Hot & Sticky: The Magic of Polymer Modified Bitumen in Action The dispenser releases each blob of hot bitumen glue so it lands perfectly in place, even as the truck keeps moving. Polymer modified bitumen, a petroleum based binder, becomes a thick, syrupy liquid when heated to about 200 degrees Celsius, allowing it to spread and form a strong adhesive layer. As it cools, the long polymer chains inside reentangle and harden, creating a tough bond. Right after that, a worker drops reflective road s