PHA filament in practical testing: biodegradable, temperature-resistant, but expensive and with a post-curing time

PHA filament is considered a possible alternative to PLA in FDM 3D printing. PLA is the standard for many applications and is considered easy to print, but its biodegradability is often overestimated: industrial composting conditions are necessary for it to degrade. PHA (polyhydroxyalkanoates) are polyesters formed by microorganisms, often through bacterial fermentation. The advantages cited are biodegradability without an upstream hydrolysis step, UV stability, and, in the case of PLA-PHA blends, higher toughness and better temperature stability. According to the source, PHA also has applications in medicine, including where support structures are intended to dissolve over time.

JanTec Engineering has tested PHA in practice and mechanically. The filament used comes from Polar Filament and is listed at $39.99 per kilogram; a 6691 certificate for marine biodegradability is also mentioned. PLA parameters were used as a starting point: print bed 0 °C, nozzle 210 °C for the first layer and 195 °C for the subsequent layers, plus a reduced maximum volume flow. FrogTape is recommended for adhesion; in the test, masking tape and a smoother adhesive tape also worked after initial adhesion problems. PHA was also printed on a PLA layer.

In the tensile tests, the strength in the Z-direction, which is an indicator of layer adhesion, was rather low. The 3-point bending test resulted in a bending modulus of around 1900 MPa, comparable to PETG. In the impact test, the notched impact strength was around 20.4 kJ/m², about four times higher than for “normal” PLA. A heat test showed failure under load at 110 °C; the density is specified as 1.26 g/cm³.