Synthetic Resins and Plastics

LOGO

Cabral, Charlette A.

Francisco, Janine Therese J.

Mellendrez, Kristine Jhalene M.

Pineda, Jermaine Marianne F.

Plastics

The word plastics is from the Greek word Plastikos,meaning able to be shaped and molded

Plastics is a material that contains a polymerized organicsubstance of large molecular weight as an essential

ingredient, is solid in its finished state, and at some

stage in its manufacture or its processing into finished

articles can be shaped by flow.

Toughness

Water Resistance

Excellent resistance to corrosion

Ease of fabrication

Remarkable color range

Plastics

Basic Raw Materials: Coal

Petrochemicals

Cotton

Wood

Gas

Air

Salt

Water

Synthetic Resins are the largest

source of plastics with Cellulose derivatives

ranking next

History of Plastics

Commercial phenolic resin (1990) by Baekland was the start of the synthetic

plastic industry.

Cellulose Nitrate(Celluloid)

First plastic of industrial significance and was discovered about the middle of the 19th

century.

First used in 1869 by Hyatt who was searching for an ivory substitute.

History of Plastics

Cellulose Acetate

Developed in 1894 as a less flammable material and was used extensively as a base

for photographic film and as a dope for airplane coverings during World War I.

Early History of Polymers

Polymer Year Introduced

Cellulose nitrate 1868

Cellulose acetate 1894

Phenol-formaldehyde 1909

Cellulose ethers 1912

Vinyls 1927

Urea-formaldehyde 1929

Acrylates 1931

Furans 1934

Polystyrene 1937

Polyamides 1938

Melamine-formaldehyde 1939

Polyesters 1942

Silicone 1942

Polyethylene 1943

Fluorocarbons 1946

Epoxy 1948

Cystalline polypropylene 1957

Phenoxy 1962

Classification of Plastics

Plastics are often divided into:

Thermosetting

Thermoplastics

Oil soluble

Protein products


Thermoplastics Account for the majority of industry output and they

solidify by cooling and may be re-melted repeatedly to

form new shapes.

The process is reversible. Tougher (more impact strength) Less brittle High Tensile elongation High viscosity (when liquid)

Polypropene/Polypropylene

Chemical-resistant

containers

e.g. Food Containers Hinges

Fishing

nets

Medical

equipment

e.g. syringes

Bottle crates

Examples include:

Polyethene/Polyethylene

LDPE:

Packaging film

Carrier bags

TV cable

Toys

Detergent 'squeezy' bottles

HDPE:

Bottles

Pipes

Bowls

Milk Crates

Buckets


Thermosetting plastics Account for about 12% of output. Unlike thermoplastics, thermosets harden by

chemical reaction and cannot be melted and shaped

after they are created.

More mature and less dynamic segment of the industry.

Stronger More brittle Low tensile elongation Low viscosity (in liquid form) Higher temperature resistance The process is irreversible.

Urea-Formaldehyde

Electrical fittings

i.e. plugs

Textiles

i.e. clothingWood

adhesives

Coding of Plastics

Application: The Plastics Coding System is designed to be easy to

read at a glance and distinguishable from other marks put on rigid plastic containers by manufacturers for use in processing and identification.

The system uses a triangular-shaped symbol composed of three arrows, with a number in the centre indicating the material from which the bottle is made, as follows:

Range of Products

Plastics Bags

Plastic Packaging Film and Sheet

Non-packaging Film and Sheet

Plastics Profile Shapes

Plastics Pipe & Pipe Fittings

Laminated Plate, Sheet and Shape

Polystyrene Foam Products

Urethane and Other Foam Products

Plastic Bottles

Plastic Plumbing Fixtures

Resilient Floor Covering

Plastics Products, Not Classified Elsewhere

(Source: Probe Economics, Inc. 2004)

Engineering Plastics

High-strength high performance materials that can be substituted for many metal

uses

These materials show better resistance to:

Wear

Impact

Corrosive chemicals

Excellent electrical properties


Some uses:

Automobile bumpers and dashboards

Pumps

Valves

Gears

Driveshafts and transmission

in heavy-duty equipment


Common resins use: Acetal

Fluoroplastics

Nylon

Polyphenylene oxide

Polycarbonate

Polyphenylene sulfide

Polysulfone

Polyether-imide

Polyethersulfone

Nylon-polyether block amides

Several other copolymers

Raw Materials(Chemical

Intermediates and Monomers)

Phenol

The principal process in use in US is the Peroxidation of Cumene (isopropyl benzene),

Chemical Intermediates and Monomers

Formaldehyde

Results from the exothermic oxidation and endothermic dehydrogenation of methanol


Hexamethylenetetramine

Evaporation of the reaction product of formaldehyde and ammonia

Uses

Urinary Antiseptic (Urotropine)

Rubber Industry

Preparation of Explosive Cyclonite

Phenol-Formaldehyde Resins


Vinyl Esters

Addition of acids to acetylene furnishes esters

Usually prepared by:

Chlorination

Oxychlorination

Dehydrochlorination


Phthalic Anhydride

One of the most important intermediates for plastics industry

Preparation of phthalic anhydride are controlled oxidation of o-xylene or

naphthalene


Methyl Acrylate and Methacrylate

Following Dow-Badische-Reppe Synthesis

The conventional method for preparing MMA has been by the reaction of hydrogen cyanide

with acetone and subsequent treatment with

methyl alcohol

CH2=CH2 + CO + ROH CH2CH COOR

Other Raw Materials

Natural Products

Cellulose The structural material of the plant world, is itself a

polymer composed of 50 to 100 units of the

disaccharide cellobiose

Other Raw Materials

Plasticizers

Organic compounds added to plastics To improve workability during fabrication

To extend or modify the natural properties of the plastics

To develop new, improved properties no present in the original resin

Reduce the viscosity and make shaping and forming easier

Also impart flexibility and other desired properties to finished product

Other Raw Materials

Fillers and Reinforcements

Many materials may be added to plastics to increase strength, thermal conductivity,

resistance to heat distortion, and lower

thermal expansion.

Formerly asbestos was used, but due to its human carcinogenic properties, it is no longer

acceptable filler.

Other Raw Materials

Manufacturing Processes

General Polymerization Processes

Bulk Polymerization

Solution Polymerization

Suspension polymerization

Emulsion Polymerization

Polymerization

a process of reacting monomer molecules together in a chemical reaction to form

three-dimensional networks

or polymer chains.

Bulk Polymerization

commonly referred to as mass polymerization in the industry

May be carried out in liquid/vapor state

carried out by adding a soluble initiator to pure monomer into liquid state.

Monomers & activator are mixed in a reactor and heated or cooled as needed

Solution Polymerization

Often used when exothermic heat is too great to be controlled in bulk

polymerization

Monomer & initiator are dissolved in a nonreactive solvent

The polymer concentration has to be low to avoid too high viscosity

Produces polymers of low to medium MW

Flow Diagram

Suspension Polymerization

Monomer is suspended in water by agitation and stabilizers such as talk,

fullers earth and bentonite are added

Initiator is soluble in the monomer

Each monomer globule polymerizes as a spherical pearl of high MW

This process is used in the production of most PVC

Process flow diagram

Emulsion Polymerization

Similar to suspension polymerization but monomer Is broken up into droplets that form aggregates called micelles

Are rapid and can be carried out at relatively low temp

Monomer is on the interior of the micelles, initiator is in the water

Soap is used to stabilize micelles

Initiator diffuses into the micelle to start polymerization

Produces polymers of very high MW

Process flow diagram

Condensation-Polymerization Products

Phenolics

Amino resins

Polyester resins

Alkyd resins

Polycarbonates

Epoxy Resins

Polyimides

Condensation polymerization,

a form of step-growth polymerization,

process by which two molecules join together, resulting loss of small molecules

which is often water.

The type of end product resulting the reaction is dependent on the number of

functional end groups of the monomer

which can react.

Phenolics

Phenol formaldehyde resins (PF) include synthetic thermosetting resins such as obtained by the reaction of phenols with formaldehyde

are formed by a step-growth polymerization reaction that can be either acid- or base-catalysed

Initial reaction

HOC6H5 + CH2O ortho/paraHOC6H4CH2OH

Amino Resins

a thermosetting resinous product made by condensation of a compound containing

an amine (e.g., melamine or urea) with an

aldehyde (e.g., formaldehyde):

is used in making permanent-press fabrics and other products

Urea formaldehyde and melamine-formaldehyde condensates are the

commercially important amino resins

A typical low-stage resin is formed when

urea (or melamine) is mixed with

formaldehyde

Polyester Resins

Complex esters formed when a difunctional alcohol is reacted with a

dibasic acid or anhydride

Since rxn takes place at both ends of the chain, long molecules are possible and a

plurality of ester groups is obtained

Unsaturated polyesters are produced when any of the reactants contain

unsaturation, such as

Alkyd Resins

any synthetic resin made from a dicarboxylic acid, such as phthalic acid,

and diols or triols: used in paints and

adhesives

Formed by the reaction of polyhydric alcohols and polybasic acids

The most common method of preparation is the fatty acid method in w/c glyceride oil is catalytically treated w/ glycerol at 25-

250oC

Polycarbonates

Special variety of polyester in w/d a derivative of carbonic acid Is substituted

for adipic, phthalic and a diphenol is

substituted for the more conventional

glycols

Epoxy Resins

Formed by the reaction of bisphenol with epichlorohydrin.

Have excellent chemical resistance; excellent adhesion and electrical insulating poperties

Epoxy resins have many different uses. For example, resins that are cured through exposure to ultraviolet light are commonly used in fiber optics, optoelectronics, and dentistry.

Polyimides

Very stable, linear polymers

Compounds containing two anhydride groups w/c reacts with primary amines or isocyanates

The polyimide materials are lightweight, flexible, resistant to heat and chemicals. Therefore, they are

used in the electronics industry for flexible cables, as

an insulating film on magnet wire and for medical

tubing.

Polysulfones

Polysulfone describes a family of thermoplastic polymers.

These polymers are known for their toughness and stability at high

temperatures.

Resistance to autoclave sterilization makes them useful for medical instruments and

trays

Other uses: microwave cookware, coffee decanters, and corrosion-resistant piping

Addition Polymerization

Polyolefins

Vinyl resins

Vinyl alcohol resins

Vinylidene resins

Styrene resins

Acrylic resins and plastics

Addition polymerization

A chemical reaction in which simple molecules (monomers) are added to each other to form long-chain molecules (polymers) without by-products.

The molecules of the monomer join together to form a polymeric product in which the molecular formula of the repeating unit is identical with that of the monomer.

The molecular weight of the polymer so formed is thus the total of the molecular weights of all of the combined monomer units.

Polyolefins

a polymer produced from a simple olefin (also called an alkene with the general formula CnH2n) as a monomer.

Industrial polyolefins: PE, PPhave excellent chemical resistance and can only

be adhesively bonded after surface treatment because they have very low surface energies

used for blown film and heatshrink electrical insulation sleeves for crimped wire terminals, as well as rash guards or under garments for wetsuits.

Polyolefin elastomer POE is used as a main ingredient in seat cushions, arm rests, spa pillows, etc.

Vinyl Resins

Synthetic materials made from cpds having a vinyl group

Polyvinyl acetate, PVC, polyvinyl alcohol, polyvinyl acetals

Largest branch of vinyl family is PVC due to wide range of applications, ease of

processing and relatively low cost

PVC manufacture

Alloying and Bending

Blends-mixtures that are not fully compatible

Alloys-mixtures that are fully compatibles such as polyethylene oxide and polystyrene

appear as separate phases when viewed under microscope

Problem: to make components adhere together

Approach: to introduce compatibilizers

Major polymer alloys are polyphenylene

oxide/polystyrene, polycarbonate, PET

Natural Products

Cellulose Derivatives

Cellulose Nitrate-a compound made by treating cellulose with nitric and sulphuricacids, used in plastics, lacquers, and explosives

Cellulose Acetate-synthetic compound derived from the acetylation of the plant substance cellulose. Can be molded into solid plastic parts such as tool handles or cast into film for photography or food wrapping

Ethyl Cellulose plastics- thermoplastic and are noted for their ease of molding, light weight, and good dielectric strength. applications include football helmets, equipment housings, refrigerator parts, and luggage.

Shellac- a resin secreted by the female lacbug, on trees in the forests of India and Thailand. It is processed and sold as dry flakes (pictured at right), which are dissolved in ethyl alcohol to make liquid shellac, which is used as a brush-on colorant, food glaze and wood finish.

Laminates

A laminate is a material that can be constructed by uniting two or more layers of material together.

Laminated plastics are made largely from the thermosetting class of resins and have fibrous fillers such as glass, carbon, metal and some polymer

Resin is dissolved in a suitable solvent (alcohol or water) with w/c the filler is coated

Vehicle windshields are commonly made by laminating a tough plastic film between

two layers of glass.

Plywood is a common example of a laminate using the same material in each

layer.

Glued and laminated dimensioned timber is used in the construction industry to

make wooden beams

Foams

Cellular plastics available in two types Closed cell- have higher compressive

strength due to their structures

Open cell- contain pores that are connected to each other and form an interconnected network which is relatively soft.

Formed by adding blowing or foaming agents to the resin and then heating to cause the additives to foam

Common foaming agents are cpds w/c give off CO2 or N gases

Syntactic Foams- A special class of closed-cell which contains hollow particles

embedded in a matrix material. Possible

applications, such as dynamic structural

support, flexible foam core, and expandable

foam fill

Integral skin foam- is a type of foam with a high-density skin and a low-density core.

Examples of items produced using this

process include arm rests, baby seats, shoe

soles, and mattresses.

Documents

Synthetic Resins and Plastics