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      Using Supercritical Carbon Dioxide for Physical Foaming of Advanced Polymer Materials


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          Foams from high performance polymers find more and more interest. The processes to generate them can be difficult, however. It is shown how physical foaming with CO 2 can be used as a first step to assess the potentials of such materials. For investigations of such kind an autoclave on a laboratory scale which allows pressure variations up to 300 bars and temperatures up to 300°C was set up. The samples are saturated with supercritical carbon dioxide (s.c. CO 2) which acts as a foaming agent. Depending on the process and material parameters different foam characteristics and cell morphologies were obtained and characterised. The potential of this method is demonstrated for two different classes of advanced polymer materials, thermoplastic fluoropolymers (FEP), and a silicone resin. In the case of the fluoropolymer, previously prepared films were foamed and the effects of various process parameters on the foam characteristics were investigated. Besides the general potential of foams from fluoropolymers, they are candidates for polymeric piezoelectric materials with a relatively high temperature stability. Silicone polymers possess some properties superior to common organic polymers. First results on the foaming behaviour of a silicone resin are presented.

          Most cited references28

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          An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments

          The indentation load-displacement behavior of six materials tested with a Berkovich indenter has been carefully documented to establish an improved method for determining hardness and elastic modulus from indentation load-displacement data. The materials included fused silica, soda–lime glass, and single crystals of aluminum, tungsten, quartz, and sapphire. It is shown that the load–displacement curves during unloading in these materials are not linear, even in the initial stages, thereby suggesting that the flat punch approximation used so often in the analysis of unloading data is not entirely adequate. An analysis technique is presented that accounts for the curvature in the unloading data and provides a physically justifiable procedure for determining the depth which should be used in conjunction with the indenter shape function to establish the contact area at peak load. The hardnesses and elastic moduli of the six materials are computed using the analysis procedure and compared with values determined by independent means to assess the accuracy of the method. The results show that with good technique, moduli can be measured to within 5%.
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            Generation of microcellular polymeric foams using supercritical carbon dioxide. I: Effect of pressure and temperature on nucleation

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              Active-Filler-Controlled Pyrolysis of Preceramic Polymers


                Author and article information

                International Polymer Processing
                Carl Hanser Verlag
                : 26
                : 4
                : 437-443
                1 Institute of Polymer Materials, Friedrich-Alexander-University Erlangen-Nürnberg, Germany
                2 Institute of General Materials Properties, Friedrich-Alexander-University Erlangen-Nürnberg, Germany
                3 Development Center X-Ray Technology (EZRT), Fraunhofer Gesellschaft, Fürth, Germany
                4 Institute of Glass and Ceramics, Friedrich-Alexander-University Erlangen-Nürnberg, Germany
                Author notes
                Mail address: Helmut Münstedt, Institute of Polymer Materials, Friedrich-Alexander-University Erlangen-Nürnberg, Martensstr. 7, D-91058 Erlangen, Germany. E-mail: helmut.muenstedt@ 123456ww.uni-erlangen.de
                © 2011, Carl Hanser Verlag, Munich
                : 18 January 2011
                : 21 February 2011
                Page count
                References: 34, Pages: 7
                Self URI (journal page): http://www.hanser-elibrary.com/loi/ipp
                Regular Contributed Articles

                Polymer science,Materials technology,Materials characterization,General engineering,Polymer chemistry


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