Semi-Crystalline Polymer Blends for Material Extrusion Additive Manufacturing
Semi-crystalline build materials are widely used in traditional manufacturing of polymer products but are difficult to process via the fused filament fabrication (FFF) sub-category of material extrusion additive manufacturing (AM). The significant change in specific volume occurring during crystallization often leads to warpage induced build failure in FFF. Without a rigid mold, this is challenging to overcome through process parameter optimization. Work presented in this paper introduces delayed and discretized total crystallization as characteristics of polymer blends mitigating failure caused by warping during FFF. The authors have investigated a series of poly(ethylene terephthalate) (PET)/polypropylene (PP)/maleic anhydride–graft–polypropylene (MA-g-PP) blends and have analyzed the effect of thermal and morphological characteristics on printability. These blends can be extruded into a filament and printed into a three-dimensional structure. Extrapolations from this success indicate a slow rate of crystal growth and dispersion of discrete semi-crystalline polymer phases that are generalizable trends for FFF target morphology.
C. Chatham, C. Zawaski, D. Bobbitt, T. Long, and C. Williams. “Material extrusion additive manufacturing of semi-crystalline poly(ethylene terephthalate) via blending with polypropylene.” MII Technical Conference and Review. April 15, 2018. Blacksburg, VA
C. Chatham, C. Zawaski, D. Bobbitt, T. Long, and C. Williams. “Material extrusion additive manufacturing of semi-crystalline poly(ethylene terephthalate) via blending with polypropylene.” SPE ANTEC & National Plastics Expo. May 8-9, 2018. Orlando, FL.
Camden A. Chatham, Garrett Godshall