Search results for "WOOD"

The use of non-cavitating coupling fluids for intensifying sonoelectrochemical processes

2020

Abstract For the first time, we have investigated the beneficial effects of non-cavitating coupling fluids and their moderate overpressures in enhancing mass-transfer and acoustic energy transfer in a double cell micro-sonoreactor. Silicon and engine oils of different viscosities were used as non-cavitating coupling fluids. A formulated monoethylene glycol (FMG), which is a regular cooling fluid, was also used as reference. It was found that silicon oil yielded a maximum acoustic energy transfer (3.05 W/cm2) from the double jacketed cell to the inner cell volume, at 1 bar of coupling fluid overpressure which was 2.5 times higher than the regular FMG cooling fluid. It was also found that the…

A shear test for structural adhesives used in the consolidation of old timber

2001

A test method was developed specifically for structural adhesives used in thick joints. It is based on compressive shear loading of glued joints (GJ) and solid wood (SW) specimens, before and after a suitable accelerated ageing cycle. The evaluation of results is based on the ratios of wet strength to dry strength and on the comparison of GJ specimens to SW specimens which are prepared from the same batch of wood, in order to minimise the influence of the variability in wood characteristics. On a group of 10 epoxy-based adhesives, specifically marketed for the consolidation of old timber structures, the method has proved to be effective to differentiate the performances of each product. Amo…

Halloysite nanotubes/pluronic nanocomposites for waterlogged archeological wood: thermal stability and X-ray microtomography

2020

Filling a polymer with halloysite nanotubes is considered a promising strategy to generate nanocomposites with tailored physicochemical properties. We have focused our attention on pluronic block copolymer/halloysite nanocomposites prepared by melt blending. The effect of composition on thermal stability and polymer crystallinity was investigated by thermogravimetry and differential scanning calorimetry. Electron microscopy was used to monitor the nanoparticle distribution in the polymeric matrix. The pluronic thermal stability is reduced by the clay nanoparticles. Concerning the polymer crystallinity, it is slightly decreased even if the melting temperature is lowered by halloysite. Furthe…

Engineering the crack path in lattice cellular materials through bio-inspired micro-structural alterations

2019

Abstract A computational study on the fracture behaviour of bio-inspired finite-size lattice configurations is performed in this work. The study draws inspiration from recent investigations aimed at increasing the fracture energy of some materials through small modifications of their microstructure. The main question here is whether it is possible, to some extent, to engineer the crack path in metallic cellular materials through such small micro-structural modifications and how to quantify the effect of alternative strategies. Nature provides several examples of strategies used to delay or arrest damage and crack propagation. One striking example is given by the micro-architecture of severa…

X-ray micro-tomography based FEM modelling of hygroexpansion in PLA composites reinforced with birch pulp fibres

2017

This article presents a microscale modelling approach coupled with X-ray computed micro-tomography for the evaluation of material properties of polylactic acid (PLA) reinforced by birch pulp fibers under the effect of moisture. The results in terms of elastic moduli and hygroexpansion deformation were found in good agreement with the measurements taken at different levels of water uptake.

Effect of the processing techniques on the properties of ecocomposites based on vegetable oil-derived Mater-Bi® and wood flour

2009

Polymer composites based on biodegradable polymers and natural-organic fillers are becoming more and more important because of their interesting properties in terms of environmental impact, manufacturing cost, and esthetic features. In particular, the use of biodegradable polymer matrices allows obtaining a full biodegradability. One of the most interesting biodegradable polymer families is the Mater-Bi® one. In this work, we investigated the processability, the influence of different processing techniques, and the influence of the filler particle size on the properties of Mater-Bi/wood flour composites. Injection molding caused a partial degradation of the macromolecular chains, whereas si…

Thermal and dynamic mechanical properties of beeswax-halloysite nanocomposites for consolidating waterlogged archaeological woods

2015

Abstract Thermal and mechanical properties were determined for the halloysite nanotubes (HNT)/beeswax composites at various compositions. The beeswax degradation temperatures and time course, provided by thermogravimetry (TG), evidenced the improvement of the thermal properties operated by HNT. Differential scanning calorimetry (DSC) allowed us to determine the enthalpy of melting as well as the time course of the melting process for beeswax. A slight loss of beeswax crystallinity was observed upon HNT addition. The dynamical mechanical analysis (DMA) provided the loss and the storage modulus for the nanocomposites upon heating and it was shown that the nanoclays create an inorganic framewo…

Pickering Emulsions Based on Wax and Halloysite Nanotubes: An Ecofriendly Protocol for the Treatment of Archeological Woods

2020

A novel green protocol for the consolidation and protection of waterlogged archeological woods with wax microparticles has been designed. First, we focused on the development of halloysite nanotubes (HNTs) based Pickering emulsions using wax as the inner phase of the oil-in-water droplets. The optimization of the preparation strategy was supported by both optical microscopy and scanning electron microscopy, which allowed us to show the morphological features of the prepared hybrid systems and their structural properties, i.e., the distribution of the clay at the interface. Also, the dependence of the overall dimensions of the prepared systems on the halloysite content was demonstrated. Micr…

Influence of pulp bleaching and compatibilizer selection on performance of pulp fiber reinforced PLA biocomposites

2019

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…