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M. Jastrzębska, M. Rutkowska



Thermal properties of the polyurethanes ion-grafted on a styrene-styrenesulfonic acid copolymer

Polimery 1998, No 9, 540


DOI: dx.doi.org/10.14314/polimery.1998.540


Summary

N-Methyldiethano laminę (MDEA) was ion-combined with the sulfonic group (SO3-) of a styrene/styrenesulfonic acid (S/SSA) copolymer to yield an ammonium salt (Scheme 1) and next to graft on PUR the hydroxylic groups (Scheme 2) present in the system. Differential scanning microcalorimetry (DSC) and thermal gravimetric analysis (TGA) were used to establish the glass transition temperatures (Tg) and the thermal stability of the grafted-ion products. Each product, whether containing long or short flexible PUR segments, exhibited two Tg-values, a fact indicative of two phases present. This finding is in conflict with the results of dynamical mechanical studiem [4] which suggested only the long flexible PUR segments to separate out into an individual phase and the S/SSA copolymer to become mixed with hard PUR segments to produce a phase that is hard on account of strong Coulombie interactions between the SO3- anion on the copolymer's macrochain and the MDEA-originating (SO3-) N+ cation of the rigid PUR segment. The prezent studies showed the phase richer in flexible PUR segments and the phase richer in S/SSA copolymer to exist, which have borne out the earlier nanometricscale microscopic investigations [6 ]. The grafted PUR was found (by TGA) to decompose in two steps, viz ., over 240—265°C, characterized by a considerable weight loss due to the decomposition of rigid PUR segments, and over 330—380°C, when flexible PUR segments and the S/SSA copolymer undergo decomposition.


Keywords: grafted polyurethanes, styrene/styrenesulfonic acid copolymers, phase structure, glass transition temperature, thermal stability


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