Effects of the organic modification of different clay minerals and their application in biodegradable polymer nanocomposites of PHBV

• Halloysite and montmorillonite were modified with (3-aminopropyl)triethoxysilane.
• PHBV nanocomposites with 3 mass% of modified clay minerals were prepared.
• The interactions of the functional groups with the polymer matrix were evaluated.
• Different results were found depending on the interactions between the components.

The aim of this work is to study the interactions of different nanoparticles modified with (3-aminopropyl)triethoxysilane (APTES) and to relate them with the morphology and the final properties of the PHBV nanocomposites. The compounds were prepared by melt processing in a twin screw extruder with 3 mass% of nanoparticles and the resulting nanocomposites were physically and mechanically characterized to evaluate the effect of the different reactive groups available for interactions within the polymer matrix. The nanocomposites prepared with either the unmodified montmorillonite (Mt) or the modified (m-Mt) form presented similar or improved thermal and mechanical properties of the matrix, while those prepared with organically modified halloysite (m-Hal) presented a general decrease in the properties compared to neat PHBV. The differences between the properties can be attributed to the different interactions of the clay minerals with the modifier and with the polymer. In the m-Hal the amino groups are located at the edges and freely react with the carbonyl groups of the PHBV decreasing its molecular weight. In the m-Mt, these groups are confined to the clay mineral interlayer and thus the interactions with the polymer are nondestructive.

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