Monitoring of polyurethane dispersions after the synthesis

Abstract

Chemical and physical parameters of the aqueous polyurethane dispersion (PUD) were studied after the synthesis. A prepolymer mixing process with a limited-chain extension step was used in order to examine the polymer and dispersion behavior with respect to the ageing time. Measurements of free isocyanate groups were performed with the aid of Fourier transform infrared spectroscopy (FT-IR). The pseudo-first-order kinetics of NCO disappearance was proposed and the value of the corresponding constant was determined. Additionally, particle size, particle size distribution, pH, conductivity and molecular mass were monitored and compared. Keywords: polyurethane dispersion, colloid, FT-IR V raziskavi smo preu~evali spreminjanje kemijskih in fizikalnih parametrov vodne poliuretanske disperzije (PUD) po sintezi. Disperzijo smo sintetizirali po postopku vme{avanja prepolimera z omejenim podalj{evanjem verig za preu~evanje polimerne disperzije z ozirom na~as po sintezi. Merjenje prostih izocianatnih skupin smo izvedli z metodo Fourierjeve transformacijske infrarde~e spektroskopije (FT-IR). Predpostavili smo kineti~ni model psevdoprvega reda z ozirom na reakcije izocianatnih skupin ter dolo~ili vrednost kineti~ne konstante. Dodatno smo spremljali in primerjali povpre~ne velikosti delcev, porazdelitev velikosti delcev, pH, prevodnost in molekulsko maso.

Green alternative cosolvents to N-methyl-2-pyrrolidone in water polyurethane dispersions

“…Reaction rate was evaluated by monitoring the conversion of NCO groups ($2260 cm À1 ) using Fourier-transform infrared spectroscopy (FTIR), 39 which is a technique widely used in the synthesis of polyurethane. [40][41][42][43] The polyurethanes synthesized in green solvents achieved similar NCO conversion with time to the polyurethane synthesized in NMP (see ESI †).…”

“…This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. some characteristics like particle distribution, Z potential or density 39 Meanwhile, PUD synthesised with GVL continues the destabilization process for longer time. By these means, extra stabilization effort is probably needed by maybe increasing the concentration of internal emulsier in PU structure or adding surfactants to dispersion.…”

“…Reaction rate was evaluated by monitoring the conversion of NCO groups (∼2260 cm −1 ) using Fourier-transform infrared spectroscopy (FTIR), 39 which is a technique widely used in the synthesis of polyurethane. 40–43 …”

“…However, PUD with NMP and CY become stable with time by observing the asymptotical evolution of Turbiscan Stability Index (TSI). As a consequence, the material became stable but probably with slight changes in some characteristics like particle distribution, Z potential or density 39 Meanwhile, PUD synthesised with GVL continues the destabilization process for longer time. By these means, extra stabilization effort is probably needed by maybe increasing the concentration of internal emulsifier in PU structure or adding surfactants to dispersion.…”

Waterborne poly(urethane-urea)s films as a sustained release system for ketoconazole

“…The polydispersity index (PDI), which evaluates the distribution width of the particles, ranged from 0.1 to 0.2. Some dispersions presented lower values of PDI (0.1), being considered monodisperse fluids (47). However, some other systems presented a wide distribution of size (PDI>0.2), mainly drug-loaded ones.…”