[Chemical composition of linear polyurethanes and the rate of their destruction in physiological solution and animal body]. / Khimicheskoe stroenie lineinykh poliuretanov i skorost' ikh destruktsii v fiziologicheskom rastvore i organizme zhivotnogo.

The examinations of biodestruction of segmental polyurethanes from hexamethylene diisocyanate ethylene glycol and polyesters with different chemical composition: polydiethylene glycol succinate, molecular mass 750 (formula A-19), polydiethylene glycol adypates, molecular mass 800 and 1500 (formula A-14 and A-10) were performed employing physico-chemical and histological methods. It was noted that in physiological liquids and animal organisms that polyurethanes containing more polyester bounds, which easily undergo hydrolytic decomposition, had decomposed in higher rate - A-10 > A-19 > A-14. Histological examination revealed the hydrolytic destruction of samples A-19 and A-10 during 24 weeks. However, the rate and biodestruction degree in sample A-10 (especially in ensuring period) was found to be higher than in sample A-19. This appears in its fragmentation and cell activation in connective tissue, surrounding the alloplastic material. These data are consistent to the results of physico-chemical examinations which revealed that sample A-10 after 24 weeks completely loose the durability and the molecular mass diminishes almost four times, while the sample A-19 maintains 37% of durability comparing to initial condition and molecular mass diminishes only two times. Sample A-14 undergoes destruction, at lower degree maintains 50% of durability and its molecular mass diminishes almost two times. The performed examinations show that the changes of ester groups concentration in polyurethanes give the possibility of regulation of the biodegradation rate.

[Comparative evaluation of biodestruction of polyurethanes synthetized on the basis of simple and complex polyesters]. / Sravnitel'naia otsenka biodestruktsii poliuretanov, sintezirovannykh na osnove prostykh i slozhnykh poliéfirov.

In model liquids and experimental animals (rats, rabbits) with the aid of physico-mechanical and histological methods (using interferentially polarizating microscopy) a comparative evaluation was made of the biodestruction of polyurethanes from synthetized simple and complex polyesters. The tissue reaction to intra-abdominal, intramuscular and subcutaneous implantation of perforated stripes of A-19 and Nr. 36 polymer was moderate. Two weeks post-operative increased volumetric biodestruction of the polymers was observed. The course was different in various standards and depended upon the chemical structure of the polymers. Taking into account the slight macrophage tissue reaction, in counterdistinction to the significant volumetric biodestruction which envolved the entire width of the polymer strip, it is assumed that the destruction of the investigated polyurethane composition (adhesive KL-3) takes place by hydrolysis 3 to 6 months post-implant.