Lecture 16 Ptolemy on the Shape of Heaven and Earth

Description

• cours magistral
• exposé

Lecture 16 Ptolemy on the Shape of Heaven and Earth Patrick Maher Scientific Thought I Fall 2009

• argument from circular motion of stars
• part of theoretical philosophy
• kind of proof proceeds by indisputable methods
• highest reaches of the universe
• theoretical philosophy
• stars
• distance

Sujets

• Cours magistral
• Exposé
• Ptolemy
• Distance
• Argument
• Universe
• Theory
• Philosophy

Informations

• Publié par: zieg
• Nombre de lectures: 16
• Langue: English
• Poids de l'ouvrage: 1 Mo

Extrait

14 MAY 2005

Modern Tools, Ancient Art

How to Craft Metalworking Fluids with “Biosynergy”

B Y M ICHAEL D. G ERNON AND B RUCE C. H EMMING

Metalworking fluid users are well aware of the problems caused by unwanted bacterial and fun- gal colonization of their fluids. Numerous species of microorganisms can cause problems in func- tional fluids and, barring the use of clean-room techniques, all industrial fluids are plagued constant inoculation with microorganisms. Microorganisms typically create very speci problems for the fluid user. Filamentous fun colonize kerosene-type aviation fuels, leadin mately to the clogging of aircraft fuel lines. species of fungi and bacteria (see picture bel right) create colored filamentous growths th destroy the appearance of paints. Numerous species of microorganisms create unwanted odors, and almost all bacteria and fungi sele tively consume specific fluid components leading to the loss of fluid function. Beyond degradation of fluid appearance and function, there can also be adverse health effects caused by microbial contami - nation, and a number of industrial health sy dromes have been linked to systemic infecti and adverse allergic reactions to microbes p in contaminated industrial fluids. With respe metalworking fluids, recent concerns about aller- gic reactions to cer tain species of aerosolized mycobacteria are a per fect example. The best way to prevent the microbial coloniza- tion of a fluid is through the addition of a biocide to the fluid. Many classes of biocides are known, and large amounts of data have been collected concerning their Minimum Inhibitory Concentrations — the minimum concentration of the biocide necessary for control of a particular species of bacteria or fungi. However, toxicity, regulatory, economic and chemical stability issues oftentimes complicate the seemingly simple strategy of adding a biocide to a fluid. When everything is considered, the mini- mization of biocide concentrations usually emerges as the best policy. So how does the for mulator deal with the con - tradictory goals of absolute biological control and minimization of biocide concentrations? One pos- sible approach, in many cases just a star t, is the use of biocide synergy. To properly describe and illustrate the utility of biocide synergy, it is neces- sary to review formulation synergy in general.

The Ancient Art of Formulation The art of formulat- ing functional fluids has developed steadily from prehistoric times to the present. Prehistoric man mixed natural pigments with a variety of natural

binders to produce paint. The pigments were chosen mostly from easily accessed inorganic ore deposits (e.g., iron oxides, pyrites, galena, cinnabar) and the binders came from a variety of natural sources. For example, Dr. Carolyn Boyd of

 , ce .seu omonas sp. is a robust and oppor- formulators used all the tunistic colonizer of knowledge and technology virtually all emulsion- at their disposal to accelerate type industrial fluids. the development process and converge on the best formula as fast as possible. Modern formulators do pretty much the same thing, albeit with a far greater array of tools and ideas to draw from in their efforts.

Formulating a Metalworking Fluid We are not aware of prehistoric efforts to formulate metal- working fluids, but lubricant materials were used in ancient times. The ancient approach to developing a lubricant would have been an empirical one. The process star ts with accidental and random observations of useful materials fol- lowed by random mixing with other known materials. The process continues until a success- ful product is obtained. If certain methods seem to be successful, then subsequent work is usual - ly based on the same approaches. The modern formulator still uses empirical methods, but empiricism is supplemented with conceptual knowledge. For example, the mod- ern formulator understands the function of all the components in a for mulation. We could call this the function concept. The function concept allows for the rapid selection of candidate mate-

15 LUBES’N’GREASES

rials to test in a given for mula. Even with the function concept, the for mulation process can be time consuming. Without it, the process is impossible. By way of example, consider a simple semi-synthetic metalworking fluid con- taining the following eight components: 1) Water Solvent: solvent carrier for com- ponents of formulation, heat transfer fluid 2) Oil Lubricant: lubricating phase to aid in machining of parts 3) Emulsifier: creates emulsion of oil in water 4) Nonionic Surfactant: modifies surface tension and possibly defoams system 5) Coupler: allows for complete solubili- ty of all additives 6) Neutralizing Alkanolamine: raises pH to optimal value (8.9 to 9.3) 7) Corrosion Inhibitor: prevents cor ro- sion of metal parts immersed in fluid 8) Biocide: prevents microbial growth in the solution The function concept allows us to think in terms of candidate materials to fill each of the necessary functions within the fluid.

Caption to go here.

16 MAY 2005

Even in a simple fluid like this the formula- tor has a great many choices. The solvent can be pure water, or a mixture of water and an alcohol (e.g., IPA). The lubricating oil can be a Group II refinery base oil, Group III refinery base oil, polyalphaolefin, diester, polyolester or more exotic type of synthetic lubricant. The emulsifier can be a “natural” material produced by the sul- fonation of refinery base oil, or a synthetic material produced by the sulfonation of a purified alkylated aromatic compound. The nonionic surfactant can be chosen from thousands of possible ethoxylated alcohols, polypropylene glycols, alkylated phenols and/or other hydrophobes. The coupler, neutralizing alkanolamine, corro- sion inhibitor and the biocide also present the formulator with long lists of choices. What additional concepts can the for- mulator use to accelerate discovery? One important idea could be called the “range of physical properties” concept. The formulator can define a necessary range for a given physical property based on a knowledge of the intended applica-

tion of the fluid. The defined range of a given property is then superimposed on the candidate materials to further win- now the candidate list. Luckily, copious amounts of physical data are available in the literature. The choices for nonionic surfactant can be limited by considera- tion of cloud point, hydrophile-lipophile balance, molecular weight, solubility, sur- face tension and other properties. The choice of the appropriate base oil can be limited by consideration of viscosity, solubility, hydrolytic stability and chemi- cal structure. After an assessment of function and the range of physical properties needed, the formulator considers a variety of other issues like availability, cost, biodegradabil- ity, toxicity and general customer accep- tance. After all this, a much smaller group of possible candidate components will emerge, and these materials can then be obtained in sample quantities for labora- tory testing. After the final formula com- ponents are chosen and the appropriate level of each component is defined, a functional fluid will hopefully result. But what other concepts, beyond those mentioned above, might have been use- ful in accelerating formulation develop- ment? One very useful idea is that of “off- diagonal effects.” In simple terms, an off- diagonal effect is the influence of a com- ponent on a proper ty of the fluid for which it was notadded — such as the influence of a corrosion inhibitor on a fluid’s emulsion stability.

Formulation and the Modern Mind If we think about the formulation process mathematically, the techniques of linear algebra immediately suggest themselves. For an eight-component system, we gen - erate an 8-by-8 matrix. Every position in the matrix represents the effect of an additive on a functional proper ty of the fluid. For simplicity, let’s imagine that every contribution of a component of the fluid to the actual properties of the fluid can be represented on a scale of 0 to 10, with 0 being the worst possible impact and 10 being the best. A value of 5 would represent no effect. We assume that the concentrations of all the compo- Continued on page 18

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Figure 1 THE MATRIX

Solvent Lubricant Emulsifier Surfactant Coupler Alkanolamine Corrosion Inhibitor Biocide

a 1,1 a 2,1 a 3,1 a 4,1 a 5,1 a 6,1 a 7,1 a 8,1

a 1,2 a 2,2 a 3,2 a 4,2 a 5,2 a 6,2 a 7,2 a 8,2

a 1,3 a 2,3 a 3,3 a 4,3 a 5,3 a 6,3 a 7,3 a 8,3

a 1,4 a 2,4 a 3,4 a 4,4 a 5,4 a 6,4 a 7,4 a 8,4

a 1,5 a 2,5 a 3,5 a 4,5 a 5,5 a 6,5 a 7,5 a 8,5

Figure 2 FORMULATION MATRIX FOR A “TYPICAL” MWF

Solvent Lubricant Emulsifier Surfactant Fatty Acid Alkanolamine Corrosion Inhibitor Biocide

10 5 5 8 4 5 5 5

1 10 2 8 6 7 5 5

5 5 10 8 6 6 6 5

5 8 3 10 7 6 6 5

5 5 4 8 10 6 6 5

a 1,6 a 2,6 a 3,6 a 4,6 a 5,6 a 6,6 a 7,6 a 8,6

5 5 3 5 2 10 3 5

a 1,7 a 2,7 a 3,7 a 4,7 a 5,7 a 6,7 a 7,7 a 8,7

2 8 3 5 7 8 10 5

a 1,8 a 2,8 a 3,8 a 4,8 a 5,8 a 6,8 a 7,8 a 8,8

0 0 5 3 2 2 2 10

An optimum formulation should rate 10’s all the way down the diagonal — showing each additive has the best impact possible on the property it is meant to influence. 0 = strong negative effect, 10 = strong positive effect, 5 = no effect or the component is a necessar y part of the effect (e.g., water is a necessar y part of an oil-in-water emulsion)

Figure 3 COMPARING EFFECTS 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.00 500 ppm

AMP Synergex

250 ppm 150 ppm [BIT as Proxel DB20], ph=8.5

50 ppm

“Growth Slope” of Pseudomonas aeruginosa, as a function of the concentration of 20 percent BIT . Note the lower growth in the system containing Arkema’s Synergex amine additive — indicative of greater biocide synergy efficacy for this molecule.

18 MAY 2005

Continued from page 16 nents of the formula have been appropri- ately optimized. The rows of the matrix represent the eight components listed above while the columns of the matrix represent the physical properties of the fluid. The formulation matrix is shown in figure 1. Within this matrix, position a 6,3 repre- sents the impact of the alkanolamine neu- tralizing agent on the emulsion stability of the fluid; a 1,8 represents the impact of the solvent on the biostability of the fluid; a 6,6 represents the impact of the alka- nolamine on the pH, and so on. Every component of the fluid is cho- sen to have the best possible impact on the property it is supposed to influence. Thus, assuming a good formulation has been developed, the fluid formulation matrix should have 10’s all the way down the diagonal — implying that each addi- tive has the best impact possible on the property it is meant to influence. If the formulation matrix does not have a diag - onal of high values, then the formulation is not optimized. However, the off-diagonal effects of the additives are harder to predict. The for- mulator may decide to use pure water as the solvent for its good solvency and heat transfer properties — but water also will have a less-than-optimal impact on the fluid’s bioresistance. To illustrate a for mulation matrix, con- sider the following typical formula for a kilogram of semi-synthetic cutting fluid concentrate:

TYPICAL SEMI-SYNTHETIC FLUID FUNCTION COMPONENT LEVEL Solvent Water Balance to 1 Kg Lubricant 100 SUS Mineral Oil 100 grams Emulsifier LAB Sulfonate 100 grams Surfactant Pluronic 25R4 40 grams Coupler Tall Oil (5% Rosin) 60 grams Alkanolamine Triethanolamine 140 grams Corrosion Caprylic Acid 40 grams Inhibitor Biocide Benzoisothiazolinone 10 grams (20% solution)

The formulation matrix for the above fluid might look as shown in figure 2. The true art of formulation lies in the Continued on page 20

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Continued from page 18 optimization of the off-diagonal effects. Much like backgammon, formulation takes only a few months to learn but a lifetime to master. The few months are necessary to learn how to handle the diagonal effects. The lifetime is necessary to learn how to handle the off-diagonal effects. To help formulators understand off- diagonal effects, Arkema has carried out

20 MAY 2005

a significant amount of research into one cell in the matrix — a 6,8 , the impact of the neutralizing alkanolamine on the efficacy of the biocide in the generic formulation matrix above. The term used to describe a 6,8 is biocide synergy. A compound used purposely for biocide synergy is known as a “biocide adjuvant,” “biocide synergist” or most simply as a “biosynergist.”

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KEYLINE DOES NOT PRINT

Historic Understanding The first use of biocide synergy is prehistoric. Early Man made soap by boiling ground ani- mal bones with animal fat and/or veg- etable oil. The soaps produced in this way display biocide synergist properties when used in combination with natural astringents like witch hazel. General descriptions of the biocide synergist effect are also found in the writings of Pliny the Younger, late First Century his- torian and scientist. This intuitive use of biocide synergy in metalworking fluids was put on a firmer footing in the late 1970s, when E.O. Bennett published a series of papers describing the effects of many “non-bio- cides” on the overall biostability of met- alworking fluids (International Biodeterioration Bulletin, 1978, v.14, p.21-9; Lubrication Engineering, 1979, 35, 137-44). Since then, many additional publications have discussed various aspects of biocide synergy in metalwork- ing fluids. Arkema’s contribution to the general work in this field has been the develop- ment, in collaboration with Microbe Inotech Laboratories in St. Louis, Mo., of standardized methods for the compari- son of various alkanolamines as biocide synergists. We used high throughput optical absorbance measurements of bacterial growth in transparent broth media to compare various alka - nolamines as synergists. In brief, the Arkema/MIL method involves dosing an appropriate pH buffered transparent broth with various levels of biocide (e.g., triazine, BIT, CMIT/MIT) and alkanolamine. The pre- pared broths are dosed into the wells of a microtiter plate followed by standardized inoculation of all wells with a bacterial sus- 7 pension of approximately 10 CFU/ml 6 (about 10 CFU/ml after dilution). The prepared microtiter plate is placed in a temperature controlled instrument chamber (typical inoculation temperature: 25 degrees C) and absorbance measurements at 660 nm are made on all wells once every 15 min- utes. The incubation is allowed to con - tinue for two or more days. A fter two