Polyurea-nitryle-urethanes (PUNU) are block copolymers containing soft and hard segments. Soft and hard segments of these polymers differ in polarity. At temperatures below 120^oC polar hard segments typically do not mix homogeneously with less polar soft segments. As a consequence hard and soft domains are formed. Properties of PUNU such as: tensile strength, hardness, abrasive wear, chemical and thermal resistance are determined by parameters of synthesis process. Hard segments of hybrid polyurea-nitryle-urethanes are obtained with dicyandiamide (DCDA). DCDA is crystalline powder with diameter of particles higher than 0,05um. Dicyandiamide contains two amino groups and highly polar cyanimine group. The strong polar hard segments influence PUNU properties, especially high thermal stability. This polymers oxygen index is 36% (without antioxidants).
The aim of this paper is to characterize the hybrid polyurethanes, synthesized by different dehydrating and curing temperatures. Cast segmented polyurea-nitryle-urethanes were obtained from: poly(ethylene adipate) (PEA) mol.wt 2000, 4,4’diphenylmethane diisocyanate (MDI) and dicyandiamide. Polyurethanes with PEA:MDI:DCDA molar ratio 3:4:1 were synthesized. The mixtures of PEA and DCDA were dehydrated for 2h at temperature from 140 to 170+/-5^oC under vigorous stirring. Synthesis was performed in one-shot process. The polymers were cured for 16h at temperature from 110 to 190+/-5^oC. The samples were conditioned for two weeks at room temperature.
The mechanical (tensile strength, ultimate elongation, hardness, abrasive wear) and thermal (glass transition temperature, DSC thermograms, thermal stability – TGA, dynamical mechanical thermal analysis - DMTA) properties of hybrid polyurea-nitryle-urethanes were investigated. Images of the structure were obtained using HRSEM and AFM.

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