Production of non-crosslinked thermoplastic foams with a controlled density and a wide range of cellular structures

A novel foaming route, with respect to existing industrial foaming processes, called Improved Compression Molding (ICM), which allows producing non-crosslinked thermoplastic foams in a wide density range, is described in this work. This process is different from others because it is possible to control independently density and cellular structure and therefore, tailored cellular polymers can be produced. To understand the process, a collection of polypropylene foams, with relative densities ranging from 0.3 to 0.6 were produced. The influence of foaming parameters, on foams microstructure and mechanical response was analyzed. Results revealed that for similar densities, foams with different open cell content and cell size can be achieved. In addition, it was proved that mechanical behavior strongly depends on the degree of interconnectivity of the cells. The analysis of the relative mechanical properties allowed determining the influence of microstructure on mechanical behavior as well as quantifying the efficiency of the foaming process to produce light-weight stiff materials. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42324.