Title: Influence of Vacuum in Isothermal Healing of Additively Manufactured Thermoplastic Composites

Authors: Jimesh Bhagatji, Ryan Guenthner, Oleksandr Kravchenko

DOI:

Abstract: This study examines the role of vacuum in enhancing isothermal healing during hot isostatic pressing (HIP) of fused deposition modeling (FDM) thermoplastic composites composed of long discontinuous (LCF) and short carbon fibers (SCF) embedded in a semi‑crystalline PA6 matrix. While FDM enables tailored fiber orientation for improved structural and functional performance, printed parts often exhibit high void content (1520%) and inter/intra‑bead cracks, which degrade mechanical and thermal properties. The vacuum‑assisted HIP (VaHIP) process is a partial‑melt treatment conducted at isothermal temperatures in an autoclave. Mechanical testing post‑VaHIP revealed performance gains: flexural modulus and strength increased by 74% and 64%, respectively, while tensile modulus and strength improved by 54% and 44%. VaHIP also showed substantially enhances thermal transport in all directions, increasing through‑thickness conductivity to 0.708 W/mK, which is 75% higher than pristine SCF‑LCF; in the in‑plane directions, conductivity increases to 0.98 W/mK longitudinally, representing a 86% increases relative to the pristine SCF‑LCF state. The process-structure-property relationships established here provide a framework for designing vacuum‑assisted consolidation cycles that tailor crystallinity and interlayer fusion FDM processed components for structurally and thermally demanding applications such as fuel‑cell bipolar plates and aerospace heat‑managed structures.

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Conference: SAMPE 2026

Publication Date: 2026/04/27

SKU: 82

Pages: 16

Price: $32.00