Rubbing conditions, effect

Adsorption of carboxylic acids, alcohols and amine on steel surfaces takes place by hydrogen-bonding of monomeric molecules to the oxide and hydroxide layers on the surface. Aliphatic amines, alcohols, and acids have also proved to be especially suitable for build-up of anti-wear protective layers, and greatly reduce the friction coefficient. Adsorbed and chemisorbed films are very effective in reducing friction and mild wear under moderate rubbing however, they fail fairly rapidly under severe rubbing conditions and therefore are not very effective in preventing wear and seizure. 

The effect of operating conditions in the formation of these in situ films is likely to be complex. In 1972 Forbes showed that even under fairly mild conditions with an anti-wear additive such as tricresyl phosphate surface films are formed which contain both phosphorus and organic fragments. Similarly Cann showed that a cross-linked thick surface film is formed from zinc dialkyidithiophosphate under mild rubbing conditions. It seems probable that at least some of the soluble molybdenum compounds would also experience partial breakdown under mild rubbing conditions, and that these would encourage the formation of protective surface films. 

Effect of Rubbing Conditions. Study of the molecular characteristics of the fragments transferred at various loads and speeds showed considerable changes in HD PE molecular weight even during running—in ( test time was 1 h ) ( Pig. 1, Table I ). 

Table I. Effect of Rubbing Conditions on Molecular Characteristics of HD PE Transfer Pragments...

The data given in the paper on HDPE macromolecular dispersion based on rubbing conditions allow a conclusion that the degree of dispersion depends mainly on load. Effect of velocity on this process is indirect and related to the transfer mode or to the ratio of the metal-polymer and polymer-polymer contact areas. If the metal—polymer contact area is predominant this leads to intensification of macromolecular dispersion. 

The temperature at which the NB vanished was around 90 °C for the M = 6.4 Kg/mol samples, 104 C for the M = 56 Kg/mol samples, and 110 °C for the = 99 Kg/mol samples. These temperatures are close to but do not strictly follow the Tg s of PS at these molecular weights. Also, they are almost rubbing condition independent. This effectively rules out the possibility of significant chain scissions by rubbing, as shorter chains are equivalent to smaller molecular weights which would lower the Tg and the temperature at which RBI disappears. The same were observed for the reference samples without aging. 

In the sections above we have shown that the RT s are independent of the rubbing conditions. In this section, we explore the effects of rubbing on the density... 

Isopropyl alcohol is prepared from petroleum by hydration of propene With a boil mg point of 82°C isopropyl alcohol evaporates quickly from the skin producing a cool mg effect Often containing dissolved oils and fragrances it is the major component of rubbing alcohol Isopropyl alcohol possesses weak antibacterial properties and is used to maintain medical instruments m a sterile condition and to clean the skin before minor surgery... 

Ocular Effects. Conjunctivitis has been reported in workers exposed to tetryl dusts (Brabham 1943 Hilton and Swanston 1941 Ruxton 1917 Troup 1946). This condition results from either direct exposure to airborne tetryl particles or from rubbing of the eyes. Reports of conjunctivitis were less frequent than reports of dermatitis. 

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