Tribological Behavior of Soybean Oil

This chapter presents experimental data in the favor of using soybean oil, additivated or not, as lubricants, the market share of the soybean oil on the lubricants’ market, a SWOT analysis for better configuring the tribological characteristics of the soybean oil and tribological parameters as friction coefficient, wear scar diameter, wear rate of wear scar diameter, etc. and their dependence on testing regime (load and speed). Also, the influence of temperature, shear rate, and oxidation parameters on the soybean oil viscosity is discussed

Investigating Tribological Processes in Polymeric Composites

The paper presents some results on investigation of the superficial layers of several polymeric composites intended for tribological applications. The evaluation of the tribological behavior is done with the help of SEM images, virtual images obtained by 3D profilometry and X-ray diffractometry

Tribological Behavior of Polymers and Polymer Composites

This chapter means to explain the tribological behavior of polymer-based materials, to support a beneficial introducing of those materials in actual applications based on test campaigns and their results. Generally, the designers have to take into consideration a set of tribological parameters, not only one, including friction coefficient, wear, temperature in contact, contact durability related to application. Adding materials in polymers could improve especially wear with more than one order of magnitude, but when harder fillers are added (as glass beads, short fibers, minerals) the friction coefficient is slightly increased as compared to neat polymer. In this chapter, there are presented several research studies done by the authors, from which there is point out the importance of composite formulation based on experimental results. For instance, for PBT sliding on steel there was obtained a friction coefficient between 0.15 and 0.3, but for the composite with PBT + micro glass beads, the value of friction coefficient was greater. Adding a polymer playing the role of a solid lubricant (PTFE) in these composites and also only in PBT, decreased the friction coefficient till a maximum value of 0.25. The wear parameter, linear wear rate of the block (from block-on-ring tester) was reduced from 4.5 μm/(N⋅km) till bellow 1 μm/(N⋅km) for a dry sliding regime of 2.5…5 N, for all tested sliding velocities, for the composite PBT + 10% glass beads +10% PTFE, the most promising composite from this family of materials. This study emphasis the importance of polymer composite recipe and the test parameters. Also there are presented failure mechanisms within the tribolayer of polymer-based materials and their counterparts

Influence of Micro Glass Beads Added in a PBT Matrix on the Mechanical Properties of Composites

This paper presents the influence of adding materials (micros glass spheres) in a matrix of PBT on several mechanical properties: elasticity modulus, stress at break , elongation at break, energy at break. The mechanical properties of these composites depend on the glass beads concentration. The additivation of polybuthylen therephtalate with glass beads increases the values of the elasticity modulus, but reduces quite drastically the elongation at break. Using the SEM investigation, the authors pointed out the particular aspects of fracture surfaces: a ductile process at sample margins and a brittle one in the middle of the composite

An Isothermal Model for Evaluating Stress and Strain in the Polymeric Block of the Block-on-Ring System

This paper presents the results of simulating an isothermal frictional contact between a polymeric block and a steel ring. The model takes into account the elasto-plastic behavior of the polymeric materials and the friction coefficient of the two triboelements in dry regime as determined from tests done on a block-on-ring system. The results given by the model are compared to some characteristics of the actual test ring (geometry of the wear track). The mechanical characteristic of the polymer material were modeled in accordance to the results obtained from the traction tests

Indolizines and pyrrolo[1,2- c ]pyrimidines decorated with a pyrimidine and a pyridine unit respectively

The three possible structural isomers of 4-(pyridyl)pyrimidine were employed for the synthesis of new pyrrolo[1,2-c]pyrimidines and new indolizines, by 1,3-dipolar cycloaddition reaction of their corresponding N-ylides generated in situ from their corresponding cycloimmonium bromides. In the case of 4-(3-pyridyl)pyrimidine and 4-(4-pyridyl)pyrimidine the quaternization reactions occur as expected at the pyridine nitrogen atom leading to pyridinium bromides and consequently to new indolizines via the corresponding pyridinium N-ylides. However, in the case of 4-(2-pyridyl)pyrimidine the steric hindrance directs the reaction to the pyrimidinium N-ylides and, subsequently, to the formation of the pyrrolo[1,2-c]pyrimidines. The new pyrrolo[1,2-c]pyrimidines and the new indolizines were structurally characterized through NMR spectroscopy. The X-ray structures of two of the starting materials, 4-(2-pyridyl)pyrimidine and 4-(4-pyridyl)pyrimidine, are also reported

Influence of Additive concentration in Soybean Oil on Rheological and tribological Beh

The rheology of vegetal oils, additivated or not and the factors that influence their viscosity have been studied by specialists, in order to introduce these oils as lubricants in green industries as agriculture, food processing, transportation and for complying with environmental and health regulations; the vegetal oils are also envisaged as an eco-friendly alternative to similar mineral and synthetic products. This study presents the influence of nature and concentration of additive in soybean oil on its rheological and tribological behavior, reflected by shear stress - shear rate, viscosity - temperature curves and by the wear scar diameter (WSD) after testing the formulated lubricants on a four- ball machine

Contributions concerning the study of the antiseptic effect of sulfur dioxide on the yeasts present in two wines provided by Cotnari vineyard

Sulfur dioxide is one of the most used antiseptics in vinification. Its action on the "infection" microorganisms found in wine cellars is demonstrated by numerous studies. The present study shows that the antiseptic potential of sulfur dioxide is highly dependent on the concentration of its free form. The high concentrations of free sulfur dioxide corroborated with the prolonged contact period lead to the killing of the yeast cells quickly and evenly, while at low concentrations its lethal effect is greatly diminished. At low concentrations the lethal effect of sulfur dioxide is highly dependent on the contact time of the yeast cells with the environment. In this case, their mortality rate is very uneven. This phenomenon is also explained by the losses that occur due to the volatilization of sulfur dioxide, of oxidation or on account of its binding to other compounds