Crystal structure transformation and induction of shear banding in Polyamide 11 by surface modified Cellulose Nanocrystals

Publication date: 7 April 2017
Source:Polymer, Volume 114
Author(s): Shane X. Peng, Shikha Shrestha, Jeffrey P. Youngblood
Polyamide 11 (PA11) nanocomposites reinforced with Cellulose Nanocrystals (CNC), dodecanoic acid surface modified CNC (CNC_d), and CNC with methyl laurate (CNC + ML) as plasticizer were fabricated. With the addition of CNC alone, tensile modulus and strength of the PA11 were improved, but the toughness decreased at high CNC concentration. Using CNCs that were surface modified, the tensile modulus and strength both increased while the toughness of PA11 was preserved. CNC_d also led to the formation of shear band like structures during uniaxial tensile testing. When PA11 and nanocomposites were annealed near their melting point, a higher Tm peak indicated that smaller crystals were melted and recrystallized. The addition of CNC inhibited this transformation, while CNC_d promoted it at early stages of annealing. Overall, the combination of shear banding and crystal transformation inducing properties of surface modified CNC provides an intriguing option for future improvement of CNC polyamide nanocomposites.

Graphical abstract

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