Polymers

What are the general processes in the production of synthetic rubbers?

1. Storage of raw materials amd feed 2. Purification of raw materials 3. Making up solution amd mixing components 4. Polymerization or polymer modification reactions 5. Short stopping 6. Flashing, degassing & strippjmg of unreacted monomers and solvents 7. Stabilization 8. Postmodification reactions 9. Polymer isolation, cleaning & drying 10. Finishing

It is the grades of E-SBR that contains carbon black.

1601-1622 & 1805-1849: Cold Oil - Black Masterbatch

How are thermosetting resins formed?

By condensation polymerization

The raw materials in PVC manufacture?

Ethylene - obtained from oil, produced by steam cracking. Chlorine - obtained from chlor-alkali production. Oxygen - obtained from air. Plasticizers Fillers and reinforcements

What type of polymerization occurs in E-SBR?

Free-radical emulsion copolymerization

Why is it needed to quickly remove the heat?

In order not to degrade the VCM.

Compounding processes

Includes all the processing stages between the manufacture of the crude polymer (plastic) and the molding step.

Addition polymerization

Involves a series of conversions which produce a polymer having a recurring structural unit identical with that of the monomer from which it is formed.

Polymer

It is a large molecule or macromolecules composed of many repeated sub-units called monomers

Plastic

It is a material that contains a polymerized organic sunstance of large molecular weight as an essential ingredient, is solid in its finished state,and at some stage im its manugacture into finished articles can be shaped by flow.

Rubber

It is a noncross-linked but cross-linkable polymer with rubber-elastic properties at room temperature.

Vulcanization

It is a process in which the chemical structure of rubber is changed. Rubber is converted to a condition where the elastic properties of rubber are improved over a greater range of temperature.

How is Vulcanization done?

It is done by heating rubber with sulfur.

What happens to the HCl produced in the thermal cracking of EDC from the direct chlorination process?

It is sent to another reactor where oxychlorination takes place further producing EDC.

Autoclave

It is the reactor where VCM polymerization takes place.

How is VCM polymerized?

Liquid VCM is fed into the polymerization reactor along with water and suspending agents. Small droplets of VCM are formed through vigorous agitation. An initiator or catalyst is fed to the reactor. VCM droplets turn into PVC under pressure and at 40-60°C.

What are the two types of rubbers?

Natural Rubbers & Synthetic Rubbers

How is VCM separated from the polymer?

The contents of the the autoclave is sent to a stripping tower (stripper) where unreacted VCM is separated from the polymers.

VCM / vinyl chloride monomer

The monomers used in PVC manufacture. It is a gas with a molecular weight of 62.5g and boiling point of -13.9°C, and has a high vapor pressure at ambient temperatures. It is stored under high pressures to keep it liquid.

How are the unreacted butadiene monomers separated from the polymer?

The unreacted butadiene monomers are flashed off from the flash tanks under steam heating and reduced pressure and subsequently condensed and treated for recycling.

What happens in the stripping column in E-SBR manufacture?

The unreacted styrene monomer is stripped off tne polymer as it flows down a column perforated plates with a counter current of steam

What are the uses of the blowdown tanks and flash tanks?

The unstripped rubber latex (emulsified SBR) is sent to a series of blowdown tanks and flash tanks to remove the unreacted butadiene monomer from the polymer.

What is the use of the cooling tower?

The water used in the the heat exchangers is cooled in the cooling tower and is sent back to the exchangers.

The classifications of plastics according to general application

Thermoplastic Thermosetting Protein products Oil soluble

What synthetic resin is formed by addition polymerization?

Thermoplastics

What are fillers and reinforcements?

They are materials of organic or imorganic origin that are used to increase strength, thermal conductivity, resistance to heat distortion, and lower thermal expansion.

How are emulsifiers prepared?

They are prepared by making a dilute soap-water solution with small amounts of caustic and electrolyte.

Why are plasticizers added?

They improve the workability during fabrication. They modify the natural properties of plastics and develop properties not present in the original resin. They also reduce viscosity and make shaping and forming easier.

How is VCM quickly cooled?

VCM from the cracking furnace is looped through coiled pipes that serve as heat exchangers. Water is used as coolant.

Condensation polymerization?

Yields polymers whose recurrimg units lack certain atoms present in the original monomer. The reaction takes place by the combination of two or more units and the elimination of a small molecule.

PVC / polyvinyl chloride

a polymer of vinyl chloride monomers and is the largest branch of the vinyl family. It is a thermoplastic that is formed by additiom polymerization.

What are the uses of carbon black?

as pigment as a filler

How is VCM produced?

Chlorination of ethylene and chlorine produces EDC. The EDC produced is sent to the cracking furnace producing VCM and HCl. The HCl produced is sent to another reactor along with ethylene and oxygen gas, this is where oxychlorination takes place, further producing EDC. The EDC from oxychlorination is dehydrated and is cracked along with the EDC from the direct chlorination process producing the VCM.

What is the widely used synthetic rubber?

SBR: Styrene-Butadiene rubber : It can be produced as E-SBR & S-SBR

What are the raw materials in E-SBR manufacture?

Styrene monomer - obtained from ethyl benzene Butadiene monomer - obtained as coproduct of the steam cracking of petroleum for ethylene manufacture. Soap and water - emulsifiers Activator Modifier - chain modifying agents (tertiary mercaptans)