Solid State Phenomena Vol. 329

Abstract: VPCS with [Si-CH₂-CH₂-Si] structure were synthesized through hydrosilylation reaction of divinyldimethylsilane and diphenylsilane. VPCS were mixed with additive liquid PMPS silicone rubber and VPCS/PMPS based ablative composites were also prepared. VPCS play an important role in improving the thermal stability of PMPS. The 10% weight loss of VPCS/PMPS is 530.6°C, and T_max is at 601.3°C, 43°C and 48°C higher than PMPS. Anti-ablation fillers have great important on composites. VPCS/PMPS/ZrB2 showed higher mechanical properties and ablative resistance, which is accordance with the results of SEM morphology observation.

Abstract: A kind of MDT polysiloxane was prepared by step hydrolysis and polycondensation of alkoxysilane. It could be cured at elevated temperature with existence of microencapsulated platinum catalyst. The effects of crosslinkable groups’ contents and PhSiO_1.5 content on properties of cured silicone resin were studied in detail. When the contents of crosslinkable groups were 20mol% to 30mol% and the PhSiO_1.5 content was 25mol% to 30mol%, the cured silicone resin had good tensile strength, flexural strength, moderate elasticity, and low viscosity. With the increase of PhSiO_1.5 content from 17mol% to 32mol%, T_g of the silicone resin could be improved by 50°C to 128°C. The thermal stability was explored by thermo gravimetric analysis. The onset temperature of thermal degradation and the center temperature of thermal degradation were 486°C and 548°C, respectively. The average dielectric constant was about 2.45 and the dielectric loss tangent value was less than 0.01. The silicone resin also showed a high-volume resistivity of 5.6×10¹⁶Ω•cm. These results suggest that such silicone resin is suitable for utilization in electronic packaging.

Abstract: Polybutylene terephthalate (PBT) has been proven to be a potential material for modern car bumpers. However, the potential of PBT is limited by its low notched impact strength. The main aim of this study is the improvement in the notched impact strength of PBT by blending with polycarbonate (PC). PBT/PC blend at different ratios (95/5, 90/10, 85/15, 80/20) is investigated in notched Izod impact strength (ASTM D256) and hardness (ASTM D2240). Results are compared to those of neat PBT. It was found that notched Izod impact strength decreased with increasing PC rate in the blend, overall, from 4.35 kJ/m² of neat PBT to 3.37 kJ/m² of 80/20 blend. The microstructure of testing samples was observed through FESEM images taken at fracture surfaces to determine the cause of the decrease. The low interfacial adhesion between PBT and PC phases is believed to be the main reason. However, an increase in notched impact strength was shown, from 4.18 kJ/m² of 95/5 blend to 4,71 kJ/m² of 90/10 blend. This result is presumed to be due to the compatibilizing effect of PBT-PC copolymers formed during the melt blending process. Hardness testing result demonstrates neither significant improvement nor deterioration. It concluded that it is possible to improve the notched impact strength of PBT by blending with PC. The PBT/10% PC blend is a suitable choice for car bumper material since its notch impact strength is higher than neat PBT.

Abstract: For machine design, determining the machine’s technical specifications as the basis for design element computation and choosing an appropriate electric motor are among the most crucial tasks. Especially, considering the scarcity of studies about tropical wood materials, it is more important to determine the specific work by the experimental approach. The scope of the study includes the research of dependency of the cutting power on the working parameters such as feed per tooth S_z, the cutting depth h, and the tooltip’s radius r in the process of wood material machining. Employing the response surface method, the experiments following the Central Composite Face design (FCCCD) plan were undertaken with 4 replicates. The author used Minitab software to process experimental results, analyze the regression equation and variance (ANOVA). In addition, the cutting force components in wood milling is also determined, which is the basis for the design of machine elements of wood milling machines and CNC woodworking machines.

Abstract: The corrosion mitigation effect of aminophen (an organic fluid derivative) on 1070 aluminum alloy was studied in 1 M HCl solution by potentiodynamic polarization and weight loss analysis. Data obtained showed aminophen performed poorly at low concentrations (2.5%, 5% and 7.5%) with optimal value of 49.9% and 30% (potentiodynamic polarization and weight loss analysis) at 7.5% aminophen concentration. At 10% concentration, significant improvement in inhibition efficiency value was observed (53% and 61.33%), but the value is below the threshold minimum for effective inhibition. Effective inhibition efficiency occurred at 12.5% and 15% aminophen concentration with values of 71% and 81.67% at 12.5% concentration, and 89% and 70.77% at 15% concentration. Plots from weight loss indicated stable thermodynamic behavior throughout the exposure hours. Aminophen demonstrated anodic-cathodic type inhibition characteristics with dominant cathodic inhibition action. Corrosion inhibition behavior of aminophen aligned with Frumkin and Freundlich adsorption isotherm models. However, thermodynamic calculations show adsorption did not occur. Inhibition behavior of aminophen on 1070 aluminum occurred through modification of the corrosive media.

Abstract: The protection performance of admixed Lavandula latifolia and Ricinus communis (LLRC) oil distillates on low carbon steel in 0.5 M H₂SO₄ and HCl was performed by gravimetric measurement. Data output shows LLRC distillate effectively stifled the corrosion of the carbon steel with peak protection performance of 96.35% at 1% LLRC concentration in H₂SO₄ solution and 88.72% at 6% LLRC concentration in HCl solution. LLRC performed more effectively in H₂SO₄ solution than in HCl. The performance of LLRC in H₂SO₄ exhibited significant non dependence on observation time while LLRC concentration strongly influenced its performance. In HCl solution observation time and LLRC concentration influenced the performance output of LLRC distillate in different proportions. Statistical evaluation rated the influence of LLRC concentration the protection performance of LLRC at 90.66% compared to 2.22% for observation time, while the corresponding values in HCl are 55.37% for LLRC concentration and 21.04% for observation time. Calculated data for standard deviation shows relatively minimal variation from mean values with respect to LLRC concentration and observation time at lower LLRC concentration in H₂SO₄ solution. At higher LLRC concentration, the degree of variation increases due to relative instability with respect to exposure time. The standard deviation values in HCl are significantly and relatively higher than the values obtained in H₂SO₄ solution due to significant deviation from mean values which signifies extensive instability with respect to exposure time. The margin of error shows 91.7% and 93.3% of LLRC protection performance data in H₂SO₄ and HCl solution are greater than 80% inhibition efficiency at margin of error of +6.99% and +6.31%.

Abstract: The protection performance Aloe vulgaris (AV) and Nicotiana tabacum (NT) leaf extracts on 1070 aluminum (Al) were separately studied while the combined admixture of the extracts (AVNT) on mild steel (MS) was also studied in 3.5% NaCl solution by gravimetric analysis. Data output showed AV and NT effectively stifled the redox reaction process responsible for Al corrosion in NaCl with protection performance data above 98% throughout the exposure hours signifying strong resilience of the extract molecules withstanding the corrosive anions and thermodynamic stability with respect to exposure time. AVNT performed effective on mild steel at relatively lower efficiency, but with final values above 80% efficiency. Statistical data for standard deviation shows the degree of variation of protection performance data for AV, NT and AVNT extracts from mean value is minimal signifying consistent data value with respect to exposure time. Data also showed 100% of AV and NT protection performance data are above 98% efficiency value at +0% margin of error while 14.29% of AVNT protection performance data are above 95% efficiency at margin of error of +14.97%. Data from analysis of variance shows AV extract concentration and observation time strongly influences the performance out of AV at rated value of 42.06% and 29.41%. NT extract concentration solely dominated the performance output of NT at 95.37% while the performance of AVNT was independent of its concentration with values below threshold significance. However, AVNT performance varied significantly with observation time signifying progressive improvement in performance in over time.

Abstract: The paper presents the results of exposure of normal concrete to elevated temperatures (400 and 700) °C covered by layers (gypsum and plaster) with different thicknesses (10 and 20) mm. Through the figures shown in the paper, which were obtained from the experimental side of the research, the load-strain curves improved when the gypsum thickness increased during the specimens' exposure to fire. Where the relationship between them at a temperature of 400°C in a thickness of 20 mm was better than 10 mm when exposed to fire, so by increasing the thickness of the gypsum, the occurrence of strain is less because it protects the surface of the concrete from direct exposure to heat and thus prevents the occurrence of cracks in the outer surface of the concrete.

Abstract: In Masonry buildings, walls are the main structural elements resistant to lateral loads. Reinforcing masonry walls by shotcreting one- or two-sides is one of the most common reinforcement methods. Considering the economic losses and casualties caused by damage to these elements in previous earthquakes, it is necessary to investigate the seismic behavior of these walls. The existing data can train artificial neural networks, and the behaviors could be generalized for future cases. In this study, the prediction of cyclic behavior parameters of reinforced masonry walls with one- and two-way shotcrete is investigated using different artificial neural network methods. Input parameters of the neural network include length, thickness, height, mortar shear strength, mortar compressive strength, mesh type, spring dimensions, rebar diameter, average thickness of shotcrete, and concrete compressive strength. Output parameters were the relative displacement of yield, relative displacement corresponding to maximum resistance, final relative displacement, yield strength, displacement resistance corresponding to maximum resistance, ultimate resistance, and initial stiffness. The results showed that the feed-forward back-propagation neural network could accurately predict the examined output parameters compared to other models, which can be considered as an alternative to some time-consuming and costly laboratory and analytical investigations.