Interlaminar tensile properties of raw and carbon fiber-wrapped additively manufactured polyetherimide

High-performance engineering thermoplastics are important emerging materials, particularly when processed using additive manufacturing technologies. One of the most important among these is polyetherimide, also known as PEI or ULTEM. Using the fused filament fabrication (FFF) additive manufacturing (AM) process to form this material is a good option, but it is difficult to control the properties in some cases due to the very high processing temperature compared with most engineering thermoplastics. One way to "even-out" the properties is to wrap the specimens in continuous glass or carbon fibers embedded in a thermosetting matrix, as this allows strategic placement and orientation of reinforcement. This also complements the natural structure of the FFF-manufactured materials, helping to minimize the amount of additional weight that needs to be added to a part. To further knowledge in this area, the present study explored and compared the interlaminar tensile strength of FFF-processed PEI/ULTEM 9085 specimens and compared them with ones wrapped in carbon fibers with a 2-part resin matrix. Experiments were performed in accordance with the guidelines given in the ASTM D6415 standard and replicated five times. Variations were introduced in thickness of the specimen and raster angle during the manufacturing process to identify the significant impact of the failure. The results show a fall in interlaminar tensile strength with increasing specimen thickness and a very large effect from natural printing defects in the samples. The carbon fiber wrap decreased the ILTS but made the results far more consistent between experimental runs. This study provides a good, replicated dataset on the performance of raw and fiber-wrapped FFF-processed ULTEM 9085 and gives insights into the structural behavior of the material that will be useful for use in design decisions and material selection.Highlights Polyetherimide, also known as PEI/ULTEM, is a high-performance engineering thermoplastic. Explored the interlaminar tensile properties (ILTS) of this material using ASTM D6415. Raster angle, thickness, and use of fiber wrap were experimental parameters. Fiber wrap was found to have little effect on strength but made results more consistent. Results are useful for material selection and design decisions using PEI. Performance of FFF-processed PEI as printed and with reinforcing fiber wrapping. image