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This study aimed to investigate the water sorption levels of 3 different condensable bulk fill composites, two flowable bulk fill composites, two microhybrid composites, one nanofilled composite, and one nanohybrid composite material polymerized with the same beam device on the 14th and 30th days.We evaluated nine different composite materials. The materials were prepared as cylindrical blocks (n=7) with a diameter of 7 mm and a thickness of 2 mm and polymerized. Each sample was kept in distilled water for specified times and measured by the ISO 4049 method.We used The Kruskal-Wallis test to compare more than two independent groups where numerical variables had no normal distribution. The Dwass-Steel-Critchlow-Fligner test evaluated differences between the groups if the non-parametric tests were applied. We used The Wilcoxon test to compare the numerical variables without normal distribution (water sorption values in the 14th and 30th-day measurements for each cement material).For water sorption, there was no statistically significant difference between the water sorption values of the resin composite materials on the 14th and 30th days. No statistically significant difference was found in comparing water sorption values between the 14th and 30th measurements for each resin composite material. There is a need for more extended studies by keeping the conditions constant for the evaluated composites and for bulk fill composites to be evaluated with 4mm samples.

The flexural response of externally strengthened RC beams with GFRP and HFRP (hybrid FRP) sheets under monotonic and cyclic loading conditions are investigated. Fourteen beams in two series (Series1and 2) were cast for this study. Each series consisted of seven beams. A total number of 14 beams were cast, out of which 2 beams considered as control specimen. The 12 beams were externally strengthened with GFRP sheets (4 beams) and HFRP sheets (8 beams). Series 1 and Series 2 beams were tested for two-point static and cyclic loads. The experimental for ultimate strength, deformation, stiffness, ductility, energy absorption and modes of failures are conversed for all the tested beams. The peak load for the RC beams tested specimens under static loads were computed using ACI 440.2R-08 guidelines. An optimum increase of 171.43 % in ultimate load carrying capacity was found for the beam strengthened with HFRP sheets than the control beam. Also, the predicted ultimate loads exhibited the good convergence with the test results.

In this research some composite materials built in sandwich type style are studied. The lower and upper layers, that reinforce the samples, are made from poplar strips. The core is made from crushed corn cob and the adhesion of all parts (layers and core) is made by using hybrid resins based on a combination from dammar resin and the synthetic acrylic one (with its hardener). The static and dynamic mechanical behaviour by testing the samples to tensile and bending were studied. Two types of hybrid resins were used: one abbreviated as type B with the percentage of 60% dammar and 40% acrylic resin with hardener and one abbreviated as type C with the percentage of 65% dammar and 35% acrylic resin with hardener. A general conclusion from this study it was: the mechanical properties decrase with the dammar percentage increase. This fact can be explained by the decreased mechanical properties of the natural dammar resin compared to the synthetic acylic on

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.