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EPDM/hemp fiber composites with fiber loading of 0–20 phr were prepared by the blending technique on a laboratory electrically heated roller mill. Test specimens were obtained by vulcanization using a laboratory hydraulic press. The elastomer crosslinking and the chemical modification of the hemp fiber surface were achieved by a radical reaction mechanism initiated by di(tert-butylperoxyisopropyl)benzene. The influence of the fiber loading on the mechanical properties, gel fraction, swelling ratio and crosslink degree was investigated. The gel fraction, crosslink density and rubber–hemp fiber interaction were evaluated based on equilibrium solvent-swelling measurements using the Flory–Rehner relation and Kraus and Lorenz–Park equations. The morphology of the EPDM/hemp fiber composites was analyzed by scanning electron microscopy. The water absorption increases as the hemp fiber loading increases.

The aim of this paper is the biological and morphological characterization of an antibacterial compound based on silicone rubber (Elastosil R701/70-OH), reinforced with ZnO and TiO2 nanopowders (with antibacterial, antifungal and antimicrobial properties), charged (chalk), crosslinked with peroxide (dicumyl peroxide - powder 40% with calcium carbonate and silica, specific to the food, pharmaceutical, but also medical field). ZnO and TiO2 nanopowders, by their homogeneous dispersion in the mass of the compound, have a determined role on its antibacterial and antimicrobial sterilization properties. The mixture of antibacterial compound based on silicone rubber was made on a laboratory roller, provided with cooling, in the form of a sheet (maximum thickness 5 mm), in strict compliance with the technological recipe and the established mode of operation. Subsequently, the mixture is processed into forming molds at predetermined parameters by determining the vulcanization time using the Monsanto rheometer (to determine the optimum temperature and vulcanization times), but also the biological and morphological characterization, according to current standards in specific food and pharmaceutical environments.

This paper presents the process of obtaining biodegradable polymeric composites based on post-consumption thermoplastic polyurethane and post-consumption vulcanized rubber waste, in various ratios (5, 10, 20, 30, 50%), cryogenically ground to min. 100 nm, and maleic anhydride grafted polyethylene as compatibilizer between the two phases. This composite will be formed into a low-density product, with low cost, recovery and reuse of waste, containing post-consumption polymers, and last but not least, biodegradable. The methodology for making the new materials involves the following steps: sorting waste, grinding, functionalization and compounding. These operations are easy to manage and do not involve new equipment. Compounding, the most important operation, will be carried out on a corotating twin-screw extruder-granulator with the possibility to adjust parameters such as temperature and speed depending on the material, having a screw ratio (L/D-35). The tested biodegradable composites were characterized structurally and physico-mechanically. Waste transformation (ground and functionalized) into new value-added products will lead to remarkable improvements in the life cycle of raw materials and the responsible use of this waste, contributing to sustainability, improving eco-efficiency and economic efficiency and reducing the “pressure” of waste on the environment.

The aim of the paper is to modify the surface of dolomite with titania (TiO2) and silica (SiO2) precursors, in order to use it as a potential reinforcement material in a polymeric matrix or for environmental applications (photocatalyst for the degradation of organic pollutants based on TiO2). The dolomite surface modification was performed by 2 methods. The first method consisted in modifying the direct dolomite surface with SiO2 and TiO2. The second method consisted in the initial treatment of dolomite with TEOS, in order to form silanol bonds, followed by the addition of SiO2 and TiO2 precursors. The obtained powders were characterized by FTIR, SEM-EDS and DSC-TG. The FTIR spectra prove the formation of the silica network while the samples modified with PDMS exhibit the characteristic peaks of methyl groups from PDMS. In EDS, the presence of the characteristic elements of dolomite (calcium, magnesium, oxygen and carbon) can be observed. When analyzing the modified dolomite powders the presence of titanium and silicon can be observed. The characteristic morphology of the dolomite is preserved in all the samples but, the surface of the larger particles is decorated with smaller particles proving the functionalization of the dolomite, according to the two routes. The thermal analysis is characteristic for dolomite-based materials, the main difference between the samples appearing as a consequence of the burning of the organic part of PDMS, which occur between 400 and 600°C.

In a circular economy, the value of products and materials is maintained as much as possible; waste and resource use are kept to a minimum, and resources do not leave the economic flow once they reach the end of their life, but are reused and create further value. The paper presents the obtaining and characterization of a composite based on butadiene-co-acrylonitrile rubber - continuous phase, where are added post-consumer recycled wood particles, with dimensions of 500 nm - discontinuous phase, and ingredients, such as: active fillers, plasticizers, vulcanizing agents, antioxidants. Wood waste acts as a filling material which leads to the biodegradability of the composite and the decrease in density. The small size of the waste particles and their functionalization with potassium oleate leads to the formation of bonds between the matrix and the particles so that the physical-mechanical characteristics of the composite correspond to the requirements of the products obtained from it.

The aim of this paper is to obtain and study the properties of wood waste reinforced elastomer composites with various fibre contents (10-50 wt%). The composite is based on chloroprene rubber, and added post-consumer recycled wood particles, with dimensions of 500 nm eco-reinforcing material, and active fillers, plasticizers, vulcanizing agents, antioxidants. In order to enhance the compatibility and their level of interaction, the wood waste was finely ground (cryogenic mill) and functionalized with potassium oleate. Wood waste acts as a filling material which leads to the biodegradability of the composite and the decrease in density. Tensile, tear strength, elasticity, hardness, abrasion resistance, melt flow index and morphological study (FT-IR) of those composites were examined in order to determine the viability in various applications domains.

In the European Union, the potential for recycling technological and post-consumer polymeric waste is untapped. Their recycling and reuse are very low, compared to other types of waste such as glass, paper, etc., and the rates of storage, even of incineration, is very high in terms of percentage. Therefore, by reusing them, but also making use of new advanced technologies, we can contribute to improving the quality of products, and to environmental protection by recycling waste, protecting human health by eliminating toxins during their incineration, but also increasing turnover for global economic agents. Thus, this paper presents the obtaining and characterization of an antibacterial compound based on EPDM elastomer and wood waste (sawdust). The antibacterial compound is characterized from a physical-mechanical and structural point of view (FT-IR), all according to standards in force.

The aim of this paper was to assess the influence of the modification of the surface of dolomite and kaolin with SiO2 and TiO2 precursors, on the block copolymer styrene-butadiene-styrene (SBS) type thermoplastic rubber properties. These composite materials were obtained by compounding SBS with various ratio of powders. Based on the SEM images it can conclude that the powders were homogenously dispersed in to the SBS matrix. The dolomite particles can be clearly identified in the SEM images as particles of 10 micrometers. The samples obtained with modified dolomite have similar morphology. The EDS elemental distribution confirming a good corroboration between the elements of the dolomite, kaolin and titanium or silicon elements. Based on the thermal analysis according to the residual mass, the presence of 20% mineral phase can be confirmed. According to the DSC curves a strong stabilization of the composite appears, because of the presence of the mineral component. According to the physical-mechanical data all the composite materials exhibit improved mechanical properties. Additionally, the modification of the kaolin and/or dolomite bring important improvements in mechanical properties. The samples 13 and 14 exhibit high tensile and tear strength. These composites can be used for various applications, such as, for instance, soles for firefighters' footwear.

Elastomeric and plastic materials are used in different sectors of the European Union, and their recycling and reuse is still at a low level, compared to other types of waste (paper, glass, etc.). By approaching an efficient global strategy related to waste management, it is possible to make the transition to a circular economy with low CO2 emissions, offering the population a cleaner and safer environment. Due to the transformation of waste by various methods into new value-added products, we can say that their life cycle contributes to the efficiency of the economy and to the reduction of the negative impact on the environment. Research can make a difference in preventing the generation of technological and post-consumer polymeric waste by making biodegradable polymer composites that are harmless to the environment and ecosystem. The biodegradable polymer composites based on EPDM elastomer and rubber waste (rubber powder) were made on equipment specific to elastomers and characterized rheologically and physically-mechanically according to the standards in force.

The paper refers to the obtaining of new types of eco-nano elasto-plastic materials with high-performance characteristics based on ethylene-propylene-terpolymer rubber (EPDM), high-density polyethylene (HDPE), plasticized starch and organically modified montmorillonite (OMMT). The new materials were obtained by the technique of dynamic vulcanization and melt intercalation in a Plasti-Corder Brabender internal mixer, at 80 rpm and a temperature of 170°C. The influence of using the OMMT type nanofiller and the plasticized starch filler on the characteristics was observed. The new materials have a melt flow index of over 12g/10 min at 180°C for a force of 10 kg, which allows injection processing - an ecological method of processing polymeric materials. The samples show very good physical-mechanical characteristics both in the normal state and after accelerated aging at 168 hours at 170°C (tensile strength over 16 N/ mm2, tear strength over 102 N/mm, hardness 55-59°ShD, elasticity over 30%, etc.). The materials show high values of abrasion resistance (below 30 mm3), and very good results for mass and volume variation after 22 hours at 23°C in: water, acids and concentrated bases. These characteristics are due both to the composition of the new materials and to the obtaining technology. For evaluating the structural modification, analysis of the FT-IR spectral of the samples was carried out. The new materials can be used in different fields such as: in the footwear industry (soles, heels and plates), safety equipment (boots, etc), obtaining gaskets, hoses, technical rubber products for cars etc.

This paper presents the obtaining and characterization of new elastomeric nanocomposites based on natural rubber reinforced with plasticized starch, precipitated silica and layered clay, for obtaining consumer goods for the food industry. Obtaining nanocomposites was carried out by the technique of mixing and melt interleaving. The mixtures were vulcanized in the press, at high temperatures, using peroxides as vulcanizing agents, and triallyl cyanurate as vulcanizing coagent. In order to obtain products with improved characteristics, the influence of the amount of modified organic montmorillonite layered clay (OMMT) Nanomer I31PS and the adhesion promoter between mineral filler and polymer - bis-[3-(triethoxysilyl)-propyl]-tetrasulfane (TEPS) on the characteristics of the mixtures, was analysed. The rheological characteristics of the samples show an increase of the minimum torque at the increase in the amount of OMMT type nanofiller and a decrease in the optimal vulcanization time by adding the adhesion promoter between the rubber and the filler. An improvement of the mechanical characteristics of the samples was observed at the introduction of both OMMT and TEPS. These changes may be due to both the nanofiller reinforcement effect and the changes in the morphology of the mixture. The samples showed a good behaviour after immersion in different environments specific to the food industry (water, ethyl alcohol, 10% glucose solution, 0.9% sodium chloride solution and sunflower oil). SEM analyses indicate that the starch particles, together with the other ingredients of the mixture, are quasi uniform distributed in the elastomer matrix. Several superficial microcracks are observed, on the surface of the analysed material, without structural discontinuities or other defects.

The paper presents the obtaining of new green polymeric composites using a sustainable reactive processing method, namely electron beam irradiation. EPDM rubber mixtures were reinforced with different amounts of short hemp fibers, which were then irradiated at doses between 75 and 600 kGy. The samples were analyzed by determination of physical&ndash, mechanical properties, sol&ndash, gel analysis, crosslink density (using the well-known modified Flory&ndash, Rehner equation for tetra functional networks), determination of rubber&ndash, fiber interactions (using the Kraus equation), water uptake test and FTIR analysis. The obtained results indicate an improvement of the hardness, the tensile and tear strength as the quantity of hemp fibers increases. As the irradiation dose increases, there is an increase in the degree of crosslinking and the gel fraction. Analyzing the behavior of the irradiation samples using the Charlesby&ndash, Pinner equation, it is observed that all the samples tend to crosslink by irradiation, the share of degradation reactions being low. For these reasons, the new materials can be used in the food, pharmaceutical or medical field, because the obtained products are sterile and can be easily resterilized by irradiation. They have high elasticity values and can be used to make packaging, seals and other consumer goods.

This paper presents the development of dynamically cured polymer composites and nanocomposites based on plastomer - PP (polypropylene) and EPDM elastomer (ethylene-propylene-diene-terpolymer) compatibilized and reinforced with nanometric particles-MMT (montmorillonite, chemically modified layered clay) in two stages, by extrusion-granulation and mixing. Nanoparticles increase the thermal resistance of dynamically cured polymer nanocomposites. By means of compatibilization and dynamic curing, elastomer particles - EPDM are more easily dispersed in the mixture. The materials obtained were tested physicomechanically (Melt Flow Index) and morpho-structurally (FT-IR and DSC).