The effects of incorporating different cross-linking agents into starch/poly(vinyl alcohol) (PVA) blend were examined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), mechanical characterization, dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), moisture absorption tests, and scanning electron microscopy (SEM). Different cross-linkers such as borax, formaldehyde, epichlorohydrin, and ZnO were used to cross-link the films at the same weight percent. The films were prepared by gelatinization followed by a solution casting method. SEM microstructures revealed that the destructuring of starch granules was significantly influenced by the presence of cross-linkers during the gelatinization process. The extent of cross-linking was measured through the determination of the normalized gel mass and the normalized swelling degree of the films in dimethyl sulfoxide (DMSO) solvent. Tensile strength and tensile modulus were highest in borax cross-linked film, while the highest flexibility was achieved with the epichlorohydrin cross-linked film. Damping was remarkably increased, and moisture absorption was considerably decreased in the cross-linked films. The onset of thermal degradation was lowered, but the char yield was slightly increased in the cross-linked films.

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Microcrystalline cellulose (MCC) particles are mostly prepared by acid hydrolysis of various agro sources. Acid hydrolysis is usually carried out with high concentration (64 wt%) of sulfuric acid. Here, an attempt has been made to optimize lower acid concentrations which can effectively produce MCC particles. In this work, different concentrations of sulfuric acid (20, 30, 35, 40, 47 and 64 wt%) have been used to prepare MCC particles, which have been characterized by XRD, particle size analysis, scanning electron microscopy, transmission electron microscopy, nanoindentation and thermogravimetric analysis. MCC prepared with 35 and 47% sulfuric acid (MCC 35 and MCC 47) had finest particle size and fibrils were produced in the range of 15-25 nm. MCC 20 showed wide particle size distribution, indicating low breakdown of the cellulose chains. The energy absorption behavior and mechanical properties of the MCC pellets were determined by nanoindentation test for the first time. MCC 35 pellets exhibited lowest modulus and hardness.