130,476 research outputs found
Analisi energetica ed economica nella produzione di biogas e compost da biomasse residuali,
No full textInfluence of wood substrate on bonding joint with structural silicone sealants for wood frames applications
No full textThe interest on silicone structural sealants application in the field of wood window frames is growing fast, because of the introduction of novel production processes and stringent energy performance requirements of buildings. Structural timber-glass-sealant adhesive bonding assessments were carried out in several researches.
The goal of this paper is to investigate the mechanism of adhesion and the properties of wood-structural silicone joints in order to understand the failure modes and strength of these bondings. For this purpose, tensile tests on wood-silicone joints were carried out in order to investigate the adhesion strength with different wood species. Moreover, peel tests have been carried out on wood-silicone joints in order to better understand the adhesion properties of the different materials. For this purpose, a dedicated belt was used, to avoid typical problems encountered during the standard peel test execution.
In this investigation, both tests on untreated wood-silicone bonding and on coated wood-silicone bonding have been carried out, in order to capture the influence of wood species and wood primers on the adhesion to silicone.
The results clearly proved that the adhesion strength between wood and structural silicone is highly influenced by the wood species, and a good correlation was found between tensile strength and breakage load in peel test.
These results can be useful when assessing the strength of wood-silicone-double glazing glass joints and when informing FE models of wood frames joints and also to provide indications about optimal structural sealant application modes and selection of silicone typologies in wood frames applications
Wooden window frames with structural sealants: manufacturing improvements and experimental validation of a finite element model
No full textThis paper proposes a finite element (FE) model of a novel wooden window frame typology and validates it by experimental tests on a whole window frame and corner joint specimens. The focus is on double glazing glass frames and dowelled butt corner
joints. The innovation consists on the application of the structural silicone sealant only
at the interface between wood and one of the thin glass layers of the double-glazing glass, so achieving a low application depth. This application mode reduces the sealant
quantity and allows the disassembly and substitution of the glass from the frame in case of breakage.
In order to inform the FE model of the whole frame, the corner joint strength is
measured by specific experimental tests. The test are carried out on meranti wood species and using a SIKA WT-40 structural silicone. The results show an high correlation between the FE model and the experimental results in the range of small
frame deformations, that are of interest for this application. The model is then applied to various wooden frame geometries in order to evaluate if the silicone application
mode and dowelled corner joints allow an acceptable stiffness of the frame, and in particular low deformations of the bottom corner joint, in order to maintain the wooden
frame functionality under external loads. This approach could be useful in the assessment of optimal wood-sealant-glass joint geometries, corner joint geometries and window frame geometries to limit the bottom corner joint deformation in the required range
Tests for outdoor window profiles: 90° mortise tenon corner joints strength assessment
No full textThe research focuses on the assessment of the performances of glued laminated wood corner joints for outdoor window
profiles applications, proposing a methodology to appreciate the strength of 90° tenon mortise corner joints. The rationale
relies on the potential damage (i.e. breaking of the frame) that can be caused by poor glueing processes and/or typology of
adhesives. There is a number of standards for assessment of wood-adhesive bonds for outdoor windows; however, there is a
lack of specific standards related to glueing assessment for outdoor wood frames, which can take into account all the factors
influencing the glueing quality. The proposed methodology was tested on red oak window profiles. A commercially available
polyvinyl acetate-based adhesive was used for corner joints. Bending strength of 90° tenon mortise corner joints was
measured and compared with maximum admissible loads on the frame to limit its deformations within admissible ranges.
The test results show that the 90° tenon mortise corner joints strength exceeds the admissible load to preserve the
functionality of the frame. In order to appreciate the influence of conditioning processes on adhesion, shear strength tests of
the flatwise glued joint samples (bond lines of lamellae) were carried out after different conditioning processe
Structural silicone sealant modelling for wood frames: influence of adhesion on bonding strength
No full textThis paper provides a quantitative measure of the bonding strength of structural silicone
sealant applied to wood–double glazing glass joints for wood frame applications. The joint
strength is assessed by tensile and shear experimental tests. The paper aims to characterize
the joint behaviour through experimental tests in order to implement and validate a finite
element (FE) model of the joint that can be used for whole frame characterization. The
experimental tests are carried out on three wood species (Meranti, White Oak and Pine),
and two different FE models of the wood–silicone–glass joint are implemented: the first
basic model assumes the modulus of elasticity and modulus of rupture of the silicone as
provided by the manufacturer, while the second model assumes the results of the experimental tensile tests. The results of the first FE model do not fit well with the tests carried
out, while the second FE model proves to be more reliable and is validated by experimental results. The results report that, when modelling wood–double glazing glass joints by FE
methods, the equivalent structural sealant modulus of elasticity assigned in the model
should be about 50% lower than what is declared by the manufacturer. This result can be
useful when modelling whole wood frames and dimensioning sealant depth and thickness
in wood–glass joint applications
Tridentate N-N-N chelating systems as potential antitumor agents [Sistemi chelanti tridentati N*-N*-N* quali potenziali agenti antitumorali]
No full textTridentate chelating agents, as potential antitumor agents, were prepared by condensing 2-quinolylhydrazines, 2-pyridylhydrazine and 2-benzothiazolylhydrazine with pyridine-2-aldehyde, 6-methylpyridine-2-aldehyde, 2-acetylpyridine and 2-benzoylpyridine. All compounds were tested against Lymphocytic leukemia P388. The active pyridine-2-aldehyde-4-methyl-2-quinolylhydrazone [1-(4'-methyl-2'-quinolyl)-3-(2'-pyridyl)-1,2-diaza-2-propene] (I d) was also tested against other experimental tumors and proved inactive
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