Development and characterization of mineral-filled (calcium carbonate or talc) polypropylene porous membranes obtained by extrusion
One of the techniques to make porous membranes from polymers is based on the stretching a polymer film containing a row-nucleated !amellar structure.This special crystalline structure may be achieved using a processing technology called MEAUS, which is based in the extrusion of a polymer film under...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2019 |
| País: | España |
| Institución: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/668390 |
| Acceso en línea: | http://hdl.handle.net/10803/668390 https://dx.doi.org/10.5821/dissertation-2117-176426 |
| Access Level: | acceso abierto |
| Palabra clave: | Àrees temàtiques de la UPC::Enginyeria dels materials 66 |
| Sumario: | One of the techniques to make porous membranes from polymers is based on the stretching a polymer film containing a row-nucleated !amellar structure.This special crystalline structure may be achieved using a processing technology called MEAUS, which is based in the extrusion of a polymer film under fast cooling, its annealing and at last a uniaxial strain along the machine direction is applied. While many progresses has been made in material polymers such as polypropylene, filled polypropylene compounds have scarcely received attenUon for in order to produce this kind of membranes . In this sense, two of the main fillers employed in the industrial market used in polypropylene are calcium carbonate and tale.This thesis deals with the possibility of producing polypropylene/based membranes, using these two types of fillers .Commercial grades of calcium carbonate and tale were selected for this purpose. The first step of the experimental tasks has been the production of stable precursor films at scale laboratory, using an extrusion-calender system .These films had a nominal thickness of 25 micrometer, and the extrusion processlng was stable. Annealing was performed mainly at 140 ºC but in sorne cases the annealing temperature was varied . Finally, uniaxial strain was carried out on the annealed precursor films, giving this last step of the methodology a porous structure. Rheologicalstudies did not show any significant differences than could affect to the first stage of the MEAUS process. The orientation of non-annealed and annealed precursor films showed the high dependence of this feature on the annealing treatrnent, filler content, and filler type.Also,therm al studies carried out through DSC revealed differences in aspects related with the melting endotherm of the non-annealed precursors, annealed precursors, and membranes . The surface pare morphology was analysed through electron microscopy.lt was observad that the pore density, porous area and finally the permeability of the produced membranes was highly dependen!on the crystalline orientation factor,as well as on the filler content and the filler type. The thermal stability of the membranes, studied through TGA, was not affected bythe different porous morphology, and only depended on the chemical composition . Finally, the mechanical characterization carried out through tensile tests, revealed significant changes due to the annealing treatrnent, and also, due to the polymer composition. |
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