Synthesis and characterization of crosslinked polyurethane dispersions based on hydroxylated polyesters

Abstract

Stringent environmental regulation has endowed dispersible coatings with excellent property profiles in industrial applications. In this aspect, aqueous polyurethane dispersions (PUDs) are of special interest. The present study reports on the synthesis of hydroxylated polyester (HP) based polyurethane polyols containing internal carboxyl group with different diisocyanates. These polyurethane polyols were partly acetoacetylated with ethyl acetoacetate to incorporate ␤-ketoester in the polyurethane polyol backbone. The synthesized polyols were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and differential scanning calorimetry. Polyurethane polyols and their acetoacetylated cousins were used to develop PUDs. Particle size of the reactive PUDs was evaluated by a particle size analyzer. PUDs were crosslinked with hexamethoxy methyl melamine and their film properties were studied by dynamic mechanical and thermal analyzers and thermogravimetric analyses. The effects of different diisocyanate and acetoacetylation on the stability of reactive dispersion and properties of the crosslinked films were evaluated.

Photo-oxidation of acrylic-urethane thermoset networks. Relating materials properties to changes of chemical structure

“…While little information is available on the evolution of the macromolecular architecture and mechanical properties under ageing, acrylic-urethane thermosets have been shown to increase in hardness and elasticity [11,12] and decrease in fracture energy in response to ageing [13]. These results are in accordance with other studies [14] that have used PAS (Positron Annihilation Spectroscopy) to identify a decrease in the free volume during ageing.…”

Effects of flame‐retardant ramie fiber on enhancing performance of the rigid polyurethane foams

“…Polyurethane is one of the most versatile materials which have been widely used in furniture, roofs, medical equipment, automotive interior materials, etc . Rigid polyurethane foams (RPUF), for one, is extensively applied as external wall insulation, foundation reinforcement of building, and decoration due to its excellent properties such as excellent mechanical properties, low thermal conductivity, rapid expansion and solidification, excellent corrosion, and water resistance …”

The influence of the ionic concentration, concentration of the polymer, degree of neutralization and chain extension on aqueous polyurethane dispersions prepared by the acetone process

“…To reduce or eliminate organic solvents from the formulations, solvents should be partially or completely replaced with environmentally benign solvents (e.g. water), in the coating formulations to achieve little or no VOC content [5][6][7][8][9][10][11][12][13].…”