Suppression of the Skin-Core Structure of Injection-Molded Polypropylene Part: Role of Balance Effect Caused by the Incorporation of Glass Fiber

Polypropylene Random Copolymer Based Composite Used for Fused Filament Fabrication: Printability and Properties

Fused filament fabrication (FFF) is one of the most commonly used additive manufacturing technologies. However, the applied material for commercial FFF is limited. Presently, though being one of the most used polymer materials, polypropylene (PP) is rarely used in FFF because of its serious warpage and shrinkage problems. This study investigated the impact of addition of short glass fibers (GF) and ethylene propylene diene monomer (EPDM) on the printability of polypropylene random copolymer (PPR) based FFF and mechanical properties of the printed samples, as well as other properties including rheology, thermal behaviors, and morphology. The results show that the modified PPR has excellent printability, as the printed samples are of good geometrical accuracy. The addition of GF can significantly improve the strength and modulus of the composite, but it also leads to serious decrease in toughness. EPDM addition can effectively improve the toughness of the composite, showing a complementary effect with GF. This work has important meaning in expanding the FFF applicable material and in broadening the application of PP.

Suppressing the skin–core structure in injection-molded HDPE parts via the combination of pre-shear and UHMWPE

Skin–core structure of a injection-molded high density polyethylene (HDPE) part is largely relieved due to the synergetic effects of pre-shear and UHMWPE, leading to a remarkable increase of tensile strength.