Processing Time
In general, the increase in molecular weight makes the molecular chain segments longer, and the slower the center of gravity of the molecular chain moves, the more opportunities for offsetting the relative displacement between the chain segments. Because of the greater flexibility of long molecular chains and the increase in the number of entanglement points, it is difficult to release and slip the chain, needing more time and energy to confront the increasing resistance in the flow process. Normally, the molecular mass of polyester TPU is larger than that of polyether TPU, so the processing time required for processing is also longer.
Processing Temperature
Normally, because of the boarder molecular weight distribution of polyether TPU, compared with that of polyester TPU, polyether TPU needs higher temperature in the process. Due to the easiness of hydrogen-oxygen bond fracture of polyester TPU, a relative low temperature is enough for polyester TPU to process.
Pressure
Because of the quite high cohesive energy inside the molecules of polyester TPU and the very difficult in fracturing the hydrogen-oxygen bond in it, quite high temperature and more pressure are needed to fracture its molecular bonds.
Cooling
It is very hard for polyester TPU to return to normal status due to both more friction inside polyester TPU and more cohesive energy in molecules. As a result, more cooling time is needed.
Flexibility
Because of the quite low cohesive energy in the ether bond of polyether TPU and the small rotational barrier of the bond, the bond will be more flexible as the molecular mass is increasing, so polyether TPU is of greater flexibility than polyester TPU.