The present invention pertains to a substantially linear olefin polymer which has long chain branches, a high melt flow ratio, a narrow molecular weight distribution and critical shear rate at onset of surface melt fracture of a least 50 percent greater than the critical shear rate at the onset of melt fracture which is substantially higher than that of a linear olefin polymer having about the same molecular weight and molecular weight distribution. The novel polymer is an interpolymer of ethylene with at least one C3-C20 alpha-olefin and at least one unsaturated monomer.