scholarly journals Recyclable Organocatalyzed Poly(Thiourethane) Covalent Adaptable Networks

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2913
Author(s):  
Francesco Gamardella ◽  
Sara Muñoz ◽  
Silvia De la Flor ◽  
Xavier Ramis ◽  
Angels Serra
Keyword(s):  
Stress Relaxation ◽  
Mechanical Characterization ◽  
Tensile Tests ◽  
Thermomechanical Analysis ◽  
Hexamethylene Diisocyanate ◽  
Relaxation Rates ◽  
Ftir Studies ◽  
New Type ◽  
And Performance

A new type of tetraphenylborate salts derived from highly basic and nucleophilic amines, namely 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU) and triazabicyclodecene (TBD), was applied to the preparation of networked poly(thiourethane)s (PTUs), which showed a vitrimer-like behavior, with higher stress-relaxation rates than PTUs prepared by using dibutyl thin dilaurate (DBTDL) as the catalyst. The use of these salts, which release the amines when heated, instead of the pure amines, allows the formulation to be easily manipulated to prepare any type of samples. The materials prepared from stoichiometric mixtures of hexamethylene diisocyanate (HDI), trithiol (S3) and with a 10% of molar excess of isocyanate or thiol were characterized by FTIR, thermomechanical analysis, thermogravimetry, stress-relaxation tests and tensile tests, thus obtaining a complete thermal and mechanical characterization of the materials. The recycled materials obtained by grinding the original PTUs and hot-pressing the small pieces in the optimized time and temperature conditions were fully characterized by mechanical, thermomechanical and FTIR studies. This allowed us to confirm their recyclability, without appreciable changes in the network structure and performance. From several observations, the dissociative interchange trans-thiocarbamoylation mechanism was evidenced as the main responsible of the topological rearrangements at high temperature, resulting in a vitrimeric-like behavior.

scholarly journals Mechanical characterization of porous asphalt mixes modifying the asphalt with fatty acid amides -FAA-

2017 ◽  
Vol 37 (1) ◽  
pp. 43 ◽  
Author(s):  
Vanessa Senior Arrieta ◽  
Jorge Eliecer Córdoba Maquilon
Keyword(s):  
Fatty Acid ◽  
Mechanical Characterization ◽  
Experimental Methodology ◽  
Chemical Additives ◽  
Asphalt Mixes ◽  
Porous Asphalt ◽  
Fatty Acid Amides ◽  
Pavement Structures ◽  
And Performance

Porous asphalt mixes (PAM), form a special road surface for asphalt pavement structures, have a special particle size distribution that lets infiltrate to the runoff storm water through of it because of its voids content about 20 %. Many researchers conducted studies and have concluded that the use of modified asphalts is completely necessary to design PAM. Organic and chemical additives and special procedures as foamed asphalt have enhanced the performance of PAM, during their service life. This paper is focused on the mechanical characterization of PAM and how the asphalt modified with fatty acid amides, influenced on their behavior and performance. Based on an experimental methodology with laboratory tests aimed at establishing a comparison between porous asphalt mixes, using for its design and production a penetration 60-70 pure asphalt and another one asphalt modified with fatty acid amides.

scholarly journals Development and Characterization of Sustainable Composites from Bacterial Polyester Poly(3-Hydroxybutyrate-co-3-hydroxyhexanoate) and Almond Shell Flour by Reactive Extrusion with Oligomers of Lactic Acid

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1097 ◽  
Author(s):  
Juan Ivorra-Martinez ◽  
Jose Manuel-Mañogil ◽  
Teodomiro Boronat ◽  
Lourdes Sanchez-Nacher ◽  
Rafael Balart ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Mechanical Characterization ◽  
Linear Thermal Expansion ◽  
Reactive Extrusion ◽  
Thermomechanical Analysis ◽  
Almond Shell ◽  
Scanning Calorimetry ◽  
Filler Reinforcement ◽  
Lignocellulosic Filler

Eco-efficient Wood Plastic Composites (WPCs) have been obtained using poly(hydroxybutyrate-co-hexanoate) (PHBH) as the polymer matrix, and almond shell flour (ASF), a by-product from the agro-food industry, as filler/reinforcement. These WPCs were prepared with different amounts of lignocellulosic fillers (wt %), namely 10, 20 and 30. The mechanical characterization of these WPCs showed an important increase in their stiffness with increasing the wt % ASF content. In addition, lower tensile strength and impact strength were obtained. The field emission scanning electron microscopy (FESEM) study revealed the lack of continuity and poor adhesion among the PHBH-ASF interface. Even with the only addition of 10 wt % ASF, these green composites become highly brittle. Nevertheless, for real applications, the WPC with 30 wt % ASF is the most attracting material since it contributes to lowering the overall cost of the WPC and can be manufactured by injection moulding, but its properties are really compromised due to the lack of compatibility between the hydrophobic PHBH matrix and the hydrophilic lignocellulosic filler. To minimize this phenomenon, 10 and 20 phr (weight parts of OLA-Oligomeric Lactic Acid per one hundred weight parts of PHBH) were added to PHBH/ASF (30 wt % ASF) composites. Differential scanning calorimetry (DSC) suggested poor plasticization effect of OLA on PHBH-ASF composites. Nevertheless, the most important property OLA can provide to PHBH/ASF composites is somewhat compatibilization since some mechanical ductile properties are improved with OLA addition. The study by thermomechanical analysis (TMA), confirmed the increase of the coefficient of linear thermal expansion (CLTE) with increasing OLA content. The dynamic mechanical characterization (DTMA), revealed higher storage modulus, E’, with increasing ASF. Moreover, DTMA results confirmed poor plasticization of OLA on PHBH-ASF (30 wt % ASF) composites, but interesting compatibilization effects.

scholarly journals Mechanical Characterization of Spray-Dried Granules by Compression and Stress-Relaxation Technique. Analysis of Relaxation Behavior.

1999 ◽  
Vol 107 (1252) ◽  
pp. 1183-1187 ◽  
Author(s):  
JunIchiro TSUBAKI ◽  
Takamasa MORI ◽  
Toshiyuki KONISHI ◽  
Akihisa TSURUTA ◽  
Hidetoshi MORI ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Mechanical Characterization ◽  
Relaxation Behavior ◽  
Relaxation Technique ◽  
Spray Dried ◽  
Technique Analysis

Inverse Mechanical Characterization of Tissue Engineered Heart Valves

2008 ◽  
Author(s):  
Martijn A. J. Cox ◽  
Jeroen Kortsmit ◽  
Niels J. B. Driessen ◽  
Carlijn V. C. Bouten ◽  
Frank P. T. Baaijens
Keyword(s):  
Heart Valves ◽  
Soft Tissues ◽  
Mechanical Characterization ◽  
Tensile Tests ◽  
Material Behavior ◽  
Uniaxial Tensile ◽  
Mechanical Conditioning ◽  
Indentation Tests ◽  
Tissue Engineered Heart Valves

Over the last few years, research interest in tissue engineering as an alternative for current treatment and replacement strategies for cardiovascular and heart valve diseases has significantly increased. In vitro mechanical conditioning is an essential tool for engineering strong implantable tissues [1]. Detailed knowledge of the mechanical properties of the native tissue as well as the properties of the developing engineered constructs is vital for a better understanding and control of the mechanical conditioning process. The nonlinear and anisotropic behavior of soft tissues puts high demands on their mechanical characterization. Current standards in mechanical testing of soft tissues include (multiaxial) tensile testing and indentation tests. Uniaxial tensile tests do not provide sufficient information for characterizing the full anisotropic material behavior, while biaxial tensile tests are difficult to perform, and boundary effects limit the test region to a small central portion of the tissue. In addition, characterization of the local tissue properties from a tensile test is non-trivial. Indentation tests may be used to overcome some of these limitations. Indentation tests are easy to perform and when indenter size is small relative to the tissue dimensions, local characterization is possible. We have demonstrated that by recording deformation gradients and indentation force during a spherical indentation test the anisotropic mechanical behavior of engineered cardiovascular constructs can be characterized [2]. In the current study this combined numerical-experimental approach is used on Tissue Engineered Heart Valves (TEHV).

Microstructural and Mechanical Characterization of TiAl/Ti6242 Diffusion Bonds

2007 ◽  
Vol 546-549 ◽  
pp. 1393-1400
Author(s):  
Xiu Hua Zheng ◽  
Bilal Dogan ◽  
Karl Heinz Bohm
Keyword(s):  
Mechanical Characterization ◽  
Tensile Tests ◽  
Bonding Interface ◽  
Microstructural Development ◽  
High Temperature Strength ◽  
Bond Quality ◽  
Base Materials ◽  
Diffusion Bonds ◽  
Sample Size Effect

Ti-6242 alloys have been widely used in aero-engine applications due to high temperature strength and creep resistance. The γ-TiAl based intermetallics are considered as candidate materials to replace the current materials weed at high temperatures. The present paper reports on the microstructural and mechanical characterization of γ-TiA/Ti6242 diffusion bonds. The emphasis is put on the better understanding of microstructural development during diffusion process and mechanical properties of diffusion bonds. The process variables of temperature, pressure and time were optimized to produce joints with sound microstructure and bond quality for mechanical characterization. The micro and standard tensile tests were applied to determine bonding strength of joints. Metallographic and fractographic examinations on diffusion joints and tested specimens were carried out using SEM coupled with EDX. The concentration profiles of elements from EDX analysis combined with SEM/BSE investigation demonstrated that the strong inter-diffusion of main elements Al and Ti across the bonding interface occurred during DB process leading to the formation of a noticeable diffusion zone consisting of fine* α2/α grains. The micro tensile tests showed that the preference of fracture on base materials far from the bonding line, but a more marked tendency to brittle failure along bonding interface shown by the standard tensile test results, indicating a significant sample size effect on mechanical property measurements.

Mechanical Characterization of Polysilicon Through On-Chip Tensile Tests

2004 ◽  
Vol 13 (2) ◽  
pp. 200-219 ◽  
Author(s):  
A. Corigliano ◽  
B. DeMasi ◽  
A. Frangi ◽  
C. Comi ◽  
A. Villa ◽  
...  
Keyword(s):  
Mechanical Characterization ◽  
Tensile Tests ◽  
On Chip

Viscoelastic Characterization of an Epoxy-Based Molding Compound

1995 ◽  
Vol 390 ◽  
Author(s):  
V. H. Kenner ◽  
M. R. Julian ◽  
C. H. Popelar ◽  
M. K. Chengalva
Keyword(s):  
Stress Relaxation ◽  
Strain Rate ◽  
Constant Strain Rate ◽  
Viscoelastic Behavior ◽  
Tensile Tests ◽  
Prony Series ◽  
Master Curves ◽  
Molding Compound ◽  
Relaxation Curves

ABSTRACTThis paper describes the viscoelastic characterization of a highly filled epoxy molding compound commonly used in electronic packaging applications. Both stress relaxation tests and constant strain rate tensile tests were conducted. The material was found to be nonlinear in its viscoelastic behavior and to be amenable to horizontal shifting to form master curves. A representation of the master stress relaxation curves in terms of a Prony series is given, and the use of this representation illustrated in the context of both linear and nonlinear representations of the viscoelastic behavior to predict the results of the constant strain rate experiments.

An Alternative Approach for FRCM Matrix Tensile Strength Evaluation

2019 ◽  
Vol 817 ◽  
pp. 365-370 ◽  
Author(s):  
Alessandro Bellini ◽  
Marco Bovo ◽  
Andrea Incerti ◽  
Claudio Mazzotti
Keyword(s):  
Tensile Strength ◽  
High Performance ◽  
Mechanical Characterization ◽  
Experimental Tests ◽  
Tensile Tests ◽  
Test Methods ◽  
Test Method ◽  
The Matrix ◽  
Flexural Tests

Structural retrofitting with composite materials proved to be an effective technique for rehabilitation of degraded or damaged masonry and concrete buildings. Nowadays, Fiber Reinforced Cementitious Matrix (FRCM) composites are widely used as externally bonded strengthening systems thanks to their high performance, low weight and easiness of installation. Several experimental tests and numerical studies are currently available concerning the tensile and bond behavior of FRCM systems, but a debated and still open issue concerns the methods for the mechanical characterization of the mortar used as matrix within the strengthening system. The present paper analyses and compares different test methods for determining the matrix tensile strength. Pure tensile and flexural tests have been carried out on different mortar matrix samples. In order to evaluate which is the most suitable value to be considered for a correct interpretation and modeling of the composite system, the experimental results obtained through flexural tests on standard mortar specimens have been compared with the outcomes obtained from direct tensile tests on FRCM coupons. The present study represents only a first step for the definition of the most appropriate test method for the mechanical characterization of the matrix used within FRCM strengthening systems.

Mechanical Characterization of Friction Stir Welds of Two Dissimilar Aluminium Alloys of the 6xxx Series

2008 ◽  
Vol 587-588 ◽  
pp. 430-434 ◽  
Author(s):  
Pedro Miguel Guimarães Pires Moreira ◽  
T. Santos ◽  
Sérgio M.O. Tavares ◽  
Valentin Richter-Trummer ◽  
Pedro Vilaça ◽  
...  
Keyword(s):  
Aluminium Alloys ◽  
Mechanical Characterization ◽  
Element Model ◽  
Tensile Tests ◽  
Strength Properties ◽  
Bending Test ◽  
Friction Stir ◽  
Microstructure Examination ◽  
6Xxx Series

A study on the mechanical characterization of friction stir welds between aluminium alloys 6061-T6 and 6082-T6 was carried out. For comparison, single alloy joints made from each one of the two alloys were also performed. The work included microstructure examination, microhardness tests, tensile tests and bending tests of all joint types. An approximate finite element model of the joint, taking into account the spatial dependence of the tensile strength properties, was made, modelling a bending test of the weldments.

Mechanical characterization of tetraxial textiles

2017 ◽  
Vol 48 (1) ◽  
pp. 3-24 ◽  
Author(s):  
Mehdi Ghazimoradi ◽  
Valter Carvelli ◽  
Maria Chiara Marchesi ◽  
Roberto Frassine
Keyword(s):  
Mechanical Properties ◽  
Strain Field ◽  
Mechanical Characterization ◽  
Tensile Tests ◽  
Image Correlation ◽  
Correlation Technique ◽  
Digital Image Correlation Technique ◽  
Experimental Campaign ◽  
Out Of Plane

In this paper, the mechanical properties of different tetraxial fabrics are investigated. Fabrics were produced using an innovative loom capable of weaving four threads at the same time with complete discretion of yarn type and count. The experimental investigation deals with in-plane and out-of-plane mechanical testing of tetraxial fabrics, as well as yarns made of four different materials (polyethylene terephthalate, glass, aramid, and basalt). The digital image correlation technique was used to measure the in-plane strain field for both uniaxial and biaxial tensile tests. The extensive experimental campaign allowed for a complete mechanical characterization of this novel fabric architecture including interlacement of different yarns.

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