Photopolymer formulation towards large scale additive manufacturing of autoclave capable tooling

Large-scale polymeric additive manufacturing (AM) is emerging as a method for producing prototype tooling in the aerospace industry. However, material options oven/autoclave-capable are currently limited to costly thermoplastics such polyetherimide (PEI) and polyphenylene sulfide (PPS). Photopolymers can be formulated oven/autoclave use have advantages over ambient processing rapid curing under low-energy ultraviolet light emitting diode (UV LED) lamps. This study presents initial photopolymer formulation work towards large-scale AM with bisphenol A ethoxylate dimethacrylate (Bis-EMA), vinyl ester suitable moderate autoclave/oven-curing temperatures (100–135 °C, 212–275°F). Bis-EMA photopolymers were prepared cured 3 mm thick specimens by UV irradiation simulate conditions. was also blended pentaerythritol triacrylate (PETIA) determine influence of high-functionality acrylate on cure response properties. For same dose, an increase PETIA content up 50 wt% increased Vickers Hardness Number (VHN) irradiated surface from 22.6 25.0. It improved ratio top bottom hardness 65% 91%, indicating possible improvement through-thickness response. The addition decreased tensile modulus 2.8 GPa 2.1–2.3 GPa, above 20 reduced glass transition temperature (Tg) below control. blend 80 yielded optimal balance control while retaining thermal stability. To investigate suitability tooling, this 80:20 reinforced fiberglass used produce demonstration via pseudo-additive process. tools subjected five oven molding cycles, laser scanning showed average deviation < 0.05 mm, negligible degradation tool geometry. values stock did not change significantly cycling, Tg 154 °C 172 °C. first report Bis-EMA/PETIA blends AM. data confirm that formulations achieve adequate at layer thicknesses typical An thermally stable within low volume cycles expected 3D printed tool.