Characteristics of Biodegradable Poly(Ester-Urethanes) with Side Chains
Tóm tắt
Two series of segmented poly(ester-urethanes) (SPEU) have been studied. The flexible segment of SPEU was formed from polycaprolactonediols (PCL diols) with a molecular mass of 600 to 10000 and the rigid one — from a blend of 2.4 and 2.6-toluene diisocyanates (TDI) and a chain extender. The first series of SPEU contained no side branches, whereas in the second series, side branches in the form of long chains of aliphatic structure were present at the rigid segment. The tensile strength of SPEU decreased when the molecular mass of the flexible segment increased from 600 to 2000; in this case, the specimens were of amorphous structure. An increase in the molecular mass of the flexible segment from 2000 to 10000 led to an increase in its degree of crystallinity and in the melting point, fusion enthalpy, tensile strength, yield stress in tension, and packing coefficient of SPEU. The side chains at the rigid segment affected the degree of phase separation insignificantly, but decreased the order of the structure, the glass transition temperature, and strength properties of SPEU, whereas the side chains at the flexible segment reduced its crystallinity.
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