Plastic Materials

The objective of this training session is to familiarize you with the generally used plastic materials , their properties and applications.

Objective:

Contents:

• Why plastics?• What are plastics?• Classification of polymers• Classification of thermoplastic materials• Fillers, Reinforcement fibers & Additives• Plastic Blends• Commonly used plastics & their properties• Plastic material selection

Take away ... basics about plastic materials

Why Plastics???

- Polymers which are very resistant to chemicals.

- Polymers which are thermal and electrical insulators.

- Generally, polymers which are light in weight - with varying degrees of strength.

- Polymers that can be processed in various ways to produce thin and very intricate parts.

Plastic Materials

The origin of the word "plastics" comes from Greek. Meaning “to form”

PLASTICS PLASTICS PLASTICS !!!

THAT IS WHAT WE HEAR . WHY IS IT SO ???

WEIGHT OFPACKING

ENERGY CONSUMPTION WASTE VOLUME

100%

+391%

+208%

+258%

WITH PLASTIC MATERIAL

WITHOUT PLASTIC MATERIAL

Plastic Materials

Comparison of plastics as packaging materials

PLASTICS ARE A MERE 4% OF THE USES OF OIL

FUELSOTHERS PETROCHEMICALS

PLASTICS

MISC.

7% 86% 7%

4%

3%

Plastic Materials

100Kg Of plastics in a motor car replaces 200 to 300 Kg Of traditional material

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PLASTICS

Use of Plastics in Western Europe

Plastic Materials

The consumption of energy reduced by 50% in appliances from past 20 years

Plastics 8% Paper/Cardboard27% Miscellaneous 17%

Metals 5% Glass 9% Organic Material 34%

Household waste in western Europe (129 million tons/year)

Land Fill

MehanicalRecyclingEnergy Recovery

IncinerationW/OEnergy Recovery

72%

3%16.8%

8.2%

Plastic Materials

Recycling is the major advantage in plastics to reduce the waste

Plastic Materials

Applications:

• Automotive

• Medical

• Appliances

• Electrical

• Sports

Advantages:

• Greater design freedom (part complexity)

• Less number of parts

• Fewer assembly operations

• No secondary operations

• Weight reduction

• Cost reduction

• Properties tailored to specific applications

What is polymer&polymerization?

The principal structure of plastic is that a unit, or mer, is linked many times to become a polymer.

The chemical process for the formation of polymers is called as polymerization.

• Thermoplastic & Thermoset materials

• Crystalline & Amorphous materials

• Natural & Synthetic polymers

• Copolymers

• Alloys

• Elastomers

Classification:

• Organic polymeric materials .

• Mostly Petrochemical based.

• Polymer : Made of many units.– Generally a few thousand to a few million in

one molecule.

Plastic Materials

Classification of plastic materials

Thermoplastics

are resins that repeatedly soften when heated and hardened when cooled.

Nylon, Acrylic, Acetal, Polystyrene, Polyvinyl chloride, Polyethylene, Cellulose acetate are some examples.

Thermoplastic elastomers known as highly elastic and flexible resins.

Thermosets(cross-linked plastics)

Initially a liquid or a semisolid or a powder, which solidify on heating for first time, and then will only decompose on heating to a high temperature.

Phenolic, Amino, Epoxy, Polyurethane are few examples.

Vulcanization is process to convert from rubbers to thermoset plastics.

Thermoplastics materials are major contribution to engg. applications

The thermal behavior of thermoplastics leads toMelt processing techniques such as

• Injection molding - suitable for precision & complex parts • Extrusion - suitable for single cross section parts• Thermoforming - suitable for complex big parts• Blow molding - suitable for bottle shape parts• Roto molding - suitable for big components like water tanks

The thermal solidification of thermosets leads toProcessing methods such as

• Hot compression molding• Resin transfer molding• Pultrusion• Vacuum bagging , pressure bagging

Classification of plastic materials

Injection molding is the dominated process in plastics...

This is what happens to thermoplastics and thermosets, when we process them.

Classification of plastic materials

Classification of plastic materials

Classification of plastic materials

Crystalline Materials:

the chemical structure allows the polymer

chains to fold on themselves and pack

together in an organized manner during

the melting and cooling process.

• The structure the polymer is uniform and Order.• Opaque material• Shrinkage is more(around 2%)• Shrinkage is non-uniform in both direcitons• Warpage is more• Sharp transition in the Melting phase• Very good Chemical resistance• Low gloss and dimensional stability• Acetal, Nylon, Polyethylene, Polypropylene, Polyamides, Polyester(PET, PBT)Acrylic etc.

Classification of thermoplastics

Amorphous Materials:

the chemical structure of the Amorphous materials is random and not in order after the melting and cooling process.

• The structure of the polymer is no-uniform and random.• Transparent material • Shrinkage is less (around 0.5%)• Shrinkage is uniform in both the directions• Warpage is less• Gradual transition in the Melting phase• Low Chemical resistance• High gloss and dimensional stability• Polystyrene, ABS, PC, SAN, PVC etc.

Liquid crystalline materials are one having amorphous regions between and connecting the crystalline regions

Classification of thermoplastics

Classification of thermoplastics

Classification of thermoplastics

Classification of thermoplastics

Relative polymer properties

Property Crystalline Amorphous Liquid CrystallineSpecfic Gravity Higher Lower HigherTensile Strength Higher Lower HighestTensile Modulus Higher Lower HighestDuctility, Elongation Lower Higher LowestResistance to creep Higher Lower HighMax usage temp. Higher Lower HighShrinkage & warpage Higher Lower LowestFlow Higher Lower HighestChemical resistance Higher Lower HighestCreep resistance Higher Lower HighestHeat resistance Higher Lower HighestImpact resistance Lower Higher Highest

Liquid crystalline materials are best...

Plastic fillers, Reinforcing fibers & Additives

Fillers

• Glass spheres

• Carbon black

• Metal powders

• Silicon sand

• Wood flour

• Ceramic powders

• Mica flakes

• Molybdenum Disulfide

Reinforcing fibers

• Glass fibers

• Carbon fibers

• Aramid fibers

• Jute

• Nylon fibers

• Polyester fibers

Additives

• UV Stabilizers

• Plasticizers

• Loubricants

• Colorants

• Flame retardants

• Antioxicants

• Antistatics

“Fillers/Fibers/Additives” maybe any substances that is added to the polymer in small concentration in order to alter their physical properties either to facilitate processing or to change physical, chemical or electrical properties of the material.

Fillers/fibers/additives improves the properties by 30-40%

•Preservatives

• Processing aids

•Fungicides

• Smoke suppressants

• Foaming agents

• Viscosity modifiers

• Impact modifiers

Blends are mechanical mixtures of chemically different polymers or co- polymers.

What is expected of a blend?

• High performance at reasonable price.• Modification of performance as market develops.• Extending the performance of expensive resins.• Generation of unique materials.• They should be economical, competitive and should not affect other needed properties.• They should be easy to process.

Plastic Blends

Most commonly used blends:

•ABS/PVC Blends• PC/ABS Blends• PBT/PC Blends• EPDM/PP

Blending of plastics is innovative in the competitive market

Plastic Material Selection

• Identify application requirements - mechanical (load, impact, stiffness, etc.), thermal (temperature range, maximum use temperature, etc.), environmental considerations

• Identify the chemical environment - define the chemical stress, temperature, contact time and type

• Identify specific loads - regulatory (UL, FDA, etc.), outdoor or UV exposure, light transmission (clear or opaque), fatigue and creep requirements

• Define processing considerations - Injection molding, blow molding, extrusion, thermoforming, foam molding etc.

• Assembly - painting, plating, shielding, adhesion, snap fit, welding etc.

• Finish & gloss

• Cost

• Availability

Material section is the key factor in the design phase

Plastic Material Selection

Material performance• Modulus• Strength/Ductility• Thermal Conductivity• Viscosity• Material Cost

Part Performance Requirements• Load/Deflection• Time/Temperature• UV Stability, Transparency, • Chemical Compatibility, etc.

Part design• part Stiffness• Optimal Ribbed Geometry• Wall Thickness• Part Volume/Weight

Manufacturing• Maximum Flow Length• Minimum Wall Thickness• Cycle Time• Manufacturing Cost

Material SelectionGoal: Minimize System Cost =

(Material Cost) x (Part Volume) + (Machine Cost) x (Cycle Time)

Design based material selection

Plastic Material Abbreviation

Material Abbreviation Trade name TypePOM Poly oxy methylene or Polycetal Delrin CrystallinePPS Poly phenylene sulphidePC Poly carbonate Lexan AmorphousPTFE Poly tetra fluro ethylene Teflon AmorphousPEEK Poly ethyl ether ketone Victrex AmorphousPBT Poly butylene terephthalate Arnite AmorphousPMMA/Acrylic Poly methyl propenate Lucite, Plexiglass CrystallinePVC Poly chloro vinyl Indovin AmorphousNylon Polyamide Zytel, Perlon CrystallineABS Acrylonitrile butadiene styrene Abstron AmorphousPE Poly ethylene CrystallineLDPE Low density poly ethylene CrystallineHDPE High density poly ethylene CrystallinePS Poly styrene AmorphousHIPS High impact poly styrene AmorphousSAN Styrene acrylonitrile AmorphousPP Poly propylene CrystallineCA Cellulose acetate AmorphousCAB Cellulose acetate butyrate AmorphousCP Cellulose propionate AmorphousPPO Poly phenylene oxide Nyrol Amorphous

Common properties of plastic materials

Physical properties

• Density

• Specific gravity

• Refractive index

• Water absorption

• Mold shrinkage

• Rheology

• Transparency

• Elasticity

• Plasticity

• Ductility, Toughness

• Brittleness

• Notch sensitivity

• Lubricity

• Coefficient of linear expansion

Mechanical properties

• Tensile strength

• Flexural Modulus

• Elongation

• Creep

• Impact strength

• Fatigue resistance

• Hardness

• Coefficient of friction

Electrical properties

• Conductivity

• Volume resistivity

• Surface resistivity

• Dielectric strength

• Arc resistance

Thermal properties

• Melting point

• Glass transition temp

• Thermal conductivity

• Aging at elevated temp

• Flammability

Environmental conditions

• Stress level

• Temperature

• Chemical compatibility

• Weathering resistance

Chemical Properties• Molecular weight• Melt viscosity(MFI)• Glass transition temperature• Heat distortion temperature(HDT)

Commonly used plastics and propertiesMateial/Properties

Density(g/cc)

Tensile Strength(Mpa)

Elongation(%)

Impact Strength(ft-lb/in)

HDT(Deg C)

VST(Deg C)

Melting point(Deg C) Tg(Deg C)

Shrinkage(cm/m) LOI(%) Applications

Polyacetol HOMO 1.42 70 25-75 1.4 100-110 175 -13 0.02 15Polyacetol CO 1.41 58 40-75 1-1.5 100-110 105 0.035

PPS 1.88 92 1 27.5 350 300-360 85-950.001-0.005 44-53

Connectors, Coil formers, Bobins, Rey equipments, Metal replacement in the automotove industry, Street lamp reflectory, PH meter components, Encapsulation components

PC 1.2 65 6 to 7 9 to 16 135-140 158-160 220-230 1450.006-0.008 26

Insulating areas, f lame resistance, durability, impact resistance,heat resistance

PPO 1.06 48-76 5 to 10 80-149 257 116-1500.005-0.007 29-35

Water w ashing machines, dish w ashes, w ater pumps, elctronic, automotive and structural foam

PTFE 2.1-2.3 17-21 200-300 2 121 327 1150.030-0.060 90

High chemical inertness exceptional w eather properties, seals, gasket, packaging, pump parts, laboratory equipment, PCB, w ire insulation, aircraft components, non-stick w oven w are, f lexible steam hose, unsintered tape for pipes sealings.

PEEK 1.265 92 >40 8(kj/m) 150 334 1430.012-0.020 35

Heat resistance, hydrolytic stability, chemical plants, pump impeller & aircraft components

PBT 1.31 52 200 1 54 220 22-430.015-0.02 18

Automotive, electrical, electronics, homew are,pow er tools, toys & machine parts

PETP 1.4 130-150 2 to 3 77-90(J/m) 205-210 265 70-800.018-0.021 21

House hold appliances, elctrical, electronic components, coffee maker, medical devices & gear w heels

Acrylic 1.17-1.20 8,000-11,600 3 to 7 0.4-0.5 70-95 90 160 990.004-0.007 17

High optical clarity, soft contact lenses, unbreakable w atch crystals, artif icial eyes, contact lenses, artif icial dnetures, acrylic emulsions

PVC 1.36-1.42 58 5

2.18-119.68(Kgcm/cm) 92 170-220 65-80 0.004 23-43

Building frames, pipes, blow moldes parts, vinyl leather cloth, w all paper f inishing, play ball, toys, mine belting, garden hose, f looring

Nylon 1.13 12,000(lb/in) 300 1.2 90-97 204 215 500.01-0.015 21-34

Nylon 6,6 1.14 11,000(lb/in) 90 2 70-100 230-250 264 60 0.01-0.02 21-30

Nylon 6,10 1.09 8,000(lb/in) 100 1.4 65-85 193 215 30

ABS 1.01-1.07 31-45 5-200 1 to 8 87-107 95-101 200-210 110-1250.004-0.008 29-35

toughness, rigidity and good appearance

toughness, abrasion resistance

Handles, sw itch parts, gears and plumbing applications