Resistance Of Polymeric Materials Research Articles

Automated control of thermal vacuum impregnation and swelling of oil- and gasoline-resistant elastomers

Polymeric materials used in the rolling stock are currently subject to increased requirements for durability. We present a method for accelerated and automated rapid analysis of the impregnation of polymeric materials used in various aggressive environments to determine their service life as sealing products. The results of studying changes in the physical and mechanical properties of samples are given on the example of elastomeric materials used as separating and sealing materials made of oil- and petrol resistant rubber MBS-S. Hydrocarbons based on mineral oil products with different viscosity coefficients were used as working media. It is shown that the time of impregnation of the MBS-S polymer, spent on testing according to the standard method, exceeds more than 10 times the standard terms rated for repair and maintenance. Tests using the developed express filling unit showed a reduction of the impregnation time to a level acceptable in production. The derived mathematical dependences for the process of filling MBS-S oil and petrol resistant rubber with a standard working fluid and automation of filling control make it possible to predict changes in the resistance of polymeric materials. The results obtained can be used in developing database of the swelling dynamics for various materials and predicting the service life of polymers in an aggressive environment of various etiology.

UV-Induced Synthesis of Hybrid HMDSO/SiO2 Thin Films with Compositional Gradients for High-Performance Atomic Oxygen Resistance.

A flexible, dense, defect-free, highly adhesive, and highly dissociation energy-rich protective coating is essential to enhance the atomic oxygen (AO) resistance of polymeric materials in a low Earth orbit (LEO). In this work, a dense, defect-free hybrid HMDSO/SiO2 thin film coating with compositional gradients on the surface of polyimide was synthesized using vacuum-ultraviolet (VUV) irradiation. The effects of VUV irradiation on the morphology, optical transmittance, and chemical components of plasma-polymerized HMDSO (pp-HMDSO) thin-film coatings deposited on the polyimide surface were investigated in depth. There were no defects such as cracks and holes in the surface morphology of pp-HMDSO films after VUV irradiation, but the surface roughness increased slightly, and the corresponding optical transmittance decreased slightly. The chemical components of pp-HMDSO films were changed in the depth direction starting from the top of the surface, forming hybrid HMDSO/SiO2 thin films with compositional gradients. The component gradient HMDSO/SiO2 composite coating further enhanced the atomic oxygen resistance of the polyimide due to the surface layer of the UV-modified coating enriched with high dissociation energy SiOx material. Therefore, this work provides a facile UV-induced synthesis method to prepare dense, defect-free, and highly dissociation energy-rich protective gradient coatings, which are promising not only for excellent AO protection in LEO but also for potential application in water-oxygen barrier films.

Design and Construction of a New Automated Device for Testing the Scratch Resistance of Polymeric Materials

This paper aims to design and construct of an automated device for testing the scratch resistance of the polymeric materials by measuring the force required to cause a scratch on the surface of polymeric materials as well as calculating the friction coefficient from the input and output of the device. The device was made of materials available in the local market and some parts were manufactured in local mechanical workshops. The device consists of four main parts were mechanical parts, scratching mechanism parts, electrical and electronic parts and the device operating program. The device designed in this work has the following specifications: normal load (0.1 N - 325 N), sliding speed (1 mm/s - 35 mm/s), tangential force measured by the load cell (0.1 N to 294 N), the samples dimensions (length: 10 - 195 mm, width: 10 - 125 mm, and thickness: 0.25 - 50 mm), maximum scratch length of 195 mm, and the height of the indenter from the platform surface (0.25 mm to 50 mm). Scratch test and calculation of the friction coefficient were performed for samples of pure and reinforced PMMA by Silicon Oxide nanoparticles (SiO2). The results showed an increase in scratch resistance and a decrease in the friction coefficient with increasing the weight ratio of SiO2. Also, the ability of the designed device to measure the tangential force required for scratching accurately and quickly and in simple steps.

Enhancing Reliability and Life of Plastic Sliding Bearings and Mobile Seals

The antifrictional properties and wear resistance of polymeric materials when sliding on metal surface are studied. The factors contributing to enhancement of the reliability and life of plastic sliding bearings and mobile seals are determined. Plastics are used extensively as structural materials in chemical and oil and gas engineering. In spite of the wide diversity of the available engineering-purpose plastics, the number of new polymeric materials is growing steadily. For making sliding bearing and mobile seals, use is made of polyamide, polyurethane, textolite, fluoroplastic, etc. [1, 2]. The merits of these plastics when used as structural materials of sliding bearing and mobile seals are high antifrictional properties, wear resistance, corrosion resistance, ease of adapting to shaft surface without scores and with minor wear of the shaft, low heat conductivity, low cost, and adaptability to efficient manufacture of plastic parts. A marked progress in augmenting reliability and life of plastic friction parts was achieved with appearance of fluoroplastic and fluorocarbon polymers. The antifrictional properties and wear resistance of fluoroplastic-4 (Teflon) when sliding on titanium of trademark VT1-0 (roughness of titanium surface corresponded to classes 7‐8 as per State Standard GOST 2789‐73) were studied on a 2070 SMT-1 friction machine using a shaft-bushing model [3]. The sliding rate, friction path (duration of operation), and unit load (pressure in the friction zone) were varied and various lubricants were used. The friction coefficient was determined via the moment of frictional force whose value was recorded on the potentiometer chart strip. The wear resistance of the fluoroplastic bushing was determined from the wear rate [4]: I = Δm/LS, where Δm is the weight loss of the fluoroplastic bushing, kg; S is the area of the surface adjoined with the shaft, m 2 ; and L is the friction path, m. Fluoroplastic slides on titanium surface with relative ease, and in the 10 5 ‐10 6 Pa pressure range has a friction coefficient of 0.07‐0.08 at the sliding rate of 1m/sec. The sliding rate has hardly any effect on the friction coefficient and wear rate of fluoroplastic bushing. The pressure in the friction zone depends on the wear rate of the fluoroplastic bushing. The friction coefficient and, consequently, wear rate can be reduced by using various lubricating materials. Of the known lubricating materials, distilled water (compared to dry friction, the friction coefficient diminishes to 0.04‐0.06 and the wear rate diminishes by 8‐15 %) and aqueous emulsion of powdery molybdenum disulfide produced by a special procedure were found to be highly effective (friction coefficient 0.02‐0.03 and wear rate 300‐400 times lower in comparison with dry friction).

Effects of stress on conductivity insulators

In article influence of a tension on the electric resistance of polymeric materials is studied. Analytical expression for resistance depending on mechanical and rheological properties polymers, from a tension and time is received

Tracking and erosion resistance of polymeric materials in oxygen deficient conditions

This paper describes two alternate procedures for evaluating the arc tracking and erosion resistance of polymeric materials used for insulation in electrically heated high-pressure pipes by the oil industry. The materials are subjected to electrical stress in a high-pressure gaseous medium that can have little or no oxygen, and conductive contaminants such as seawater. Presently, there is no procedure for evaluating the electrical tracking performance of materials under these conditions. A series of laboratory tests were performed using the ASTM D 2303 inclined plane (IP) testing arrangement under ambient as well as high-pressure conditions produced by nitrogen and methane. The results indicate that the tracking and erosion resistance of materials obtained under ambient conditions can be significantly different from those obtained in an oxygen deficient high-pressure media. Factors contributing to this difference are listed and analyzed.

Theoretical Modeling of Mechanical Resistance and Stability and Related Characteristics of Polymeric Systems with Branching/Cross-Linking

A theoretical (thermodynamic) method for the estimation of mechanical characteristics of polymeric systems is proposed. This method uses the statistical polymer method for modeling of branched/cross-linked structures. The weak interaction between macromolecules is modeled in the approach of their mutual interpenetration. The proposed method is used for the estimation of mechanical resistance and stability of microporous polymeric materials. An engineer method for the evaluation of mechanical stability and resistance of polymeric materials is derived.

Modeling of Mechanical Properties of Polymeric Systems with Branching/Crosslinking, Particularly Their Mechanical Resistence and Stability

A theoretical method for the estimation of mechanical characteristics of polymeric structures is proposed. This method uses the statistical polymer method for modeling branched/crosslinked structures. The proposed method is utilized for the estimation of mechanical resistance and stability of microporous polymeric materials. An engineering method for the evaluation of mechanical stability and resistance of polymeric materials is derived.

Modeling of Mechanical Properties of Polymeric Systems with Branching/Crosslinking, Particularly Their Mechanical Resistence and Stability

A theoretical method for the estimation of mechanical characteristics of polymeric structures is proposed. This method uses the statistical polymer method for modeling branched/crosslinked structures. The proposed method is utilized for the estimation of mechanical resistance and stability of microporous polymeric materials. An engineering method for the evaluation of mechanical stability and resistance of polymeric materials is derived.

Effect of hydrostatic pressure on the viscosity of failure of polymeric materials

A setup and method were developed for studying the effect of hydrostatic pressure on the characteristics of the crack resistance of polymeric materials. The viscosity of failure of material K-4I based on butyl rubber was determined in a wide range of rates of crack propagation and hydrostatic pressures. It was found that an increase in the hydrostatic pressure increases the resistance to crack propagation in a polymeric material. The pressure-time analogy method, where the dependences of the viscosity of failure on the rate of crack growth are parallelly shifted to the value of the pressure-time shift and a generalized curve is formed, can be used for taking the effect of the pressure into consideration.