Authors:D. Berkün, D. Balköse, F. Tıhmınlıoǧlu, and S. Altınkaya
Two types of films consisting of sodium salt of carboxymethyl cellulose (NaCMC) and hydroxypropyl cellulose (HPC) as film
forming materials and glycerin as plasticizer were prepared, characterized and their water vapour sorption properties were
The water sorption isotherms of the films were measured using a magnetic suspension balance. Results show that diffusion of
water vapour in NaCMC based film is faster than that in HPC based films, due to the heterogeneous structure and larger pore
dimensions of the NaCMC films.
Authors:Géza Regdon Jr., Diána Hegyesi, and Klára Pintye-Hódi
The aim of our research was to investigate the effect of the length of the polymer chain and the concentration of triethyl citrate used as a plasticizer on the thermal stability of the film structure in the case of two ethyl cellulose films (EC 10 and EC 45) used for preparing MR dosage forms. The influence of storage time was studied by monitoring the changes in the thermoanalytical parameters and by performing TG–MS examinations. It was found that the decomposition of the plasticizer from the arising film structure is retarded and a more homogeneous sample, therefore a better film can be prepared from EC 45. Mass spectrography performed as a coupled technique also proved that the films stayed stable until approximately 200 °C. Based on the above results, the composition prepared from EC 45 polymer with 5% triethyl citrate as plasticizer is recommended for making MR dosage forms.
Authors:Krystyna Cieśla, H. Rahier, and Grażyna Zakrzewska-Trznadel
One to three endothermal peaks atributted to melting of bulk and interfacial water were observed by DSC in the regenerated
cellulose — water system. The profiles of thermal effects depend on water content, time of conditioning, film pretreatment
and the conditions applied during the preceding freezing-thawing cycles. The occurrence might be deduced of melting-crystallisation
processes. A large amount of non-freezable strongly bounded water was also detected.
Although cellulose absorbs water quickly after immersion, the structural changes consisting on ordering of polymer fraction
occur during further conditioning due to increase in strength of water binding. Using the membranes in the separation module
at 90C causes weakening of these bonds. Differences between interaction of particular cellulose films with water can be detected
during the first, the second and the third heating.