Search results for "Plastics"
showing 10 items of 2724 documents
Preparation and characterization of polyamide 6/polyethylene blend-clay nanocomposites in the presence of compatibilisers and stabilizing system
2010
Abstract Several compatibilising systems were added to high-density polyethylene (HDPE) and polyamide 6 (PA6) blends in the presence of an organically modified montmorillonite (OMM). All the blends were prepared by using a co-rotating twin-screw extruder and characterized by SEM, TEM and XRD analyses. In addition, the rheological behaviour and the mechanical properties – tensile and impact – were evaluated. The presence of OMM affects the dimensions of the polymeric phases in the blend but not their mutual adhesion, granted only by the compatibilisers. TEM, SEM and XRD analyses indicated that there is a strict correlation between the compatibilisation level and the final interlayer distance…
Dispersions of nanosilica in biocompatible copolymers
2010
Dispersions of nanosilica in matrices of biocompatible copolymers were prepared by melt blending. Copolymers with variable molecular size at fixed hydrophilic/hydrophobic ratio and nanosilicas with different interfacial areas were studied. For comparison, a nanoclay was also investigated. The interfacial area played a relevant role in conferring peculiar properties on the nanohybrids. Amazingly, the macromolecule adsorbed on the nanosilica surface maintains some crystallinity which was quantitatively evaluated. In contrast, all the macromolecule anchored to the nanoclay surface is amorphous. The change of the crystalline state was reflected in the dielectric and the electrical conductivity …
Film Blowing of Biodegradable Polymer Nanocomposites for Agricultural Applications
2021
Films for agricultural applications, such as greenhouses films or mulching films are generally made of polyolefins such as linear low-density polyethylene (LLDPE) or low-density polyethylene. However, the use of biodegradable and/or compostable polymers is increasing, which enjoy the additional advantage that they can be left on the site since a fine life would be gradually assimilated to the underlying soil. Nevertheless, biodegradable polymeric films often do not have suitable mechanical performances. In this work, biodegradable polymer-based nanocomposite films are prepared by film blowing and compared with traditional LLDPE based nanocomposites. In particular, a biodegradable polymer bl…
How does anodization time affect morphological and photocatalytic properties of iron oxide nanostructures?
2020
Abstract Iron oxide nanostructures are promising materials to be used as photocatalysts in different photoelectrochemical applications. There are different techniques in order to synthesize these nanostructures, but one of the most inexpensive and simple method is electrochemical anodization. This method can lead to different nanostructures by controlling its parameters. Anodization time is one of the most critical parameters since it considerably affects the properties of the obtained nanostructures. In this work, different anodization times (5, 10, 15, 30 and 60 min) were studied. The resulting nanotubes were characterized by field emission scanning electron microscopy, Raman laser confoc…
Energy and charge transfer in nanoscale hybrid materials.
2015
Hybrid materials composed of colloidal semiconductor quantum dots and π-conjugated organic molecules and polymers have attracted continuous interest in recent years, because they may find applications in bio-sensing, photodetection, and photovoltaics. Fundamental processes occurring in these nanohybrids are light absorption and emission as well as energy and/or charge transfer between the components. For future applications it is mandatory to understand, control, and optimize the wide parameter space with respect to chemical assembly and the desired photophysical properties. Accordingly, different approaches to tackle this issue are described here. Simple organic dye molecules (Dye)/quantum…
Mechanical properties of the nanometer scale pre-crystalline order of a poly (ethylene terepthalate) / poly (ethylene naphthalene) blend
2006
A previous study carried out on PET has shown that this polymer undergoes a continuous structural modification over a wide cooling rate interval when solidified from the melt[1] assuming a semi-crystalline structure below 2 K s 1 and a completely amorphous one above 100 K s 1. Most important was the existence of a state of intermediate order between the above cooling rates which was evidenced by the absence of crystalline reflections in the WAXS patterns and the occurrence of SAXS maxima[2] and exothermic peak areas (DSC) in the cooling rate range above 2 K s 1. Microhardness (MH) measurements revealed that this phase affects the mechanical properties[3] plausible if one thinks of crystalli…
From dots to doughnuts: Two-dimensionally confined deposition of polyelectrolytes on block copolymer templates
2016
© 2016 Elsevier Ltd The combination of block copolymer templating with electrostatic self-assembly provides a simple and robust method for creating nano-patterned polyelectrolyte multilayers over large areas. The deposition of the first polyelectrolyte layer provides important insights on the initial stages of multilayer buildup. Here, we focus on two-dimensionally confined “dots” patterns afforded by block copolymer films featuring hexagonally-packed cylinders that are oriented normal to the substrate. Rendering the cylinder caps positively charged enables the selective deposition of negatively charged polyelectrolytes on them under salt-free conditions. The initially formed polyelectrolyt…
Carboxymethylation of alkali extracted xylan for preparation of bio-based packaging films
2012
This study describes the synthesis of carboxymethylxylan (CMX) and investigates its suitability as a film for packaging applications. High-purity polymeric xylan was extracted from commercial bleached birch kraft pulp and converted to CMX with three different degrees of substitution (DSs). The water vapor sorption, mechanical, and barrier properties of the films prepared from CMX were tested. Increasing DS of CMX films resulted in an increase in elongation at break and a decrease in tensile strength and Young's modulus. The DS also affected the barrier properties of the films. CMX films with higher DS showed improved (reduced) oxygen permeability (OP), and the water vapor permeability (WVP)…
Effects of Nylon 6,6 Nanofibrous Mats on Thermal Properties and Delamination Behavior of High Performance CFRP Laminates
2014
none 8 no Nylon 6,6 electrospun nanofibrous membranes interleaved in Carbon Fibre Reinforced Plastic (CFRP) laminates have been proposed as a means to provide a higher threshold value to delamination on structural sites where composites are more prone to develop such failure. A model, highly crosslinked thus inherently brittle, epoxy matrix was selected for its high Young’s modulus and glass transition temperature exceeding 250 °C. The influence of the Nylon 6,6 nanofibres on the curing behaviour of the matrix and on the thermal and dynamic mechanical properties of the cured resin was investigated. These properties were related to the features of the epoxy resin and of the resin impregnated…
Thermomechanical properties and thermal degradation kinetics of poly(methyl methacrylate) (PMMA) and polycarbonate (PC) filled with cerium-doped yttr…
2016
This paper reports on the thermomechanical properties and thermal degradation kinetics of poly(methyl methacrylate) (PMMA) and polycarbonate (PC) composites filled with cerium-doped yttrium aluminium garnet (Ce:YAG) at different contents ranging between 0.1 and 5 wt%, and prepared by melt compounding. The interaction between PMMA and the filler was much stronger than that between PC and the filler, and this resulted in a significant improvement in the dynamic mechanical properties of the PMMA composites. The presence of filler did not significantly increase the thermal stability of the PC, while an observable increase in the thermal stability was only observed at higher filler loadings for …