Tomsk team examine annealing on 3D PLLA/HAp scaffolds

3D microfluidics. Using 3D capabilities of the feature-based software, bridges were printed to create an overlapping design with three channels from an offset (a) and side (b) view. (d)Top view – overlapping channels remain separate from one another. (c) Side view – the bridging structure raises off the plane of the glass slide. The expanded view shows the printing direction for the bridging structures. (e) The microfabricated structure along with an inset of the chambers with each channel independent of one another. (f) Shows 3D printed structures connecting channels and overlapping to simplify the device control.

Scientists from Tomsk Polytechnic University have recently published ‘Effect of annealing on mechanical and morphological properties of Poly(L-lactic acid)/Hydroxyapatite composite as material for 3D printing of bone tissue growth stimulating implants’.

Although annealing is a common topic regarding ways to strengthen mechanical properties in 3D printing, here the authors examine its effects on 3D-printed PLLA/HAp composite scaffolds of three compositions (12.5, 25, and 50 wt.% of HAp), using both electron microscopy and nanoindentation.

The potential for success with biodegradable implants is great, leading the researchers to biodegradable implants made of thermoplastic polymers and polymer composites. Their ability to re-absorb into the body without presenting toxins is an enormous advantage.

In experimenting through FDM 3D printing, bending and deviation were noted in scaffolds after the annealing process. Scaffolds were cooled during the printing process, causing smaller, denser crystallites. Volumetric transformation in the crystalline structure also caused tensile stressors.

Results of nanoindentation showed growth of Young’s modulus after annealing, concluded the researchers. The maximum value of 9393 ± 709 MPa Young’s modulus was reached for the annealed composite with 50 wt.% of HAp.