In a previous article nanocomposite films made from linear low-density polyethylene (LLDPE) as matrix and org-MMT clay as reinforcement were produced. Morphology, thermal stability, and barrier properties were already investigated. The actual work constitutes a complement of the aforementioned article where many mechanical aspects will be assessed: Unlike maleic anhydride grafted styrene-ethylene-butylene-styrene (SEBS-g-MA) as compatibilizer, using maleic anhydride grafted polyethylene (PE-g-MA) has shown remarkable improvement of most of the properties and this for an optimum clay content ranging between 2 and 4%: the tensile strength has increased by 45%, the stiffness in transverse direction (TD) by 48%, the dart impact has improved by 20%, the tear resistance in machine direction (MD) has increased by 33% and the creep resistance by 20%. Other properties were found to improve with the clay content. In addition, the evolution of the storage and loss moduli as well as the complex viscosity with the frequency were recorded; the drop by 76% of the crossover frequency for 6% weight of clay has shown that the solid-like behavior of the composite is pronounced with the increment of clay content. Melt flow index was found to vary inversely with clay amount; this indicates an increase in and hence a good dispersion of the clay within the polyethylene matrix.
In this study, linear low-density polyethylene (LLDPE)/clay nanocomposites with different clay contents were prepared by melt intercalation using two different compatibilizers: maleic anhydride grafted styrene-ethylene-butylene-styrene and maleic anhydride grafted polyethylene (PE-g-MA). Melt intercalation was achieved by twin extrusion and nanocomposite films were produced by blown film extrusion. Effects of clay and compatibilizer fractions and type of compatibilizer on the structure, permeability, and the barrier properties of the nanocomposite films were investigated. PE-g-MA was shown to notably improve the dispersion of clay layers in the polyethylene matrix, and this was examined by atomic force microscopy and X-ray diffraction. The latter tests have also highlighted the importance of the screw configuration: the presence of mixing elements favors the dispersion and distribution of nanoclay. Moreover, differential scanning calorimetry results have shown no significant effect of the clay on the crystallinity of the composite while thermogravimetric analysis tests have demonstrated a decrease of onset and peak of decomposition temperatures. Finally, barrier properties toward water vapor transmission were measured. It was proven that not also clay, but the compatibilizer participated in decreasing the permeability of the film.
This study highlights the synthesis of a new thermal insulating geopolymer based on the alkaline activation of fly ashes. A porous geopolymer material can be prepared without the addition of a foaming agent, using high ratio solution/ashes (activating solutions used are water, sodium or potassium hydroxide). In order to increase the porosity of the material and to make it more ecological, rice husks are incorporated into the formulation. The geopolymer materials were prepared at room temperature and dried at moderate temperature (105 °C) by a simple procedure. The microstructural characteristics of these new porous geopolymers were assessed by optical microscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and X-ray fluorescence (XRF). Infrared spectroscopy (FTIR) was used to confirm the geopolymerisation. The effect of the ratio solution/ashes and the percentage of the rice husk addition on thermal and mechanical analysis was evaluated. An insulating material for a solution/ashes ratio of 0.9 and a rice husk content of 15% having a λ value of 0.087 W/(m·K), a porosity of 61.4% and an Rc value of 0.1 MPa was successfully prepared.
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