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Élaboration et caractérisation mécanique des mousses polymères : application aux projectiles non létaux
Abstract
Pour la fabrication des mousse polyuréthanes d'une certaine densité, nous cherchons à contrôler le mieux possible la formation d’une microstructure de sorte que le produit final ait les propriétés souhaitées pour projectiles non létaux. Ces derniers doivent être en mesure de mettre hors d’état de nuire une cible sans pour autant provoquer une blessure permanente ou une issue fatale. Ce travail a pour objectif l’élaboration et la caractérisation mécanique de différentes mousses polyuréthanes élaborées par la formulation optimale. La caractérisation mécanique concerne des tests de compression quasi statique. Par ailleurs, une analyse microscopique a été effectuée afin de confirmer la structure en cellules ouvertes de la mousse élaborée.
... The elaboration of flexible polymeric foam materials, shockproof in nature, selects the type of polyol, isocyanate, and the most consistent catalyst to arrive at a reliable recipe that allows us to achieve flexible foam with the desired characteristics. 23,24 Obtaining the optimum formulation of PU by free expansion is first carried out in small cups at low stirring speeds (1000 rpm). After each step, all formulations are summarized into four main formulations; the formulation is rectified based on the appearance of the obtained foam. ...
Nonlethal projectiles are manufactured and designed proportionately, with a minimal likelihood of mortality or harm. However, numerous real-world examples indicate that nonlethal projectiles can potentially inflict severe lesions and death in some circumstances. As a result, it is essential to design and manage the manufacture of projectile materials to achieve maximum efficacy with the least amount of collateral damage. The current paper provides a technique for generating and analyzing filled polyurethane (PU) foams and studying their viscoelastic characteristics. The sand and graphite composition ranged between 5 and 10% by weight. The suggested technique seeks to exert control over the evolution of the microstructure. The mechanical characteristics were obtained by dynamic mechanical analysis (DMA) testing. We made a pneumatic launcher and a sturdy rigid wall. In addition, the artificial human head is covered with force sensors to perform dynamic characterization. Also, scanning electron microscopy (SEM) of the polyurethane foam cross sections demonstrated that the average cell size of 98 μm was unaffected by the fillings' content. Furthermore, X-ray diffraction analysis (XRD) characterized the developmental foams' physicochemical properties. Finally, we assessed the dynamic search for nonlethal projectiles. We recorded the viscous criteria (VCmax) values to check for nonlethal projectiles.
... The skeleton comprises strong struts and cell networks with gas vacuoles intermingled [15]. Polyurethane foams have significant porosity, low weight, and excellent crushability [16,17]. The term "cell" frequently refers to the minor structural component. ...
We aim to maintain as much control over the microstructure development during the manufacture of polyurethane foam with a specific density. As a result, the finished product contains the shock absorber’s required characteristics. That is why polyurethane foam loaded with zinc oxide and silica must sustain the cellular structure and strengthen it. First, mechanical characterization was carried out utilizing a dynamic drop impact test conducted on locally developed and constructed equipment. Polyurethane foams’ mechanical properties rely on their density, cell structure (size and shape), and the fraction of open or closed cells. Within the cell structure, the foam may be directed preferentially. Following that, Raman spectroscopy and SEM investigation to visualize the semi-opened cells of the cellular polymer. The cellular polymer appears to possess permanent, regular cellular structures with a high degree of reversibility in terms of overlap.
... The skeleton comprises strong struts and cell networks with gas vacuoles intermingled [15]. Polyurethane foams have significant porosity, low weight, and excellent crushability [16,17]. The term "cell" frequently refers to the minor structural component. ...
We aim to maintain as much control over the microstructure development during the manufacture of polyurethane foam with a specific density. As a result, the finished product contains the shock absorber’s required characteristics. That is why polyurethane foam loaded with zinc oxide and silica must sustain the cellular structure and strengthen it. First, mechanical characterization was carried out utilizing a dynamic drop impact test conducted on locally developed and constructed equipment. Polyurethane foams’ mechanical properties rely on their density, cell structure (size and shape), and the fraction of open or closed cells. Within the cell structure, the foam may be directed preferentially. Following that, Raman spectroscopy and SEM investigation to visualize the semi-opened cells of the cellular polymer. The cellular polymer appears to possess permanent, regular cellular structures with a high degree of reversibility in terms of overlap.
... The foams obtained showed improved thermal resistance and heat insulation compared with conventional polyurethane foam [21]. But this is not sufficient without improving the structural properties and particularly the shock resistance [22,23]. Alumina and bentonite are effective structural additives and are also flame retardants at the same time in comparison to other materials. ...
In this paper, different types of polyurethane foams (PUR) having various chemical compositions have been produced with a specific density to monitor the microstructure as much as possible. The foam may have a preferential orientation in the cell structure. The cellular polyurethane tends to have stubborn, typical cellular systems with strong overlap reversibility. Free expansion under atmospheric pressure enables formulas to grow until they are refined. Moreover, the physi-cochemical characterization of the developed foams was carried out. They later are described by apparent density, Shore hardness, Raman spectroscopy analysis, X-Ray diffraction analysis, FTIR, TGA, DSC, and compression tests. The detailed structural characterization was used by scanning electron microscope (SEM) and an optical microscope (MO) to visualize the alveolar polymer's semi-opened cells, highlighting the opened-cell morphology and chemical irregularities. Polyurethane foams with different structural variables have a spectrum characterization that influences the phase separation and topography of polyurethane foam areas because their bonding capability with hydrogen depends on chain extender nature. These studies may aid in shock absorption production; a methodology of elaboration and characterization of filled polyurethane foams is proposed.
... The foams obtained showed improved thermal resistance and heat insulation compared with conventional polyurethane foam [21]. But this is not sufficient without improving the structural properties and particularly the shock resistance [22,23]. Alumina and bentonite are effective structural additives and are also flame retardants at the same time in comparison to other materials. ...
In this paper, different types of polyurethane foams (PUR) having various chemical compositions have been produced with a specific density to monitor the microstructure as much as possible. The foam may have a preferential orientation in the cell structure. The cellular polyurethane tends to have stubborn, typical cellular systems with strong overlap reversibility. Free expansion under atmospheric pressure enables formulas to grow until they are refined. Moreover, the physicochemical characterization of the developed foams was carried out. They later are described by apparent density, Shore hardness, Raman spectroscopy analysis, X-Ray diffraction analysis, FTIR, TGA, DSC, and compression tests. The detailed structural characterization was used by scanning electron microscope (SEM) and an optical microscope (MO) to visualize the alveolar polymer’s semi-opened cells, highlighting the opened-cell morphology and chemical irregularities. Polyurethane foams with different structural variables have a spectrum characterization that influences the phase separation and topography of polyurethane foam areas because their bonding capability with hydrogen depends on chain extender nature. These studies may aid in shock absorption production; a methodology of elaboration and characterization of filled polyurethane foams is proposed.
Based on the models already on the market, we have manufactured six types of nonlethal projectiles. We have made convex heads out of polyurethane foam (PUR) filled with mineral fillers like alumina (Al2O3) and montmorillonite (MMT). We chose a suitable holder for nonlethal projectiles. Also, we made a custom industrial model and used CAD modeling in SolidWorks to simulate the deformation of the nonlethal projectiles. The polymeric nonlethal projectile holders were then 3D-printed. We performed a dynamic mechanical analysis (DMA) and discussed the results. Likewise, we conducted ballistic impact experiments on nonlethal projectiles (XM1006) and nonlethal projectiles manufactured that were evaluated using a rigid wall and a pneumatic launcher. Furthermore, we looked at cell structure, the spread of the mean pore diameter, and the particle size distributions of the mineral fillers using scanning electron microscopy (SEM). We evaluated and discussed injury risks from nonlethal impacts. Data on nonlethal projectile lethality and safe impact speed are collected. This study explains how lab studies and real-world practice coexist through nonlethal projectile properties.
The world is changing; it’s time we change too. With our mission as a company, we can confront the most challenging issues facing society, recognize the duality of our reality, and be curious and creative between seemingly contradictory ideals, such as black and white, past and future, while caring to develop a new lot. Humanity is traveling, and although we’re only at one level, steady progress has gotten us back to where we started. Innovation and corporate expansion don’t define progress. We create permanent shared value now and tomorrow. a resourceconserving, nature-connected world. A world ready for its challenges. People, ideas, and objects shape progress. No links. It propels growth and the human experience. Polytechnique daily contacts can reimagine development. Our connections allow us to build sustainable solutions for future generations in transportation, resource efficiency, consumer products, healthcare, and industrial production. The relationships we develop and innovative breakthroughs make more things feasible in a more sustainable, intelligent, and interconnected manner than ever before. Because of our connections, we can make the best environment possible and look out for the well-being of our workers worldwide.
Polyurethane foams have good shock-absorbing properties. This article discusses the study of the physical, dynamic analysis, and microstructure of filled polyurethane foams (PUR). We used mineral fillings nanoparticles of titanium dioxide (TiO2) and calcium carbonate (C1) to support and strengthen the foam cell structure to develop shock absorption and thermal resistance properties. Dynamic mechanical analysis (DMA) and compression tests compared the mechanic characterization results with different modelling approaches. For studies of physicochemical properties, we used differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). We deduced the flame retardancy mechanism. It appears that a detailed description of the characteristics of viscosity and yield stress must take into consideration the filler’s size in comparison to the cell wall’s size. The effect of size distribution on the foam’s microstructure was given by scanning electron microscopy (SEM). Half-open spherical cells were shown to be reduced in size with filling. The filler diffusion in polyurethane foams was used to model the composite foam. We observed that crystalline filler particles were uniformly distributed in the matrix, indicating that the total size is related to the density and is a crucial metric for the level of reinforcement.
This article shines light on a long term online exchange experience, with an endurance runner who lives in a camping-car, in the mountains. This paper shows the potential of instant messaging, like Facebook Messenger. It develops a way of thinking in relation to the use of social network in the collection of datas, in the fields of human and social sciences. The article compares advantages and limitations of this method with the application of the traditional method of interview, from a sociological point of view. It shows how this experience builds an other relationship with the respondent.
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