Poly(lactic acid) (PLLA) has attracted much interest in many applications such as medical and
healthcare product, textiles, and single-use packaging. Recently, the application of PLLA has expanded to
three-dimensional (3D) printing where individually customized products are produced. A critical lack of
medical supplies and personal protective equipment has occurred during the COVID-19. Fortunately, 3D
printing technology can be an effective solution to overcome this problem. Although having high stiffness,
PLLA has a relatively low heat resistance and is considered brittle for some applications. Therefore,
simultaneous improvements of impact toughness and heat resistance of PLLA need to be made while
preserving its biodegradability and sustainability.
In this work, we present an economical and effective method for obtaining high toughness PLLA
of balanced stiffness and heat resistance by manipulating the crystallization morphology through simple
blending and heat-treatment of the molded parts under appropriate conditions within a short period. A
short period of thermal annealing (10 min) is efficient for concurrently enhancing the impact strength and
heat stability of the PLLA-based materials, without scarifying a significant loss in stiffness and strength.
The production of fully biodegradable parts with comparable properties to ABS for FDM 3D printing is
highly possible.
This research project was funded by the National Research Council of Thailand (NRCT) under the
Research University Network Initiative. Associated SDG goals are Industry, innovation and infrastructure
(9), and Responsible consumption and production (12).

Kajornprai T, Suttiruengwong S, Sirisinha K*. Manipulating Crystallization for Simultaneous
Improvement of Impact Strength and Heat Resistance of Plasticized Poly(L-Lactic Acid) and
Poly(Butylene Succinate) Blends. Polymers. 2021; 13(18):3066.