Polylactic acid (PLA) has many advantages so that it is currently used in packaging materials, 3D printing, agriculture, medical, textile, and other fields, most of which are disposable products or have relatively short use cycles.
Commercial PLA itself has very obvious disadvantages, such as low crystallization rate, poor toughness, and non-flame retardant, which greatly limit the application of PLA in automotive and electronic fields. If we move to the high-end field, we need to overcome performance deficiencies and take the route of high performance. It is mainly the research of durability, and specifically, the development of PLA materials with high toughness, heat resistance, good mechanical properties, hydrolysis resistance, and excellent flame retardant properties. This article focuses on describing the hydrolysis-resistant modification of PLA.
As a polyester material, PLA is highly susceptible to degradation by the attack of water molecules. Hydrolysis is a major drawback for PLA in most cases, such as hydrolysis during processing, storage, and use of PLA, which can cause degradation of performance. Therefore, it is extremely necessary to modify PLA with anti-hydrolysis.
At present, the methods of PLA anti-hydrolysis modification mainly include blending with hydrophobic polymers, PLLA/PDLA riser compounding, and the addition of anti-hydrolysis agents. Among them, adding an anti-hydrolysis agent is simple and easy, and the effect is good.
The -N=C=N- functional group of carbodiimide is very easy to react with the carboxyl group at the end of polyester to form a stable acylurea structure (Figure below).
A small amount of carbodiimide can significantly improve the hydrolysis resistance of polyesters. After the addition of carbodiimide anti-hydrolysis agent HyMax 1010 to PLA, the effect on the hydrolysis performance of PLA was tested by aging test, and it was found that the addition of HyMax 1010 significantly prolonged the degradation process of PLA film.