Title: Influence of Diisocyanate Reactivity and Processability on Polyurethane Ambient Reactive Extrusion

Authors: Aynslie J. Fritz, Jeffrey S. Wiggins

DOI: 10.33599/nasampe/s.21.0481

Abstract: Additive manufacturing (AM) is transforming industrial processes, but key limitations, such as anisotropy and size-scale restrictions, hinder its full potential. The recent development of advanced AM methods, such as ambient reactive extrusion (ARE), have targeted these limitations. In ARE, reactive monomeric materials are pumped through a static mixer, initiating polymerization that continues after deposition, necessitating highly reactive, yet processable materials. Herein, reactivity and processability tradeoffs for ARE polyurethane printing was investigated by creating blends of dicyclohexylmethane-4,4'-diisocyanate (less reactive, ambient liquid) and 4,4'-diphenylmethane diisocyanate (more reactive, ambient crystalline solid) and determining relative crystallinity through differential scanning calorimetry. Polyurethanes were then synthesized using polytetramethylene ether glycol, 1,4-butanediol, and the diisocyanate blends. The relationship between dimensional stability and residual functionality were investigated via real-time Fourier transform infrared spectroscopy and corroborative small amplitude oscillatory shear rheology, resulting in the degree of conversion at the critical storage modulus value of 1000 Pa (print-stability threshold). This research provides a systematic study on the interdependencies of diisocyanate blend reactivity and processability for the ARE synthesis of dimensionally stable polyurethanes.

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Conference: SAMPE NEXUS 2021

Publication Date: 2021/06/29

SKU: TP21-0000000481

Pages: 14

Price: FREE