Effect of organoclay as a compatibilizer in poly(lactic acid) and natural rubber blends

• We investigate the role of organoclay in PLA and natural rubber blend.
• The clay acts as a compatibilizer below a critical content.
• The clay acts as a reinforcing filler above a critical content.
• We correlate the change in mechanical property with the localization of the clay.

In this study, the effect of organoclay as a compatibilizer in immiscible poly(lactic acid) (PLA) and natural rubber (NR) blends was studied. Structural development of PLA90/NR10 blend was examined depending on the clay content (0.5–10 wt%). The drop size of the dispersed NR phase initially decreased and then remained constant as the clay content increased. Below the critical concentration (3 wt%), the clay was selectively localized mostly at the interface between the matrix phase (PLA) and the dispersed phase (NR), whereas the clay particles were additionally observed in the matrix phase above 3 wt%. XRD analysis revealed that the gallery structure of the clay was highly dependent on the concentration and selective location of the clays. The development of the structure and the physical properties of the blend were also investigated according to the clay contents by measuring the linear viscoelasticity and surface tension. The degree of clay exfoliation was analyzed quantitatively in terms of the modulus ratio of PLA/NR/clay and PLA/clay. The elongational behavior and mechanical properties of the blends were strongly dependent on the location of the clays. The clay worked as an efficient compatibilizer below the critical content, while it worked as a reinforcing filler above the threshold, making the matrix more rigid.

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