TY - THES A1 - Purohit, Purv J. T1 - Characterization of Polymer Nanocomposites based on Layered Double Hydroxide and Carbon Nanotubes N2 - Polymer based nanocomposites by melt blending of synthesized ZnAl-Layered Double Hydroxide (ZnAl-LDH) and Polyolefines [Polypropylene (PP) and Polyethylene (PE)] and also Polylactide (PLA) with MgAl-LDH and multi-walled Carbon Nanotubes (MWCNT) were investigated. The LDH was organically modified by using a surfactant sodium dodecylbenzene sulfonate (SDBS) to increase the interlayer spacing of the LDH, so that polymer chains can intercalate the inter layer galleries. Some amount of maleic anhydride grafted PP and PE were incorporated in the nanocomposites based on PP and PE respectively to enable the interaction of the non-polar polymers (PP and PE) with the LDH. The resulting morphology was investigated by a combination of Differential Scanning Calorimeter (DSC), Small and Wide-angle X-ray scattering (SAXS and WAXS) and broadband dielectric relaxation spectroscopy (BDS). In case of LDH based nanocomposites (PP, PE and PLA), the homogeneity of the nanocomposites and the average number of stack size (4 – 7 layers) were determined using scanning micro focus SAXS (BESSY II). DSC investigations of PP and PE based LDH nanocomposites showed a linear decrease in crystallinity as a function of filler concentration. The extrapolation of this decreasing dependence to zero estimates a limiting concentration of 40 wt% and 45 wt% respectively. Above this amount of LDH the crystallinity of the polymers is completely suppressed. This finding is in agreement with WAXS investigations where the area below the crystalline reflections and amorphous halo were calculated and used to estimate the degree of crystallinity. PLA/LDH nanocomposites presented a little different behavior, the crystallinity of the polymer at first increases and then decreases as a function of LDH concentration. In this case the crystallinity will be suppressed at around 15 wt%. The dielectric spectra of the nanocomposites based on PP/LDH and PE/LDH show several relaxation processes which are discussed in detail. The intensity of the dynamic glass transition increases with the concentration of LDH. This is attributed to the increasing concentration of the exchanged anion dodecylbenzene sulfonate (SDBS) which is adsorbed at the LDH layers. Therefore, a detailed analysis of the β-relaxation provides information about the structure and the molecular dynamics in the interfacial region between the LDH layers and the polymer matrix which is otherwise dielectrically invisible (low dipole moment, non-polar). In case of PLA/LDH, three relaxation processes related to dynamic glass transition and one localized fluctuations were identified and analyzed in detail to understand the morphology. For this system, one dynamic glass transition process originates from the fluctuations of the interfacial molecules, second from the PLA matrix (polar polymer, C=O in the main chain) and the third from segments confined between the intercalated LDH sheets. Additional thermal investigations were carried out for PP/LDH and PLA/LDH samples. The increase in the rigid amorphous fraction (RAF) was observed in both the cases. This is attributed to the polymer molecules which are in close proximity to LDH sheets, as they hinder their mobility. This is analyzed in detail and related to the BDS results. PLA based MWCNT nanocomposites were investigated by BDS as initial result. The findings showed that between 0.5 and 1 wt% of CNT, a percolating network of the nanotubes is formed which leads to DC conductivity. This is due to the high aspect ratio of the CNTs and also the van der Waals interaction between the nanotubes which forms a network leading to conductivity. T3 - BAM Dissertationsreihe - 98 KW - Polymer Nanokomposite KW - Characterization KW - Carbon Nanotubes KW - Layered Double Hydroxide KW - Polymer KW - Nanocomposites KW - Hydrotalkit KW - Struktur-Eigenschaften Beziehungen KW - Charakterisierung KW - Kohlenstoffnanoröhren PY - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-604 SN - 978-3-9815360-6-5 SN - 1613-4249 VL - 98 SP - 1 EP - 144 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-60 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -