Polyethylene Coatings Research Articles

Optical and mechanical properties of waterborne nano-CaCO3/polyethylene coatings: experimental, DFT, and wave optics investigation

This study analyzed the impact of nano-CaCO3 content on the optical and mechanical properties of waterborne nano-CaCO3/polyethylene coatings. The results showed a marginal reduction in lightness (L*) and contrast ratio alongside incremental nano-CaCO3 content, but substantial increases in scrubbing resistance and stain resistance were observed. Nano-CaCO3 enhances shear resistance through intermolecular interactions. It revealed the interface interaction energy of the nano-CaCO3/polyethylene model at 11.90 kJ/mol. Measured and calculated optical properties confirmed a decrease in L* and contrast ratio when TiO2 was replaced by nano-CaCO3. Optical properties were predicted using DFT, and response and impedance matching with varying nano-CaCO3 content were assessed using the wave optics model.

Using Thin Ultra-High-Molecular-Weight Polyethylene Coatings to Reduce Friction in Frost-Resistant Rubbers.

Frost-resistant rubbers retain their highly elastic properties over a wide temperature range. They are used in various friction units (e.g., seals), but their high friction coefficient and low wear resistance lead to the need for frequent replacement. In this paper, we propose applying thin (several hundred microns) UHMWPE coatings to formed rubber rings. The application technology depends on the required coating thickness. Friction tests of the coatings and pure UHMWPE were performed using the ball-on-disk (unidirectional sliding) scheme for various loads and velocities. In the experiments, the friction coefficients and temperatures near the contact area were determined. Friction tracks were studied using microscopy methods. The sliding contact of the ball and the two-layer material was modeled to obtain the dependences of the deformation component of friction on the sliding velocity for coatings of different thicknesses. UHMWPE is sensitive to frictional heating, so the thermal problem of determining the temperature in the contact area was also solved. It is shown that the minimum friction coefficient occurs for coatings with a thickness of 600 μm. At the same time, in the case of the 300 μm coating, the surface of the friction track is practically no different from the initial one. Thus, the studied combination of polymers provides antifrictional properties and wear resistance to the surface layer while maintaining the damping properties of rubber.

Polyethylene Protective Coating with Anti-Reflective Properties for Silicon Photovoltaic Cells.

The aim of the study was to find the effect of polyethylene (PE) coatings on the short-circuit current of silicon photovoltaic cells covered with glass, in order to improve the short-circuit current of the cells. Various combinations of PE films (thicknesses ranging from 9 to 23 µm, number of layers ranging from two to six) with glasses (greenhouse, float, optiwhite and acrylic glass) were investigated. The best current gain of 4.05% was achieved for the coating combining a 1.5 mm thick acrylic glass with 2 × 12 µm thick PE films. This effect can be related to the formation of an array of micro-wrinkles and micrometer-sized air bubbles with a diameter of 50 to 600 µm in the films, which served as micro-lenses and enhanced light trapping.

Long‐term cathodic disbondment tests in three‐layer polyethylene coatings

AbstractCathodic protection allied to a polymeric coating is one of the most employed techniques to protect buried steel pipelines against corrosion. Nevertheless, cathodic disbondment, a phenomenon associated with such protection in high‐performance coatings such as (three‐layer polyethylene [3LPE]), still concerns the oil and gas segment regarding pipeline integrity. The present work was part of a Program of Integrity Management and studied in field‐like conditions the influence of cathodic potential, type of soil and coating system on the coating disbondment of buried pipelines for 450 days. The coating systems herein studied simulated the patching between aged (coal tar) and new coatings (3LPE), a standard procedure during damaged pipeline repair. Results pointed out that the combination between aged (coal tar) and new coatings (3LPE) in a pipe segment reduced coating disbondment when compared to the systems where 3LPE was the sole type of coating. Moreover, it was shown that more cathodic potentials (<−1100 mV) and the aggressiveness of the industrial soil herein tested induced disbondment diameters as high as 15.5 mm.

Silicon lenses with HDPE anti-reflection coatings for low THz frequency range

Presented in this paper have been the design, fabrication, and testing of the high resistance floating-zone silicon (HRFZ-Si) optics with the anti-reflection (AR) high-density polyethylene (HDPE) coatings, for the low part of terahertz (THz) frequency range (ν ≈ 0.14 THz), by using the precision press molding. Experimental results of the transmission of the wafers and lenses with double-sided anti-reflection HDPE coatings for radiation frequency 0.14 THz showed an increase in the transmittance T values up to ≈1.45 times as compared to T magnitudes in wafers and lenses without HDPE coatings. The capability to use terahertz lenses with HDPE interference films and the technology of press molding, as a cheaper alternative to the horn antenna applications for the terahertz range of 0.14 THz was shown. With advancements in THz imaging and 6G communication technologies, further implementation of these Si optical elements is possible.

Assessment of Adhesives Performance of 3-Layered Polyethylene Coatings in the Oil and Gas Industry

Corrosion possess a major treat to long (several thousands of kilometers) pipeline infrastructure in Pakistan and is a key engineering concern. Construction of pipeline involves field wielded joint, wherein 3 layered poly-ethylene (3-LPE) protective layer is applied in a non-controlled environment involving many complexities. The risk factor is amplified by surface degradation (corrosion) and gas leakage, which is a major economic concern for various gas transmission and distribution industries. This research work is aimed at addressing the behavior of 3-LPE on the gas transmission line to avoid the pipe (substrate) surface from harsh environmental condition and longevity in service life. There is well published and known technique at lab for carrying out the application of 3-LPE on pipelines, but in field wielded joint, it is quiet challenging to achieve the equivalent bond strength of 3-LPE applied on the wielded joint due to certain factors. The current research is aimed at the application of 3-LPE followed by on site testing using peel test and other techniques. The field application of 3-LPE starts with surface preparation using cleaning and sand blasting, followed by FBE primer application onto substrate surface at elevated temperature and finally PE layer is applied. The strength and durability of the applied layer is measured using peel test. A regression analysis is performed using ANOVA to assess the durability, strength, and service life of 3-LPE on steel substrate, wherein three key factors were, i.e., surface preparation, pre-heat, and film thickness, were selected for investigation. Surface preparation is significantly important among the three, showing a value of 38.41%, followed by film thickness then pre-heat.

Fabrication and Characterization of Transparent and Uniform Cellulose/Polyethylene Composite Films from Used Disposable Paper Cups by the "One-Pot Method".

Disposable paper cups are usually composed of high-grade paper board and an inner polyethylene coatings and are extensively used in daily life. However, most disposable paper cups are only used for a short time and then incinerated or accumulated in landfill at the end of their service due to the difficulty in separating the components, leading to a serious threat to our ecosystem. Therefore, developing a facile and green method to recycle and reuse disposable paper cups is vital. By using ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) as a solvent, transparent and homogenous cellulose/polyethylene composite films were successfully prepared from used bamboo-based disposable paper cups through the “one-pot method”, without any pre-treatment. It was found that there was a transformation of cellulose I to II after the dissolution and regeneration processes, and the crystallinity degree of the regenerated cellulose-based materials decreased significantly, resulting in a change in thermal properties. Meanwhile, compared to traditional pure cellulose films, the composite films possessed good UV-shielding properties and hydrophobicity. Moreover, they also displayed good mechanical properties. Additionally, the size of the ground PE coatings displayed obvious effects on the structures and properties of the composite films, where the CPE100 (sieved with 100–200 mesh) possessed the most homogeneous texture and the highest tensile strength (82 Mpa), higher than that of commercial polyethylene film (9–12 MPa), showing superiority as packaging or wrapping materials. Consequently, the goals to fabricate uniform cellulose/polyethylene composite films and valorize the solid waste from disposable paper cups were simultaneously achieved by a facile and green “one-pot method”.

Organic solvents effect on the physical and mechanical properties of polyethylene

High-density polyethylene (PE) swelling in organic solvents, orthodichlorobenzene and orthoxylene, was investigated. The PE specimen swelling kinetics was described with the first-order equation. For the first time, the PE specimen swelling rate constant was shown to decrease with increasing thickness of the specimens. The equilibrium PE specimen swelling was evaluated. It was found that equilibrium swelling independent of specimens’ thickness. PE specimen storage in organic solvents was shown to change its mechanical characteristics (tensile strength, Young’s modulus, and elongation at break) due to polymer plasticization. We showed that an increase in flexibility and elongation at break becomes noticeable after relatively short-term immersion of the PE specimens into these organic solvents. However, the tensile strength of swollen specimens remains enough high. The interaction between polymer chains and solvent molecules was not detected. The results obtained are important for design and operation of PE coatings and PE products, such as pipes, tanks, and other accessories subjected to contacts with oil products.

Engineering laminated paper for SARS-CoV-2 medical gowns

The COVID-19 pandemic has highlighted the need for diversity in the market and alternative materials for personal protective equipment (PPE). Paper has high coatability for tunable barrier performance, and an agile production process, making it a potential substitute for polyolefin-derived PPE materials. Bleached and newsprint papers were laminated with polyethylene (PE) coatings of different thicknesses, and characterised for their potential use as medical gowns for healthcare workers and COVID-19 patients. Thicker PE lamination improved coating homogeneity and water vapour resistance. 49 GSM bleached paper with 16 GSM PE coating showed high tensile and seam strength, and low water vapour transmission rate (WVTR). Phi-X174 bacteriophage testing revealed that paper laminated with 15 GSM coating hinders virus penetration. This research demonstrates that PE laminated paper is a promising material for low cost viral protective gowns.

Icephobic Behaviour and Thermal Stability of Flame-Sprayed Polyethylene Coating: The Effect of Process Parameters

The present work investigates the effect of different process parameters on the production of low-density polyethylene (LDPE) coatings by flame spray technology. Previously, flame spraying of polymers has been successfully performed to obtain durable icephobic coatings, providing an interesting solution for applications facing icing problems, e.g. in marine, aviation, energy, and transportation industry. However, the fine tailoring of the process parameters represents a necessary strategy for optimising the coating production due to the unique thermal properties of each polymer. For this purpose, we vary the heat input of the process during flame spraying of the coating, by changing the transverse speed and the spraying distance. The results show that the variation in the process parameters strongly influenced the quality of the polymer coating, including its areal roughness, thickness, chemical composition, thermal stability, and degree of crystallinity. Furthermore, we demonstrate that these properties significantly affect the icephobic behaviour of the surface within the spray window of the chosen parameters. In conclusion, the relationship between the thermal degradation of the polymer and the icephobicity of the surface was defined. This highlights the importance of process parameter optimisation in order to achieve the desired icephobic performance of the LPDE coatings.

Understanding deposition mechanism in cold sprayed ultra high molecular weight polyethylene coatings on metals by isolated particle deposition method

The cold spray has been shown to be one of the promising additive manufacturing technologies to process Ultra High Molecular Weight Polyethylene (UHMWPE)-metal integrated systems by successfully being able to coat UHMWPE on metals using fumed nano-alumina (FNA) as UHMWPE particle surface modifiers. However, the exact mechanism of UHMWPE deposition and role of FNA was widely unknown. This study aims at identifying the fundamental parameters involved in high strain-rate UHMWPE deposition and their role in successful adhesion by a technique called Isolated Particle Deposition (IPD). Major parameters that influenced the UHMWPE deposition efficiency significantly were the particle temperature and velocity and net surface activity of FNA. The stored elastic energy of UHMWPE decreases with increase in temperature, and the deposition criterion for a successful UHMWPE deposition is not to have net stored elastic energy after impact. Effect of FNA was seen in generating H-bonds that helped to establish bridge bond at UHMWPE-substrate interface.

Effects of stray AC on corrosion of 3-layer polyethylene coated X70 pipeline steel and cathodic delamination of coating with defects in 3.5 wt-% NaCl solution

ABSTRACTIn this work, the effects of stray alternating current (AC) on the corrosion of coated X70 pipeline steel and the delamination of 3-layer polyethylene (3PE) coatings with defects were investigated using COMSOL Multiphysics simulation, electrochemical impedance spectroscopy and three-dimensional (3D) digital microscope techniques. The results showed that under the same level of AC interference, pits with deeper maximum pit depth were observed at the smaller defect areas than those at larger defect areas. It was consistent with the simulation results that a greater corrosion current density was accompanied on samples with smaller defects. According to 3D digital images, the larger delamination of 3PE coatings was found on samples with smaller defects. With the increase of current density, the impedance of samples with small defects decreased, while that of samples with large defects increased. Additionally, with the same defect size, the maximum pit depth became deeper and the corrosion was more severe.

Modification of Cu‐PE‐PTFE composite coatings on rubber surface by low‐energy electron beam dispersion with glow discharge

Polytetrafluoroethylene (PTFE) composite coatings doped with copper acetate and polyethylene (PE) were fabricated on rubber substrate by electron beam dispersion technique. The effects of dopant nature and glow discharge treatment on morphology, structural and tribological properties of the coatings were investigated. The results showed that Cu and PE doping change the surface structure of PTFE‐based composite coatings due to the chemical reactions between the dispersion products. Cu‐PE‐PTFE coatings show the columnar and layered growth models without and with discharge treatment. Cu adding decreases the crystallinity, branched degree and unsaturated degree of PE coatings, but increases the branched degree and unsaturated bonds in the PE‐PTFE coatings. Glow discharge enhances the crystallinity and ordering degree of composite coatings. Friction experiments indicated the significant difference of composite coatings in the nature of their destruction during friction. PE‐PTFE coating is characterized of the brittle fracture with clear failure boundaries but Cu‐PE‐PTFE coating shows a rough surface without cracking and delaminating after friction. Cu doping increases the dynamic coefficient of friction of PE and PE‐PTFE composite coatings, but discharge plasma decreases the dynamic coefficient of friction. Cu‐PE‐PTFE composite coating after discharge treatment has the decreased dynamic coefficient of friction and improved wear resistance. POLYM. ENG. SCI., 58:103–111, 2018. © 2017 Society of Plastics Engineers

Incorporation of Copper Enhances the Anti-Ageing Property of Flame-Sprayed High-Density Polyethylene Coatings

High-density polyethylene (HDPE)-copper (Cu) composite coatings were prepared through depositing HDPE-Cu core-shell particles by flame spraying. The HDPE-Cu composite coatings and the HDPE coatings were aged in xenon lamp ageing testing chamber. The variations of chemical compositions and surface morphology of the coatings before and after the ageing testing were analyzed using infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry and ultraviolet-visible spectrophotometer. Results show that there is no chemical composition variation in the HDPE-Cu coatings. Cracks were found on the surfaces of the HDPE coatings, while the HDPE-Cu coating shows almost intact surface morphology. These results suggest that the HDPE-Cu coatings present better anti-ageing performances than the HDPE coatings. Further assessment of the function of Cu shells on the anti-ageing property reveals that Cu shells not only enhanced the absorption of the coatings to ultraviolet, but also increased their reflectivity to visible light. Additionally, the Cu shells enhanced the decomposition temperature and thermal stability of HDPE in the composite coatings. These results give bright insight into potential anti-ageing applications of the polymer-based structures.

Significant Improvement of Electrochemical Performance of Ni-rich Cathode Material by Polyethylene Coating

We attempted to use polyethylene (PE) to coat the surface of the cathode material in order to suppress these unnecessary reac-tion, and the results obtained via electrochemical impedance spectroscopy (EIS) suggest the growth of the SEI resistance and charge trans-fer resistance was suppressed in the samples consisting of 0.1 wt% PE-coated Li[(Ni0.6Co0.1Mn0.3)0.36(Ni0.80Co0.15Al0.05)0.64)]O2 (NCS). The initial discharge capacity of the coated material was of 190.56 mAhg-1 at 0.1 C between 3.0 and 4.3 V, and 94.6 % of this capacity was retained after 30 cycles. A notable of effect of the PE coating, is that the resulting exothermic temperature appears at approximately 258.1 °C, which is higher than that for bare NCS at 249.3 °C.

Influence of Aluminum Oxide Nanofibers Reinforcing Polyethylene Coating on the Abrasive Wear

Experiments have been carried out to investigate the abrasive wear of steel specimens coated by polyethylene (PE) coating in a sandy soil. Aluminum oxide (Al2O3) nanofibers were employed as fillers in PE for fabricating the tested composites. The reinforced polyethylene coating has been impregnated by oil. An abrasive wear tester was developed to simulate the abrasion caused by a sandy soil against surfaces subjected to abrasive contaminants. Motion was transmitted to the disc via the drill chuck. The test time was 15 min. Experiments were carried out at 25 °C. Wear was measured by digital balance with an accuracy of ± 0.001 g. Wear and embedment of sand particles were analyzed using optical microscopy after the test. Based on the experimental results, it was found that, the addition of aluminum oxide fibers showed a considerable mitigation in the wear. When oil content increased, the wear decreased. Embedment of the sand particles for the smaller size particles is higher than the larger particles. Increasing of oil content enhanced the embedment of sand particles. The compatibility of Al2O3 nanofibers with PE leads to the inseparability of aluminum oxide due to good adhesion and decreased the wear.

Cavitation erosion of low-density polyethylene coatings for pipe liners

The relationship between mechanical properties and the erosion rate was examined for chloroprene rubber and a number of polyethylene materials produced by different methods. As electric power plants are in operation over long periods of time, the effect of aging was also examined by testing material intended for use in pipes in electric power plants. Cavitation erosion tests were carried out by using a flowing apparatus as specified in the American Society for Testing Materials G134-95 standard. A flow velocity of 150 m/s and a test time of 24hours, were the experimental conditions used for a cavitating liquid jet test on polyethylene. The maximum depth of erosion rate (MaxDER) of polyethylene was found to decrease with the increase in hardness. Among all the tested materials, the relatively high molecular weight polyethylene with low density (m-LLDPE-H), showed the best resistance to cavitation erosion in terms of MaxDER. The effect of aging on the erosion rate of polyethylene was limited.

Deuterated polyethylene coatings for ultra-cold neutron applications

We report on the fabrication and use of deuterated polyethylene as a coating material for ultra-cold neutron (UCN) storage and transport. The Fermi potential has been determined to be 214 neV, and the wall loss coefficient η is 1.3 × 104 per wall collision. The coating technique allows for a wide range of applications in this field of physics. In particular, flexible and quasi-massless UCN guides with slit-less shutters and seamless UCN storage volumes become possible. These properties enable the use in next-generation measurements of the electric dipole moment of the neutron.

Failure Analysis of Disbondment of Three-Layer Polyethylene Coatings from the Surface of Buried Steel Pipelines

A failure analysis was conducted to analyze the mode and causes of the disbondment of the three-layer polyethylene coatings from the surface of buried steel pipelines. The failure interface was analyzed through visual and microscopy investigations. Analysis of the coating at the disbonded interface revealed that the fusion bonded epoxy (FBE) layer had a fragile integrity which may have resulted from the in-service conditions of the pipeline. According to failure analysis of the disbonded interface, it can be concluded that degradation of the molecular structure of FBE layer was the most probable cause of the coating failure. It is believed that degradation of the molecular structure of FBE layer and subsequent disbondment of the coatings was caused by a mechanical-assisted cathodic delamination process which was due to the simultaneous action of chemical degradation and residual stresses at the coating-substrate interface. It is believed that surface pretreatment of the steel substrate in addition to coating process parameters of the powder coating are the main parameters in determining the long-term performance of the coating-substrate interface and should be carefully controlled.

Development of Ultra-High Molecular Weight Polyethylene (UHMWPE) Coating by Cold Spray Technique

Ultra-high molecular weight polyethylene or UHMWPE is an extremely difficult material to coat with, as it is rubbery and chemically very inert. The Cold Spray process appears to be a promising alternative processing technique but polymers are in general difficult to deposit using this method. So, attempts to develop UHMWPE coatings were made using a downstream injection cold spray technique incorporating a few modifications. A conventional cold spray machine yielded only a few deposited particles of UHMWPE on the substrate surface, but with some modifications in the nozzle geometry (especially the length and inner geometry) a thin coating of 45 μm on Al substrate was obtained. Moreover, experiments with the addition of fumed nano-alumina to the feedstock yielded a coating of 1-4 mm thickness on Al and polypropylene substrates. UHMWPE was seen to be melt crystallized during the coating formation, as can be seen from the differential calorimetry curves. Influence of nano-ceramic particles was explained by observing the creation of a bridge bond between UHMWPE particles.