A mathematical model of rheological behavior of novel bio-based isocyanate-terminated polyurethane prepolymers

Abstract

In this paper, the results of rheological study on isocyanate-terminated polyurethane prepolymers, containing modified soybean oil residues incorporated into the chemical structure are described. Isocyanate-terminated prepolymers were synthesized from 4,4′-diphenylmethane diisocyanate and the mixture of hydroxylated soybean oil and commercial polyether. The measurements were performed by using rotary rheometer R/S-CPS+ (Brookfield, USA), while the rheological parameters were calculated by using Rheo3000 program. Based on rheological measurements, the viscosity curves and flow curves for prepolymers in the temperature range from 50 to 70°C were plotted. Prepolymer samples were tested with controlled shear rate (CSR). It was found that a viscosity of bio-based isocyanate-terminated prepolymers decreases with increasing content of hydroxylated soybean oil in the polyol mixture. The rheological data for bio-based polyurethane prepolymers were also mathematically modeled. It was found that the synthesized prepolymers are non-Newtonian fluids that can be described by Ostwald-de Waele and Herschel Bulkley functions as optimal individual models. The conducted investigations showed that the dynamic viscosity and rheological behavior of bioprepolymers samples could depend on the amount of hydroxylated soybean oil used in the polyol mixture.