Micro-composites based on polylactic acid with kaolinite or rice husk particles and their performance on water vapor permeability

ABSTRACT

In this work, the effect of addition of kaolinite and rice husk microparticles on the water vapor permeability of polylactic acid (PLA) was evaluated. The PLA-composites materials were characterized by X-ray diffraction, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and optical microscopy. For the composite preparation, an experimental design was established using two factors: additive type and concentration. When evaluating the water vapor permeability of the composites, it was found that the incorporation of kaolinite at 1% and 5% reduced the permeability coefficient of PLA. Furthermore, the inclusion of 5% kaolinite showed an increase on the tensile strength of the material. By contrast, the addition of rice husk produced an increase on water vapor permeability of the material and a decrease of both the tensile strength and ductility (percent of elongation at fracture). The higher dispersion and more regular morphology of the kaolinite particles could explain the enhancement of the gas barrier. A similar thermal behavior was observed for both PLA and composite materials, confirming that no damage of these properties was caused with the incorporation of the filler particles.

KEYWORDS:

• Polylactic acid
• composite
• rice husk
• clay
• kaolinite

Acknowledgments

The authors would like to thanks the financial support provided by “Fundación para la promoción de la investigación y la tecnología del Banco de la República” through the project 3631 entitled: “Estudio de mejoramiento en la barrera de permeabilidad a los gases de H2O y O2 en el polímero del ácido láctico (PLA) para su aplicación en el empaque de productos alimenticios.” This work was also supported by “Dirección de Investigación sede Bogotá Universidad Nacional de Colombia” through the project 308010020853.