Investigation of Rubber-to-Metal Bonding on Solid Rubber Tires

The knowledge on rubber-to-metal adhesion, which is an important issue in manufacturing processes of some automotive and aircraft parts and solid rubber tires, is generally confined within the patented information. This study investigates the factors contributing to the ability to produce strong and permanent rubber-to-metal bonds. Consideration is given to the material factors and methods of surface preparation, for which the quantitative data available in the open literature are very limited. Bonding strengths achieved by two different surface preparation methods are compared. Also discussed are percent elongation, bonding strength, and tensile strength measurements on the samples prepared in accordance with the solid tire recipe and cured at 140°, 150°, 160°, and 170°C. The effect of molding forces on rubber-to-metal bonding is established by applying different force values. The use of “cushion gum” as adhesion medium is proposed as a new way of obtaining successful rubber-to-metal bonding. The effect of the thickness of cushion gum layer on bond strength is presented.     

Neural models for an asymmetric coplanar stripline with an infinitely wide strip

This paper presents a new approach, based on artificial neural networks (ANNs), to determine the characteristic impedance and the effective permittivity of an asymmetric coplanar stripline (ACPS) with an infinitely wide strip. ANNs are trained with five learning algorithms to obtain better performance and faster convergence with simpler structure. The best results for training and test were obtained from the models trained with the Levenberg–Marquardt and the Bayesian regularization algorithms. The results obtained by using the neural model are in very good agreement with the results available in the literature. The neural models presented in this work provide simplicity and accuracy to determine both the parameters of an ACPS. The method is not time consuming and is easily included in a CAD system.     

Multi-featured epoxy composites filled with surface-modified PTFE powders treated by Na-naphthalenide system

This study aimed to produce new multi-featured epoxy composites that are advanced in terms of mechanical properties, wear and impact resistance, and glass transition and heat deflection temperatures. Epoxy composites filled with chemically surface-treated poly (tetrafluoroethylene) (PTFE) powders at various ratios were prepared to obtain these improved properties. The chemical treatment was carried out via a Na-naphthalenide system. After this treatment, the x-ray photoelectron spectroscopy results presented the existence of functional groups such as OH, carbonyl groups, and CC unsaturation points on the surface of the PTFE powders. On the PTFE surfaces, while the atomic ratios of carbon and oxygen were substantially increased, the fluorine ratio presented a significant decrease after the chemical treatment. However, the wear rates of the novel composites were highly advanced despite this large decrease in the fluorine ratio on the surface of the PTFE powders. Moreover, functional groups such as OH, carbonyl groups, and CC unsaturation points and spongelike or network structures on the PTFE surfaces provided the opportunity to obtain strong adhesion and interfacial bonding between the surface-modified PTFE powders and the matrix. Strength and modulus values showed substantial enhancement besides the IZOD impact resistance. All glass transition and heat deflection temperatures were also substantially improved.     

The role of different salt solutions and their concentration ratios in salt crystallization test on the durability of the Döğer tuff (Afyonkarahisar,Turkey) used as building stones of cultural heritages

Bulletin of Engineering Geology and the Environment - Volcanic tuff is widely used in Anatolian architecture and represents building stones of cultural heritage. The present study included a...     

Design of Rupture Strength of Side Blocks in Elevated Steel Girder Bridges with Elastomeric Bearings

Elastomeric rubber bearings with side blocks have been extensively used as a seismic response-control device in steel girder bridges in Japan. In real scenarios, the behavior of the girder bridges with elastomeric bearings are usually complex because of the complex mechanism by which the seismically induced inertia forces at concrete deck transmits to the girder bearings. Therefore, it is important to carry out seismic response analysis of a whole bridge system considering the interaction between different structural components in order to check the performance of the side blocks during an event of severe earthquakes. The objectives of the present study are to develop a detailed three-dimensional finite element (FE) model of an elevated girder bridge system and to propose a design rupture strength for the side blocks. The FE-model is constructed based on an existing plate girder bridge considering the effect of concrete slab, girders, stiffeners, rubber bearing, pier and the damage control by the side blocks. A sequence of seismic response analysis is then performed using four different rupture forces of the side blocks by considering the Level-2 design earthquake, the 1995 Kobe earthquake and the 2016 Kumamoto earthquake. The analytical investigation reveals that the side blocks should be designed to withstand a horizontal force of at least 1200 kN in order to prevent the rupture of the side blocks and to mitigate damage of bridge piers. Moreover, the damage to the critical parts of bridge superstructure can be mitigated by strengthening the side blocks. Based on the analysis results, a retrofit plan to strengthen the side blocks of existing girder bridges is proposed.

     

Residual monomer release from orthodontic adhesives cured with different light sources

Introduction: The aim of this study was to evaluate the residual monomer release from orthodontic adhesives cured with light-emitting diode (LED) and halogen light sources.

Methods: Seven hundred and twenty stainless steel brackets were divided into 3 groups according to the adhesive system used (Transbond XT light-cure adhesive [TXT], Transbond LR capsule [LR], and Light Bond light-cure adhesive paste [LB]), and each group was divided into 2 subgroups according to light-curing procedure (LED or halogen). Brackets were bonded with adhesives onto tooth buccal surfaces and polymerized. Each specimen contained 24 brackets that simulated the oral environment (n = 5). The specimens were immersed in a 75% ethanol/water solution at 37 °C for 10 min, 1 h, 1 d, 7 d, 14 d, and 30 d, respectively. Eluted monomers (Bis-GMA, UDMA, and TEGDMA) were detected using HPLC.

Results: There was residual monomer release at all time periods, and the highest amount of release was observed cumulatively on the 30th day. The cumulative Bis-GMA released from adhesives was not different (p > 0.05). The cumulative TEGDMA released from adhesives was statistically different (p < 0.05). There was no statistical difference between QTH and LED light-curing units for each adhesive (p > 0.05).

Conclusions: The release of residual monomers stays at a high level for a long time after polymerization. The total leaching of residual monomers from the Light Bond light-cure sealant resin plus Light Bond light-cure adhesive paste was higher than that of other materials for both curing units. Different curing units (LED or QTH) did not affect the monomer release from the orthodontic adhesives.     

Silicified microcrystalline cellulose based pellets and their physicochemical properties

Silicified microcrystalline cellulose (SMCC), Prosolv SMCC 50 was used as spheronization aid to manufacture pellets by extrusion and spheronization. Different ratios of SMCC to lactose were used to manufacture pellets using appropriate levels of water as liquid binder. Avicel PH101 based pellets were also manufactured for comparison of their physical properties. The ratio of liquid binder to spheronization aid was critical to produce pellets of desired size and shape. Extrudates composed of 20% aid could withstand only smaller spheronization force in order to be shaped into pellets. The successful products fulfilled the quality of pellets such as narrow size distribution and spherical in shape. The highest surface tensile strength was observed in pellets with equal ratio of lactose to SMCC while pellets having 20% aid disintegrated rapidly within 15 min. Furthermore, Prosolv SMCC 50 based pellets possessed a stronger surface tensile strength when compared with Avicel PH101 based pellets. In conclusion, Prosolv SMCC 50 has showed to be a good spheronization aid for extrusion and spheronization when used in the range of 20 to 80% content. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43829.     

Plasma transferred arc surface modification of atmospheric plasma sprayed ceramic coatings

In this study, a 90MnCrV8 steel surface was coated with aluminum oxide and chromium oxide powders through the Atmospheric plasma spray (APS) and Plasma transferred arc (PTA) methods. The effects of PTA surface melting on the microstructure, hardness, and wear behavior were investigated. The microstructures of plasma-sprayed and modified layers were characterized by Optical microscopy (OM), Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDS). The dry-sliding wear properties of the samples were determined through the ball-on-disk wear test method. Voids, cracks, and nonhomogeneous regions were observed in the microstructure of the APS ceramic-coated surface. These microstructure defects were eliminated by the PTA welding process. The microhardness of the samples was increased. Significant reductions in wear rate were observed after the PTA surface modification. The wear resistance of ceramic coatings increased 7 to 12 times compared to that of the substrate material.

     

Gelam Honey Has a Protective Effect against Lipopolysaccharide (LPS)-Induced Organ Failure

Gelam honey exerts anti-inflammatory and antioxidant activities and is thought to have potent effects in reducing infections and healing wounds. The aim of this study was to investigate the effects of intravenously-injected Gelam honey in protecting organs from lethal doses of lipopolysaccharide (LPS). Six groups of rabbits (N = 6) were used in this study. Two groups acted as controls and received only saline and no LPS injections. For the test groups, 1 mL honey (500 mg/kg in saline) was intravenously injected into two groups (treated), while saline (1 mL) was injected into the other two groups (untreated); after 1 h, all four test groups were intravenously-injected with LPS (0.5 mg/kg). Eight hours after the LPS injection, blood and organs were collected from three groups (one from each treatment stream) and blood parameters were measured and biochemical tests, histopathology, and myeloperoxidase assessment were performed. For survival rate tests, rabbits from the remaining three groups were monitored over a 2-week period. Treatment with honey showed protective effects on organs through the improvement of organ blood parameters, reduced infiltration of neutrophils, and decreased myeloperoxidase activity. Honey-treated rabbits also showed reduced mortality after LPS injection compared with untreated rabbits. Honey may have a therapeutic effect in protecting organs during inflammatory diseases.     

Seawater effect on pin-loaded laminated composites with two parallel holes

The aim of this study was to investigate the effects of seawater on the failure mode, first failure load and bearing strength behaviour of the pinned joint of fibreglass-reinforced woven epoxy composite prepregs. The specimens were kept in seawater for 3- and 6-month periods. After each period, their mechanical properties were examined. The edge distance-to-upper hole diameter (E/D), the two hole-tohole centre diameter (K/D), the distance from the upper or the lower edge of the specimen to the centre of the hole-to-hole diameter (M/D), and the width of the specimen-to-hole diameter (W/D) ratios were selected as parameters. Moreover, the finite element models of the specimens were developed using ANSYS software, and the Tsai-Wu criterion was used to obtain the first failure load. The numerical and experimental results were compared and were found to be in good agreement for the first failure load.