Fig. 4: Reactive infiltration and demonstration of high strength and washout capability.
From: Additive manufacturing of strong silica sand structures enabled by polyethyleneimine binder
a 1H NMR spectra of ECA (Blue), PEI (Red), and ECA: PEI = 5:1 (Black) in CDCl3 at room temperature. (1) and (2) Representative of C=C (3) Representative of CH2 (4) Representative of CH3 (5) Representative of all primary, secondary, and tertiary amine connected to CH2 (6) Representative of Michael Addition reaction (7) Representative of anionic addition polymerization of ECA. b Michael addition and ECA polymerization mechanism. c Demonstration of high-strength PEI + ECA sand part by the survival of a part run over by a car and supporting an aluminum block that is 300 times its weight on the 6.5 cm bridge. d Washout properties of PEI and PEI + ECA parts, and formation of advanced fiber composites by washout tooling.
