Taipei – Polylactic acid is a polyester formed by the polymerisation of lactic acid, usually derived from the fermentation of plant starches from renewable sources such as corn. The biodegradable polymer is now in widespread use, and can also be used to make thermoplastic polyurethanes.
Scientists at Taiwan Medical University have been investigating how to tune the properties of TPUs derived from polylactic acid and MDI. They looked at the effects of the chain extenders PDO, BDO and HDO on the properties of the TPU.
All three were successfully used to make TPUs. They found that there was potential for greater crystallisation in the TPUs made with BDO and HDO, and the HDO-derived polymer with a 55% hard segment content had the highest molecular weight and fracture stress, along with an appropriate elongation value.
They also looked at the stress relaxation rates and residual forces, and found they fell within clinically acceptable ranges. They suggest that, therefore, the PLA-derived TPUs could be used in orthodontic applications.
The work has been published in the Journal of Polymers and the Environment.