Compatibilization and degradation of PLA composites reinforced with sisal fibers

• Grant number: 17/18678-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): March 01, 2018
• Effective date (End): December 31, 2018
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Nonmetallic Materials
• Principal Investigator: Silvia Helena Prado Bettini
• Grantee: Julia Florez Ablan
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

The PLA is an eco-friendly polymer known for its good mechanical performance. Therefore, it is an excellent candidate for the replacement of polluting commodity polymers. The high price of PLA prevents it from occupying a more important role in the market. This issue can be solved reinforcing the PLA with natural fibers that increase their mechanical properties and reduce its cost, making it a more competitive product. Compatibilizers are used in order to obtain a good interfacial cohesion between the polymer and the fiber. Nevertheless, previous studies have shown that these compatibilizers can degrade the polymeric matrix. As a result, in spite of the good matrix-fiber cohesion the mechanical properties can be strongly compromised. Additives can be used to reduce the degradation; however, they can prejudice the interfacial cohesion. For this reason, this project intends to evaluate the effect of a compatibilizer, PLA grafted with maleic anhydride (PLA-g-MA), and an additive, containing carbodiimide groups, in the mechanical properties of PLA composites with 30% of sisal as the reinforcing fibers. In this sense, it will be made a 22 factorial experiment where the two factors will be the PLA-g-MA concentration and the additive concentration, maintaining constant the sisal proportion. A double screw extruder will process the PLA. Tensile tests will be made for the evaluation of the mechanical properties. Size-Exclusion Chromatography (SEC) analyses will be able to determine the molar mass of the polymeric matrix. Scanning Electron Microscope (SEM) fracture surface images will allow the evaluation of the matrix-fibers interfacial cohesion and finally, Differential Scanning Calorimetry (DSC) analyses will help in the thermal characterization and the degree of crystallinity of the samples. (AU)