3D printing biofilaments based on pineapple leaf fibers

Researchers at Universiti Teknologi Malaysia and Newcastle University in Singapore launched a joint research project in which they experimented with adding pineapple leaf fibers to PLA thermoplastic to develop new environmentally friendly bioplastics. The research team set out to demonstrate the cost-effectiveness of using biodegradable materials such as pineapple leaf fiber (PALF) and alkaline pineapple leaf fiber (APALF) in combination with PLA granules to produce filaments for 3D printing.

The research was successful, and the resulting PLA composite fiber reinforced with pineapple showed improvements in many mechanical properties. This means that adding powdered pineapple fibers to PLA can actually increase the strength-to-weight ratio (specific strength) of your printed samples. Additionally, the samples showed improved crystal properties, chemical bonding and thermal properties.

Pineapple leaves were brought from Thailand, cut into smaller pieces and then pulverized by hand using a pestle and mortar. The powdered leaf material has been surface-modified by adding sodium hydroxide solution (lye), which is a caustic base. After soaking in the lye solution for one hour, the PALF was removed and washed to remove excess alkaline solution. The PALF treated were then neutralized with acetic acid prior to oven drying. The result was APALF, which was then pulverized.

After the PALF and APALF powders were formed, they were mixed with unmodified, finished PLA granular raw material and extruded on a filament making machine.

After the extrusion process, the pineapple-PLA composite was ready for printing on test samples. Various variants of the APALF / PLA and PALF / PLA composites were made with different amounts of plant matter in weight percent ranging from 0% to 5% PALF / APALF content, the remainder being unmodified PLA.

Samples of various compositions were subjected to mechanical tests of tensile and bending strength, as well as various chemical, thermal, crystallinity and microstructure analyzes. The results were as follows:

• pure PLA samples have a tensile strength of 29.5 MPa; adding 3% PALF and APALF increases the tensile strength to 42.3 MPa and 42.9 MPa, respectively;
• in the case of flexural strength tests, the starting unmodified PLA was 32.2 MPa, and the maximum increase in flexural strength was again achieved by adding 3% PALF / APALF, which increased the flexural strength to 48.5 and 51.9 MPa, respectively;
• fracture elongation and fracture toughness showed similar results.

Ultimately, scientists determined that 3% was the optimal saturation of PALF or APALF to PLA. The results showed that using the optimal combination of PALF or APALF, it is possible to create biodegradable materials based on pineapple fibers.

Source: www.onlinelibrary.wiley.com via www.3dprinting.com
Photo: www.pixabay.com