Strength of glued-welded joints under long effect of negative temperature

The experimental test results of strength of glued and glued-welded joints at room and negative temperatures after long exposure of them at –30 °С and –50 °С are presented. As glue materials, epoxy adhesive, anaerobic adhesive-sealant, silicone sealant and adhesive-melt based on copol-ymer of ethylene with vinyl acetate were used, as substrates, steel and aluminum alloy samples were used. It has been found out that silicone sealant ensures the best strength of glued-welded joints at low temperatures. It was determined that for all the studied types of the glued-welded joints, strength at –30 °С was worse than at –50 °С.

A qualitative study of seven simulation models for tendon repairs

Seven models for tendon repair simulation (urinary catheter, liquorice, fishing lure, dental rolls, drinking straw, silicone sealant and the authors’ modification of silicone sealant with Micropore™ tape) were assessed for their performance in a number of domains. The silicone sealant and surgical tape model scored highest overall and for each individual domain. This was significantly higher than all other models with the exception of the silicone sealant alone. The lowest scoring model was the drinking straw model.

Evaluation of resistance of silicone sealant to ultralow temperature effect

Properties of the silicone sealant VGO-1 have been examines, which is used for production of glue-welded joints made by contact welding. Conditions to produce glue-welded joints are described. It was found out that when welding steel specimens of the 08kp brand on the VGO-1 sealant there was a decrease in a welding current value and an increase in welding time and the electrode compression force. The study of sealant structures after storage at different temperatures demonstrated that the used sealant had good resistance at –30 °С in the air environment and satisfactory resistance at –50 °С in a liquid environment. The swelling index of the sealant after 20 day storage in medicinal ethyl alcohol was no more than 4.5%.

Investigation of adhesion properties of silicone sealant “Elasil 137-180”

The article presents the results of a study of the influence of vibration and shock effects on the adhesive properties of the silicone sealant "Elasil 137-180". The possibility of its reception for fixing the protective tubes of light guides in the device is shown.

Reverse torque values of abutment screws after dynamic loading: The effects of sealant agents and the taper of conical connections

This in vitro study evaluated the influence of taper angles on the internal conical connections of implant systems and of the application of chlorhexidine gel as an antibacterial agent or a polyvinyl siloxane (PVS) sealant on the reverse torque values of abutment screws after dynamic loading. The current study tested four implant systems with different taper angles (5.4°, 12°, 45°, and 60°). Specimens were divided into three groups: control (neither chlorhexidine gel filled nor silicone sealed), 2% chlorhexidine gel-filled or silicone-sealed group, and group subjected to a dynamic load of 50 N at 1 Hz for 500,000 cycles prior to reverse torque measurements. Quantitative positive correlation was observed between the taper angle degree and the percentage of tightening torque loss. However, this correlation was significant only for the 60° connection groups except in the group in which a sealant was applied ( p = 0.013 for the control group, p = 0.007 for the chlorhexidine group). Percentages of decrease in the torque values of the specimens with silicone sealant application were significantly higher compared with both the control and chlorhexidine groups ( p = 0.001, p = 0.002, p = 0.001, and p = 0.002, respectively, according to the increasing taper angles); the percentage of decrease in torque values due to chlorhexidine application was statistically insignificant when compared with the control group. The application of gel-form chlorhexidine as an antibacterial agent does not significantly affect the stability of the implant–abutment connection under dynamic loads. PVS sealants may cause screw loosening under functional loads.

Effect of adhesive interlayers on protective performance of bio-inspired building ceramic covering

The brick-and-mortar microstructure of nacre is usually considered as a source of inspiration for the development of strong and tough artificial materials. In this article, a nacre-inspired layered-and-staggered structural building ceramic protective covering was fabricated, and the effect of four types of adhesive materials on the ballistic performance of the protective covering was investigated through the ballistic test. The experimental results showed that under the impact of the 7.62-mm ordinary rifle bullet at a speed of 790–820 m/s, the average crater diameter in the concrete targets with protective covering was reduced by 40%–72%, and the penetration depth in the concrete was reduced by 70%–100%, compared with those of unprotected concrete targets. For the concrete targets with protective covering, that adopting the silicone sealant interlayers exhibited a smaller crater area but a maximum penetration depth, while that adopting the epoxy adhesive interlayers showed a larger crater area but a minimum penetration depth. Since the targets with the low-cost polyurethane sealant interlayers presented the smallest crater area and the shallower penetration depth, it can be concluded that the concrete with the protective covering using polyurethane sealant interlayers showed the better projectile impact resistance.

UV_Blue Light Conversion Using Dyes Polymeric Materials

White light-emitting diode (LED) is used in a new generation of solid-state lighting due to its advantages in energy saving and environmental friendliness. Based on this assumption, Emphasis was put on trying to establish a laboratory technique to convert UV-blue light into white light by using polymeric materials. In this work, an laboratory technique to convert UV-blue light into white light by using polymeric materials, consisting of red (R), green (G) and blue (B) for a white light generation. The project employed the use Colouring polymorph plastic as an active materials mixed with Silicone Sealant in different ratio and pumping by UV-Blue light. Colour rendering index (CRI) and correlated colour temperature (CCT) as main measurement parameters to evaluate the performance of the white light. The best white light appearance an indicated by photo and colour meter were achieved by mixing red (R), 0.05gm and green (G), 0.1gm the optimum results were CCT =3606k, CRI =70.3, x=0.3661, y=0.2925, and by mixing red (R), 0.005gm and green (G), 0.005gm the results were CCT=4891 k, CRI =63.8 and x=0.3359, y=0.2405.