ISSN:0265-6582    

DOI:10.1002/jsl.3000180402

出版商:John Wiley&Sons, Ltd    

年代:2002

数据来源: WILEY

摘要:

AbstractEthyl hexyl esters of oleic, linoleic, and linolenic acids were synthesised and thermally polymerised to obtain products with viscosities in the range of hydrocarbon lubricants at 100°C (11–22 cSt). Molecular weight, elemental analysis, IR,13C NMR, and intrinsic viscosity data showed that most of these derivatives are mixtures of monomers, dimers, and trimers and have linear and cyclic products with predominantly trans characteristics.The lubricity characteristics were determined on a friction and wear tester under conditions of thick‐film lubrication. A comparison was made with hydrocracked hydrocarbon lubricants of comparable viscosities at 100°C and comparable viscosity indices.It is inferred that all the esters maintained relatively thicker surface films and much lower friction coefficients than the hydrocarbon oils. The wear‐scar data show that the antiwear characteristics of polymerised ethyl hexyl oleate and linoleate are only slightly inferior to those of the hydrocarbon oils, but at higher temperatures their antiwear characteristics rapidly deteriorate while the friction coefficients markedly increase and become comparable to those of hydrocarbon oils. These studies are being undertaken with a view to selecting and modifying vegetable oils containing mixtures of fatty acids for obtaining esters of outstanding friction, wear, and film‐forming charac

ISSN:0265-6582    

DOI:10.1002/jsl.3000180403

出版商:John Wiley&Sons, Ltd    

年代:2002

数据来源: WILEY

摘要:

AbstractThis overview describes the development of polymeric composites for operation with low friction and wear against steel counterparts, with special emphasis on injection‐mouldable short‐fibre‐reinforced thermoplastics. This work has aimed to optimise their friction and wear properties and to carry out systematic parameter studies using artificial neural networks; information is presented on the systematic development of continuous‐fibre polymer‐based composites with high wear resistance and on the prediction of their load‐bearing capacity using a finite‐element approach. Finally, some new steps towards the development of functionally graded tribo‐material

ISSN:0265-6582    

DOI:10.1002/jsl.3000180404

出版商:John Wiley&Sons, Ltd    

年代:2002

数据来源: WILEY

摘要:

AbstractVegetable oils are a type of easily biodegradable ester‐type lubricant derived from renewable resources. Their importance, from the environmental view‐point, is evident, especially in loss lubrication, hydraulic systems with increased risk of damage, etc. They are characterised by good lubricity and good anticorrosion and temprature‐viscosity properties. Some disadvantages, particularly low thermal oxidation stability and poor cold flow behaviour, can be mitigated by structural modifications. In this study, possible substitutions of the alcohal part of triacylglycerols as well as changes in acyl unsaturated chains are discussed. Attention is paid particularly to the epoxidising of double bonds in acyls resulting in the formation of oxirane rings. By opening these in the presence of hydrogen donors, it is possible to obtain new derivatives and polyfunctional compounds that are acceptable as environmentally friendly lubri

ISSN:0265-6582    

DOI:10.1002/jsl.3000180405

出版商:John Wiley&Sons, Ltd    

年代:2002

数据来源: WILEY

摘要:

AbstractSynthetic lubricants were originally developed and used for applications where petroleum products were inadequate (e.g., at extremely high and low temperatures, under extreme wear conditions) or where special characteristics, such as long life, improved equipment efficiency, or non‐flammability, were needed. However, the use of synthetic lubricants is not restricted to special applications, but is also useful when they can provide cost efficiency in areas such as machine reliability, oil life, energy consumption, biodegradability, and safety. Among many successful applications, typical cases where synthetic fluids have clear advantages over conventional lubricants include: high‐temperature lubricants for plastic calenders (significant lengthening of oil‐change intervals, fewer machine shutdowns): worm gear drives under severe service conditions (increase in efficiency, lower operating temperatures); air compressors (elimination of combustible petroleum residues); hydraulic fluid in fire‐resistant applications (mining equipment, pressure casting machines, steam turbine control systems); and high‐speed greased bearings (reduced friction losses).The benefits of synthetic lubricant base stocks are derived not only from their basic molecular structures but also from the absence of harmful molecular species often unavoidably present in conventional mineral oils in small, but significant, concentrations. There are very many compounds in crude oil, and while many, or most, of the harmful ones are removed or upgraded by refining, depending on the methods used, a significant number will inevitably remain in lubricating oil stocks, whether solvent‐ or hydrotreated. Thus, conventional oils comprise a wide variety of molecular species, many of which are not well characterised. In contrast, synthetic products normally are produced by chemical reactions of very pure, small molecules in which pressure, tempesutuse, und the ratio of reactants cun he curefully controlled. Frequently, the synthesis o j the reaction up to the desised end product includes severul steps, each of which necessitutes a pusifcution of the intermediute psoducts. It is this resulting ji‐eedom jhom undesisuhle compounds that gives synthetic lubricants their distinctiiie characteristics. It also contrihutes to their higher cost, compased to mineral oils, the oiserall cost of u synthetic product being the sum of the costs of the raw materials und the costs of the individual reuction steps.It is estimuted thut approximutely 80% of the worldwide synthetic luhsicants market is repsesented by three generic groups: polyulphaolejins (∼45%), organic esteia (∼25%), and polyglycols (∼10%). Of the remaining synthetic luhricunts, phosphate esters and polyhirtenes make up probably the largest sules volumes, with about S% each in total. This paper. provides an overview of the types, characteristics, uses, und udwrztages of synthetic lubricants, based on these major te

ISSN:0265-6582    

DOI:10.1002/jsl.3000180406

出版商:John Wiley&Sons, Ltd    

年代:2002

数据来源: WILEY

摘要:

AbstractMany of the lubricants used in the world today cause environmental pollution through total‐loss applications, spillage, evaporation, and in other ways. To reduce this environmental damage, new lubricants that are rapidly biodegradable and ecologically non‐toxic have started to be developed and marketed. This paper discusses the introduction of environmentally friendly lubricants and their constituents, with particular emphasis on their environmental benefits, applications, the limits to their use, their technical performance characteristics, and relative cost aspects; many of these lubricants are based on vegetable oils and esters. Comparisons are also made in the paper with conventional mineral‐oil based mate

ISSN:0265-6582    

DOI:10.1002/jsl.3000180407

出版商:John Wiley&Sons, Ltd    

年代:2002

数据来源: WILEY

ISSN:0265-6582    

DOI:10.1002/jsl.3000180408

出版商:John Wiley&Sons, Ltd    

年代:2002

数据来源: WILEY

ISSN:0265-6582    

DOI:10.1002/jsl.3000180409

出版商:John Wiley&Sons, Ltd    

年代:2002

数据来源: WILEY

ISSN:0265-6582    

DOI:10.1002/jsl.3000180401

出版商:John Wiley&Sons, Ltd    

年代:2002

数据来源: WILEY