Composites comprising additively manufactured lattice structures and resorcinol-formaldehyde xerogels

Abstract

The ever-growing importance of saving energy implies the use of increasingly efficient insulating materials. Particularly for mobile applications, such materials also have to display light-weight characteristics. Owing to their highly open-porous nature, aerogels and xerogels are excellent insulating materials with low density [1-2]. However, their fragility limits direct applications as structural materials, e.g. in vehicles. Lattice structures offer high specific strength and can be readily produced using additive manufacturing techniques including selective laser sintering (SLS). Thus, a combination of lattice structures with aerogel materials represents a promising approach for the development of mechanically robust lightweight insulation materials [3-4]. Here, we report on the development of composites comprising polyamide 12 (PA12) lattice structures and resorcinol-formaldehyde xerogels. While the former was accessed using high-speed sintering (HSS) of PA12 powder, the xerogel filling was obtained by sol-gel synthesis followed by ambient-pressure drying. Specifically, we describe a rational approach of selecting the unit cell geometry of the lattice structure using simulation methods. The production of a variety of composites varying in unit cell dimensions and lattice strut thickness is described. The subsequent characterization of compressive and thermal properties is presented, and the findings are discussed with respect to future applicability.