The applications of additive manufacturing (AM) for producing complex, precisely designed structures by using high performance thermoplastic polymers are currently receiving remarkable attention. It is expected that the inherent advantages of high performance thermoplastics regarding mechanical strength, thermal stability, and chemical resistance can be transferred into additively manufactured structures for end-use purpose. However, unlike conventional molding methods where the solidification of the polymer occurs continuously in a confined cavity, extrusion-based additive manufacturing takes place in a highly non-isothermal condition, the bonding strength of successive layers are dominated by several discrete events during the extrusion and deposition processes. In particular, for semicrystalline polymers, the first-order phase transition by which a supercooled polymer fluid transforms into its semicrystalline form remains unclear regarding the evolution of microstructure during solidification. Polyphenylene sulfide (PPS) is a semicrystalline thermoplastic utilized in demanding engineering applications. The presence of repeating phenylene linkages in the backbone induces regularity and rigidity to the molecular chain due to the energy barrier associated with the conformational change of the repeating aromatic ring structure. As a result of these structural characteristics, PPS possesses several desirable properties such as a relatively high melting point, as well as remarkable mechanical strength. In this study we shall illustrate the crystal structure of a carbon fiber filled PPS composite resulting from a large-scale AM process. The study is focused on characterizing the state of the crystalline domains located in vicinity of the interfacial region that is formed under a non-quiescent condition in a large-scale AM process. The aims of the study are to establish fundamental understanding of the microstructure and related properties of carbon fiber filled PPS fabricated by a large-scale AM process. It is hoped that this study will provide insight into advancements of processing high performance polymers by using large-scale AM techniques.

Structure-property relationships in additive manufacturing of carbon fiber reinforced polyphenylene-sulfide

256th National Meeting (2018)

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