Effect of Particle Size and Particle Agglomeration on Composite Membrane Performance

M.G. GARCIA; J. MARCHESE; N.A. OCHOA

JOURNAL OF APPLIED POLYMER SCIENCE

JOHN WILEY & SONS INC

Lugar: London; Año: 2010 p. 1 - 8

0021-8995

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0pt; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 85.05pt 70.85pt 85.05pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> One of the most used method to study the rigidification of polymer matrix in composite membranes is the differential scanning calorimetry (DSC). Glass transition temperatures (Tg) give information about filler/polymer interaction and the rigidify of polymer matrix. In this work, optical microscopy, mechanical properties and X-ray diffraction were performed to study both Polyetherimide (PEI) matrix rigidification and Activated Carbon/PEI interfacial adhesion instead of DSC technique usually used. Then permselective properties of mixed matrix membranes were interpreted. The change of rigidity in these composite membranes was in agreement with the decrease of flexibility of composite materials as the filler content increases. This fact was confirmed by the tension and elongation data and DRx measurements. However, Young’s modulus (E) value decreases as carbon content increases. It was observed that there is an increment in all gas permeability coefficients measured in composites when compared with that of PEI. As particle size grows a low particle surface area and a poor interfacial adhesion is observed. The carbon agglomerates act as sites of stress concentration within polymeric matrix. This decreases the intercatenary distances and it limits the movement of polymer chains resulting in a more rigid matrix. The higher selectivity of H2/CH4, H2/CO2 and O2/N2 systems observed in composite membranes reveals that there are both a preferential sorption of certain gases in the carbon surface or carbon/polymer interface and a molecular size exclusion, which are responsible for that increment, in spite of the poor interfacial adhesion.