Motivated by many exclusive and useful features of cellulose nanocrystals (CNC) and the underutilized resource of waste newspaper, this study aimed to extract CNC from waste newspapers by means of alkali and bleaching treatments followed by acid hydrolysis. The morphological structure of the obtained CNC was analysed by optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) methods. The remarkable removal of surface contamination and the reduction in fiber diameter during alkali and bleaching treatment were observed and the nano-dimension of the extracted CNC was revealed with the average diameter of 12.3 ± 2.8 nm. Characterization of the extracted CNC showed a high whiteness index of 80%, and high transparency of about 80% of the light at 600 nm calculated for a 0.02 mm thick nanocellulose film. Fourier transform infrared spectroscopy (FTIR) indicated that lignin, hemicellulose and other coloring agents were successfully removed. A comparably high crystallinity index of 80.15% was calculated from x-ray diffraction data. Thermogravimetric analysis showed that the product had a typical maximum thermal degradation at 300 °C. The analysis results indicated the successful extraction of good CNC from waste newspaper with the shortest processing time ever reported for acid hydrolysis with conventional alkali and bleaching pretreatment. The findings also strongly support for further research of nanocomposites reinforced by CNC produced from waste newspaper.

Experimental studies on polymer materials with spatially graded structures are reviewed in this paper. A wide variety of principles and experimental methods utilized to prepare and control these specific structures of polymer materials are summarized and discussed. In particular, the method of using light to generate and control these gradient morphologies in the micrometer scales is summarized with great detail for binary polymer mixtures. Finally, recent studies on copolymers with various gradient compositions at nanometer length scales are also summarized in this review.