Engineering Toughness in a Brittle Vinyl Ester Resin Using Urethane Acrylate for Additive Manufacturing

Abstract

Thermosetting polymers tend to have a stiffness–toughness trade-off due to the opposing relationship of stiffness and toughness on crosslink density. We hypothesize that engineering the polymer network, e.g., by incorporating urethane oligomers, we can improve the toughness by introducing variations in crosslink density. In this work, we show that a brittle methacrylated Bis-GMA resin (known as DA2) is toughened by adding a commercial urethane acrylate resin (known as Tenacious) in different proportions. The formulations are 3D printed using a vat photopolymerization technique, and their mechanical, thermal, and fracture properties are investigated. Our results show that a significant amount of Tenacious 60% w/w is required to produce parts with improved toughness. However, mechanical properties drop when the Tenacious amount is higher than 60% w/w. Overall, our results show that optimizing the amount of urethane acrylate can improve toughness without significantly sacrificing mechanical properties. In fact, the results show that synergistic effects in modulus and strength exist at specific blend concentrations.

The effect of resin properties on toughness translation in interleaved composites

“…All K IC values reported in this work were measured previously using ASTM D 5045 and are reported in Table 1 with their corresponding reference. 19,26–28 Similar to reference, 9,10,29,30 and ASTM D5045, in this manuscript, pure resin G IC , i.e. without laminates, is referred to as resin toughness and K IC is used to refer to resin fracture toughness.…”

“…The mechanical properties of Tenacious are published in reference. 19,28 The DA2 and Tenacious were mixed at different weight ratios to formulate resins with varying fracture toughness, referred to here as DT-XX, where XX is a number representing the weight fraction of Tenacious in the mixture (∼40%–80%). DT-XX resins are formulated by mixing the two resins for one hour.…”

“…DT-XX resins are formulated by mixing the two resins for one hour. Details about their formulation and mechanical and fracture properties were published in reference 28 A fabric, namely, plain weave E-glass with an areal density of 0.025 g/cm 2 , thickness of 0.025 cm and a single fiber diameter of ∼12.5 μm, was purchased from FiberGlast Developments Corp. The fabric contains general-purpose sizing.…”