The Nanocomposites Derived from the ME100-ODTMA - Essay Example

XRD & TEM Nano-composite structure was characterized using XRD and TEM. XRD defined the shape intensity and amount of basal reflection from layered silicates. After adding polymer chains between layered silicates, the interlayer distances increased that interrupted diffraction peaks by 001- and to lower angles, however where silicate layers were distributed in a continuous polymer matrix, no diffraction peaks were observed. A broadening of this diffraction pattern can indicate partial exfoliation of the silicate layers as crystallite size and degree of registration is decreased. Figure 1a shows the XRD patterns for pristine ME100, ME100-ODTMA and the corresponding patterns of Hy3078/ME100-ODTMA nanocomposites with various amounts of ME100-ODTMA in the diffraction angle range 2θ = 2–10°. Diffraction ranging from 2θ = 2–10° indicated an intercalated hybrid or an immiscible system. The 001 diffraction peak indicated for ME100 appeared at 2θ = 7–10°, of which the interlayer distance was 1.24nm. The presence of alkyl ammonium ions in the basal spacing reduced the attractive forces between the clay and enabled the polymer to be intercalated into the clay-polymer easing up clay distribution. an increase in intercalated structures with organoclay content and pristine clay caused smaller interlayer distances, , which might have impeded the higher basal spacing or exfoliation of individual silicate layers.25 Figure 1b represents XRD patterns for pristine WXFN, WXFN-ODTMA and the corresponding patterns of Hy3078/WXFN-ODTMA nanocomposites. The interlayer gallery height for the pristine WXFN, Distanced (001) between XRD and individual layer of silicate thickness ( ̴ 1 nm), was 1.28 nm (2θ = 6.90°). The XRD profile of Hy3078 composites of the silicate reflected a disruption of silicate layers layers in Hy3078/WXFN matrix, but in the case of Hy3078/WXFN-ODTMA with 4wt% clay content, it indicated an unorderly added structure with a (001) plane peak at 2θ = 2.40° (= 3.68 nm). In Figure 1c, the XRD profile of the pristine WXFP and their respective composites showed the same trend as that of WXFN. This is an indication that as the clay content increases, the mobility of the nanofiller is decreased, providing low driving force for the intercalated polymer to break the tactoids. However, 2ME100-ODTMA showed orderly diffraction peaks in comparison to ME100, associated to interlayer distances of k4.7, 2.2, and 1.6 nm, respectively. Extra peaks were as a result of longer range registration and interstratified superstructure of the largest ME100 synthetic clay, which originates from a well-published inherent charge heterogeneity.26, 27 this charge heterogeneity might have allowed various wetter chains to add to the fluoromics layers making monolayer-bilayer or bilayer pseudo triple-layer arrangements possible. The proportional relationship between the width and height of ME100 could result in long range order of organosilicate tactoids which would have contributed to strong diffraction peaks in the resulting organosilicate tactoids ( with respect to synthetic WXFN and WXFP or natural nanosilicates) These results matched with XRD results that indicated that these nanocomposites produced intercalated and exfoliated structure types. In conclusion we can deduce that high aspect ratio of ME100, which has lower mobility and higher space restrictions experiences frustrated orientational freedom in the matrix, making it hard for intercalated hy3078 to fleece platelets from well structured tactoids Mechanical properties The effects of pristine clay and organoclay loading on the mechanical properties of melt compounded Hy3078 (pure Hy3078 and composites) are summarized in Table 2. Achievement of ideal mechanical properties was when 2wt% ME100-ODTMA was incorporated, increasing the tensile and tear strength by 17% and 10% respectively. Up to 2wt% filter loading organoclays are uniformly dispersed and gives rise to well exfoliate morphologies in the Hy3078 matrix, as has been reported in the TEM results. The organoclay platelets of ME100-ODTMA possessed a very high aspect ratio were more efficient reinforcing elements, assuming reasonable filler-polymer interactions.29 the tensile strengths of WXFN and WXFP decreased with the incorporation of filler. The slightly higher degree of nanofiller agglomeration in these systems, combined with a platelet size which could be considered below the critical diameter required for effective reinforcement, reduced tensile strength. Re-agglomeration by added organoclay content is because the amount of matrix molecules becomes fewer than those required for a complete exfoliation (this means molecules of the polymer and those of intercalating compounds of organoclay intermingle). Practically speaking, the much longer extruder residence time that would be required for supreme dispersion at higher nanofiller loadings would be associated with other deleterious problems such as thermal degradation and loss of TPE molecular weight, so these process ability constraints are also important to consider. Elongation properties, the elongation at break for pure Hy3078 was 2075%, which decreased alongside other composites and nanocomposites to various extents after incorporation of fillers into the polymer matrix. This indicated an interruption of mobility or deformation of the matrix through physical interaction and immobilization of polymer matrix in presence of mechanical restrains. 10 Table 3 shows that Young’s modulus for the composites and nanocomposites increased continuously with increasing clay content, especially Hy3078/ME100-ODTMA, which achieved almost 16 MPa, up from approximately 9 MPa for the host. The improvement of the modulus has been attributed to good dispersion of nanosized clay particles that hinder mobility of polymer chains under loading and good interfacial adhesion of clay interlayer and the polymer as reported by several researchers 9,31 the tensile-creep analysis was performed for a few samples to determine their time-dependent dimensional stability under tensile deformation. The tensile-creep modulus (Et) (ratio of stress applied to the strain of tensile creep) was used to determine creep resistance of the Hy3078 and the Hy3078/ME100 composites and nanocomposites. Et values for pure Hy3078, Hy3078/ME100 and Hy3078/ME100-ODTMA measured at 3.5MPa creep resistance are shown in table 3 below and their representative creep curves in figure 3. The highest Et was achieved by Hy3078/2ME100-ODTMA, with an increase of 18%. This proved that the highest aspect ratio and best dispersed organoclay was at a position to raise creep resistance and stability of the Hy3078. The DSC cooling and subsequent heating scans of the pure Hy3078, Hy3078/ME100, Hy3078/WXFN and Hy3078/WXFP composites and nanocomposites are shown in Figures 4a, c and e and 4b, d and f, respectively, while the summary of DSC features is as shown in table 4 below. DSC A previous DSC analysis by Aso et al.9 on nanosilica-based Hytrel nanocomposites, it was shown that the Tc while it was being cooled increased from 155°C in the pure Hytrel to 163°C in the nanocomposites but crystalline content of PET increased with fumed silica content, both modified and unmodified. 32 and epoxy-modified fume silica nucleated the crystallization of a propylene-ethylene copolymer.33 From the heating scan, we observed three to four endotherms, and they have been labelled T1–T4. A discrete soft segment glass transition at approximately −70°C was found in all samples. Addition of filler did not affect temperatures or enthalpy associated with endotherms. The T1 endotherm was observed at 5 °C in all samples. This endotherm may have been attributed to distortion of the hard segment consisting molecular units of esters. Immediately A broad exotherm was seen after the T1 endotherms and it’s believed to be in relation to conformational changes in hard phase following melting of endotherms. Samples with WXFN showed a disappearance or weak endotherm of t2 at temperatures between 48 -58°C which was not resolved in fig 3d.reason this weak endotherm disappears after annealing below the melting point is probably because melting of crystalline aggregates of soft segments formed in these co polyester composites not yet in equilibrium DMA When performance of WXFP composites is compared to hy3078, the higher tan δ values of Hy3078 with modified WXFP-ODTMA indicate an elastic contribution of the filler. The different response was attributed to presence of quaternary ammonium modification despite the full elastic response of the inorganic filler at the levels of stress.this difference in response is due to an increase in amount of non-crystalline hard segments in the amorphous phase or an increase in the mobility of the soft phase. 36 WVTR The reductions in water vapour transmission through the nanocomposites were attributed to the layered silicates providing a difficult diffusion path for water molecules, as opposed to the layered silicates changing the diffusivity of the polymer matrix. CONCLUSIONS The nanocomposites derived from the ME100-ODTMA high aspect ratio modified clay of 2wt% provided the best product in terms of tensile and tear strengths, and improved creep resistance. Improvement in mechanical properties can be linked to good dispersion and delamination and strong interaction between TPE-e and clay. The nanoclay of the MMME100-ODTMA high aspect ratio nanocomposites showed a great reduction in transmission rate of water vapour due to difficulties caused by filler inclusions. Read More