Determination of melt processing conditions for high performance amorphous thermoplastics for large format additive manufacturing

As the application space for large-scale 3D printed components continues to grow, it is necessary to identify appropriate processing conditions for high-performance thermoplastics on large format Additive Manufacturing (LFAM) systems. This study compares the rheological behavior of a high-performance thermoplastic, polyphenylsulfone (PPSU), with that of a commonly used low-temperature polymer, acrylonitrile butadiene styrene (ABS), to identify suitable processing conditions for large format AM systems. The linear viscoelastic properties (complex viscosity, storage modulus, loss modulus, and tan delta) of these materials are evaluated as a function of temperature, angular frequency, and carbon fiber content. Over the range of frequencies of interest to LFAM (10-100 rad/s), ABS behaves more like an elastic solid whereas PPSU behaves more like a viscous liquid. The addition of 20-35% by weight of carbon fiber increased the shear thinning effect of both thermoplastics, showing a potential variation of 2-3 x over the range of expected LFAM extrusion shear rates (10-100 s−1).