TY - JOUR

T1 - Reducing part deformation of isotactic polypropylene specimens fabricated with powder bed fusion technique through controlling crystallization behaviors

AU - Gao, Xia

AU - Guo, Junqiang

AU - Zhang, Daijun

AU - Li, Jing

AU - Su, Yunlan

AU - Arbeiter, Florian

AU - Li, Huayi

N1 - Publisher Copyright: © 2024 Wiley Periodicals LLC.

PY - 2024/4/24

Y1 - 2024/4/24

N2 - Serious shrinkage and warpage are obstacles to the development of ideal isotactic polypropylene (iPP) materials for polymer-based powder bed fusion (PBF) technique. In this work, the variations of the dimensional accuracy of the PBF-printed iPP parts were investigated with various printing parameter and nucleating agent. The iPP parts printed at a scanning speed of 700 mm/s exhibit smaller extents of shrinkage and curling than those at lower speeds, due to a lower degree of crystallinity. Interestingly, iPP blended with the α- or β-nucleating agent demonstrates more serious part deformation with respect to neat iPP. Especially, α-nucleating agent tends to trigger the most severe curling under the investigated printing parameters. Based on X-ray diffraction and differential scanning calorimetry (DSC) results, both neat iPP and α-iPP parts crystallize into α-crystal, while β-iPP parts display the coexistence of β- and α-crystals. And, the difference of the crystallinity is less than 3% in three specimens. This suggests that both crystallinity and crystalline structure are not the main reasons for the shrinkage and warpage in this case. Instead, the severe part deformation of the α-iPP parts is assigned to the narrower sintering window as well as the higher onset crystallization temperature of α-iPP, which hinder relaxation of residual stresses. This work provides insights into the part deformation mechanism for PBF-processed polymer materials.

AB - Serious shrinkage and warpage are obstacles to the development of ideal isotactic polypropylene (iPP) materials for polymer-based powder bed fusion (PBF) technique. In this work, the variations of the dimensional accuracy of the PBF-printed iPP parts were investigated with various printing parameter and nucleating agent. The iPP parts printed at a scanning speed of 700 mm/s exhibit smaller extents of shrinkage and curling than those at lower speeds, due to a lower degree of crystallinity. Interestingly, iPP blended with the α- or β-nucleating agent demonstrates more serious part deformation with respect to neat iPP. Especially, α-nucleating agent tends to trigger the most severe curling under the investigated printing parameters. Based on X-ray diffraction and differential scanning calorimetry (DSC) results, both neat iPP and α-iPP parts crystallize into α-crystal, while β-iPP parts display the coexistence of β- and α-crystals. And, the difference of the crystallinity is less than 3% in three specimens. This suggests that both crystallinity and crystalline structure are not the main reasons for the shrinkage and warpage in this case. Instead, the severe part deformation of the α-iPP parts is assigned to the narrower sintering window as well as the higher onset crystallization temperature of α-iPP, which hinder relaxation of residual stresses. This work provides insights into the part deformation mechanism for PBF-processed polymer materials.

KW - crystallization behavior

KW - isotactic polypropylene

KW - part deformation

KW - powder bed fusion technique

UR - http://www.scopus.com/inward/record.url?scp=85191175212&partnerID=8YFLogxK

U2 - 10.1002/pol.20240121

DO - 10.1002/pol.20240121

M3 - Article

AN - SCOPUS:85191175212

VL - 62.2024

SP - 3025

EP - 3037

JO - Journal of polymer science

JF - Journal of polymer science

SN - 2642-4150

IS - 13

ER -