Classification of lubricants

General classification of lubricants

Mineral lubricants
Fluid lubricants (Oils)
Mineral fluid lubricants are based on mineral oils. Mineral oils (petroleum oils) are products of refining crude oil. There are three types of mineral oil: paraffinic, naphtenic and aromatic. Paraffinic oils are produced either by hydrocracking or solvent extraction process. Most hydrocarbon molecules of paraffinic oils have non-ring long-chained structure. Paraffinic oils are relatively viscous and resistant to oxidation. They possess high flash point and high pour point.Paraffinic oils are used for manufacturing engine oils, industrial lubricants and as processing oils in rubber, textile, and paper industries.

Naphtenic oils are produced from crude oil distillates.Most hydrocarbon molecules of naphtenicnic oils have saturated ring structure. Paraffinic oils possess low viscousity, low flash point, low pour point and low resistance to oxidation.Naphtenic oils are used in moderate temperature applications, mainly for manufacturing transformer oils and metal working fluids.Aromatic oils are products of refining process in manufacture of paraffinic oils.Most hydrocarbon molecules of aromatic oils have non-saturated ring structure.

Aromatic oils are dark and have high flash point.Aromatic oils are used for manufacturing seal compounds, adhesives and as plasiticezers in rubber and asphalt production.
Semi-fluid lubricants (greases)
Semi-fluid lubricants (greases) are produced by emulsifying oils or fats with metallic soap and water at 400-600°F (204-316°C).Typical mineral oil base grease is vaseline.Grease properties are determined by a type of oil (mineral, synthetic, vegetable, animal fat), type of soap (lithium, sodium, calcium, etc. salts of long-chained fatty acids) and additives (extra pressure, corrosion protection, anti-oxidation, etc.).Semi-fluid lubricants (greases) are used in variety applications where fluid oil is not applicable and where thick lubrication film is required: lubrication of roller bearings in railway car wheels, rolling mill bearings, steam turbines, spindles, jet engine bearings and other various machinery bearings.
Solid lubricants
Solid lubricants possess lamellar structure preventing direct contact between the sliding surfaces even at high loads. Graphite molybdenum disulfide (MoS2) particles are common solid lubricants. Boron nitride, tungsten disulfide and polytetrafluorethylene (PTFE) are other solid lubricants.Solid lubricants are mainly used as additives to oils and greases. Solid lubricants are also used in form of dry powder or as constituents of coating

Synthetic lubricants
Polyalphaolefins (PAO)
Polyalphaoleins are the most popular synthetic lubticant. PAO’s chemical structure and properties are identical to those of mineral oils.Polyalphaoleins (synthetic hydrocarbons) are manufactured by polymerization of hydrocarbon molecules (alphaoleins). The process occurs in reaction of ethylene gas in presence of a metallic catalyst.
Polyglycols are produced by oxidation of ethylene and propylene. The oxides are then polymerized resulting in formation of polyglycol.Polyglycols are water soluble.Polyglycols are characterized by very low coefficient of friction. They are also able to withstand high pressures without EP (extreme pressure) additives.
Ester oils
Ester oils are produced by reaction of acids and alcohols with water.Ester oils are characterized by very good high temperature and low temperature resistance.
Silicones
Silicones are a group of inorganic polymers, molecules of which represent a backbone structure built from repeated chemical units (monomers) containing Si=O moieties. Two organic groups are attached to each Si=O moiety: eg. methyl+methyl ( (CH3)2 ), methyl+phenyl ( CH3 + C6H5 ), phenyl+phenyl ( (C6H5)2 ).The most popular silicone is polydimethylsiloxane (PDMS). Its monomer is (CH3)2SiO. PDMS is produced from silicon and methylchloride.Other examples of silicones are polymethylphenylsiloxane and polydiphenylsiloxane.Viscosity of silicones depends on the length of the polymer molecules and on the degere of their cross linking. Short non-cross-linked molecules make fluid silicone. Long cross-linked molecules result in elastomer silicone.Silicone lubricants (oils and greases) are characterized by broad temperature range: -100ºF to +400ºF (-73ºC to 204ºC).
Vegetable lubricants
Vegetable lubricants are based on soybean, corn, castor, canola, cotton seed and rape seed oils.Vegetable oils are environmentally friendly alternative to mineral oils since they are biodegradable. Lubrication properties of vegetable base oils are identical to those of mineral oils.The main disadvantages of vegetable lubricants are their low oxidation and temperature stabilities.
Animal lubricants
Animal lubricants are produced from the animals fat. There are two main animal fats: hard fats (stearin) and soft fats (lard). Animal fats are mainly used for manufacturing greases.

GLASSES

Glass is an amorphous, hard, brittle, transparent or translucent, super –cooled liquid of infinity Viscosity, obtained by fusing a mixture of a number of metallic silicates, most commonly of Na, K, Ca and Pb. It possesses no sharp melting point, definite formula or crystalline structure.
Definition amorphous: Having no determinate form; of irregular; shapeless

Definition transparent: Having the property of transmitting rays of light, so that bodies can be distinctly seen through; pervious to light; diaphanous; pellucid; as, transparent glass .

Definition super-cooled :To cool (a liquid) below a transition temperature without the transition occurring, especially to cool below the freezing point without solidification

a glass is defined as an inorganic product of fusion which has been cooled through its glass transition to the solid state without crystallising

General properties of glass

· Glass is amorphous, no definite melting point
· Reflect or transmit light, brittle, softens on heating.
· Electrical insulator
Manufacture of glass
Commercially produced glass can be classified as soda-lime, lead, fused silica, borosilicate, or
96 percent silica. Soda-lime glass, since it constitutes 77 percent of total glass production, is discussedhere. Soda-lime glass consists of sand, limestone, soda ash, and cullet (broken glass).
The manufacture of such glass is in four phases: (1) preparation of raw material, (2) melting in a furnace (3) forming and (4) finishing.

1. Melting: CaCO3+ SiO2 → CaSiO3 + CO2 ↑
Na2CO3+ SiO2 →Na2SiO 3 + CO2↑
The basic three raw materials (quartz sand, limestone, soda ash) with the addition of some oxides which act as catalysts to melt the glass, are made into precise batches and are routed to be melted in a glass furnace, i.e. tank furnace, with standing high temperatures of up to 1600 degrees, to produce molten glass. A charger continuously feeds the batch into the furnace.
2. Forming and shaping: Melting glass is then worked into articles of desired shapes by either blowing or moulding or pressing between rollers.
3. Annealing: Glass articles are then allowed to cool gradually to room temperature by passing through different chamber with descending temperatures. It allowed and cools rapidly, glass being bad conductor of heat, the superficial layer cools down first, leaving the interior portion in a sate of strain. Owing To this unequal expansion, the articles are likely to crack to pieces
4. Finishing: Cleaning, grinding, polishing, cutting, sand – blasting, etc.
5. Inspection: The glass containers are channeled individually through inspection stations and are checked for dimensional accuracy, body and neck quality. Inspection can be manual, semi-automatic or automatic to optimize quality.
6-Packing: After the inspection stations, the glass containers are put on pallets and protected with shrink-wrap ensuring safe delivery to its customers

The observation that old windows are often thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a matter of centuries. It is then assumed that the glass was once uniform, but has flowed to its new shape, which is a property of liquid . The pieces were not, however, absolutely flat; the edges of the disk became thicker as the glass spun. When actually installed in a window frame, the glass would be placed thicker side down both for the sake of stability and to prevent water accumulating in the lead came at the bottom of the window. In glass factories, molten glass was poured onto a large cooling table and allowed to spread. The resulting glass is thicker at the location of the pour, located at the center of the large sheet. These sheets were cut into smaller window panes with nonuniform thickness. Modern glass intended for windows is produced as float glass and is very uniform in thickness.

References
Doremus, R. H. (1994) Glass Science, 2nd Edition. John Wiley & Sons, New York, 339 pp.

Elliott, S. R. (1994) Amorphous Solids: An Introduction. In: Catlow, C. R. A. (eds.), "Defects and Disorder in Crystalline and Amorphous Solids", NATO Advanced Studies Institutes Series; Series C, Mathematical and Physical Sciences, 418, Kluwer Academic Publishers, Dordrecht: 73-86.

Feltz, A. (1993) Amorphous Inorganic Materials and Glasses. VCH Verlagsgesellschaft mbH, Weinheim/VCH Publishers, New York, 446 pp.

definition of glass from 1945; also Glas – Begriffe für Glasarten und Glasgruppen, September 1986
Zallen, R. (1983). The Physics of Amorphous Solids. New York: John Wiley.

Cusack, N. E. (1987). The physics of structurally disordered matter: an introduction. Adam Hilger in association with the University of Sussex press.

Elliot, S. R. (1984). Physics of Amorphous Materials. Longman group ltd.

PLASTICS

The term plastics or plastic material, Organic materials of high molecular weight which can be moulded into any desired from , when subjected to heat and pressure in the presence of a catalyst.

Resin: Resin is the basic building materials which constitute the greater bulk of plastics and which have undergone polymerization condensation reactions during their preparation.

Plastic have certain unique properties
Lightness in weight : sp. Gravity -1 to 2.4
Good thermal and electrical insulator.
Corrosion –resistance.
Easy workability.
Adhesiveness.
Low fabrication cost in to desired shaped products,
Decoration surface effect.
Easy moulding.
Insect resistant.
Low thermal expansion coefficient.

Classification of Plastic
(1) Thermosetting resins (2) Thermoplastic resins
(A) Thermoplastic resins :Poly ethylene (PE) obtained by the polymerization of ethylene.

By using free radical initiator, low density polyethene ( L D P E ) is obtained .Ionic catalyst : (HDPE) High density polyethene is obtained .

1. Preparation : Low density polyethene
2. Properties : polyethene produced by high pressure process has a branched structure and, therefore is flexible and tough.
Non polar polymer, back bone flexible (LDPE) temp. 115o C.
Film carries bags, gen. packing
Excellent insulation properties.
1. Preparation

High density polyethene (HDPE) :

2.Properties :
Low pressure process result in a completely linear
Polyethylene having higher density and better chemical resistance. It have excellent electrical insulator.
Temp 135oC, Film carries wrapping ,food production
Polyamides : are synthetic polymers , which have recurring amide groups. Nylons , used mostly for making fibers.

Nylon - 6: 6 : is obtained by the polymerization of adipic acid with hexa methylene diamine.

Nylon-6 :is produced by self condensation of epsila– amino caproic acid

Nylon-11 is made by self –condensation of -amino undecanoic acid.

Properties of Nylon
1.Nylons are translucent and whitish and having high melting point .
2. They show good resistance to abrasion and high tensile strength, high thermal stability.

Uses of Nylons
- Nylon -6,6 is used in the preparation of - sheets , fibers for cloth weaning, ropes bristles, tyre, cord brushes, monofilament etc .

Good substitute for metals in gears and bearings.
-Nylon-6 and Nylon 11 is used in the preparation of textile fibers and threads present in tyres, ropes etc.
(B) Thermosetting Resins:
Bakelite: Phenol formaldehyde Resin ( PF)
Preparation : P F is synthesized by poly condensation between phenol and formaldehyde in the presence of acidic or alkaline catalyst.

Properties: Bakelite is rigid hard, resistant to scratch, non- oxidizing
acids salt and many organic solvents .
Use of PF : used for moulding electrical items , telephone instrument ,Cabinets for radio, TV etc.
-used for making impregnation paper, fabric or abestos cloth.used for core binders in foundries when mixed with sand.

polyester resins - Terylene or Dacron.

Preparation :
Properties : It is resistant to heat and moisture and unattacked by many chemicals .
- It has good mechanical strength up to 175oC
- wrinkle resistance and high starch resistance.
Use : - To make textile fibers .
- Making films , magnetic recording tapes , aluminised sheets .
Rubber or Elastomer

Synthetic Rubber : styrene rubber . (Buna -S)

Properties : high abrasion resistance High loading bearing capacity

USE : Motor tyres , footwear component , shoes soles, Insulation of wires and cables carpet backing etc.

Based on synthesis:

Addition polymers :

(2) Condensation polymers :

CLASSIFICATION OF POLYMERS

1. ON BASIS OF SOURCES:
1. Natural : Starch, cellulose, protein, nucleic acid, natural rubber,etc.

2. Synthetic: polyethene, polypropylene, polystyrene, polyvinyl chloride (PVC) ,nylon, terylene, bakelite, etc.

ON BASIS OF STRUCTURE:
1.Linear: Monomeric units are joined in the form of long straight chains, such polymers have high densities, high tensile strength and high melting point.

LINEAR CHAIN
e. g. Polyethylene, nylons and polyesters.

2.Branched chain: are mainly linear in nature but also possess some branches along the main chain. E.g. low density polyethene (LDPE)
They have densities, lower tensile strength and low melting point

BRANCHED CHAIN
e. g. Amylopectin and glycogen
3.Crossed Linked polymers : Monomeric unit’s are linked together to constitute a three dimensional network. They are hard, rigid, and brittle.

CROSS LINKED
e. g. Bakelite, Melamine formaldehyde resin, etc,

Based on Interparticle forces:
1. Elastomer: Polymer chain is held up by weakest attractive forces. They are amorphous polymers having high degree of elasticity.
E.g. Synthetic rubber.
2. Fibers : These are the polymer which have quite strong Interparticle forces such as H - bond . They have high tensile strength and high modulus.
E.g. Nylon 6,6
3. Thermoplastic polymer: Interparticle forces of attraction are in between those of elastomer and fibers. They are linear, long chain polymers, they are linear, long chain polymers, which can be softened on heating and hardened on cooling reversibly.
e.g. polyethene ( P E ), Polypropylene( P P ), polyvinyl polyethene ( P V C ), polymers ( P S ), Nylons, Polytetrafluoro ethylene ( P T EE or teflon ), etc.
4. Thermosetting polymers: These are the polymers which become hard and infusible on heating. Once they have solidified, they cannot be softened. Heating results excessive cross linking between the chain forming three dimensional network. They are permanent setting polymers.
E.g. polyester (Terylene), bakelite, melamine.

TYPES OF POLYMERIZATION

Functionality:

Functionality: The number of bonding sites in a monomer, is referred to as its functionality.(at least two reactive sites or bonding sites)

Tacticity:

Atactic polymer
If the arrangement of functional group is at random the main chain, it is called Atactic polymer
E .g . POLYPROPYLENE
Syndiotactic: If the arrangement of side group is in alternative fashion is called ‘Syndiotactic’ polymer. E.g. Gutta percha.

Graft Copolymers:

Graft Copolymers: are branched structures in which the monomer segments on the branches and back bone differ.

Tacticity: The orientation of monomeric unit in a polymer molecule can take place in an orderly or disorderly fashion with respect to main chain. The difference in configuration (tacticity) does affect their physical properties

Isotactic polymer: The head - tail configuration, in which the functional groups are all on the same side of the chain, is called Isotactic polymer.

chainpolymer

If the main chain is made up of same species of atoms, the polymer, is called “Homochainpolymer “and if the main chain is made up of different atoms, then it is called “Heterochainpolymer”.

Nomenclature of polymers

A polymer may consist of identical monomers or monomers of different chemical structure.
Identical monomers- homopolymers
Different chemical structure- copolymers
(Monomer)
The monomeric unit is a polymer may be presented in linear, branched or cross linked (three- dimensional) structure.

repeating unit (n)

The number of repeating unit (n) in chain formed in a polymer is known as the degree of polymerization.” (D P)

Thus, small molecules which combine with each other to form polymer molecule, are termed monomers and the repeat unit in a polymer is called mer.

INTRODUCTION OF POLMER

Introduction

Polymers (Greek poly-many, mers-units or parts)

Polymers are macromolecules built up the linking together of a large number of small molecules (called monomers)
For e.g. polyethene is a polymer formed by linking together of large number of ethene ( ) molecules.