Lawrence Livermore National Laboratory (LLNL) material scientists have recently found that 3D-printed foam works better than standard cellular materials in terms of durability and long-term mechanical performance. As an improved alternative, scientists at the additive manufacturing lab at LLNL recently demonstrated the feasibility of 3D printing of uniform foam structures through a process called direct-ink-write. However, since 3D printing requires the use of polymers of certain properties, it is important to understand the long-term mechanical stability of such printed materials before they can be commercialized.
To address the stability question, the LLNL team performed accelerated aging experiments in which samples of both traditional stochastic foam and 3D-printed materials were subjected to a set of elevated temperatures under constant compressive strain. A method called time-temperature-superposition was then used to quantitatively model the evolution of such properties over a period of decades under ambient conditions.
This study convincingly demonstrated that 3D-printed materials age slowly — i.e., better retain their mechanical and structural characteristics — as compared to their traditional counterparts. Interestingly, native rubber (i.e. elastomer) comprising each foam showed exactly the opposite effect — i.e., the rubber in the printed material aged faster than the corresponding rubber used in the traditional foam.
“3D printing of foams offers tremendous flexibility in creating programmable architectures, customizable shapes and tunable mechanical response,” said lead author Amitesh Maiti. “Now that our work strongly indicates superior long-term stability and performance of the printed material, there is no reason not to consider replacing traditional foam with appropriately designed 3D-printed foam in specific future applications.”