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Autori: E. Scortanu, C. Prisacariu, A.A. Caraculacu, M. Bruma, and N. Sulitanu
Editorial: J W Connell, NASA Langley Research Center, Hampton, VA,USA, SAGA Publications, High Performance Polymers, Volume 18, Nr. 2,, p.127 - 145, 2006.
A series of polyurethane-ureas has been synthesized by solution polyaddition reaction of the following components: a polyester-diol (PEA), or a polyetherdiol (PTMG) and a diisocyanate, such as 4,4′-dibenzyl diisocyanate (DBDI) or 4,4′-methylene-bis(phenyl-isocyanate) (MDI). For the chain extention step some aromatic diamines like: 2,5-bis-(4-amino-phenylene)-1,3,4-oxadiazole (DAPO), 4,4′-methylene dianiline (MDA) and 4,4′- diamino-dibenzyl (DAB) were used as chain extenders. The hard segment content ranges between 1.384 – 1.819 mol NHCOO/ 1000 g polymer. The resulting linear polymers were characterized by IR spectra, elemental and thermogravimetric analyses (TGA), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), inherent viscosity measurements, wide-angle X-ray scattering (WAXS) and mechanical properties. The study of the relationships between structure and properties reveals the influence of the great number of hydrogen bonding that formed between urea and urethane groups as well as the presence of oxadiazole rings in the polymer chain that induced an improved thermal stability and good mechanical properties. The mechanical behavior of these polymers was discussed and compared with that of earlier reported linear polyurethane-ureas based on MDI or with that of related polyurethanes chain-extended with diols.
Cuvinte cheie: stiinta polimerilor, tehnologia polimerilor // polymer science, technology