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The structure of polyurethane and the physico-chemical properties of its components are considered. The most promising modifiers have been selected: TiO2, CaCO3. The features of the preparation of the studied polyurethane mixture, its composition, manufacturing technology and equipment are described in detail. The geometric properties, manufacturing processes and testing methods of samples are presented. The graphical dependencies of the influence of the parameters of sample preparation on their mechanical properties such as hardness, tensile stress at break, Jung`s modulus are given. The rational parameters of the technology for the production of samples modified with fillers to give them stable mechanical properties have been set. The maximum proportions of these fillers in polyurethane rubber are limited to 30-35%. It is proved that the addition of TiО2 and CaCО3 to the composition of polyurethane rubbers gives them special properties that allow them to expand the range of their industrial usage.

In this paper, the authors propose to carry out a case study, on a visual part made of thermoplastic material from the automotive industry. Using the most up-to-date CAE systems, we will try to highlight the main appearance problems in long parts, namely the appearance of weld lines at the meeting of the flow fronts. The part will be processed using sequential, as well as non-sequential injection systems, respectively, in order to highlight the difference between the two, respectively to compare these two tests with the results of rheological simulation (CAE).

Bromelain, a natural substance sourced from pineapples, was found effective in various colds, in preventing heart attack and respectively in excess weight. On the other hand, it is well-known that pineapples juice increases the gastric acidity and respectively the people with hemophilia, internal bleeding must also be very careful in consuming this fruit. The objectives of this study were to obtain and to characterize a drug delivery system used for the transmembrane transfer of bromelain. The samples based on polyurethane matrices with and respectively without bromelain were synthesized and characterized by measurements of pH, encapsulation efficacy, cumulative drug release in a degradative media and in simulated gastric acid, electron microscopy and by modern techniques such as Zetasizer, cytotoxicity assay, and various non-invasive skin irritation assessment. The results indicate the obtaining of polyurethane matrices with mean sizes between 322-342 nm and neutral pH, that have a medium stability against the clusters formation tendency and a medium drug release rate. The non-irritative potential and the results on their cytotoxicity are important evidences that can be used for the further clinical trials of the polyurethane carriers.

Lignin fiber/epoxy resin compositeused for energy absorbing was prepared by atmospheric stirring method. Quasi-static compressive mechanics tests were implemented by using the electronic universal mechanics tester (WDW-100KN) under ambient conditions to analyze the compressing behavior of the matrix material and composite at the strain rate of 10-2s-1 .Scanning electron microscope (SEM) was used to observe the microstructure of the composite after quasi-static compression damage. The results showed that when the ratio of epoxy resin and curing agent was 3:1, the internal structure of the matrix material was more uniform with smoother cross-section, which represented better mechanical properties. It was found that the addition of lignin fiber changed the compression characteristics of the matrix material, resulting in a strengthening stage appeared. At the same time, when the lignin fiber content was 2% or 3%, the composite could absorb more impact energy and delay crack generation, which met the performance requirement of energy absorbing materials.

This study aimed to evaluate the efficacy of disinfectant solutions on Candida albicans (C. albicans) for different types of denture materials. A total of 144 specimens (10x10x2 mm) were obtained from three different materials: autopolymerized acrylic resin, heat-cured acrylic resin, and hard relining material (n = 6). Three disinfectant solutions were used: 100% white vinegar, 2% chlorhexidine digluconate (Saver) and denture cleaning tablets (Corega). The specimens were placed on Eliza plates and 1.5 mL of Yeast Extract Peptone (YPD) was added to each well. Then, 30µL of candida culture was added to the wells. Next, the specimens were incubated at 37°C at 80 rpm for 48 h. Disinfectants were added to the Eliza plates. For all specimens, the disinfectants were replaced with 2 mL of sterile water and kept at 100 rpm for 30 min. Then, 0.1 mL of the liquid was taken and inoculated into the pads containing YPD medium. After incubation, the candida colony growth on the pads was measured. Scanning electron microscope (SEM) images were taken from randomly selected specimens from each group. Statistically significant differences (𝑃 [ 0.05) were found between the disinfectant method groups and the control group for the three types of denture materials. The 2% chlorhexidine gluconate (Saver) disinfectant was the most effective for C. Albicans ATCC 60193 and oral isolate of C. Albicans for all three of the tested denture materials. The effect of cleaning of tabs (Corega) and white vinegar was found to be similar.

Biomass fibers are promising materials for applications in modern vehicles. They have great economic and ecological significance, as well as a great potential in the fabrication of composite materials due to the relatively high level of strength and rigidity, low density, availability, recyclability, and biodegradability. In this context, the focus is on the development of automotive brake pad materials from sustainable sources. This work refers to the investigation of the behavior of composite materials made of biomass fibers, phenolic resin, graphite and aluminum oxide. These materials are intended to be used for brake pads on automobiles with moderate efficiency. For this purpose, three recipes of composite materials with different percentages of coconut fiber and wood powder were developed in laboratory. The physical and mechanical as well as functional properties of these composite materials with varying amounts of biomass fibers are examined in this paper. The best performances in this terms was obtained for the composite material containing the highest amount of wood powder and the lowest amount of coconut fiber.

The waste recycling of epoxy resin-based fiber reinforced plastics is an important topic of current environmental protection. This work investigated the potential engineering benefits of applying simply crushed recycled epoxy resin-based fiber reinforced plastic in structural concrete. In this paper, the mixing and mechanical properties of concrete products with crushed and recycled waste epoxy plates instead of some fine aggregate were studied experimentally. Three kinds of recycled crushing materials with different particle sizes below 4mm, 4mm to 9mm, and 9mm were used to prepare 10 groups of concrete samples with different proportions by replacing sand with 5, 10, and 15% volumes, respectively. The results showed that the density of the recycled plastic concrete was reduced and the slump of the concrete was increased, with the increase of the recycled crushing materials, and the mechanical properties of concrete were improved within the 5%-10% admixture, and the best results of comprehensive mechanical properties were achieved when the admixture was 10% and the particle size was 4-9mm. These results indicated that it is feasible to replace concrete fine aggregates with recycled crushing materials of waste epoxy plate, and this study not only explores a new way to recycle waste epoxy resin-based fiber reinforced plastic, but also reduces the over-exploitation of sand natural resources, which have a high social and economic value.

The purpose of this study was to evaluate the effect of finishing/polishing systems on the translucency parameter (TP) of resin composites after accelerated artificial aging (AAA). Four composite resins (Filtek Z250, Admira, IPS Empress Direct, Clearfil Majesty Esthetic) were evaluated. Thirty samples were prepared with each resin composite and divided into three subgroups: control (Mylar strip), disc (Optidisc), and rubber (Dimanto) (n=10). The spectrophotometer was used to determine color measurements. TP was calculated the using the CIEDE 2000 formula. Data were analyzed using Generalized Lineer Model (p[0.05). The three factors (composite resin, finishing/ polishing, and AAA) had no statistically significant influence on the TP. However, composite and finishing/polishing influenced the TP. Filtek Z250 showed the lowest TP values and the IPS Empress Direct showed the highest TP values before and after AAA. Polished groups showed higher TP values than control groups before and after AAA. IPS Empress Direct with Dimanto had higher TP values than other groups (except for IPS Empress Direct with Optidisc); Filtek Z250 with finishing/polishing groups showed lower TP values than other groups. Composite type and finishing/polishing systems influenced TP values. Unfinished groups exhibited lower TP values than finished groups. There was no difference in TP values between finishing/polishing systems (Dimanto and OptiDisc).

The etiology of maxillofacial injuries is represented by car accidents, human aggression, and work-related trauma. Trauma to the maxillofacial area requires a complex treatment that involves functional and aesthetic rehabilitation. To restore the functionality of the damaged areas, a correct surgical technique is necessary along with the use of the ideal prostheses for a better reconstruction. Along with the development and improvement of facial fractures osteosynthesis techniques, an attempt was made to identify the right material to complete these surgical methods. We analyze in this paperwork the benefits of polyetheretherketone-based materials in the prosthetics of different facial fractures in comparison with other materials like titanium.

The increasing concern for the protection of the environment, through the use of renewable natural resources, has led in the last decades to the realization of a number of natural polymers or hybrids to be able to replace petroleum-based polymeric materials. Rosin is a low-cost wood resin extracted from conifers. In this paper, based on FTIR and Raman analyses, the spectra of natural Rosin resin and some hybrid resins with volume proportions of 45, 55 and 65% Rosin were studied. Some mechanical properties such as modulus of elasticity, elongation at break, tensile strength were determined from stress-strain diagrams obtained from tensile stress. Increasing the volume proportion of Rosin leads to a decrease in stiffness and strength properties and obtaining a visco-elastic behavior.