Effectiveness of lubricants

Table 18.3 Effect of lubricants on the kinetic coefficient of friction of nylon 66 (like surfaces) ...

The electric voltage also has an influence on the film thickness in TFL. Shen et al. [50] used hexadecane with the addition of cholesteryl LCs in chemically pure as the lubricant to check the variation of its film thickness by applying an external DC voltage. With the technique of ROII [3,4,51], the effects of LCs polarity and concentration on film thickness and the effects of lubricant molecules on a film-forming mechanism were investigated by them. 

Similar results were reported by other investigators, [19,20], but attention was paid to investigating the effect of lubricant additives on the boundary film thickness. It is speculated that there should be no adsorbed layers formed on rubbing surfaces if purified and nonpolar lubricants are applied. The interferometer measurements show that in the case of using base oils, the relation between the film thickness and rolling speed follows the EHL power law pretty well down to 1 nm (Fig. 6(a)), or sometimes the film thickness may deviate from the Hamrock and Dowson s line and turn down quickly (Fig. 6(b)). If there is a small percentage of additives in the lubricant, on the other hand, the deviation from the power law occurs in a different way that the h-V... 

Fig. 16 Effect of lubricant on dissolution of rate of salicylic acid contained in compressed tablets, x, 3% magnesium stearate , no lubricant 0> 3% sodium lauryl sulfate. (From Ref. 21.).

Fig. 20 Effect of lubricant level on hydrochlorothiazide dissolution from hard gelatin capsules (filler, dicalcium phosphate disintegrant, croscarmellose sodium, type A). (From Ref. 132.)... 

It was recognized quite some time ago that DTA analysis could be used to deduce the compatibility between a drug substance and its excipients in a formulation. The effect of lubricants on performance was as problematic then as it is now, and DTA proved to be a powerful method in the evaluation of possible incompatibilities. Jacobson and Reier used DTA to study the interaction between various penicillins and stearic acid [17]. For instance, the addition of 5% stearic acid to sodium oxacillin monohydrate completely obliterated the thermal events associated with the antibiotic. Since that time, many workers employed DTA analysis in the study of drug-excipient interactions, although the DTA method has been largely replaced by differential scanning calorimetry technology. 

In the first stage, preliminary trials were performed in order to study the effect of lubricant added before and after precompression. 

The study of surface rheology is useful in connection with the stability of emulsions and foams (Chapter 10) and the effectiveness of lubricants, adhesives, etc. 

FIGURE 32.3 Effect of lubricant cosmetic ingredient on skin friction coefficient. Amount applied of each material 2 mg/cm2. Reproduced from Nacht et al.14 (mean of five subjects but P value was not published). Time = — 1 is immediately prior to application Time = —0 is immediately after application. 

FIGURE 17 Effect of lubricant and its mixing time on dissolution rate of drugs. 

Dynamic mechanical analysis has been used to study the compatibility of ester lubricants, and stearic acid and its derivatives (403, 420). On the basis of a PVC melt flow test (ASTM D 3364), the effect of lubricants on processing has been determined (313). 

EFFECT OF LUBRICANTS ON PROCESSING. I. DETECTION BY PVC MELT FLOW... 

Muller, K., How to Reduce Fretting Corrosion - Effect of Lubricants, Tribology Inti., 8, 57, (1975). 

Fig. 14 The effect of lubricant concentration (% w/w) on the measured adhesion (kPa) of hydroxypropyl methyl-cellulose films (A) Pharmacoat 606 (B) Methocel 60HG viscosity 50 ( ) stearic acid ( ) magnesium stearate ( ) calcium stearate. (From Ref. l)...

Delacourte, A. Guyot, J.C. Colombo, P. Castellani, P.L. Effectiveness of lubricants and lubrication mechanism in tablet technology. Drug Dev. Ind. Pharm. 1995,2i, 2187-2199. 

Larger ejection forces may lead to an increased wear on tooling and eject cam surface. Ejection force may also be used to evaluate the effectiveness of lubrication (of both the press and the product) and punch sticking. Sensitivity and linearity of an ejection transducer are design dependent shear force designs are always preferable over split cam or cantilevered beam designs. 

The tooth surface is lubricated by the pellicle, thus making mastication and speech more comfortable [80, 81]. The effect of lubrication has been... 

Measurement of the effect of lubricating oils on engine gasket materials. Am. Soc. Lubr. Eng. Trans. 1969, 12. 

Hutton, J.E., Jackson, K.P. and Wdliamson, B.P. (1984) The effects of lubricant rheology on the performance of journal bearings. ASIE Preprint No. 84-LC-IC-l. 

Matsuoka, T., Ohashi, A. and Nakayama, T. Effect of Lubricating Oils on Flaking of a Wet autch JSAE Review 17(1996) 127-132. 

Nersasian, A. The Effect of Lubricating Oil Additives on the Properties of Fluorohydrocar-bon Elastomers, ASLE Preprint No. 79-AM-3C-3, presented at the 34th Annual Meeting, St. Louis, Missouri, April 30-May 3, 1979. 

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