Analysis of polyethylene-particle filled SiCN precursor and the resulting porous ceramics with emphasis on using micro computed tomography

Abstract

Porous, polymer derived SiCN ceramics are synthesized from a solid polysilazane (PSZMS) and an ultra-high molecular weight polyethylene (PE) as sacrificial filler. Common analytical methods for the investigation of the thermal decomposition processes and the formed (macro) porosities, such as thermogravimetry and mercury porosimetry respectively, were supplemented by micro computed tomography (µ-CT) measurements. Due to its non-destructive nature, this method enables the comparative analysis of both, the in the first step formed preceramic duromers, to distinguish between the different polymers, as well as the resulting porous ceramics. The via µ-CT determined values for the two polymer phases after cross-linking are in a good agreement with the used original amounts of PE and PSZMS. In contrast the values for the porosity resulting from the PE filler and for the formed SiCN ceramic after pyrolysis differ in greater extent due to the limiting resolution that can be achieved by applying µ-CT measurements.

Planar, Polysilazane‐Derived Porous Ceramic Supports for Membrane and Catalysis Applications

“…A wide variety of sacrificial porogens have been used in combination with preceramic polymers, including salts, silica beads, wood, as well as a number of conventional polymers such as PS, PMMA, low‐density PE, or PVA . Schmalz and co‐authors successfully produced porous polysilazane‐derived silicon carbonitride (SiCN) by using ultra‐high molecular weight polyethylene (UHMW‐PE) as a sacrificial template . UHMW‐PE was shown to be a very well suited template due its chemical compatibility with polysilazane as a result of its oxygen‐free chemical composition, its full conversion into gaseous species upon thermal decomposition, and its compatibility with the polysilazane precursor during mixing.…”

Polymer‐Derived Silicoboron Carbonitride Foams for CO2 Capture: From Design to Application as Scaffolds for the in Situ Growth of Metal–Organic Frameworks

“…However, the process is time‐consuming, complex to control, and the materials do not provide in general open and accessible network structures. Another strategy consists to use sacrificial polymeric fillers that are homogeneously mixed to the polymer during shaping of the pre‐ceramic polymer . The shaping consists to warm‐press a solid mixture or to cast a slurry before the pyrolysis.…”

“…Another strategy consists to use sacrificial polymericf illers that are homogeneously mixed to the polymer during shapingo ft he pre-ceramic polymer. [23][24][25] The shaping consists to warm-press as olid mixture [23,24] or to cast as lurry [25] before the pyrolysis. The main advantage of using sacrificial fillers is the presence of open and interconnected pores.…”

“…Organosilicon precursors are making an increasingly important contribution to the research development and manufacture of these Si‐based non‐oxide ceramics by pyrolysis in an inert atmosphere . In addition, this concept, called the polymer‐derived ceramic (PDC) route offers the possibility to develop materials bearing a tailored porosity through its combination with a pore‐forming approach.…”

A novel processing approach for free-standing porous non-oxide ceramic supports from polycarbosilane and polysilazane precursors

“…Porous polymer-derived ceramics can be obtained through a combination of the polymer pyrolysis route with a variety of pore forming techniques, including replica forming, direct foaming, or by using sacrificial fillers [6,7] . The use of sacrificial fillers such as polymethyl methacrylate (PMMA) [8] , polystyrene (PS) [9] , or polyethylene (PE) [10] , which are removed by thermal decomposition during the thermal conversion of the preceramic polymers, allows for a high tailorability and reproducibility of the pore structure, which is highly desired for potential applications with reproducible strength and permeability properties [11] . In the majority of reports, compaction processes (cold- or warm-pressing) were used for the consolidation of the precursor/porogen mixtures.…”