Radical polymerization of ethylene under high pressures creates a complex molecular structure of branches on branches. The rheology of low density polyethylene (LDPE) is strongly affected by the number branches. This paper uses attenuated total reflectance (ATR) to calculate the average number of branches per LDPE molecule. It is concluded that the high number of branches per molecule amplifies the strain hardening behavior of LDPE in uniaxial elongational flow. Since ATR does not distinguish between short/long branches, it is also concluded that radical polymerization of LDPE produces long chain branches rather than short chain ones.