Search results for "mechanical analysi"
showing 10 items of 96 documents
Evaluation of mechanical and morphologic features of PLLA membranes as supports for perfusion cells culture systems
2015
Abstract Porous biodegradable PLLA membranes, which can be used as supports for perfusion cell culture systems were designed, developed and characterized. PLLA membranes were prepared via diffusion induced phase separation (DIPS). A glass slab was coated with a binary PLLA–dioxane solution (8 wt.% PLLA) via dip coating, then pool immersed in two subsequent coagulation baths, and finally dried in a humidity-controlled environment. Surface and mechanical properties were evaluated by measuring pore size, porosity via scanning electron microscopy, storage modulus, loss modulus and loss angle by using a dynamic mechanical analysis (DMA). Cell adhesion assays on different membrane surfaces were a…
Solid State NMR Spectroscopy Investigation of the Molecular Structure of Epoxy Based Materials Cured in Different Conditions
2012
In this work two epoxy resin model systems, whose monomers are typically used in structural composites, were thermally cured in different cure conditions in order to obtain different cross-linking densities. Their molecular structures were investigated through solid state NMR spectroscopy in order to correlate them to the cure process conditions used and the results were discussed in the light of the dynamical mechanical thermal analysis (DMTA) performed.
Can biomechanical analysis shed some light on aneurysmal pathophysiology? Preliminary study on ex vivo cerebral arterial walls
2019
Abstract Background The pathophysiology of cerebral aneurysm is complex and poorly understood, and it can have the most catastrophic clinical presentation. Flow dynamics is a key player in the initiation and progression of aneurysm. Better understanding the interaction between hemodynamic loading and biomechanical wall responses can help to add the missing piece on aneurysmal pathophysiology. In this laboratory study we aimed to analyze the effect of the application of a mechanical force to cerebral arterial walls. Methods Displacement control tests were performed on five porcine cerebral arteries. The test machine was the T150 Nanotensile. The stiffness variation with the increment of the …
Static and dynamic mechanical properties of Arundo Donax fillers-epoxy composites
2014
Abstract Aim of this work is to investigate the feasibility of using a natural and inexpensive filler obtained by grinding the culms of Arundo Donax as reinforcement of epoxy resins. The effect of the content and size of Arundo Donax fillers on static and dynamic mechanical properties was evaluated showing that the composites exhibit higher tensile moduli, comparable flexural moduli and lower strength properties in comparison to the neat resin. Moreover, changes in the storage and the loss moduli only above the glass transition temperature (i.e. in the rubbery region) were found while neither significant shifts of tan δ peaks to higher temperatures nor reductions in the peak height of the c…
The effect of alkaline treatment on mechanical properties of kenaf fibers and their epoxy composites
2015
Abstract In this work, kenaf fibers were pre-treated in a NaOH solution (6% in weight) at room temperature for two different periods (48 and 144 h). The chemical treatment of kenaf fibers for 48 h allowed to clean their surface removing each impurity whereas 144 h of immersion time had detrimental effect on the fibers surface and, consequently, on their mechanical properties. Untreated and NaOH treated kenaf fibers (i.e. for 48 h) were also used as reinforcing agent of epoxy resin composites. The effect of the stacking sequence (i.e. using unidirectional long fibers or randomly oriented short fibers) and the chemical treatment on the static mechanical properties was evaluated showing that t…
Mechanical, Thermomechanical and Reprocessing Behavior of Green Composites from Biodegradable Polymer and Wood Flour
2015
The rising concerns in terms of environmental protection and the search for more versatile polymer-based materials have led to an increasing interest in the use of polymer composites filled with natural organic fillers (biodegradable and/or coming from renewable resources) as a replacement for traditional mineral inorganic fillers. At the same time, the recycling of polymers is still of fundamental importance in order to optimize the utilization of available resources, reducing the environmental impact related to the life cycle of polymer-based items. Green composites from biopolymer matrix and wood flour were prepared and the investigation focused on several issues, such as the effect of r…
Filling of Mater-Bi with Nanoclays to Enhance the Biofilm Rigidity
2018
We investigated the efficacy of several nanoclays (halloysite, sepiolite and laponite) as nanofillers for Mater-Bi, which is a commercial bioplastic extensively used within food packaging applications. The preparation of Mater-Bi/nanoclay nanocomposite films was easily achieved by means of the solvent casting method from dichloroethane. The prepared bio-nanocomposites were characterized by dynamic mechanical analysis (DMA) in order to explore the effect of the addition of the nanoclays on the mechanical behavior of the Mater-Bi-based films. Tensile tests found that filling Mater-Bi with halloysite induced the most significant improvement of the mechanical performances under traction force, …
Morphology, mechanical properties and thermal degradation kinetics of PMMA-zirconia nanocomposites prepared by melt compounding
2012
Zirconia nanoparticles were synthesized by means of a sol-gel method and embedded in poly(methyl methacrylate) (PMMA) by melt compounding. The zirconia was well dispersed in the PMMA matrix, with only a few clusters, especially for the highest investigated zirconia content. NMR results showed heteronuclear dipolar interactions involving the carbons and the surrounding hydrogen nuclei. The effect of the amount of zirconia, in the range of 1–5!wt%, on the thermomechanical properties and thermal degradation kinetics of PMMA was also investigated by means of dynamic mechanical analysis (DMA), thermogravimetric analyses (TGA), and Fourier-transform infrared spectroscopy (FTIR). The presenc…
Incorporation of Silica Nanospherical Particles in Epoxy–Amine Crosslinked Materials II. Dynamic Mechanical Measurements of Epoxy Matrix-Silica Nanoc…
2009
The mechanical strengths of epoxy composites reinforced with silica nanospheres, unfunctionalised or functionalised with either amine or epoxy groups, increase up to a proportion of 5 wt.% of filler, as reflected in a study of the shear storage modulus carried out in dynamic mechanical analysis. This improvement is observed in both glassy and rubbery states, moderately affecting the glass transition temperature of the material. From this percentage of strengthening substance the mechanical properties begin to deteriorate, but keeping (up to 10 wt.% of strengthening material), a greater storage modulus in shear than that of the pristine epoxy resin. A trend can be discerned as the percentag…
Dynamic Mechanical Measurements of Epoxy Matrix-Silica Nanocomposites II
2009
The mechanical properties of epoxy-silica nanocomposites have been studied; the silica nanosphere fillers used were un-functionalised, functionalised with amine, with epoxy, or a mixture of both kinds. Dynamic mechanical analysis measurements revealed an increase in the shear storage modulus, for all samples with a filler content of 3–5%. Improvements were observed in the glassy and rubbery states, without affecting the glass transition temperature of the materials. Above these strengthening percentages, the mechanical properties began to deteriorate, but in all cases they remained superior to those of the pristine epoxy resin. For low strengthening percentages, samples reinforced with bot…