Polypropylene Copolymers Designed for Fused Filament Fabrication 3D-Printing

Abstract

Several chemical properties which influence the printability for fused filament fabrication 3D-printing are derived from analyses of commercially available filaments. In preliminary experiments, polymerization conditions are optimized and suitable monomers and selectivity control agents (donors) are selected. An experimental series in which propene is copolymerized with the comonomers 1-butene and 1-hexene with an industrial Ziegler–Natta catalyst will be discussed here. The experiments are planned using design of experiments. Based on a split-plot design, the design is adapted for mixtures and the combination of homo- and copolymerization. The observed factors, besides the mixture composition, are hydrogen partial pressure and the amount of donor. The obtained polymers are analyzed by means of high-temperature size exclusion chromatography, differential scanning calorimetry, and rheology. 1-Butene copolymers show good printing results and promising properties almost matching the desired ones. The targeted polymer properties are achieved within certain limits. 1-Hexene copolymers result in lower molecular masses while crystallinity remains slightly higher, which does not match with the desired profile. Beneficial properties are likely to be achieved within a wider factor range, for example, higher comonomer amount and lower hydrogen partial pressure.