Relationship on structure and properties of polyurethane modified Diels–Alder addition polymer

Abstract

A series of linear and crosslinked polyurethane modified materials were prepared by Diels-Alder cycloaddition reaction. Based on raw materials, some novel equations were designed and effects of equation parameters on the mechanical properties of modified material were explored. It was demonstrated that tensile strength of modified materials and elongation at break were changed from 3.68 to 18.71 MPa, 200 to 866%, respectively. In addition, the optimal reaction temperature of retro-Diels-Alder (r-DA) reaction was determined by differential scanning calorimeter (DSC). Gel permeation chromatography (GPC) and tensile experiments were used to characterize the properties of repolymerized material after degradation. The results indicated the optimal temperature of r-DA for linear and crosslinked polyurethane modified materials is 127 and 150 C. Moreover, after decomposed, the product was slowly repolymerized at 60 C, and can more effectively restore material strength under the action of the solvent to achieve self-healing effect.

Rationally Engineering a CuO/Pd@SiO2 Core–Shell Catalyst with Isolated Bifunctional Pd and Cu Active Sites for n-Butylamine Controllable Decomposition

“…The band at 1671 cm –1 can be ascribed to ν­(CO) of amide (which even formed at room temperature), indicating that n -butylamine can be readily oxidized over Pd sites . The band at 1250 cm –1 is assigned to δ­(CH 2 ) of n -butylamine and intermediates . As the temperature rose above 160 °C, the C–N bond cracked and the bands due to n -butylamine and amide species gradually vanished.…”

“…3 The band at 1250 cm −1 is assigned to δ(CH 2 ) of n- butylamine and intermediates. 39 As the temperature rose above 160 °C, the C−N bond cracked and the bands due to nbutylamine and amide species gradually vanished. Some new bands at 1027 (ν(C-O)), 1076 (ν(C-O)), and 1700 cm −1 (ν(C�O)) appeared, which suggests the formation of alcohol and acids.…”

Synthesis and properties of UV‐curable waterborne urethane modified acrylic coatings with varying vinyl content

“…This was because crosslinking points would hinder the movement of molecular chains if being stretched, and the more crosslinking points, the more obvious this kind of effects was. [ 22,23 ] However, the tensile strength and elongation at break of UV‐WUA‐5 cured film were slightly lower than those of UV‐WUA‐4 cured film, which probably resulted from the incomplete curing caused by the decrease of C=C conversion rate and defects produced during the curing process in UV‐WUA‐5 and this will be discussed later. Overall, UV‐WUA‐4 cured film had the most desirable mechanical properties among these samples.…”

Healable and reprocessable silica/poly(oxime‐urethane) composite elastomer with high mechanical robustness and exceptional damage‐tolerant capacity

“…The service life and safety of elastomers can be significantly extended by the self-healing ability when the cracks or notches appears in the materials. [22][23][24][25][26] Currently, the intrinsic self-healing materials are favored for their repeatability and simplicity of preparation. [27][28][29] The reversible non-covalent or covalent bonds were usually introduced into the polymer to form intrinsic self-healing materials.…”

“…The service life and safety of elastomers can be significantly extended by the self‐healing ability when the cracks or notches appears in the materials 22–26 . Currently, the intrinsic self‐healing materials are favored for their repeatability and simplicity of preparation 27–29 .…”