Abstract Scope |
The majority of FFF feedstock has been limited to amorphous polymers due to the shrinkage or poor adhesion during printing of semi-crystalline polymers. In comparison to amorphous polymers, the process/structure/property relationship for semi-crystalline polymers in FFF is not well established. As FFF printing process induces a variable thermal history, the resultant part’s crystallinity can vary significantly, which prevents FFF from producing semi-crystalline parts that offer constant and ideal performance. In this work, a widespread semi-crystalline polymer (Poly(ethylene terephthalate, PET) is processed via FFF, to explore process/structure/property relationships. The authors investigate two influencing factors of thermal history: the specific area (SA), which affects the convective cooling efficiency, and build rate (BR), which affects the interlayer cooling time. It is shown that at higher BR, together with a smaller SA, leads to an extended time under higher temperature, thus resulting in a higher crystallinity together with an increased Young’s modulus around 20%. |