Recrystallization of Cellulose, Chitin and Starch in Their Individual and Native Forms.

Semi-crystalline natural polymers are involved in many technological processes. Biopolymers having identical chemical compositions can differ in reactivity in heterogeneous transformations depending on their crystal structure (polymorphic modification). This paper compares the crystal structure recrystallization processes occurring in natural polysaccharides (cellulose, chitin, and starch) in the individual form and as a component of native biomass.

Disordering of Starch Films as a Factor Influencing the Release Rate of Biologically Active Substances.

The release of a spin probe (nitroxide radical) from polymer films was studied by electron paramagnetic resonance (EPR). The films were fabricated from starch having different crystal structures (A-, B-, and C-types) and disordering degrees. Film morphology (analysis of the scanning electron microscopy (SEM)) depended on the presence of dopant (nitroxide radical) to a larger extent rather than on crystal structure ordering or polymorphic modification.

Mechanical Amorphization of Chitosan with Different Molecular Weights.

Mechanical amorphization of three chitosan samples with high, medium, and low molecular weight was studied. It is shown that there are no significant differences between the course of amorphization process in a planetary ball mill of chitosan with different molecular weights, and the maximum degree of amorphization was achieved in 600 s of high intensity mechanical action. Specific energy consumption was 28 kJ/g, being comparable to power consumption for amorphization of cellulose determined previously (29 kJ/g) and 5-7-fold higher than that for amorphization of starch (4-6 kJ/g).