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Woven fiber reinforced concrete is a material, which contains various quantities of polymer materials in composition, in addition to the conventional components of an ordinary concrete (mineral binder – cement, aggregates, water and additives). The present work refers to the concrete in which the reinforcement is made of polymeric materials (polyethylene terephthalate), originated from the recycling programs of PET–type packaging. The experimental program was aimed at constructing some samples of woven fiber reinforced concrete from recycled material coming from PET packaging wastes, their testing to the compression demands and the comparison of results with the characteristics of the standardized samples of concrete (class C30/37). Based on a sufficient number of determinations, certain correlations can be established between the compressive strength of the concrete at 28 days depending on the dosage of components (aggregate, binder, and reinforcement), water / cement ratio, reinforcement volume, etc., essential parameters from a compositional point of view. These correlations, customized by cement type and strength class, are very important to determine – with approximation – to what dosage of components (aggregate, binder, reinforcement) the respective level of compressive strength of concrete is obtained.

Simulating the biomechanical behavior of a reconstruction using the finite element analysis method is a modern method necessary before the practical stage of a research, thus enabling the precise shaping of certain trajectories in the approach of certain directions of practical applicability, as well as obtaining final results with relevant data (results coupled with experimental models that reiterate the clinical situation that will be later analyzed).

The present paper is focused on evaluating the mechanical characterization of dicyclopentadiene (DCPD) and 5-ethylidene-2-norbornene (ENB) healing systems synthetized by in-situ polymerisation. Both healing systems were embedded in glass fibre reinforced polymer (GFRP) composite and subjected to three-point bending test regime. Microstructural and FT-IR analysis showed the formation of microcapsules and a successful integration in the composite material. To observe the influence of temperature variation, some specimens were exposed to thermal cycling (-20oC to +100oC) for 12 hours and tested in the same conditions. It was observed that the addition of microcapsules in the composite material decreased its mechanical properties by 8% and 10% for DCPD system and ENB system respectively. Thermal cycling suggested a drop of 24% on bending strength for DCPD system and 17% for ENB. Resting after 24 hours showed a healing recovery of 74% for DCPD healing system and of 97% for ENB system.

The main objective of this study was to investigate thermoplastic materials design and fabrication processes for manufacturing composite impeller blades. Polyurethane (Necuron) and ABS (3D printed) thermoplastics were chosen due to their good mechanical properties, tooling applications, easy manufacturing and lifetime. For both thermoplastics, workability and hardness tests were performed, as well as microstructural and mechanical characterization evaluating their physical and mechanical properties. A 1:2.5 scale mould was designed and milled from Necuron N651 and N1001 and used for manufacturing of 1:2.5 scale composite impeller blades. Also, 1:1 scale ABS mould components were 3D printed and used to manufacture full scale composite impeller blades. All composite impeller presented good surface quality and tolerances with respect to CAD design, thus answering to requirements related to composite processing

The aim of our study was to compare the fracture resistance of teeth presenting non-carious cervical lesions restored with different types of esthetic composite materials. 20 extracted unspoiled maxillary first molars were mechanically cleaned and immersed in saline solution containing 0.1% thymol at 4°C for a period of 48 hours. Cervical cavities with a cervical-occlusal diameter of 2 mm and a mesial-distal diameter of 3mm were filled with ormocer, flow nano-composite, nano-composite and compomer. Fracture resistance was tested with a universal loading machine (Lloyd Instruments), with a maximum force of 5 kN and a crosshead speed of 1.0 mm/min; the authors used NEXYGEN Data Analysis Software and ANOVA method. For the group A (commercial grade ormocer), the smallest load that determined the sample failure was 650 N and the highest load was 1050 N, the mean value being 858 N ± 150.89 N. For the group B (commercial grade flow nano-composite), the smallest load is 530 N, the highest load is 800 N, mean value being 654 N ± 112.6 N. For the group C (commercial grade nano-composite), the smallest load is 680 N, the highest load is 1200 N, mean value being 926 N ± 209.35 N. For the group D (commercial grade compomer), the smallest load is 1100 N, highest load is 1250N, mean value being 1180 N ± 62.04 N. A p value of 0.000311 (p[0.05) shows that there are significant differences between the four groups. Conclusions. The best fracture resistance of teeth presenting non-carious cervical lesions, restored with different types of esthetic composite materials is assured by the compomer, followed by the nano-composite, which proved to be superior to ormocer. The flow nano-composite gives the lowest fracture resistance.

The global concern in wastewater recycling technologies has grown steadily since the early 1990s and is gaining more and more interest due to the increase in water supply needs. This growing need affects many global regions and leads to an increase in the strictness of environmental regulation, both in developing and developed countries. Many countries, cities and local governments are trying to recycle wastewater as a potential source of water for various uses, especially non-potable uses, such as land use, water for toilets and industrial processes. Analysts and statisticians around the world are trying to provide a perspective on an industry that is poised to see significant developments in the next decade. The researches summarize the experimental tests carried out using a new cellulosic adsorbent material to purify the wastewater resulted from the industrial processes for leather manufacturing. The study highlights the influence of the pH used for the wastewater depollution. The tracked and measured parameters include the pH, chemical oxygen demand, biochemical oxygen demand, total suspended solids, ammoniac nitrogen, organic compounds extractable in organic solvents and the solid residue adsorbed by the material. The obtained values were discussed in concordance with the national legislation for wastewater treatment and the levels accepted for releasing the used water in the surface waters.

This study aims to find the most effective method in terms of clinical working time when applying fibreglass splints in the lower frontal group, depending on the type of composite material used. We have selected a group of 30 patients, aged between 50 and 70, with an average age of 57, in the interval March 2016 – June2017. These patients received immobilisations as part of their periodontal treatment, using a system consisting of fibreglass and three different types of composites. The shortest work time was obtained when using the Grandioso heavy flow composite, the next closest time being obtained with Gaenial flow universal. Our study indicated that the highly viscous flow composite resins offers the shortest clinical working time out of all tested materials.

Painful periapical manifestations are inflammatory responses of periapical connective tissue to pulpal irritants, when the exudative forces become hyperactive. From the point of view of tooth preservation, apical resection is a valuable procedure in avoiding early edentation, as it is a factual surgical method that comes to aid the conservative endodontic therapy. Polymers are chemical compounds (in most cases organic) with large molecules (macromolecules) obtained from the union of a molecular chain (catena) of a large number of monomers usually with identical structural units. In our research we evaluated the resistance to traction 9 test specimens for which the structure was aimed at the improvement of the self-polymerizable acrylic structure by adding sodium maleate co-polymers, namely maleic anhydride, whose structure was linked to the anti-microbial substances, of the thymol type with controlled release, versions with greater resistance, they found clinical applicability on 244 cases. An increased resistance to fracture was registered for the test specimens II, which unites polymer powder together with the sodium maleate co-polymer, in a ratio of 3 to 1 (F = 1030 and max = 37.73), test specimen III, which unites polymer powder together with the co- anhydride maleic polymer, in a ratio of 3 to 1 (F = 950 and max = 37.88), followed by the same combinations to which it was added the care antibacterial substance, thymol. An important role in the long term in the success of the apical resection, in addition to the applied surgical technique, accrues to the retrograde obturation material, which insures an optimal healing at the peri-apical level insuring the bony apposition at this level.

The exhaustive use of light advanced polymer composites into the development of the future high-efficiency long-range commercial aircrafts (primary) structures for increasing strength while decreasing weight for lower fuel consumption and less pollution has attracted great attention in the last decade. In this context, solutions for the integration and joining composites into the aircraft structures metallic sub-assemblies or components, while providing the necessary strength to sustain heavily loaded joints, are urgently required. The paper comes to meet an area of interest for many researchers and large integrators and manufacturers, by presenting several type of metallic join geometrical designs, along with metallic joint part integration solutions into a composite structure directly during production. Performances evaluation of the developed metallic join geometrical designs was performed in static regime by means of „pull-out” compressive tests. The paper focuses on the strength of the hybrid metallic/advanced polymer composites joints. It was concluded that an efficient design of the metallic joint and a proper transition from hybrid to the composite structure can lead to proper integration solutions while assuring safety requirements.

Two types of biocomposite materials are made (original fabrication recipes) containing different resins as base: version A with natural resin and version B with polyester resin. For both of them the reinforcement element is a natural one namely fir needles. The samples are mechanically tested by compression in order to obtain the stress-strain curves and the elasticity longitudinal modulus.