ABSTRACT HDPE‐ block ‐PA6 polymers for fused filament fabrication (FFF) were prepared in two consecutive polymerization processes. Intermediate acid chloride endfunctionalized polyethylenes (PE) of 2000 and 6500 Da were obtained in multiple steps from ethylene by the initial action of an iron bisimine pyridine catalyst. They were used as macroinitiators in the anionic ring opening polymerization of ε‐caprolactam. The degree of polymerization of PA6‐block ranged from 18 to about 300. Imaging, blending experiments (compatibilization of PE and PA6), Molau‐type testing and thermal properties show that phase‐separated block copolymers are obtained. The tensile strength of the materials was between 7.5 and 56 MPa with an elongation at break between 7% and 140%; low molecular weight block copolymers are brittle, ductile properties arise when the reaches 300 for a HDPE block of 2000 Da. FFF‐printed specimens of the block copolymer with a HDPE block of 6500 Da and of 176 could be annealed at 140°C (2 h) without a dimensional loss to yield a material with about the same mechanical properties as an injection molded sample, almost doubling the tensile strength of the FFF‐printed sample.
Schoeneberger et al. (Thu,) studied this question.