The effects of silane coupling agents on the properties of PHBV/halloysite nanocomposites

• Halloysite nanotubes were modified with different functionalized organosilanes.
• PHBV nanocomposites with 3 wt.% of halloysite were prepared and characterized.
• Nanocomposite properties were dependent on the functional group of organosilane.

The aim of this work was to characterize poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) nanocomposites with halloysite nanotube (HNT) filler, both natural HNT and HNT modified with different functionalized organosilanes. Nanocomposites with 3 wt.% HNT were obtained by melt processing in a twin screw co-rotating extruder. The nanocomposites were characterized in terms of their morphology and thermal and mechanical properties. TEM images provided evidence of the nanocomposite formation. The incorporation of modified HNT altered the mechanical properties of the material depending on the silane functional group responsible for interacting with the polymer. The HNT modified with aminosilanes did not exhibit the expected reinforcing effect. It is possible that the amino group reacted with the carbonyl group of PHBV, changing its chemical structure and thus its final properties. A thermo-mechanical study and TGA results corroborated these findings, indicating a lower viscosity and a decrease in the degradation temperatures of the polymer in the presence of aminosilane-modified HNT.

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