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La production de caoutchouc au Brésil est généralement associée à une extraction du latex de l’Hévéa (Hevea brasiliensis) « sauvage » dans la forêt amazonienne. Cependant, plus de la moitié de la production du caoutchouc naturel du pays vient des nombreuses plantations de l'Hévéa de la région nord-ouest de l'État de São Paulo. La saignée de l'Hévéa est une activité́ manuelle qui se trouve au cœur d’un secteur agricole attaché à l'industrie, notamment l'industrie du pneu. Cette activité exige un haut niveau de compétence technique du saigneur, puisque la précision de ses incisions sur l'arbre détermine la rentabilité et la longévité de la plantation. Dans cet article, l’objectif est de mettre en évidence comment les saigneurs travaillent avec les hévéas dans les plantations à São Paulo, au Brésil et de caractériser leurs relations de travail avec ces arbres à partir de l’ethnographie de la technique, un parcours méthodologique capable de donner à voir les médiations entre humains et plantes dans les contextes de travail agricole. Natural Rubber production in Brazil is mostly associated with the extraction of latex from “wild” rubber trees in the Amazon rainforest. However, almost half of the country's natural rubber production comes from numerous rubber plantations (Hevea brasiliensis) in the north-western region of the State of São Paulo. The tapping of rubber trees is a manual activity at the heart of an agricultural sector attached to industry, in particular the tire industry. This seemingly simple activity requires a high level of technical skill from the tapper, since the accuracy of his incisions on the tree determines the profitability and longevity of the plantation. In this article the objective is to highlight how tappers work with rubber trees in plantations in São Paulo, Brazil and to characterize their working relationships with these trees from the perspective of the ethnography of techniques, a methodological journey capable of to show the mediations between humans and plants in the context of agricultural work. La producción de caucho natural en Brasil generalmente está asociada con la extracción de látex de los árboles de Siringa (Hevea brasiliensis) «silvestres» en la selva amazónica. Sin embargo, casi la mitad de la producción de caucho natural del país proviene de las numerosas plantaciones en la región noroeste del Estado de São Paulo. La sangría del caucho natural es una actividad manual que está en el corazón de un sector agrícola ligado a la industria, en particular la industria del neumático. Esta actividad, aparentemente simple, en realidad requiere un alto nivel de habilidad técnica por parte del siringuero, ya que la precisión de sus incisiones en el árbol determina la rentabilidad y la longevidad de la plantación. En este artículo el objetivo es resaltar cómo los siringueros trabajan con los árboles de caucho en plantaciones en São Paulo, Brasil y caracterizar sus relaciones de trabajo con estos árboles a partir de la etnografía de la técnica, un recorrido metodológico capaz de destacar las mediaciones entre humanos y plantas en el contexto del trabajo agrícola.

This study assessed the performance of self-compacting rubberized concrete against carbonation and chloride penetration. In addition to fresh-state and compressive strength tests, durability of the studied mixes was evaluated by measuring carbonation and chloride penetration depths, total porosity, and pores'size distribution. It was found that an increase in rubber content leads to a decrease in compressive strength. However, stadequate strength for structural applications was achieved up to an incorporation of 15% rubber byvolume. As for durability, the presence of rubber was found to enhance performance against carbonation, but to worsen the resistance to chloride ion penetration.

Ovaj rad opisuje razvoj kalupa za injekcijsko prešanje kaučukove smjese. Dan je uvid u najvažnije vrste kaučuka, dodatke kaučukovim smjesama i postupke smješavanja. Opisana su preradbena svojstva kaučukovih smjesa, tijek reakcije umrežavanja i vulkanizacije te sustav za injekcijsko prešanje. U praktičnom dijelu rada, koncepcijski je oblikovan kalup za injekcijsko prešanje manžete, a dimenzioniranje kalupa provodi se izradom reološkog i toplinskog proračuna. Temeljem analize rezultata proračuna, donosi se zaključak o parametrima prerade i konstrukciji kalupa za injekcijsko prešanje gumene manžete. Pri razvoju konstrukcije kalupa za injekcijsko prešanje manžete korišten je programski paket Solidworks2020. This paper describes the development of an injection mould for rubber compounds. An overview of the most important caoutchouc types, additives to rubber compounds, and mixing procedures is given, as well as the description of processing properties, the course of vulcanization and reaction of cross-linking, and the injection moulding system. In the practical part of the paper, the injection mould for cufflinks is designed, and dimensions are defined through rheological and thermodynamic calculations. Based on the analysis of the calculated results, a conclusion is formed about the processing parameters and the construction of the injection mould for rubber cufflinks. The design of the injection mould for cufflinks was developed by using Solidworks2020 software.

The mineral composition of three types of Hevea latex samples was determined by inductively coupled plasma atomic emission spectroscopy using a microwave-assisted wet digestion method. This method was compared in Round Robin tests to a dry reference method used to analyze leaf minerals. The results show on the one hand that for all elements, the methods studied are robust in terms of performance. Indeed, the low z scores obtained on the reference sample for both methods prove the accuracy of the methods studied. On the other hand, the results of the percentages of Mg, P and K obtained by the wet method are 5 to 10% higher than those obtained by the dry method. This significant difference shows that the wet method is more efficient than the dry method due to less loss of elements and can be used to quantify all elements of interest, especially sulphur, which to date had remained non-quantifiable by the dry method. The results confirmed the technique to be reliable, easy to use in the laboratory, and relatively mild in terms of chemicals However, certain limitations were found for calcium where, given the low contents and heterogeneity of the materials, inductively coupled plasma mass spectrometry, which is more suited to trace analyses, remains the preferred method.

The coagula derived from Hevea latex are the main raw material for block natural rubber production, especially for the two most commercialized grades (TSR10 and TSR20). The properties and mesostructure of dry natural rubber depend on several factors during coagula maturation. This work investigated an experimental design allowing concomitant control of several factors during maturation of cup coagula, namely, temperature, relative humidity, atmosphere, vertical weight, coagulation conditions, clone, and maturation duration. For each combination of factors, several indicators were measured. They dealt with the coagula (thickness, DRCcoag), with the dry rubber (physical properties (P0, PRI, ASHT), and the mesostructure (Gel>1µ, Mn, Mw, Mz). Statistical treatment of the results (recursive partition) led to a hierarchical ranking of factors for each measured indicator. The first-ranked parameter was coagulation mode followed by genotype (clone) or maturation duration, temperature, or weight application. The provided identification of the most important drivers occurring during coagula maturation could allow improvements of the post-harvest operational handling aiming at a better control of the variability of produced natural rubber properties.

Mixtures of rigid sand particles and soft rubber particles (rubber chips) are prepared and submitted to vertical taps in a confined cell to investigate their propensity to segregate. The mixture evolution is characterized by means of image analysis of slices obtained by a gelification technique. We show that, in case of equally sized particles, the rubber particles tend to migrate towards the bottom of the system. Yet, the segregation is not complete and is reduced when the rubber fraction is increased. Also it competes with the size induced segregation if rubber chips are larger than sand particles. A tendency to form horizontal clusters is clearly observed and increases with the number of taps. This horizontal segregation is reduced if the rubber fraction is smaller and is weakly influenced by grain size difference. Both the vertical segregation and the formation of horizontal heterogeneities are prevented by adding a small amount of water.

International audience; Natural rubber is obtained by processing natural rubber latex, a liquid colloidal suspension that rapidly gels after exudation from the tree. We prepared such gels by acidification, in a large range of particle volume fractions , and investigated their rheological properties. We show that natural rubber latex gels exhibit a unique behavior of irreversible strain hardening: when subjected to a large enough strain, the elastic modulus increases irreversibly. Hardening proceeds over a large range of deformations in such a way that the material maintains an elastic modulus close to, or slightly higher than the imposed shear stress. Local displacements inside the gel are investigated by ultrasound imaging coupled to oscillatory rheometry, together with a Fourier decomposition of the oscillatory response of the material during hardening. Our observations suggest that hardening is associated with irreversible local rearrangements of the fractal structure, which occur homogeneously throughout the sample.

International audience; A method to extract proteins from natural rubber (NR) samples has been developed to characterize the protein composition of NR by SDS-PAGE electrophoresis. While the incubation of NR pieces in aqueous buffers did not provide satisfactory results (no protein bands detected by SDS-PAGE), the solubilization of NR pieces in an organic solvent, prior to centrifugation and protein extraction from the obtained pellet, was found efficient to highlight protein bands by SDS-PAGE. Pure cyclohexane was used to solubilize NR pieces and resulted in a low share of nitrogen in the pellet (29%). The addition of 10% (v/v) ethanol to cyclohexane allowed to significantly increase this share to 73% and to detect 13 protein bands by SDS-PAGE. The molecular weights of the four most intense bands suggest the presence in NR of the following proteins: rubber elongation factor, small rubber particle protein, hevamine, and β-1-3 glucanase.

This work is part of a larger project aiming at elucidating the mechanisms by which the biochemical components naturally occurring in Hevea brasiliensis latex influence the structuration of natural rubber (NR). To achieve this overall objective, our strategy consists of measuring the physical properties of NR samples made of reconstructed lattices which were obtained by mixing different proportions of C-serum and bottom fraction (lutoids) to rubber fraction made of small and large particles. This work represents the first step of the above-mentioned project where we carried out a systematic study to identify and locate the main biochemical components of latex that might drive NR structuration. Fresh latex from RRIM600 and PB235 clones was fractionated by centrifugation into 4 fractions: large rubber particles, small rubber particles, C-serum and bottom fraction (lutoids + Frey-Wyssling particles). The fractions were further analyzed to provide a comprehensive description of their biochemical composition (lipids, proteins, minerals) in comparison with the original whole latex. The results gathered in this work are essential for further study of the quantitative influence of each component on NR structuration and properties.

Проект містить опис технологічного процесу, виготовлення автомобільних шин, опис, призначення та місце в технологічній схемі агрегатів які використовуються при виготовлені автомобільних шин. У проекті виконано літературний пошук на тему дослідження технічних та експлуатаційних характеристик шин, модифікованих вуглецевими наночастинками. В результати роботи: розроблено розрахункову модель типової автомобільної шини; розроблено скінчено-елементну модель композиту «нанортубка-гума»; досліджено вплив на межу міцності наномодифікованої гуми від коефіцієнту армування її нанотрубками; встановлено оптимальне значення коефіцієнту армування; результат аналізу даних розрахунків було виявлено слабкі місця у клейовому шарі, який з’єднує протектор і основу шини; розглянуто вимоги охорони праці на лінії по виробництву шин. The project contains a description of the technological process, the manufacture of automobile tires, a description, purpose and place in the technological diagram of the units that are used in the manufacture of automobile tires. The project conducted a literary search on the study of the technical and operational characteristics of tires modified with carbon nanoparticles. Results of work: design model of typical automobile tyre has been developed; A skincene-element model of the nanotube-rubber composite has been developed; Effect of nanomodified rubber strength on its nanotube reinforcement from coefficient has been investigated; the optimal value of the reinforcement factor is set; The result of these calculations revealed weaknesses in the adhesive layer that connects the tread and the tire base; labor protection requirements on the tyre production line were considered.

This work discusses the rubber’s trajectory from the history of science’s perspective and traditional knowledge that have been interconnected since the 18th century. Rubber, originating from traditional knowledge, became a technologically sophisticated industrial product, but it never lost its origins. Produced from the sap of a plant, unlike most natural resources explored in the forest and exported in natura, it left the Amazon already processed. Scientists, between the field and the laboratory, faced two challenges: To know the best “gum” producing plant, hence the botanical and agricultural studies; To understand the chemical transformation process of latex into rubber. Only today, with nanotechnology, scientists begin to unravel the “mystery” of “carbon black”: Traditional knowledge remained invisible in the weaving of sciences, transforming natural rubber into a symbol of colonisation resistance., Ce travail analyse la trajectoire du caoutchouc du point de vue de l’histoire des sciences et des savoirs traditionnels, qui sont entremêlés et interconnectés depuis le XVIIIe siècle. Le caoutchouc, issu des savoirs traditionnels, est devenu un produit industriel technologiquement sophistiqué, mais n’a jamais perdu ses origines. Produit à partir de la sève d’une plante, contrairement à la plupart des ressources naturelles explorées en forêt et exportées in natura, il quittait l’Amazonie déjà transformé. Les scientifiques, entre le terrain et le laboratoire, ont été confrontés à deux défis : connaître la meilleure plante productrice de « gomme », d’où les études botaniques et agricoles ; et comprendre le processus de transformation chimique du latex en caoutchouc. Au XXIe siècle seulement, grâce à la nanotechnologie, les scientifiques commencent à percevoir le « mystère » du « noir de carbone ». Le savoir traditionnel est resté invisible dans le tissage des sciences, faisant du caoutchouc naturel un symbole de résistance à la colonisation.

Écosystèmes majeurs dans la lutte contre le réchauffement climatique, hauts lieux de biodiversité, les forêts tropicales humides abritent en ce début de XXIe siècle plus de 700 millions de personnes. Considérées tantôt comme gardiennes de la forêt, tantôt comme responsables de la déforestation, ces populations forestières font l'objet de nombreuses idées reçues. Mais qui sont-elles véritablement, et comment vivent-elles dans le monde contemporain ? Des derniers peuples chasseurs-cueilleurs aux migrants sans terre, des cultivateurs aux planteurs de caoutchouc en passant par les exploitants de palmier à huile et les forestiers, cet ouvrage décrit la réalité de ces populations dans toute leur diversité. Il met en lumière la richesse de leurs rapports à la forêt, de leurs représentations, de leurs pratiques et de leurs usages. Il illustre la façon dont elles s'ins­crivent dans la globalisation, et comment le marché mondial et les politiques publiques affectent leurs modes de vie. Enfin, il souligne l'impact du changement global et des mécanismes financiers qui en résultent sur les modes de gestion des forêts tropicales et sur le devenir des populations forestières. Panorama inédit des forêts tropicales d'Amazonie, d'Afrique centrale, d'Asie du Sud-Est et de Madagascar, cet ouvrage réunit les textes d'anthropologues, d'écologues, de géographes, d'économistes... Il s'appuie sur une iconographie riche et originale, au plus près des populations et du terrain.

The article starts by reviewing what has been called ‘the flux of modernity’ that it then goes on to examine in terms of the connection of different forms of space to explore the multiple geographies of modernity. The article borrows from the field of anthropocene studies, thing theory and new materialism to investigate how Howards End thinks through the connections between micro- and macro-levels of materiality. It investigates things (such as dust and rubber) as actants and addresses Forster’s ecological concerns which leads to a re-reading of movement in terms of energy in relation to fossil-fuel capitalism.\ud \ud L’article commence par passer en revue ce que l’on a appelé ‘le flux de la modernité’ qu’il examine ensuite en termes de connexion de différentes formes d’espace pour explorer les multiples géographies de la modernité. L’article emprunte au domaine des études environnementales, de la théorie des choses et du nouveau matérialisme pour étudier comment Howards End travaille les connexions entre les micro- et les macro-niveaux de matérialité. Il étudie les choses en tant qu’actants et met au jour les préoccupations écologiques de Forster, pour proposer à une relecture du mouvement en tant qu’associé à l’énergie et aussi au capitalisme fondé sur la consommation des combustibles fossiles.

Non-aqueous Taylor dispersion analysis (TDA) was used for the size-characterization of natural and synthetic polyisoprenes (4 × 103–2 × 106 g/mol molar mass). Not only the weight-average hydrodynamic radius (Rh), but also the probability distribution of the hydrodynamic radius, were both derived from the Taylorgrams by a simple integration of the elution profile and by a more sophisticated constrained regularized linear inversion of the Taylorgram, respectively. Results in terms of size characterization (hydrodynamic radii between 2 and 100 nm) were compared to size exclusion chromatography coupled to a refractive index-based mass detector. Multimodal size distributions were resolved by TDA for industrial and natural polyisoprenes, with the advantage over the chromatographic technique that, in TDA, there is no abnormal elution of microaggregates (hydrodynamic radii ∼ 40–50 nm). Considering the importance and the difficulty of characterizing polyisoprene microaggregates, TDA appears as a promising and simple technique for the characterization of synthetic and natural rubber. (Resume d'auteur)

Rubber-like materials are currently used in machine design for suspension or connection functions, such as pneumatic tyres. The elastomers of interest are reinforced by carbon-black particles. The addition of these particles improves mechanical properties such as stiffness and abrasion resistance. However, it also leads to undesired strong softening of these materials, commonly known as Mullins effect, when first stretched. Elastomers can be submitted to extreme loading conditions according to the applications, generating critical crack propagation.This works studies the impact of softening caused by Mullins effect on crack propagation in filled rubbers submitted to monotonic loading.Some early experimental results point out the difficulties to characterize a crack propagation criterion. A local analysis is developed, allowing to study the highly heterogeneous strain fields witnessed when loading notched specimens. These observations lead to the validation of assumptions, which enable to calculate the strain energy release rate that characterizes the crack propagation. An experimental campaign was then performed to evaluate the impact of various preloads on crack propagation in a carbon-black filled rubber. In order to explain some of the results obtained, the theoretical global energy balance when the crack propagation occurs was revisited in order to take into account the dissipation caused by the Mullins softening. Finally, the experimental measures of local strain were used to complete the energy balance and characterize the localized energy dissipation due to Mullins effect.; Les élastomères sont utilisés dans les systèmes mécaniques pour assumer des tâches de suspension ou de liaison, comme dans le cas des pneumatiques. Les élastomères d’intérêt sont renforcés par des particules de noir de carbone. L’ajout de charges améliore certaines propriétés mécaniques telles que la raideur ou la résistance à l’abrasion, mais induit aussi un fort adoucissement de ces matériaux, dit effet Mullins, lors de l’étirement initial. Certaines applications soumettent des élastomères à des sollicitations extrêmes, pouvant provoquer une fissuration critique.Ce travail étudie l’impact de l’adoucissement par effet Mullins sur la propagation de fissures lors de chargements monotones.Des résultats expérimentaux préliminaires font ressortir des difficultés à caractériser la fissuration dans les matériaux étudiés. Une méthode d’analyse locale est développée, estimant les champs de déformation fortement hétérogènes auxquelles sont soumises les éprouvettes pré-entaillées. Ces observations valident des hypothèses permettant le calcul du taux de restitution d’énergie, qui caractérise la fissuration. Une campagne expérimentale est menée pour évaluer l’impact de précharges variées sur la propagation de fissures dans un élastomère chargé au noir de carbone. Afin d’expliquer certains résultats obtenus, l’équilibre énergétique théorique inhérent à la propagation de fissure est réévalué pour prendre en compte le caractère dissipatif de l’adoucissement. Enfin, les mesures expérimentales de la déformation locale sont ensuite exploitées pour compléter le bilan énergétique, en caractérisant la dissipation énergétique localisée due à l’effet Mullins.

Rubber-like materials are currently used in machine design for suspension or connection functions, such as pneumatic tyres. The elastomers of interest are reinforced by carbon-black particles. The addition of these particles improves mechanical properties such as stiffness and abrasion resistance. However, it also leads to undesired strong softening of these materials, commonly known as Mullins effect, when first stretched. Elastomers can be submitted to extreme loading conditions according to the applications, generating critical crack propagation.This works studies the impact of softening caused by Mullins effect on crack propagation in filled rubbers submitted to monotonic loading.Some early experimental results point out the difficulties to characterize a crack propagation criterion. A local analysis is developed, allowing to study the highly heterogeneous strain fields witnessed when loading notched specimens. These observations lead to the validation of assumptions, which enable to calculate the strain energy release rate that characterizes the crack propagation. An experimental campaign was then performed to evaluate the impact of various preloads on crack propagation in a carbon-black filled rubber. In order to explain some of the results obtained, the theoretical global energy balance when the crack propagation occurs was revisited in order to take into account the dissipation caused by the Mullins softening. Finally, the experimental measures of local strain were used to complete the energy balance and characterize the localized energy dissipation due to Mullins effect.; Les élastomères sont utilisés dans les systèmes mécaniques pour assumer des tâches de suspension ou de liaison, comme dans le cas des pneumatiques. Les élastomères d’intérêt sont renforcés par des particules de noir de carbone. L’ajout de charges améliore certaines propriétés mécaniques telles que la raideur ou la résistance à l’abrasion, mais induit aussi un fort adoucissement de ces matériaux, dit effet Mullins, lors de l’étirement initial. Certaines applications soumettent des élastomères à des sollicitations extrêmes, pouvant provoquer une fissuration critique.Ce travail étudie l’impact de l’adoucissement par effet Mullins sur la propagation de fissures lors de chargements monotones.Des résultats expérimentaux préliminaires font ressortir des difficultés à caractériser la fissuration dans les matériaux étudiés. Une méthode d’analyse locale est développée, estimant les champs de déformation fortement hétérogènes auxquelles sont soumises les éprouvettes pré-entaillées. Ces observations valident des hypothèses permettant le calcul du taux de restitution d’énergie, qui caractérise la fissuration. Une campagne expérimentale est menée pour évaluer l’impact de précharges variées sur la propagation de fissures dans un élastomère chargé au noir de carbone. Afin d’expliquer certains résultats obtenus, l’équilibre énergétique théorique inhérent à la propagation de fissure est réévalué pour prendre en compte le caractère dissipatif de l’adoucissement. Enfin, les mesures expérimentales de la déformation locale sont ensuite exploitées pour compléter le bilan énergétique, en caractérisant la dissipation énergétique localisée due à l’effet Mullins.

The natural rubber biosynthetic pathway is well described in Hevea, although the final stages of rubber elongation are still poorly understood. Small Rubber Particle Proteins and Rubber Elongation Factors (SRPPs and REFs) are proteins with major function in rubber particle formation and stabilization. Their corresponding genes are clustered on a scaffold1222 of the reference genomic sequence of the Hevea brasiliensis genome. Apart from gene expression by transcriptomic analyses, to date, no deep analyses have been carried out for the genomic environment of SRPPs and REFs loci. By integrative analyses on transposable element annotation, small RNAs production and gene expression, we analysed their role in the control of the transcription of rubber biosynthetic genes. The first in-depth annotation of TEs (Transposable Elements) and their capacity to produce TE-derived siRNAs (small interfering RNAs) is presented, only possible in the Hevea brasiliensis clone PB 260 for which all data are available. We observed that 11% of genes are located near TEs and their presence may interfere in their transcription at both genetic and epigenetic level. We hypothesized that the genomic environment of rubber biosynthesis genes has been shaped by TE and TE-derived siRNAs with possible transcriptional interference on their gene expression. We discussed possible functionalization of TEs as enhancers and as donors of alternative transcription start sites in promoter sequences, possibly through the modelling of genetic and epigenetic landscapes.

L'année 2019 est assez atypique tant sur le plan de l'évolution du cours du caoutchouc naturel que sur les quantités produites et consommées dans le monde. Si l'année 2018 avait été marquée par une lente, mais durable chute des cours tout au long de l'année, en revanche, 2019 présente un profil assez chahuté, mais avec un niveau moyen légèrement plus rémunérateur comparé à l'année 2018.

U ovom radu objašnjeno je što je guma, od čega se izrađuje, te njezina svojstva. Također su opisane vrste kaučuka od kojih se proizvodi guma te postupak proizvodnje gume – mastikacija, priprava smjese kaučuka i dodataka, oblikovanje poluproizvoda te vulkanizacija. Prikazani su najčešći primjeri primjene gume u izradi dijelova strojeva i uređaja u poljoprivrednoj proizvodnji., This paper explains what rubber is, what it is made of, rubbers properties, etc. Types of caoutchouc from which rubber is produced and the process of rubber production – mastication, preparation of mixture of rubber and additives, shaping of semi-finished products and vulcanization. The most common examples of rubber application in the manufacture of machine parts and devices in agricultural production are presented.

Saludemos un libro necesario que nos aleja de los redundantes debates sobre la etnicidad para llevarnos al mundo material y concreto del trabajo indígena desde los inicios del capitalismo industrial de fines del siglo XIX hasta los años 1960. La explotación de la mano de obra principalmente indígena fué la condición del funcionamiento y de la rentabilidad de los enclaves industriales que son los ingenios azucareros del Noroeste argentino, las barracas caucheras amazónicas y los obrajes madere...

A huge amount of waste tires is dumped at the landfill sites. Such a waste is posing an environmental hazard. It is high time to reduce their impact on the environment in a sustainable way and hence recycle them. One of the options is to recycle these waste tires, convert them into powdered form and use this granular rubber with other granular materials, e.g. soil to improve their properties. This study is based on the analysis of such sand-rubber mixtures. In particular, the focus of this study is to investigate the effect of quality of mixing on the mechanical response of such sand-rubber mixtures. The study began with characterizing the segregation of sand and rubber for specific conditions, i.e. mixing and under vertical taps. The experiments pointed out segregation in such mixtures. Hence, it was interesting to study its effect on the mechanical response of these mixtures by performing classic oedometer experiments and also with the help of Discrete Element Method (DEM) simulations. It was concluded that the segregation did not have a crucial effect on the mixtures, especially for important rubber volume fractions. For rubber volume fractions up to 25% however, it showed a considerable effect on the mechanical response of these mixtures. The use of DEM simulations helped to better understand the effect of mixing quality by relating the properties observed at the grainscale level such as contact forces, force distribution, etc. with the macroscopic response of these mixtures.; Les déchets issus de caoutchouc (pneus usagés) sont produits en grand nombre par nos industries et par notre mode de vie. Afin de réduire leur impact sur l’environnement et de s’inscrire dans une logique d’économie circulaire, il est envisageable de recycler ces déchets dans des matériaux granulaires dans le but d’obtenir des composites aux propriétés notables. L’objectif de ce projet est d'étudier si l'ajout de grains de caoutchouc dans les sols à base de sable améliore les propriétés des matériaux ainsi obtenus. Ce projet porte ainsi sur l’étude des composites caoutchouc-sable et en particulier sur la relation entre la qualité du mélange obtenu et les propriétés mécaniques. Les expériences caractérisant le mélange du sable et du caoutchouc ont été effectuées. La caractérisation de nos mélanges sable/caoutchouc a montré la présence de ségrégation. Dans le but de quantifier l’effet de cette dernière sur les propriétés mécaniques de nos mélanges, des tests mécaniques classiques à l’oedomètre ont été réalisés et en plus des simulations de type éléments discrets (DEM) ont été réalisées. L’importance de cette ségrégation sur les propriétés mécaniques n’est pas forcément cruciale, notamment à forte fraction volumique de caoutchouc. Nous avons également montré que des outils numériques pouvaient être utilisés à bon escient pour comprendre les mécanismes à l’échelle du grain.

Tema ovog rada je ispitati mehanička svojstva automobilskih pneumatika različitih proizvođača, te uspoređivati dobivene rezultate. Ispitivanja su obavljana u poduzeću Gumiimpex – GRP d.o.o. u Varaždinu i Trnovcu Bartolovečkom. U radu se izlaže pojam polimera i njihova podjela, opći podaci o poduzeću Gumiimpex – GRP d.o.o., svojstva guma, metode ispitivanja guma, te se za eksperimentalni dio četiri automobilske gume (pneumatici) uzorkuju i ispituju određenim metodama. The theme of this work is to study the mechanical properties of car tires from different manufacturers and compare the results. Testing are conducted at the company Gumiimpex – GRP d.o.o. in Varaždin and Trnovec Bartolovečki. The work presents the concept of polymers and their division, general information about the company Gumiimpex – GRP d.o.o., the properties of the tire, the methods of tire testing and for experimental part, from four tires are token samples and reviewed specific techniques.