Thermoplastics - properties & applications

What are the properties of thermoplastics?

• structure : linear/branched polymer chains, no crosslinking at all, no atomic bonds between the different chains

• Can be melted and reshaped multiple times

• Can be recycled by melting and reforming

• Analogy : chocolate

What’s aging?

Gradual degradation of a material’s properties over time due to environmental factors (light, heat, oxygen, chemicals)

List all the thermoplastics you know

(14)

• ABS Acrylonitrile-butadiene-styrene

• PA Polyamide

• PBT Polybutylene terephthalate

• PC Polycarbonate

• PE polyethylene

• PET Polyethylene terephthalate

• PIB Polyisobutylene

• PMMA Polymethyl methacrylate

• POM Polyoxymethylene / Polyacetal

• PP Polypropylene

• PS Polystyrene

• PTFE Polytetrafluoroethylene

• PVAC Polyvinyl acetate

• PVC Polyvinyl chloride

Properties & applications of polyethylene PE

• 2 types:

  • PE-LD (low density) → produced at high pressure

  • PE-HD (high density) → produced at low pressure

• properties can be changed by changing the the chain length or the degree of crystallinity

• Good abrasion resistant

• films

• Packaging

• Containers

• Tubes

• Ice skating sheets

Properties & applications of polypropylene PP

• better temperature resistance than polyethylene

• Very brittle at cold temperatures

• Copolymerisation with ethylene is possible

• packaging

• Pipes

• Films

• Chemical tanks/ storage containers

• Textiles

• Chairs

• Ropes (good impact resistance & strength)

• Plastic boxes with hinged lids (couvercles pliables)

Properties & applications of polyisobutylene PIB

• linear polymer (1D chains, no branches)

• Polymerisation degree ranges from oily to rubber-like

  • oily → low deg, short chains, liquid

  • Rubber-like → high deg, long chains, elastic, flexible

• Free of plasticisers

• ~ const. properties between -50 & 100°C

• low molecular weight → adhesives, sealants (mastic, joints)

• High molecular weight → films, chewing-gum, sealing membranes

Properties & applications of polyisobutylene PIB

• linear polymer (1D chains, no branches)

• Polymerisation degree ranges from oily to rubber-like

  • oily → low deg, short chains, liquid

  • Rubber-like → high deg, long chains, elastic, flexible

• Free of plasticisers

• ~ const. properties between -50 & 100°C

• low molecular weight → adhesives, sealants (mastic, joints)

• High molecular weight → films, chewing-gum, sealing membranes

Properties & applications of polymethyl methacrylate PMMA

• clear acrylic glass (Plexiglas)

• Density ~1/2 traditional silicate glass

• Significantly lighter than real glass

• Easily scratched

• Quite resistant in cold conditions

• Resistant to aging

• luminaires

• sheets (transparent roofs, aquariums glass)

• profiles

• moulded parts

Properties & applications of polycarbonate PC

• clear

• Hard-elastic (rigid but can bend/stretch)

• Impact resistant between -100 and 100°C

• light domes

• transparent housings

• suitcases

• CD, DVD

• automotive

• electronic housings

• bulletproof vests/car windows

Properties & applications of polyvinyl acetate PVAC

• high adhesive capacity

• Softens from 30°C

• binding agents (liants) for paints/coating (revêtements), glue

• Varnishes (vernis)

• Adhesives

• Sealing compounds (étanchéité)

• Chewing-gum

Properties & applications of polystyrene PS

• high adhesive capacity

• rigid & brittle in pure form (w/ additives/fillers)

• Can be clear & transparent

• binding agents for paints/coatings

• Varnishes

• Adhesives

• Sealing compounds

• Packaging

• Disposable cutlery & cups

• Chewing-gum

• Thermal insulators in houses

Properties & applications of acrylonitrile butadiene styrene ABS

• high toughness

• Dimensional stability up to 100°C (keeps its shape/size)

• Good surface finish, smooth

• Low water absorption

• impact resistant

• High mechanical damping (absorbs & dissipates mechanical vibrations & shocks effectively)

• safety equipment (helmet)

• Car bumpers (pare-chocs)

• Toy’s building blocks

Properties & applications of polytetrafluoroethylene PTFE

• outstanding (exceptional) thermal & chemical resistance

• Temperature resistance up to 327°C

• Mechanical & chemical properties ~ const. between -90 and 250°C

• Extremely low coefficient of friction

• Releases agressive acid when it burns

• sliding bearings (roulements)

• Separating agents

• Anti-adhesive coatings (pans)

Properties & applications of polyamide PA

• Wide adjustment options

• High water absorption → mechanical properties can be decreased by 50% when it’s wet compared to dry state

• Strength can be increased by 5 when stretching

• automotive

• Power tools

• Fibres (ropes, geotextiles)

• Dowels (chevilles, tiges)

Properties & applications of polyethylene terephthalate PET

• high strength, hardness & stiffness

• Temperature resistance up to 100°C

• Crystal clear in the amorphous state

• Good electrical properties

• Physiologically harmless

• films

• Bottles

Properties & applications of polybutylene terephthalate PBT

• similar structure to PET

• good electrical insulator (properties slightly differ with water absorption, temperature & frequency)

• electronics housings (boîtiers/habillages)

• Plain bearings (roulements lisses)

• Roller bearings (roulements à rouleaux)

• Valve parts

• Screws (vis)

• Power strips (multiprises)

• Pump housing & wheels

• Parts for household appliances (appareils électroménagers)

Properties & applications of polyoxymethylene / polyacetal POM

• high abrasion resistance

• Low coefficient of friction

• high chemical resistance

• Low water absorption

• Good electrical properties

• gears (engrenages)

• Pumps

• springs (ressorts)

• Clips (attaches)