Paper by Wang, Gardner Published in Polymer

A paper by Lu Wang and Dr. Douglas Gardner was accepted for publication in Volume 113, March 2017 edition of Polymer. The paper is titled, “Effect of fused layer modeling (FLM) processing parameters on impact strength of cellular polypropylene.”

Highlights from the paper:

• This is the first research to study polypropylene (PP) by fused layer modeling (FLM) from a cellular plastic perspective.
• Izod impact strength of PP from FLM can be similar to injection molded PP by controlling the processing parameters.
• Increase in β-cystal content was the major source for improved Izod impact strength during FLM.


Fused layer modeling (FLM) or fused deposition modeling (FDM) can be used to produce polymer components with a cellular structure. The existence of cells (voids) in FLM parts degrades mechanical properties. This study was done to understand the influence of two printing parameters, layer height (0.1 mm and 0.3 mm) and extrusion temperature (200 °C and 250 °C), on the Izod impact strength of polypropylene (PP). Morphological analysis showed that smaller layer height and higher extrusion temperature generally resulted in smaller cell size but larger cell density. Printed PP components were lighter than injection molded PP parts. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses confirmed that both α and β type crystals existed in printed PP. PP printed at 250 °C had lower impact strength while components printed at 200 °C had similar impact strength to injection molded PP.


This work was supported in part by the Maine Agricultural and Forest Experiment Station (MAFES) project ME0-M-8-00527-13 and the USDA ARS Forest Products Research Agreement 58-0202-4-003.


Authors thank J. Elliott Sanders for the CAD drawing and Dr. Alper Kiziltas and Emily Pfaff from Ford Motor Company for performing the impact tests.


Lu Wang, Douglas J. Gardner, Effect of fused layer modeling (FLM) processing parameters on impact strength of cellular polypropylene, Polymer, Volume 113, 24 March 2017, Pages 74-80, ISSN 0032-3861, (