Abstract: A composition including a first polypropylene having at least 90 wt. % propylene by weight of the first polypropylene, an alpha nucleation inhibitor, and a beta nucleation additive is provided. Also provided is a method of preparing a foamable polypropylene composition. The method includes the steps: a) compounding a first polypropylene including at least 90 wt. % propylene by weight of the first polypropylene with an alpha nucleation inhibitor to form a polypropylene blend; b) compounding the polypropylene blend with a blowing agent to form a pre-annealed polypropylene composition; and c) annealing the pre-annealed polypropylene composition at an annealing temperature Ta for an annealing time ta to form the foamable polypropylene composition. The foamable polypropylene composition has a first melting peak T1 and a second melting peak T2 as measured by differential scanning calorimetry at a heating rate of 20° C. per minute.