Multifunctional polyurethane network structures

Abstract

A series of thirteen polyurethanes were synthesized using blends of monofunctional, difunctional, and trifunctional poly(propy1ene oxides) reacted with 4,4'-diphenylmethane diisocyanate in a stoichiometric ratio. Experimental measurements were made of glass transition temperature, sol fraction, and dynamic mechanical properties. Computer simulations based on the theory of branching processes were made on the same systems. The glass transition temperature was correlated with the number average functionality of the components. Dynamic mechanical data was fitted to the Havriliak-Negami model.A correlation was demonstrated between the measured rubbery modulus and the concentration of elastically active network chains.

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“…[25] The sol fraction was determined by extraction with 2methoxyethyl ether from the difference in weight of dry samples before and after extraction. A small content of mono-and bifunctional polyol in the triol was accounted for.…”

“…[25,26] ) were analyzed as a function of calculated network parameters. Experimental data for stoichiometric systems A1 þ A2 þ A3/B2 (ref.…”

“…Input parameters as in Figure 5 and Figure 6. [25,26] for systems described in the Experimental Part. Dependence of molecular weight of dangling chains, (M dc ) n , a function of the weight fraction of dangling chains, w dc calculated from experimental data of ref.…”

“…Dependence of molecular weight of dangling chains, (M dc ) n , a function of the weight fraction of dangling chains, w dc calculated from experimental data of ref. Dependence of the width of loss factor peak [25] on the weight fraction of dangling chains, w dc . Figure 9.…”

“…According to Equation (25), the weight fraction of sol n is given by According to Equation (25), the weight fraction of sol n is given by…”