Dielectric Relaxation in Cellulose and its Derivatives

Dielectric Relaxation in Cellulose and its Derivatives

The relaxation processes in cellulose, methyl cellulose, hydroxypropyl cellulose, and hydroxypropylmethyl cellulose were studied by dielectric spectroscopy. The dielectric spectra for these polysaccharides were measured in the frequency range from 100 Hz to 1 MHz and in the temperature range from 100 to 450 K. The dielectric relaxation data for cellulose, methyl cellulose, hydroxypropylmethyl c...

Study of Sorption Properties of Cellulose and Its Derivatives

The sorption of vapors by cellulose samples and by some cellulose derivatives was studied at 25 o C. To describe sorption isotherms, a thermodynamic equation was proposed: A=Ao/[1-(RT/g)lnφ], where Ao is maximal sorption value, φ is relative pressure of vapors, and g is specific thermodynamic potential. Depending on the g-value, this equation can describe isotherms of various shapes that occur ...

Nanofibers of cellulose and its derivatives fabricated using direct electrospinning.

A short review with 49 references describes the electrospinninng (ES) process for polysaccharides, cellulose and chitosan, and their derivatives, including cellulose acetate and hydroxypropyl cellulose. A majority of applied studies adopted a two step-process, in which the cellulose acetate was used for the first ES process, followed by acetyl group removal to regenerate cellulose thin fibers. ...

Application of Cellulose and Cellulose Derivatives in Pharmaceutical Industries

Dielectric Relaxation of Diethylsulfoxide

The dielectric loss spectrum of the title substance has been measured in its pure liquid state between 10 MHz and 72 GHz at 20°C. In comparison to the Debye function, it is slightly broadened towards the high frequency side. The maximum corresponds to a relaxation time of 51 ps. In view of the molecular size and viscosity, this is relatively long and thus indicative of associative intermolecula...