Influence of the chain extender of a segmented polyurethane on the properties of polyurethane-modified asphalt blends

• Published in: Construction & building materials Vol. 328; p. 127061
• Main Authors: Gallu, Raïssa, Méchin, Françoise, Gérard, Jean-François, Dalmas, Florent
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 18.04.2022; Elsevier
• Subjects: Chemical Sciences; Engineering Sciences; Hansen solubility parameters; Materials; Mechanical properties; Morphology; Polymer-modified bitumen; Polymers; Thermoplastic polyurethane; Mechanical properties; Thermoplastic polyurethane; Hansen solubility parameters; Polymer-modified bitumen; Morphology; thermoplastic polyurethane; polymer-modified bitumen; morphology; mechanical properties
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2022.127061

•3 types of TPU were synthesized differing by the nature of their chain extender.•TPUs were either phase separated or homogeneous, semi-crystalline or amorphous.•Bitumen-incompatible HS dissolved in soft phase lower its swelling by light fractions.•Highly phase separated TPUs offer elasticity improvement to the bituminous blend. This paper reviews the influence of the hard segment (HS) chemical structure on the properties of thermoplastic polyurethanes based on dimer fatty acid soft segments, and on their resulting blends with bitumen. Three types of hard segments were used which consist in 4,4′-methylene bis(phenyl isocyanate) (MDI) reacted either with 1,4-butanediol (BDO), 1,4:3,6-dianhydro D-sorbitol (isosorbide) or 2-ethyl-1,3-hexanediol (EHDO). The characterization of thermoplastic polyurethanes (TPUs) containing 13 wt% HS was conducted by differential scanning calorimetry, dynamic mechanical analysis, Hansen solubility parameters measurements and morphology analysis. The use of Hansen solubility parameters combined with thermal and swelling analyses provides information about the quality of phase separation occurring in the neat TPUs. Phase separation depends on the hard segments used and on their ability to self-organize within crystalline structures. Morphology analysis and swelling measurements of the TPU blended with bitumen by fluorescence microscopy show that the swelling of the polymer is highly dependent on the quality of phase separation between soft and hard segments in the pure polymer as well as on the compatibility of these segments with bitumen. Highly phase separated TPUs offer elasticity improvement to the bituminous blend.