METHOD FOR DETERMINING RESISTANCE OF MATERIALS TO BIODEGRADATION Russian patent published in 2018 - IPC G01N33/00 C12Q1/02 G01N3/00 

FIELD: materials science.

SUBSTANCE: invention relates to materials science, namely to the determination of the resistance of materials to biodegradation. For this purpose prepare samples with the tested materials, sterile liquid nutrient medium (SLNM) and nutrient medium with test microorganisms (MLNM). SLNM is an aqueous solution with a pH of 6.8–7.4, containing 4–6 g/l glucose, 16–20 g/l protein hydrolyzate and 1.8–2.2 g/l NaCl. MLNM is SLNM with the addition of a strain of Escherichia coli ATSS 25922 in an amount of from 5×10⁶ up to 5×10⁷ viable cells per ml. Then the samples are incubated in SLNM and MLNM for 8–10 days at a temperature of 29–31 °C with a daily replacement of 40 % of the incubation liquid nutrient medium on SLNM. Mechanical properties of the samples are measured before and after incubation. Calculation of changes in the mechanical properties of the tested samples as a result of their degradation induced by various factors is made according to the following formulas: C_MD=100×(σ_P-σ_R)/σ_R, C_CHD=100×(σ_K-σ_P)/σ_P, C_BD=100×(σ_B-σ_K)/σ_K, where C_MD – coefficient of mechanical degradation, C_{CHD –} coefficient of chemical decomposition, C_BD – coefficient of biodegradability, σ_R – strength of samples containing reference products, σ_P – strength of samples containing test products, σ_K – strength of samples containing test products or materials, after incubating them in SLNM, σ_B – strength of samples containing the tested products or materials, after incubating them in the MLNM. With values of C_BD more than -10 % of the tested samples are considered to be hydrolytically stable in the presence of microorganisms; with values of C_BD less than -30 % of the tested samples are considered to be hydrolytically unstable in the presence of microorganisms. With values of C_CHD more than -10 % of the tested samples are considered to be hydrolytically stable in the absence of microorganisms, with values of C_CHD less than -30 % of the tested samples are considered to be hydrolytically unstable in the absence of microorganisms.

EFFECT: invention provides a rapid assessment of the hydrolytic resistance of materials to biodegradation and can be used in the development and evaluation of new materials.

1 cl, 1 tbl, 1 ex