*2.3. Characterization*

IR spectra were obtained on an IR spectrophotometer SPECORD 75 UR at 20–25 ◦C in the frequency range 4000–500 cm−<sup>1</sup> under the following conditions: slit—3, recording time—13.2 min., time constant—1 s.

Conductometric studies of polyvinyl alcohol solutions were carried out on a combined TDS-meter HM digital COM-100 (HM Digital Inc., Redondo Beach, CA, USA), scale range:


Microscopic studies were carried out using the electron microscope Digital Microscope HD color CMOS Sensor (Shenzhen Huahai Hong Communication Technology Co. Ltd., Changzhou, Jiangsu, China).

The viscosity was determined according to ISO 2431. The method is based on determining the viscosity of a solution, with the free flow being taken as the time of continuous flow in seconds of a volume of 50 mL of the test material through a calibrated nozzle with a 4 mm diameter and a VZ-246 viscometer at a certain temperature.

The gelation time was determined by the loss of stickiness time [27].

The water absorption of hydrogel film samples in cold water was carried out according to ISO 62:2008.

Antibacterial properties were determined by the inhibition time of the active growth zones of *Aspergillus niger* (*A*. *niger*) molds on the surface of HESBHM in a nutrient medium using an electronic microscope, the Digital Microscope HD color CMOS Sensor.

The method described in ISO 846:1997 was used to measure the degree of biodegradation.

cording to ISO 62:2008.

**3. Results and Discussion**

als [31,32].

Sensor.

radation.
