Preparation and evaluation of waste PET derived polyurethane polymer modified bitumen through in situ polymerization reaction

- New polyurethane polymer is synthesis in situ in bitumen by BHETA with MDI.
- The chemical evolution of polyurethane formation in bitumen is examined through FTIR.
- The FT-IR study confirms that the developed new polymer is polyurethane.
- Better dispersion of polymer in bitumen was attributed by in situ polymerization.
- BHETA-PU improved the low temperature, high temperature and fatigue property of bitumen.

Polymer modified bitumen (PMB) pavement have gained significant importance in the twentieth century and they now play a very crucial role in the field of road construction in every part of world. However, due to well-known difficulties related to the poor solubility of polymers, high temperature stability, sever manufacturing condition and high polymer cost restricts the use of polymer for bitumen modification. To overcome all these difficulties the present study has attempted to demonstrate a new approach where in situ polymerization of monomers bis(2-hydroxyethyl) terephthalamide (BHETA) (which is synthesized from aminolysis reaction of waste Poly Ethylene Terephthalate (PET)) with diphenylmethane-diisocyanate (MDI) in the body of bitumen for the development of polyurethane based Polymer modified bitumen (BHETA-PU). The resulting BHETA-PU product is comparable performance under laboratory condition with conventional styrene butadiene styrene (SBS) based PMB. To investigate the modified bitumen properties and mixture properties, conventional binder tests (Penetration, Softening Point, Marshall Stability, Hot water Stripping & short-term aging test) and Superpave binder tests (Rotational Viscosity, Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR) were carried out. The result reveals that BHETA-PU show significant improvement of antistripping as well as other physico-chemical properties and Marshall Stabilities. This research studies, therefore, suggests not only a new method for making PMB based on PET but also opens a new chapter for the recycling of waste PET in bitumen concrete roads which may help in easy disposal of waste PET polymer.