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

Abstract

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.

Mechanical Properties of PMMA‐Sepiolite Nanocellular Materials with a Bimodal Cellular Structure

“…It has been reported by several authors that a given material property of a cellular polymer ( P c ) is related to the material property of the solid polymer ( P s ) by where K and n are constants to be experimentally determined. For most cellular polymers K is close to 1, while n is related to the cellular morphology of the cellular material, being close to 1 for closed cell structures and in the range of 1.5 to 2 for open cell and high density materials .…”

“…for high relative densities (>0.5) is in agreement with several previous works. [53,[55][56][57] For this analysis, as only the high density materials are considered, the samples with 5%-S are also included. Figure 6 shows the results of this analysis for the high density materials.…”

Technological characterization of PE/EVA blends for foam injection molding

“…An increase in the mold temperature causes an increase in weight, density and mechanical properties. Lopez-Gil et al [18] proposed an improved compression molding process to vary density and cellular structure independently, producing tailored cellular polymers. The main feature of this process is the use of self-expandable molds which implies the control of the final expansion ratio by mechanical means.…”

Study on Foaming Quality and Impact Property of Foamed Polypropylene Composites

“…Nowadays, the microfoamed polymer materials [1,2,3] have attracted increasing attention due to their excellent comprehensive properties. Compared with traditional foamed materials, the microfoamed polymer materials possess highly specific properties, including good thermal stability, excellent sound absorption property, low thermal conductivity and dielectric constant, etc.…”