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In this work, blended composites with ultra‐high molecular weight polyethylene (UHMWPE) as matrix polymer, α‐zirconium phosphate (α‐ZrP) as filler, and sodium polyacrylate (PAANa) as compatibilizer were prepared. The interfacial interaction between PAANa as a compatibilizer and the components of α‐ZrP/UHMWPE was studied by molecular dynamics simulation. The friction and wear behavior of the GCr15 ball/composite friction pair under seawater lubrication under different loads were explored, and the friction and wear mechanism were analyzed. The results show that PAANa as a compatibilizer can effectively improve the interfacial interaction force between components of PAANa/α‐ZrP/UHMWPE composites. The composites exhibited different trends regarding the relationship between tribological properties and α‐ZrP content under various loads. The wear mechanism of composites under low load is mainly represented by extrusion deformation. With the increase of load, the wear mechanism of composites gradually changed into adhesive wear and abrasive wear (depending on the content of α‐ZrP). This work provides a theoretical basis for preparing and applying other α‐ZrP/polymer blend composites. [ABSTRACT FROM AUTHOR]

Objective: As disc fragment completely loses contact with the parent disc and can migrate in all directions of the epidural space, making it appear similar to schwannoma, it is fairly difficult to make a definitive diagnosis for mimicking tumor discs. The aim of this research is to differentially diagnose mimicking tumor discs and schwannomas using coronal magnetic resonance imaging (MRI) of three‐dimensional fast‐field echo with water‐selective excitation (CMRI). Methods: Among 76 patients (38 men and 38 women; mean age, 52.88 ± 15.80 [range, 18–78 years]) who were retrospectively examined in this study, 38 were primarily diagnosed with schwannomas and pathologically diagnosed with mimicking tumor discs after surgery, and 38 were primarily diagnosed with neurogenic tumors and pathologically diagnosed with schwannomas after surgery. Open surgery was performed in all the patients between March 2016 and April 2020. The preliminary diagnosis of all patients was considered an intraspinal tumor based on conventional two‐dimensional MRI sequences. After open surgery, the final diagnosis was confirmed to mimic a tumor disc or schwannoma based on postoperative pathology reports. The sensitivity, specificity, and reliability of CMRI and conventional MRI for identifying mimicking tumor discs and schwannomas were compared. Chi‐square and McNemar tests were used for statistical analyses. Results: Symptoms were considerably relieved in all the patients after surgery. Seven patients had grade 1 extensor digitorum longus, triceps surae, or quadriceps femoris muscle strength prior to surgery. No nerve root injury was observed in any of the patients. CMRI showed significantly higher sensitivity (94.74%) and specificity (94.74%) than conventional MRI (71.05% and 92.11%, respectively; p = 0.012 < 0.05, and p = 1 > 0.05, respectively) for differential identification between mimicking tumor discs and schwannomas. Moreover, CMRI showed a higher reliability (kappa value = 0.787) than conventional MRI (kappa value = 0.374). Conclusions: CMRI is a better non‐invasive technology for the identification of intraspinal lesions, especially for differentiating between mimicking tumor discs and schwannomas. [ABSTRACT FROM AUTHOR]

This study aims to investigate a novel high‐efficient antioxidant for synthetic ester oils. An ester‐bridged antioxidant, phloroglucinol tris (3‐[3,5‐di‐tert‐butyl‐4‐hydroxyphenyl]) propionate (PTP), was successfully synthesised in high yield under relatively mild reaction conditions. Thermal stability and oxidation resistance of diisooctyl adipate (DOA) ester oil were determined and compared to the typical commercial phenol antioxidants, including its tribological properties. The results indicate that the prepared PTP antioxidant exhibits considerably higher thermal stability than commercial antioxidants, and it also improves the oxidation resistance of the synthetic ester oil more effectively. Moreover, the addition of PTP antioxidant enhanced the wear protection of DOA ester oil without deteriorating its lubricating performance. The ester‐bridged antioxidant can be used as a multifunctional additive, which not only exerts excellent thermal stability and oxidation resistance, but can also act as an efficient anti‐wear agent in synthetic ester oils. [ABSTRACT FROM AUTHOR]

Using thermal‐oxidative aging and tribological experiments, effects of thermal‐oxidative aging processes on tribological properties of polyformaldehyde (POM) and ultra‐high molecular weight polyethylene (UHMWPE) were evaluated and compared with each other. It was found that the color of UHMWPE surface after aging has turned to yellow, while that of POM surface has no obvious change. The aging factors lead to dimensional change of UHMWPE disk specimens from the original circle to the ellipse in the meantime. Tribological experiments show that friction coefficients of the pairs of POM/GCr15 and UHMWPE/GCr15 tend to decrease after thermal‐oxidative aging, and the decreasing tendency in friction coefficients of POM/GCr15 is more distinct. The results of this study will contribute to the understanding of the relationship between aging and tribological properties of POM and UHMWPE, and enrich the theory of polymer tribology. [ABSTRACT FROM AUTHOR]

Polymer blends have been widely used as tribological materials for replacements of traditional metals and ceramics. Polymer blends consist of the reinforced phase, the matrix phase and interfaces between reinforced and matrix phase. Although the interface structure of polymer blends is usually small in size, it is one of the key factors for deciding the physical and tribological properties of polymer blends. Thus, this review highlights the most recent trends in the field of influences of interface structure on tribological properties of engineering polymer blends. Emphasis is given to the improvement methods of interfacial compatibility of polymer blends and the behavior variation of interface structure during friction process. [ABSTRACT FROM AUTHOR]

The oxidation behavior of the synthetic ester oils di‐isooctyl adipate (DOA) and tri‐isodecyl trimellitate (TDTM) was investigated by analysing the oxidation induction time and oxidation onset temperature via pressure differential scanning calorimetry tests, and the variation in viscosity after oven accelerated oxidation tests. Moreover, theoretical calculations of the fractional free volumes and oxygen diffusion coefficients of DOA and TDTM were performed, and atomistic‐scale insights into the oxidative mechanisms of both oils were proposed based on reactive molecular dynamic (RMD) simulations. Better oxidation resistance for TDTM was confirmed with experimental observations. RMD results indicated that the C―O bonds of the alcohol chain and ester group of DOA were susceptible to oxidation. However, only the dissociation of the C―O bond of the alcohol chain initiated the oxidation of TDTM. Additionally, more degradation fragments for DOA were identified, along with the formation of a polymerized product, while no large molecules formed for TDTM. [ABSTRACT FROM AUTHOR]

Abstract: As oxidation stability of engine oil was hard to evaluate in field, this paper tried to propose a field test method to determine the oxidation onset temperature (OOT) of gasoline engine oil. A theoretical model of grey average value of oil spot image and OOT was established by using spot test method, image processing, and Pressure Differential Scanning Calorimetery method. The oil sample unknown OOT was taken to spot test and image processing in field to obtain the grey average value. The OOT can be calculated by bringing the grey average value to the established theoretical model. This approach was successfully used for OOT determination of 4 different kinds of engine oils with good accuracy and precision. The absolute error of mineral oils was less than 4.52°C, and synthetic oils were less than 1.2°C. This convenient, low‐cost, and reliable method can achieve OOT of engine oil in field determination and provide reference for engine oil drain interval evaluation. [ABSTRACT FROM AUTHOR]

ABSTRACT Ultraviolet aging restricts the outdoor application of polyformaldehyde as the friction material. In this work, ultraviolet aging processes were applied to polyformaldehyde specimens and effects of the processes on their surface properties and tribological performance were evaluated. Surface morphology results show that a thin layer of white powder and micro-cracks with further ramifications in other directions were observed on the surfaces after 400 h of ultraviolet exposure, while it is not detectable for the unaged specimens. Analysis of aging surface indicates that ultraviolet leads to the increase of micro-cracks and the degree of crystallinity. All the tribological test results demonstrate that with the extension of ultraviolet aging time, (i) the process of damage on polyformaldehyde surface induced by ultraviolet aging is first slowly and faster afterward; (ii) the fluctuation of the friction coefficients of polyformaldehyde/GCr15 rubbing pairs increases; and (iii) the wear rate of polyformaldehyde markedly increase after aging test 400 h. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44684. [ABSTRACT FROM AUTHOR]

A method is reported for the determination of diphenylamine and butylated hydroxytoluene in mineral and synthetic oil. The procedure used differential pulse voltammetry with a glassy carbon electrode. This method was then used for determining these antioxidants in supporting electrolyte consisting of dilute sulfuric acid and sodium dodecyl sulfonate in ethanol. Anodic peaks were obtained for both analytes. Oxidation peaks at 250 mV were observed from a mixture of butylated hydroxytoluene and dinonyl diphenylamine, allowing their simultaneous determination. This approach was successfully used for the determination of dinonyl diphenylamine and butylated hydroxytoluene in fortified mineral and synthetic oils with good accuracy and precision. [ABSTRACT FROM AUTHOR]

Effects of thermal aging on the blend phase morphology of polyimide/ultrahigh molecular weight polyethylene (PI/UHMWPE) blend composites were studied by using Raman Mapping. Friction and wear tests were conducted to study the influence of thermal aging on the tribological properties of the blend composites. The results indicate that the phase morphology of PI/UHMWPE blend composites could be controlled by thermal aging. At relatively low thermal aging temperatures (100 °C, 120 °C), the blend with high PI/UHMWPE ratio tended to form continuous layered structures. As a consequence, the tribological performance was significantly improved. While for the blend with low PI/UHMWPE ratio, the improvement of tribological performance was not significant. For the blends thermal aged at relatively high temperature (150 °C), the tribological performance was poor due to significant phase separation that occurred after thermal aging. • Thermal oxidation resistance of UHMWPE could be significantly improved by blending PI to the UHMWPE matrix. • The phase morphology of PI/UHMWPE blend composites could be controlled by thermal aging. • The wear resistance of PI/UHMWPE blend was improved after thermal aging at the temperature below melting point. [ABSTRACT FROM AUTHOR]

A simulation of magnetic-field-induced ion motion in vacuum arc deposition for the inner surfaces of a tubular workpiece was performed. An auxiliary magnetic field was set to guide the motion of ions inside a pipe, with different magnetic flux densities and ion emission parameters. The results showed the trajectories, deposition ratio and depth of the ions can be controlled via a magnetic field. Within a certain range, the deposition ratio of the ions increases with magnetic flux density. When the magnetic flux density reached a certain value, both the trajectories and deposition ratio of the ions exhibited an obvious periodicity. The depth at which the ions were deposited decreased as an exponential function of the magnetic flux density and ion emission radius, respectively. With an increase in the emission angle, the deposition depth decreased linearly. A numerical model was proposed to express the distribution of the deposition depth. In addition, the deposition ratio and depth are improved with a magnetic field in an environment with a certain density of neutral gas. [ABSTRACT FROM AUTHOR]