Research Thrust III

Thrust III in Big Picture

The simulations across different length scales need the support from experimental inputs. The motivation of this RT is to (1) provide experimental validations for the DLC predictions and AI-enabled materials and process designs, including those for high temperature and/or high strain rate conditions, as well as optimized properties related to them; (2) experimentally create composites discovered by the inverse design platform with pre-determined microstructure parameters both for the matrix and the filler system; and (3) provide material and processing inputs and correlation feedback to the AI-based inverse design platform and E3 model via the use of experiments and a machine-agnostic process-monitoring.

Objectives of Thrust III

Construct polymer composites with high-fidelity physical microstructure optimized by the multiscale modeling and AI-enabled composite design
Create a transformative open framework for discovering and implementing fundamentally new/hybrid thermoplastic composites processes that combine existing or new scalable processing routes
Integrate the sustainable characteristics into the inverse design by establishing feedback between the composites data and the manufacturing framework

Experimental Research

Characterization: Microstructural-Mechanical-Physical Properties of Additive Manufactured Materials

Composite test specimens were prepared at SRNL using additive manufacturing (3D printing)
Characterization of samples have been performed at the University of Florida.
Carbon fiber loaded amorphous thermoplastic composite samples were prepared via fuse deposition modeling (FDM) using a variety of base materials and both continuous and chopped carbon fiber reinforcement.
A continuous fiber extruder head and heated build chamber are currently under development.

Sternberg, J. & Pilla, S. Chemical recycling of a lignin-based non-isocyanate polyurethane foam. Nature Sustainability, 6, 316–324, 2023.

Optimized Chemical Recycling Platform and Synthesis from Recycled Content towards Discovery of New Polymers

Post-consumer PET has been chemically recycled using a series of diamines, creating amine-terminated precursors for polymer synthesis. Initial polymerization reactions have yielded rather low molecular weights from these precursors (~ 5000 kDa) demonstrating the need to optimize the recycling strategy to create higher performing polymers. Despite low molecular weight results, polymers synthesized from recycled products have shown impressive thermal properties with high melting points (225C – 270C) and thermal degradation temperatures (T5% ~ 400C).

Microstructure Control: Sequential Dual Alignments Approach for Printing Platelet-Based Composites

Sequential dual alignments approach for printing hexagonal boron nitride platelet-based composites was explored employing an extrusion printing-induced force and rotating magnetic field (RMF)-induced force couple for platelet alignment in a yield-stress matrix bath. The dual-alignment approach induces a synergistic effect on thermal conductivity improvement compared to the cumulative influence of individual extrusion and magnetic field-assisted approaches. Particularly, the thermal conductivity of the 40% mhBN/epoxy composites, aligned with the sequential dual-alignment approach, is 692% higher than that of unaligned composites, and this outperforms the sum of using two individual methods collectively (133% improvement only) by more than five times, meaning a five-time more synergistic effect.

Chen, Y., Gao, Z., Hoo, S.A., Tipnis, V., Wang, R., Mitevski, I., Hitchcock, D., Simmons, K.L., Sun, Y., Sarntinoranont, M., Huang, Y., “Sequential Dual Alignments Introduce Synergistic Effect on Hexagonal Boron Nitride Platelets for Superior Thermal Performance,” Advanced Materials, Accepted, 2024.

S.A. Pradeep, H. Kharbas, L-S. Turng, A, Avalos, J.G. Lawrence, G. Li, S. Pilla, Advancements in Bimodal Foam Generation in PLA-PBSA Biopolymer Blends via Supercritical Fluid-Assisted Injection Molding, Manufacturing Letters, accepted, 2024.

New Composites and Processes: Generation of Bimodal Cellular Structures in PLA/PBSA through ScF IM

We have demonstrated successful generation of bimodal cellular structures in PLA/PBSA through ScF IM. The incorporation of a compatibilizer significantly influenced the foams cell morphology, resulting in a bimodal distribution that enhanced the mechanical stiffness. Bimodality was attributed to the interface of the compatibilized blend serve as nucleation sites for multimodal cellular distributions.The amalgamation of bimodal cellular distribution leading to a 3 % increased crystallinity in compatibilized foams offers a promising avenue for future research.