Crosslinked polyurethane–epoxy hybrid emulsion with core–shell structure

Abstract

An epoxy resin was used to prepare crosslinked polyurethane hybrid emulsion through the blocked NCO prepolymer mixing process. Due to their hydrophobicity, the amine chain extender, blocked -NCO, and epoxy are located inside the emulsion particles. Thus, the crosslinking reaction occurs mostly in the interior of the particles. In this way, the crosslinking density of the resin is increased without the use of solidifying agents or heating during film formation, and the stability of the emulsions remains uninfluenced. The effects of the type of amine chain extender and the type, dosage, and addition mode of the epoxy resin were studied in terms of mechanical properties and swelling properties in water and toluene of the cast films. Additionally, the stability of the single-pack hybrid emulsion was studied. The results showed that the sample prepared with diethylene triamine had good stability, chemical resistance, and high mechanical strength. The modulus and water resistance of the films increased with the epoxy resin content, which could reach 20 wt%. The type of amine chain extender affected the stability of the emulsions significantly. The molar ratio of NH/NCO at 1:1 led to the best film performance. The optimal temperature of the chain-extension reaction was approximately 80°C. The hybrid emulsions could be stored for at least 6 months without apparent performance changes.

Preparation and characterization of waterborne polyurethane containing PET waste/PPG as soft segment

“…Solvent‐borne coatings not only pollute the environment but also threaten human health because of the relatively high volatile organic components (VOCs) present in them. Waterborne polyurethanes (WPUs) are taking an important role in polyurethane industry because of the fact that they are eco‐friendly and can be formulated into coatings containing little or no co‐solvent . WPU makes an effective substitute for solvent‐based analogues.…”

Bio‐based high‐performance waterborne hyperbranched polyurethane thermoset

“…It is because of the presence of hydrophilic groups in the polymer chains which causes the hygroscopic nature of the dried films, resulting in poor mechanical properties. [10] However, we found improved mechanical properties of the polymer system after modification with epoxy. The data documented in Table 3 shows an increase in tensile strength, toughness, tensile modulus, scratch resistance, and impact resistance for the modified films.…”

“…WPUs are mostly thermoplastic with little or no gel fraction which contains a large number of hydrophilic ionic groups. [10] Hence, they are very sensitive towards moisture and other chemical environments. This leads to inferior mechanical properties, thermal stability, and poor chemical resistance compared with the solvent-borne counterpart.…”

Development of styrene-acrylic polymeric compositions for the coating of textile materials used for packing

“…On the one hand, studies were aimed at catalysis, on the other hand, on selectivity of addition, since in addition to α-addition to the carbon atom of methylene group, β-addition to the carbon atom of the CH group is also possible. Epoxides are multi-hydroxide compounds and can introduce branch points into the polyurethane backbone to form a crosslinked structure [16,17]. Glycidyl esters are used for the preliminary crosslinking of the aqueous dispersion of polyurethane.…”