Mohammadali Azadfar

The surface chemical compositions of powdered cellulose have been characterized utilizing X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) techniques. Powdered cellulose was prepared by milling of bleached softwood pulp residues through a lab-scale planetary ball mill. Here we show how milling a mixture of the powdered cellulose with potassium hydroxide determines the surface chemical compositions of the obtained powdered cellulose, in a completely dry condition. The XPS analysis indicated the presence of new carbon and oxygen atoms as C4, C5, and O3. In turn, the FTIR analysis showed the stretching vibrations of the carbon–carbon double bond. The results suggest the formation of active oxygenated species on powdered cellulose surfaces.

Powdered cellulose-reinforced (20 wt%) polypropylene composites were prepared by melt compounding and subsequent injection moldings. We assessed the effect of cellulose reducing ends on the capacity of powdered cellulose to reinforce polypropylene composites after seven days exposure to air circulation during the conditioning of samples. Tensile tests on the composites were performed at 5.08 mm/min. Fourier transform infrared spectroscopy revealed some changes that occurred within the composites by demonstrating a practical decrease in –C=O (1744 cm⁻¹) absorption band intensity. A thermogravimetric analysis indicated differences within the thermal behavior of the prepared composites, showing a higher onset of degradation. Scanning electron microscopy of the fracture areas, together with load–extension curves, further characterized the development of interfacial cellulose/matrix adhesion as well as the brittle and ductile behavior of the composites. The results indicate that the thermal and tensile properties of powdered cellulose/polypropylene are improved by decreasing the amount of cellulose reducing ends in the system.