Influence of the chain extender of a segmented polyurethane on the properties of polyurethane-modified asphalt blends. (18th April 2022)

• Record Type: Journal Article
• Authors: Gallu, Raïssa; Méchin, Françoise; Gérard, Jean-François; Dalmas, Florent
• Is Part Of: Construction & building materials. Volume 328(2022)
• Publication Date: 2022-04-18
• Subjects: Polymer-modified bitumen -- Thermoplastic polyurethane -- Hansen solubility parameters -- Morphology -- Mechanical properties; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2022.127061
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: 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. Abstract: 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.