Characterization of dimethylphenyl-grafted polyurethane: the impact on tensile and shape recovery properties

Abstract

Dimethylphenyl groups were grafted onto polyurethane (PU) to investigate its disrupting effects on the intermolecular attractions, but the dimethylphenyl-grafted PU required fortification by cross-linking with 4,4'- methylenebis(phenyl isocyanate) (MDI) to compensate for the decrease in the PU’s physical properties. The cross-link density, solution viscosity, maximum tensile stress, and shape recovery initially increased due to the chemical cross-linking with MDI but decreased with the increase in dimethylphenyl groups due to its disrupting effects: maximum tensile stress and shape recovery increased up to 57.1 MPa and 98.5 %, respectively, but finally decreased to 17.2 MPa and 66.2 % with the increase of dimethylphenyl group content. Low temperature flexibility was not observed due to the poor shape recovery with the increase in dimethylphenyl groups. Therefore, the grafted dimethylphenyl groups disrupted the intermolecular attractions between PUs and resulted in a significant reduction in the tensile stress and shape recovery properties of PU compared to plain PU.