molecules that can be aligned prior to cure resulting in anisotropic mechanical and physical properties. A magnet outside the resin vat can be used to control the molecular alignment. Alignment can be varied within a layer or from layer-to-layer to achieve desired properties much as is done with fiber reinforced plastics. Two properties that are important for many applications are toughness and thermal dimensional-stability. Initial studies showed that fracture toughness values of LC coupons were about twice that of isotropic coupons manufactured from the same resin. Also, we have demonstrated that the in-plane thermal expansion of LC parts can be minimized over a wide temperature range by rotating the molecular alignment 90Њ from one layer to the next.