PLA Application Straw Disposable Tableware

The degradation products of PLA assist plants in photosynthesis to become raw materials for PLA, so PLA is a "cradle-to-cradle" green material. At present, PLA is the mainstream raw material for disposable tableware on the market. PLA is relatively stable at room temperature, but it is easy to degrade rapidly in a slightly high temperature environment, acid-alkali environment or microbial environment, and has poor impact resistance, which often cannot meet the requirements of circulation in harsh environments.

Methods for modifying to improve thermal stability
The thermal stability of PLA material is comparable to that of PVC, but lower than that of PP, PE and PS, and the processing temperature is generally controlled between 170~230 °C, which is suitable for ordinary processes such as injection, stretching, extrusion, and blow molding. However, in the actual processing process, the crystallization rate of PLA is slow, and modification is generally required. At the same time, due to the slow crystallization rate and low crystallinity, PLA has a low heat deflection temperature, which limits its application in hot fill or heat sterilized product packaging.

In order to increase the crystallization rate and crystallinity of PLA, the optical purity of PLA can be maximized during production. The crystallinity of PLLA containing a small amount of PDLA will be greatly reduced, annealing treatment is also a way to improve the crystallinity of PLA, in addition, a nucleating agent can be added to improve the crystallization behavior, increase its crystallinity, and then increase the heat deflection temperature and improve its heat resistance.

At present, blending with inorganic fillers or natural fibers is the main modification method to improve the performance of PLA materials in all aspects. For example, LiWH et al. modified PLA with bamboo fiber, and the bending strength and elongation at break of the composite materials were increased by 19.3% and 30.1%, respectively. Shyif et al. used the melt blending method to prepare PLA banana fiber composites, and by using coupling agent and chemical modification to combine banana fibers to the PLA chain, the thermal stability and mechanical properties of the composite materials were significantly improved.