Wanzhen Gao

Design to Modify UHMWPE with Schiff Base Copper Complex for Use as Tribological Material

Based on the theory of tribology, a new kind of modified ultra-high molecular weight polyethylene (UHMWPE) was designed using Cu(II) chelate of bissalicylaldehyde-ethylenediamine and glycerine microcapsules with polyethylene wall (glycerol-polyethylene microencapsule) as additives. Ring-block tester was used to investigate the dry tribological properties of the modified UHMWPE pairing up with CGr15 steel at room-temperature condition. Results demonstrated that the modified UHMWPE formed a selective transfer system when rubbing against steel under the dry frictional condition, and brought about self-selective transferring effect without the need to apply any selective transfer medium to the lubrication. Study also illustrated the obvious improvement of its material characteristics in providing lower viscoelasticity and in strengthening rigidity when compared with the pure UHMWPE.

Study of Wear Self-Repair of Steel 100Cr6 Rubbed With Lubricants Modified With Schiff Base Copper Complex

Preparation of a Cu (II) chelate of bis(salicylaldehyde)ethylenediamine was carried out directly in epoxidized rape oil via a water/oil microemulsion reactor. Detailed characterization of the friction of boundary lubrication produced by epoxidized rape oil with and without the Cu (II) chelate of bis(salicylaldehyde)ethylenediamine was performed in reciprocating sliding tests with a microtribometer. In the presence of a modification of the epoxidized rape oil with 2 wt % of the Cu (II) chelate of bis(salicylaldehyde)ethylenediamine, the friction coefficient decreased by 15%. The Cu (II) chelate of bis(salicylaldehyde)ethylenediamine served as the additive in the epoxidized rape oil and self-assembled on the surface of 100Cr6 steel. The self-assembled monolayer was detected with atomic force microscopy and scanning electron microscopy, and characterized with cyclic voltammetry. It was verified by energy dispersive spectroscopy and X-ray photoelectron spectroscopy analyses that steel/steel rubbing pairs underwent a selective transfer of organic substance and copper, as a result of lubrication with the modified lubricant. It indicated that the modification of epoxidized rape oil with Cu (II) chelate of bis(salicylaldehyde)ethylenediamine led to wear self-repair on the steel surface, with selective transfer of a film of organic substance and copper metal.

Study of the Preparation of a Modified Lubricant Using a W/O Microemulsion Reactor and a Cyclic Voltammetry Study of Rubbing Steel S45C with Lubricants

A successful preparation of a Schiff base copper complex was carried out directly in rap oil, using a W/O microemulsion reactor. The prepared Schiff base copper complex dispersed equably and spontaneously in the oil. Owing to a modification of the rap oil, by addition of 2%wt of Cu (II) chelate of bissalicylaldehyde-ethylenediamine, the friction coefficient decreased by 80% compared to that of the original one. It was verified by energy dispersive spectroscopy (EDS) and x-ray photoelectron spectroscopy (XPS) analyses that steel/steel rubbing pairs underwent a selective transferring process with such modified lubricants. It was suggested that the mechanism for the improvement in the tribological characteristics of the modified lubricants was due to a selective transferring effect. The Cu (II) chelate of bissalicylaldehyde-ethylenediamine not only served as an additive in the rap oil, but also self-assembled on the surface of the 100Cr6 steel. The self-assembled monolayer (SAM) was examined using SEM techniques. The SAM was characterized with cyclic voltammetry (CV). It indicated that the SAM could activate the rubbing surface of 100Cr6 steel, which benefited the tribological chemical reaction.

Elementary Study of Modifying UHMWPE with Schiff Base Copper Complex for the Use as an Artificial Hip Joint Material

Elementary micro-tribological test for UHMWPE modified with 15 wt% of Schiff base copper complex (Cu(II) chelate of bissalicylaldehyde-ethylenediamine rubbed by titanium alloy showed that a reduction of 20% friction coefficient when compared with the pure UHMWPE/titanium alloy pair under the condition of dry friction. Under a simulating loading level of an artificial hip joint, the highest frication coefficient of the modified UHMWPE pairing with steel was 15% lower than its pure UHMWPE/steel pairing counterpart. Furthermore, wear of the modified UHMWPE was very mild almost without any sign of worn debris even being run for a sufficiently long period, while the pure UHMWPE could run only for a very short period. Test results confirmed that the Cu(II) chelate of bissalicylaldehyde-ethylenediamine modifying UHMWPE was able to reduce friction, wear and debris during application. Besides excellent tribological characteristics, good biocompatibility of the modified UHMWPE was also demonstrated by a cell toxicity test in vitro. T Consequently, attempts to develop this modified UHMWPE for artificial joint is obviously beneficial.

Study on preparation of modified lubricant containing nano-Schiff base and Schiff base copper complex in W/O microemulsion reactor

A successful preparation of Schiff base and Schiff base copper complex was carried out directly in polar base oil (vegetable oil) using a water/oil microemulsion reactor. The prepared nanometer sized Schiff base and Schiff base copper complex dispersed uniformly and spontaneously in the oil. The nanometer sized particles of the Cu(II) chelate of bissalicylaldehyde-ethylenediamine and the bissalicylaldehyde-ethylenediamine in oil were observed directly by SEM. Owing to a modification of the polar base oil (vegetable oil) by 1 wt % of nano-scale Cu(II) chelate of bissalicylaldehyde-ethylenediamine and 1 wt % of bissalicylaldehyde-ethylenediamine, the last nonseizure load had gone up 40% over that of the original ones. It was verified by AES analysis that steel/steel rubbing pairs went through a selective transfer process under lubrication with the modified polar lubricant. It was suggested that the mechanism of the improvement of tribological characteristics of the modified lubricant was selective transfer effect. An antibacterial activity of the modified lubricant was inspected also.

An In Vitro Investigation of UHMWPE Modified with Cu (II) Chelate of Bissalicylaldehyde-Ethylenediamine

This article investigates the performance of ultra high molecular weight polyethylene (UHMWPE) modified with 15 wt% Cu (II) chelate of bissalicylaldehyde-ethylenediamine, a type of Schiff base copper complex that has antibacterium and antitumor activity, as a potential artificial hip joint material. The modified UHMWE demonstrated excellent tribological and biocompatible properties, and a higher wear resistance, a better thermal conductivity and increased deformation resistance as compared to pure UHMWPE.

Preparation and Tribological Behaviors of Lubricants—Oil Based on Modified Microbial Oil with Nano-Schiff Base Copper Complex

A W/O microemulsion reactor was used to prepare four kinds of modified lubricants: (i) modified lubricant 1, modified epoxidized microbial oil + rape oil in volume ratio of 1:1; (ii) modified lubricant 2, modified esterified microbial oil + rape oil in volume ratio of 1:3; (iii) modified lubricant 3, modified epoxidized rape oil; and (iv) modified lubricant 4, modified PAO. The individual modified lubricants were further modified with 0%, 0.5%, 1%, and 2% content of nano-Schiff base copper complex (nano-SBCC). A microtribometer was used to evaluate the friction coefficient between ball/flat point contacts immersed in the modified lubricants and operated in reciprocating and linear sliding mode. A comparison of the values of the friction coefficient with the lubricants further modified with nano-SBCC with those of their individual 0% nano-SBCC counterparts indicated significant decrease: (i) almost 19.18% was obtainable for the modified lubricant 1 with 2% of nano-Schiff base copper complex, (ii) almost 16.5% was obtainable for the modified lubricant 2 with 0.5% of nano-Schiff base copper complex; (iii) almost 7.42% was obtainable for the modified lubricant 3 with 1% of nano-SBCC; and (iv) almost 7.01% was obtainable for the modified lubricant 4 with 0.5% of nano-SBCC. These suggested that the addition of nano-Schiff base copper complex can efficiently decrease the friction coefficient of epoxidized or esterified microbial oil. Analyses of two-dimensional images, average profiles (across the mid-section y = 0 of the reciprocating sliding path), and three-dimensional topographies by confocal white light microscope for the worn surfaces of flats immersed in modified lubricant 1 and modified lubricant 2 suggested better wear-resistance of the modified lubricant 2 than that of the modified lubricant 1. The ability of wear resistance for the modified lubricant became better with the increasing content of nano-Schiff base copper complex from 0% to 2%. The study revealed the modification of epoxidized microbial oil + rape oil (1:1 volume ratio) and esterified microbial oil + rape oil (1:3 volume ratio) with Cu(II) chelate of bis(salicylaldehyde)ethylenediamine, reducing the magnitude of friction and wear because of their respective wear self-repairing ability. Such self-repairing ability furnishes the suitability of epoxidized microbial oil or esterified microbial oil to be effectively modified by nano-Schiff base copper complex and to substitute ordinary base oil as a mixture with rape oil.

Study on preparation of nano-TiO2 by W/O microemulsion reactor and its photocatalytic degradation of air pollution

Nanoscale and photocatalytically active TiO2 is widely used in many fields, such as environmental protection, pollution control, and the self-cleaning of textile and architecture. This paper (i) describes the preparation of nano-TiO2 in W/O microemulsion reactor, (ii) considers the photocatalytic degradation of air pollution caused by formaldehyde and toluene in terms of the bionics theory, and (iii) discusses the similarity between the photocatalytic degradation by nano-TiO2 and the photosynthesis of a plant that makes the degradation of pollutions by nano-TiO2 essentially important for ecologically safe treatment and recovery of natural resources.