RT info:eu-repo/semantics/masterThesis
T1 Study of the effects of different polymerization methods on open-cell microcellular materials based on PMMA gelled with acetone
A1 Fernández de la Fuente, Mario
A2 Universidad de Valladolid. Facultad de Ciencias
K1 Microcellular polymer
K1 Poly(methyl-methacrylate)
K1 Open cell
K1 Gas dissolution foaming
AB Microcellular polymers are characterised by cell sizes in the range of tens to hundreds of micrometres and cell nucleation densities higher than 109nuclei/cm3. These materials have aroused great interest in Materials Science area due to their interesting properties, such as a reduced thermal conductivity and good mechanical properties in comparison to conventional cellular polymers (with cells above hundreds of microns). One interesting application for such materials is their use as membranes or filters due to its high specific surface and small pores. For these applications it is mandatory for the cells need to be connected one with each other’s.Microcellular polymers are usually produced through gas dissolutions foaming, however control the open cell content while tailoring the cellular structure is not an easy task.This work focuses on the production of cellular materials by expanding a PMMA-based gel, using acetone as solvent and dissolution gas foaming process with super critical CO2. This PMMA has been polymerized specifically for this subject by different methods (Suspension, Emulsion, Bulk and Dispersion). The parameters of foaming temperature (55ºC), saturation pressure (250 bar) and saturation time (1 hour) have been kept constant throughout the work.Five of these foamed materials (Suspension, Suspension_1, Emulsion, Bulk_0.04, Bulk_0.3 and Dispersion) and a commercial one (V825T) with different molecular weights and polidispersities have been manufactured to later characterize them. With the images obtained by electron microscopy (SEM) and the ImageJ/FIJI analysis-software tool, the relative density has been measured; the average cell size; nucleation density and homogeneity in their structures.PMMA solid materials have a range of 964.500-63.750 g/mol for molecular weight, 6.4-1.5 for polydispersity and 126.29-114.57 ºC for glass transition temperature.The manufactured cellular materials present a completely interconnected cellular structure with a wide range in their internal structures. These cover relative densities between 0.15-0.52; cell average sizes between 1.2-73.9 μm and nucleation densities between y 2.9·107-2.9·1011 cells/ cm3.The relationship between the obtained cellular structures and the initial characteristics of the synthesized polymers have been stablished.
YR 2023
FD 2023
LK https://uvadoc.uva.es/handle/10324/63635
UL https://uvadoc.uva.es/handle/10324/63635
LA eng
NO Departamento de Física de la Materia Condensada, Cristalografía y Mineralogía
DS UVaDOC
RD 30-jun-2024