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Atomic force microscopy investigation of electron beam (EB) irradiated composites based on biodegradable polymers and coconut fiber*

Kodama Y., Oishi A., Nagasawa N., Nakayama K., Tamada M., Machado L. D. B.

Nukleonika

2013

Vol. 58, No. 4

459--468

In this study, the addition of natural fibers to biodegradable PCL, PLLA blend and the effect of ionizing radiation on the surface of composites were investigated by force modulation microscopy (FMM), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Hot pressed sheets were prepared using pellets of twin extruded PCL:PLLA 20:80 (w:w) blend containing 5% or 10% weight concentration of coconut fiber. In this study coconut fibers non treated chemically and acetylated ones were used. Irradiation was performed using an electron beam (EB) accelerator and an absorbed dose of 100 kGy. FMM images acquisition was obtained using a silicon cantilever, intermittent contact mode (tapping mode). Also, AFM images were obtained using tapping mode but J scanner. By FMM, it was possible to observe regions with different elasticity indicating fiber presence under the surface of the composite. Furthermore, it appears that the spherical structures size decreased on composites. This probably was induced by ionizing radiation.

Investigation of irradiated biodegradable blends by FTIR and wide-angle X-ray diffraction

Kodama Y., Machado L. D. B., Giovedi C., de Lima N. B., Nakayama K.

Nukleonika

2009

Vol. 54, No. 2

107-113

In the present work, twin screw extruded films of PLLA and PCL biodegradable homopolymers and 50:50 (w:w) blend were irradiated with gamma rays from Co-60 and electron beam at doses in the range of 50 to 500 kGy in order to evaluate the effect of irradiations on homopolymers and blend. The FTIR results have shown that this technique was neither sensitive enough to observe the degradation promoted by ionizing radiation of studied homopolymers and blends and, nor on the miscibility of the blends. Wide-angle X-ray diffraction (WAXD) of PCL samples, non-irradiated and irradiated showed two strongest reflections at angles 2theta = 21.4 degrees centigrade and 2theta = 23.7 degrees centigrade that have been attributed in the literature to the (110) and (200) reflections, respectively. As for extruded non-irradiated and irradiated PLLA, it was observed broad diffusion peaks corresponding to an amorphous polymer. PLLA annealed samples showed reflections at angles 2theta =16.4 degrees centigrade and 2theta =18.7 degrees centigrade previously attributed in the literature to distorted 103 (alfa-form) helices. It was possible to observe slight alteration of the crystallite size of all irradiated samples of PCL in the dose range studied.