New T-Shape Polyurethanes: Synthesis, Thermal and Mechanical Properties

Abstract

A series of new T-shaped polyurethanes were prepared from various diisocyanates and 2,5-dihydroxybenzelidene aniline (azomethine bisphenol). The latter compound was synthesized by the reaction of 2,5-dihydroxy-benzaldehyde with aniline. The structures of azomethine bisphenol and T-shaped polyurethane were confirmed by FT-IR, 1 H-NMR, 13 C-NMR Spectroscopy and elemental analysis (CHN). The mechanical properties were characterized by tensile strength, tear strength and shore hardness. Thermal properties were also studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Mechanical and thermal studies showed that the synthesized polyurethanes possess good mechanical and thermal properties. INTRODUCTIONPolyurethanes are industrially important polymers with various structures and wide applications [1][2][3][4] . Changes in the field of the polymers are frequently desirable as per need of the application requirements. Fully aromatic polymers exhibit good mechanical properties, but are limited by their low thermo-oxidative stability. A typical example was found in polyurethanes [5] . However, few researchers have paid attention to high thermal stability with good mechanical properties. The attempts either by synthesized fully aromatic polyurethanes containing phosphorus group [6][7][8][9] , substituted the aromatic by halogens [10] or inserting azomethine group in the main chain of the polyurethanes [11][12][13][14][15][16] to enhance their thermal properties.However, fully aromatic rings in the polymers backbone exhibit difficulties in the processing as well as in solubility. Therefore, the design and synthesis of polymers with better processability and high thermal stability become the key point to addressing these problems. To overcome these problems, several methods achieved such as incorporation of flexible spacers [17][18][19] , bulky alkyl substituents [20][21][22][23] and nonlinear links into the main chain of the polymers [20] .