Bld62003 mak rubber

BLD62003 BUILDING MATERIALS

MAK/BLD62003/RUBBER 1

Known as Polyterpene. Elastic hydrocarbon polymer.

Elastomers.

Occurs as a milky colloidal

suspension. Known as latex in the sap of

plants.


NATURAL RUBBER

• The most complex agricultural industry & requires years of growing & processing natural rubber.

• Combines of various knowledge on botany, chemistry & sophisticated machinery with skilled people to harvest the rubber trees.

• Includes: planting, tapping, producing liquid concentrate, producing dry stock, forming sheets, producing other products.

SYNTHETIC RUBBER

• Known as American-made rubber.

• Made through polymerization of monomers to produce polymers.

• Polymerization: a process where ethylene monomer is converted into the clear polymer polyethylene under high pressure at 200 degree Celsius.

• Known as: Polysoprene




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1. A rubber tree is tapped by cutting a thin strip of bark about 0.04 in (1 mm) deep off the tree as high up as the worker can easily reach.

2. Later strips will be cut below the first one. 3. Each strip reaches about halfway around the circumference

of the tree and slants downward at an angle of about 30 degrees to allow the latex to drain into a container.

4. If the latex is allowed to coagulate (thicken) naturally, each cut will produce about 1 oz (28 g) of latex before the latex stops flowing after a few hours.

5. A chemical may be applied to the bark to prevent the latex from coagulating, allowing it to flow for several days.


6. The collected latex passes through a sieve to remove foreign objects.

7. Water is added to the latex and the mixture is pumped into large horizontal tanks containing aluminum partitions.

8. Dilute acetic acid or formic acid is added to make rubber coagulate into slabs on the partitions.

9. The slabs are sprayed with water while they pass through a series of rollers.

10. Excess water is removed by another series of rollers. The slabs are packed in bales, usually weighing 225-250 lb (102-113 kg), in the shape of cubes about 2 ft (60 cm) on each side.

11. The bales (packages) are coated with clay to prevent sticking, bound with metal straps, and shipped to manufacturers.



Depending on what kind of synthetic rubber is being made, a wide variety of manufacturing processes may be used.

The most common form of synthetic rubber, styrene-butadiene rubber, is usually made in an emulsion process.


1. Various chemicals are obtained from petroleum by fractional distillation.

2. This process involves heating petroleum to about 600-700° F (315-370° C) and allowing the vapor to pass through a tall vertical tower.

3. As the vapor rises through the tower, it cools. Chemicals with different boiling points change from gas to liquid at different points inside the tower and are collected.

4. Chemicals with very high boiling points remain in the liquid state when the petroleum is heated and can be removed from the bottom of the tower. Chemicals with very low boiling points remain in the form of gases and can be removed from the top of the tower.


5. Other chemicals are obtained by catalytic cracking. This process involves heating petroleum to about 850-900° F (454-510° C) under pressure in the presence of a catalyst. The catalyst causes chemical reactions to take place. The new mixture of chemicals are then separated by fractional distillation.

6. Styrene and butadiene are obtained by subjecting certain chemicals derived from petroleum to various chemical reactions. The styrene is a liquid under normal conditions, but the butadiene is a gas and must be stored under pressure to keep it in a liquid form.



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Elastomers Thermoplastic Thermoset



Elastomer materials are those materials that are made of polymers that are joined by chemical bonds, acquiring a final slightly cross-linked structure.

Characteristics: 1. High elongation and flexibility or elasticity of these materials,

against its breaking or cracking. 2. Dimensionally stable 3. Extremely resistant to aging, temperature, pressure & chemicals .

Categories: 1. Thermoset Elastomers - are those elastomer materials which do

not melt when heated. 2. Thermoplastic Elastomers - are those elastomers which melt

when heated.


Can not melt, before melting they pass into a gaseous state

Swell in the presence of certain solvents

Are generally insoluble.

Are flexible and elastic.

Lower creep resistance than the thermoplastic materials

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• Material used in manufacture of gaskets, shoe heels etc Natural rubber

• Used in textile industry i.e lycra clothing • Foams & wheels Polyurethanes

• Wheels or tires of vehicles, given the extraordinary wear resistance. Polybutadiene

• In the manufacture of wetsuits is also used as wire insulation, industrial belts, etc Neoprene

• Pacifiers, medical prostheses, lubricants, mold (due their excellent thermal and chemical resistance) Silicone


Materials that are made of polymers linked by intermolecular interactions or van der Waals forces, forming linear or branched structures.

Greater the mixing of string = Greater the effort to separate the

strings from each other. Due to friction that occurs between each of the cords which offers

resistance to separate. Friction represents the intermolecular forces that holds together the

polymer.


Polymer can take 2 types of structures (depending on the degree of intermolecular interactions between polymer chains.

1. Amorphous (formless) structure: Polymer chains acquire a bundled structure – responsible for

the elastic properties of thermoplastic materials.

2. Crystal (crystal-like) structure: Polymer chains acquire an ordered & compacted structure such

as lamellar structures.

Responsible for mechanical properties of resistance to stresses or loads & temperature resistance of thermoplastic materials.


Polymers with high concentration of amorphous (formless) structures = material have less resistance to loads but excellent elasticity.

Polymers with high concentration of crystalline (crystal-like) structures = material will be very strong & even stronger than thermoset materials but little elasticity = the materials become more fragile.


It may melt before passing to a gaseous state.

Allow plastic deformation when it is heated. They are soluble in certain solvents. Swell in the presence of certain solvents. Good resistance to creep.


High pressure polyethylene as applied to rigid material covered with electrical machines, tubes, etc.

Low pressure polyethylene elastic material used for insulation of electrical cables, etc.

Polystyrene applied for electrical insulation, handles of tools.

Polyamide used for making ropes, belts, etc. PVC or polyvinyl chloride for the manufacture of

insulation materials, pipes, containers, etc.


Acrylates Cyanoacrylates Epoxy cured by ultraviolet

radiation Acrylates cured by ultraviolet

radiation


Materials that are made by polymers joined together by chemical bonds, acquiring a highly cross-linked polymer structure.

The highly cross-linked structure produced by chemical bonds in thermoset materials, is directly responsible for the high mechanical and physical strength compared with thermoplastics or elastomers materials

Highly cross-linked structure provides a poor elasticity or elongation of thermoset.


IMAGINE: A set of strings mixed with each other; Each of these strings = polymer Make knots between each strings = more knots made more

ordered & rigid set of strings Knots represent chemical bonds. Thus polymers are strongly linked to each other & form

highly cross-linked polymeric structures.


GEL POINT Refers to the time when the material changes from

an irreversible way-viscous (sticky) liquid state to a solid state during the curing process.

Once has been transferred, the material stops flowing & it can not be molded.

DISADVANTAGES No ability to recycle – once they are cross-linked or

cured it is impossible to return to a liquid phase material.

Have the property of not melt or deforming in presence of temperature or heat to a gaseous state to a liquid state.


It can not melt. Generally do not swell in the presence of certain

solvents They are insoluble High resistance to creep


Epoxy resins - used as coating materials, caulks, manufacture of insulating materials, etc

Phenolic resins - tool handles, billiard balls, sprockets, insulation, etc

Unsaturated polyester resins - manufacture of plastics reinforced fiberglass commonly known as polyester, fillers, etc


Epoxy Adhesives Unsaturated polyester adhesives Polyurethane Adhesives by heat curing 1 component Anaerobic Adhesives



Adhesive or glue as a non-metallic material which is able to join 2 substrates using adhesion mechanisms (developed between the adhesive and substrate) and cohesive mechanism (developed within the adhesive itself).

Composed by organic polymers in a liquid state when applied and become a solid state after further curing or hardening.


Substrate = Corresponds to the material we wish to adhesive or join, for example: If we bond 2 aluminum plates, each of the aluminum

plates will be the substrate, in this example both the substrate 1 and substrate 2 are equal.

If you want to bond a glass front of a painted aluminum frame, we will have the substratum of glass and painted aluminum substrate in this example the substrate 1 is different from the substrate 2.


Adhesion – adhesion are all the forces or mechanisms that keep the adhesive with each substrate,

The term refers to all adhesion mechanisms or forces located in a thin layer (boundary layer) between the substrate and the adhesive itself.


Cohesion forces are all the forces or mechanisms that hold the adhesive itself.


The adhesives materials allows joint substrates with different geometries, sizes and composition. With the adhesive we can joint glass, plastics, metals, ceramics.

The use of adhesives eliminates the corrosion associated with dissimilar metals joining with different galvanic potential, such as the joining of steel with aluminum.

The use of adhesive as bonding material does not produce any deformation in the materials or substrates, eliminating metal grinding processes (grinding and putty), reducing the manufacturing cost and improving the aesthetics of the product.

Does not produce any mechanical aggression to the substrate, avoiding any damage to the structure of the material.


Great flexibility in the product design as well as an improvement in its aesthetics.

Reduction of the product weight, in the case of traction vehicles (cars, ships, locomotives) weight reduction is directly linked to reducing energy consumption and pollutant emissions to the environment.

Increasing the resistance to impact and fatigue resistance using elastic adhesive, increasing reliability and product life cycle.

Homogeneous distribution of tensions throughout the union allowing the elimination of stress concentrations that can lead to the fracture of the union.


Reduction of noise and vibration.

Reduction in the number of components such as screws, nuts, washers, rivets, etc necessary for the union, reducing the manufacturing cost of the union.

Sealing function and protection against corrosion.

Special adhesives prepared to conduct electricity or electrical insulator, are usually used in the field of electronics.



Time to cure - The final strength of the adhesive bond is not obtained immediately, unlike the case with a rivet or a screw, you must wait a time to solidify or cure the adhesive, this time depends on the choice of adhesive to be used, and also sometimes it depends on the environmental conditions that make the bonding process. If you want to reduce this waiting time you can use a chemical booster compatible with the adhesive.

Resistance to temperature - Adhesives are polymer-based materials, for this reason the adhesives and glues have an average resistance to temperature, adhesives silicone-based are more resistant to temperature adhesives, that kind of glues can withstand temperatures reaching point of 800 °C.


Ageing i. The long-term strength of adhesive bonding is affected by various

physical and chemical actions which are in the environment, actions such as ultraviolet light, chemical attacks on the environment, the presence of moisture .

ii. There are adhesives that are not altered against ultraviolet light while others break down in front of this radiation.

iii. The solution to this problem is to select an adhesive according to the environmental conditions in later work; this will allow us to perform a series of accelerated aging tests in order to observe the goodness of the adhesive bond.

Surface Preparation i. As in the process of painting, surface preparation required prior to adhesive

application process in order to achieve good adhesion between the adhesive and the substrate.

ii. Surface preparation that will vary depending on the materials to be bonded, the adhesive selected and technical requirements needed to fulfill the adhesive bond.


Removal or disassembly

i. As in the welding or rivet process, the process of disassembly adhesive bonds can destroy or distort the substrates joint together.

ii. being an expensive process to do, this does not happen when using techniques such as bolting, so that those unions that require disassembly during maintenance work during the life of the product, must perform techniques that allow easy disassembly and assembly, such as using screws, velcro, etc.

Safety and Environment

i. Due to the basis of the adhesives are chemical compounds, it is necessary to define the necessary actions to prevent human exposure to these products during the time of application.

ii. These measures will depend on the application amount and the type of the adhesive, glue or sealant used. Also you must properly manage the waste generated during the application process for further treatment and recycling.


Special process i. Like with the technique of welding, adhesive technique is a special

process, depending on the complexity and risk involved in the union made with adhesive, and the area or sector that uses it

ii. It is necessary to have staff who deal with the design, monitoring, verification and application with the proper skills and capacity that can ensure the correct process of adhesive, such as an industrial level is currently being implemented.


• Adhesive for bonding structures or

racks.

• Adhesive for bonding the front, side and

rear window glass.

• Adhesive for bonding body roof

structure.

• Adhesive for bonding side panels of the

structure.

• Adhesive for bonding the floor.

• Adhesive for bonding the cabins of the

vehicles.

• Adhesives for bonding different

elements of the equipment.



ELASTIC Bond distortion

Electrostatic energy is stored when force is applied (Mullins effect)

Mullins effect is where stress-strain response in filled rubbers which typically depends on the maximum loading previously encountered

Polyterpene (natural rubber) has long & loose molecular chain: zig zag or helical molecular chains



ELECTRICAL INSULATOR Synthetic rubber has a disulfide bonding, where all

electrons in the chain are occupied & no free electrons to allow electrical ions to move

Thus, rubber is non-electrical component in which rubber is not able to dissolve in water

ACID & ALKALINE RESISTANT

Prone to pH changes When attacked by alkaline releasing microorganism, the

high pH will form bonds with free acidic H+ ions & harden For synthetic rubber, pH resistant component is added to

ensure rubber can withstand high pH changes



Stress strain behavior of rubber can be demonstrated through:

Mullins effect

Payne effect

Hyper Elastic


MULLINS

• Stress strain response in filled rubbers

• Depends on the previous maximum load encountered

• Instantaneous & irreversible softening of stress strain curve increase load beyond maximum value

PAYNE

• Initially in formless solid material that undergo phases of transformation due to application of strain

• Starts to crystalize when the strain exceeded fatigue level

• Occurs in natural rubber & elastomers

• Important effect on strength & fatigue properties

HYPER

• Derived from strain energy density function

• Behavior unfilled, vulcanized elastomer often conforms closely to a hyper elastic ideal



Hardness test Compression test Rebound resilience elasticity test Abrasion test Freezing test Flexing fatigue test



For quick & reliable tensile, compression, peel, fatigue cycling & constant load tests


Rebound resilience elasticity test: ratio of the regained energy in relation to the applied energy


Performed on materials which are subject to wear & tear during their working life e.g tires, conveyors & drive belts, shoe soles etc


Test the bending/ flexing durability of rubber, plastics, synthethic leather, shoes etc under cold temperatures as low as -30 degree or -50 degree Celsius depending on the selected model.


Advanced dynamic system for determination of the flex properties of rubber, leather etc in air, temperature chamber or liquids.



Household or industrial products. For examples:

Tyres & tubes

The largest consumes of rubber (56% total consumption in 2005)

44% are general rubber goods (GRG) sector which all are products except tyres & tubes

Hoses, belts & dampeners

For automobile industry Known as the under bonnet

products



Gloves

For medical, household & industrial

Large consumers of rubber

Made of concentrated latex

Bearing pads Manufactured from the highest quality neoprene

rubber

Conform to the most rigid specification for highway bridges

Widely used in building construction (beam)

Economical, effective & require little maintenance

Standard thickness: .125”, .250”, .500”, .625”, .750”, .875”, 1.00”, 1.25” and 1.5”


RUBBER CORRUGATED PADS Long lasting material

Designed for floor protection

Creation of an anti-slip surface

Will not separate, curl or shrink

Clean effortlessly & quickly

Excellent product to use in heavy traffic area

Available by the linear foot or customized

Color black or brown

Standard widths: 24”, 36” and 48”

Standard thickness = .125” and .259”


PLAYSAFE RUBBER FOR PLAYGROUNDS Provides safety surface that is much

more resilient than traditional wood chips, sand or gravel materials

Made 100% from recycled tire buffing which are then treated with non-toxic organic dyes to achieve a variety of vibrant colors

Use of organic dyes also makes it non toxic to children, pets and our environment


PLAYSAFE RUBBER WALK POUR A seamless poured-in-place rubber surfacing Using a polyurethane binder & loose fill colored mulch The custom design application is popular for: Playgrounds, accessible walking trails & erosion control Provides a durable permeable surface that allows drainage off the surface for all weather use Can be installed over asphalt concrete (eliminates the need to repair cracks) or packed crusher

run


WINDOW FRAMES Frames come complete with

window as well as other parts of the frame and surround

Manufactured from the same grade of white UPVC

With larger frames, steel reinforcement is often added for extra strength & security

A water tight seal to concrete & brickwork is achieved by bedding the frame in silicone rubber & by injecting a silicone rubber bead along all joints


RUBBER ANTI-VIBRATION MOUNTS Rubber vibration isolating systems

have known for many years

The dynamic properties of rubber provides protection over wider range of frequencies

Used to isolate individuals items of equipment, e.g air conditioning & refrigeration equipment, from main structure of the building


SOUND INSULATION

Noise pollution can be dealt with by using vibration mounts

Sound insulation can be provided by: (i) simple & heavy or (ii) light & complex construction (rubber & plastics)

With floating floor construction, an air gap, created by placing a resilient material e.g rubber or foamed plastic between the timber raft & the concrete floor can achieve desired result



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ADDITIONAL INFORMATION ON SYNTHETIC RUBBER PROCESS








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