Mechanical and barrier properties of nanocrystalline cellulose reinforced poly(caprolactone) composites: Effect of gamma radiation

Nanocrystalline cellulose (NCC) reinforced poly(caprolactone) (PCL) composites were prepared by compression molding. The NCC content varied from 2 to 10% by weight. NCC played a significant role in improving the mechanical properties of PCL. The addition of 5 wt % NCC caused a 62% improvement of the tensile strength (TS) value of PCL films. Similarly, tensile modulus (TM) values were also improved by NCC reinforcement but elongation at break (Eb) values decreased montonically with NCC content. The water vapor permeability (WVP) of PCL was 1.51 g center dot mm/m2 center dot day center dot kPa, whereas PCL films containing 5 wt % NCC showed a WVP of 1.22 g center dot mm/m2 center dot day center dot kPa. The oxygen transmission rate (OTR) and carbon dioxide transmission rate (CO2TR) of PCL decreased by 19 and 17%, respectively, with 5 wt % NCC incorporation. It was found that the mechanical and barrier properties of both PCL and PCL-NCC composites further improved with 10 kGy gamma irradiation treatment. The combination of NCC and radiation significantly increased the TS, TM, and Eb (by 156, 123, and 80%, respectively, compared to untreated PCL). The WVP, OTR, and CO2TR decreased by 25-35% with respect to untreated PCL. The surface and interface morphologies of the PCL-NCC composites were studied by scanning electron microscopy and suggested homogeneous distribution of NCC within the PCL matrix. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013