8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 17
1192011
1
1
PLASTICS
Dr K SIVAKUMAR
Dept of Chemistry SCSVMV University
983107983151983157983154983155983141983098 983106983086983109 983080983109983109983109983081 991251 983120983137983154983156 983124983145983149983141 983123983157983138983146983141983139983156983098 983105983120983120983116983113983109983108 983123983107983113983109983118983107983109 983125983150983145983156983098 983126
Syllabus Plastics
Thermoplastics
Thermosetting plastics
Processingof plasticsInjection moulding
Blow moulding
Extrusion processes
2
THERMOPLASTICS
amp
THERMOSETTING PLASTICS
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 27
1192011
2
3
Thermoplastics (resins) Thermoplastics soften when
heated and subsequently melt When cooled theybecome hard and rigid once again
Example Polyethylene PVC Nylon
Uses Bags Mugs Toys
Thermosetting plastics (resins) Thermosetting resins
do not become softy on heating amp they never melt
once set
Example Bakelite
Uses Electric switches Telephone parts Cookerhandles
4
Moulding constituents of plastic
Higher polymer material is mixed with 4 to 10ingredients each of which imparts some useful
property to the moulded products
Some are
Resins Holds the different constituents together
Example Linear polymers with low molecular
weights
Resins form 40-50 of moulding mixture
Plasticisers To increase the plasticity and flexibility
Example Castor oil Dibutylphthalate Alkyl amp Aryl
Phosphate etc
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 37
1192011
3
5
Fillers To impart valuable service properties such as
strength resistance finish and workability
Reducing cost shrinkage on setting and brittlenessExample Wood flour asbestos china clay talc
gypsum saw dust
Fillers form 60 of plastics
Lubricants To facilitate the moulding operations
Gives glossy finish
Example Waxes soaps Oleates stearates
Catalystaccelerators To accelerate the
polymerisation (added only in thermosetting resins)Example Hydrogen peroxide Benzoyl peroxide
Metals (Ag Cu amp Pb)
6
Difference between Thermoplastics amp Thermosetting plastics
SNo THERMOPLASTICS THERMOSETTING PLASTICS
1 Formed by addition Polymn Formed by condensation Polymn
2 Long chain linear polymers Three dimensional network
structure joined by strong covalent
bonds
3 Soften on heating and stiffen on
cooling
Do not soften on heating
4 Can be remoulded Cannot be remoulded
5 Usually soft weak amp less brittle Usually hard strong amp more brittle
6 Can be reclaimed from wastes Cannot be reclaimed from wastes
7 Soluble in organic solvents Insoluble in organic solvents
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 47
1192011
4
7
INJECTION MOULDING (for Thermoplastics)bullMaterials of definite quantity at Hi Temp is injected into a cold mould under P
bullIn cold mould the polymer solidifies
bullPolymer is fed as granules pellets powder through hopperbullPolymer get softened in horizontal cylinder
bullHydraulic piston pushes the molten material into mould
bullUniform spreading inside the hot cylinder is ensured by torpedo
bullMolten plastic is injected through a nozzle into moulded cavity
Mould
bullConsists of movable amp stationary parts
bullMolten plastic is injected at a P of
15000kgcm2
bullProper flow of material is ensured by
preheating the mould to appropriate T
bullMould is cooled by circulating water
and then opened to eject the moulded
article
8
BLOW MOULDING (for thermoplastics) [for hollow plastic articles]bullTo produce soft drink bottles containers using Polyethylene PVC Polystyrene
bullPARISON ndash hot softened thermoplastic made by injection extrusion moulding
bullParison is placed inside a two piece hollow mould (as 2 halves)
bullParison kept between two halves encloses a blowing pin at one end
bullOther end pinches and closes
bullParison is blown using pressurized air through the blow pin
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 57
1192011
5
9
BLOWMOULDING ContinuedhelliphellipbullParison kept under hot condition is inflated and expands until it comes in
contact with inner area of the cold hollow mould
bullUnder pressure
bullParison acquires the shape of hallow cavity of mould
bullMould is cooled and the thermoplastic article is removed from the mould by
opening the mould
10
EXTRUSION MOULDING
bullFor producing common plastic materials
bulleg films filaments hoses sheets amp coating wires and cables with PVCbullPlastic material as powder granules is fed into a cylinder thru hopper
bullCylinder is with the provision for heating
bullHot plastic is pushed thru cylinder by helically revolving screw
bullDue to friction the Temperature increases
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 67
1192011
6
11
EXTRUSION MOULDING (Continueshellip)
bull Plastic material passes through three zones
1 Feed zone2 Compression zone
3 Metering zone
12
EXTRUSION MOULDING (Continueshellip)
bull In compression zone powder charge is melted by heating element
bull It is compressed by revolving screw
bull Polymer flows at a constant rate due to helical movement of screwbull Pressure in this zone enables plastic to be in melted stage amp enters the die
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 77
1192011
7
13
EXTRUSION MOULDING (Continueshellip)
bull From die moulded plastic is coming out in desired profile
bull Extrudated material from die is hot and hence it is cooled rapidly to
avoid any deshaping
bull Cooling by passing extrudate over a conveyor belt through which
tubes of cold watercold air are passed
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 27
1192011
2
3
Thermoplastics (resins) Thermoplastics soften when
heated and subsequently melt When cooled theybecome hard and rigid once again
Example Polyethylene PVC Nylon
Uses Bags Mugs Toys
Thermosetting plastics (resins) Thermosetting resins
do not become softy on heating amp they never melt
once set
Example Bakelite
Uses Electric switches Telephone parts Cookerhandles
4
Moulding constituents of plastic
Higher polymer material is mixed with 4 to 10ingredients each of which imparts some useful
property to the moulded products
Some are
Resins Holds the different constituents together
Example Linear polymers with low molecular
weights
Resins form 40-50 of moulding mixture
Plasticisers To increase the plasticity and flexibility
Example Castor oil Dibutylphthalate Alkyl amp Aryl
Phosphate etc
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 37
1192011
3
5
Fillers To impart valuable service properties such as
strength resistance finish and workability
Reducing cost shrinkage on setting and brittlenessExample Wood flour asbestos china clay talc
gypsum saw dust
Fillers form 60 of plastics
Lubricants To facilitate the moulding operations
Gives glossy finish
Example Waxes soaps Oleates stearates
Catalystaccelerators To accelerate the
polymerisation (added only in thermosetting resins)Example Hydrogen peroxide Benzoyl peroxide
Metals (Ag Cu amp Pb)
6
Difference between Thermoplastics amp Thermosetting plastics
SNo THERMOPLASTICS THERMOSETTING PLASTICS
1 Formed by addition Polymn Formed by condensation Polymn
2 Long chain linear polymers Three dimensional network
structure joined by strong covalent
bonds
3 Soften on heating and stiffen on
cooling
Do not soften on heating
4 Can be remoulded Cannot be remoulded
5 Usually soft weak amp less brittle Usually hard strong amp more brittle
6 Can be reclaimed from wastes Cannot be reclaimed from wastes
7 Soluble in organic solvents Insoluble in organic solvents
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 47
1192011
4
7
INJECTION MOULDING (for Thermoplastics)bullMaterials of definite quantity at Hi Temp is injected into a cold mould under P
bullIn cold mould the polymer solidifies
bullPolymer is fed as granules pellets powder through hopperbullPolymer get softened in horizontal cylinder
bullHydraulic piston pushes the molten material into mould
bullUniform spreading inside the hot cylinder is ensured by torpedo
bullMolten plastic is injected through a nozzle into moulded cavity
Mould
bullConsists of movable amp stationary parts
bullMolten plastic is injected at a P of
15000kgcm2
bullProper flow of material is ensured by
preheating the mould to appropriate T
bullMould is cooled by circulating water
and then opened to eject the moulded
article
8
BLOW MOULDING (for thermoplastics) [for hollow plastic articles]bullTo produce soft drink bottles containers using Polyethylene PVC Polystyrene
bullPARISON ndash hot softened thermoplastic made by injection extrusion moulding
bullParison is placed inside a two piece hollow mould (as 2 halves)
bullParison kept between two halves encloses a blowing pin at one end
bullOther end pinches and closes
bullParison is blown using pressurized air through the blow pin
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 57
1192011
5
9
BLOWMOULDING ContinuedhelliphellipbullParison kept under hot condition is inflated and expands until it comes in
contact with inner area of the cold hollow mould
bullUnder pressure
bullParison acquires the shape of hallow cavity of mould
bullMould is cooled and the thermoplastic article is removed from the mould by
opening the mould
10
EXTRUSION MOULDING
bullFor producing common plastic materials
bulleg films filaments hoses sheets amp coating wires and cables with PVCbullPlastic material as powder granules is fed into a cylinder thru hopper
bullCylinder is with the provision for heating
bullHot plastic is pushed thru cylinder by helically revolving screw
bullDue to friction the Temperature increases
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 67
1192011
6
11
EXTRUSION MOULDING (Continueshellip)
bull Plastic material passes through three zones
1 Feed zone2 Compression zone
3 Metering zone
12
EXTRUSION MOULDING (Continueshellip)
bull In compression zone powder charge is melted by heating element
bull It is compressed by revolving screw
bull Polymer flows at a constant rate due to helical movement of screwbull Pressure in this zone enables plastic to be in melted stage amp enters the die
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 77
1192011
7
13
EXTRUSION MOULDING (Continueshellip)
bull From die moulded plastic is coming out in desired profile
bull Extrudated material from die is hot and hence it is cooled rapidly to
avoid any deshaping
bull Cooling by passing extrudate over a conveyor belt through which
tubes of cold watercold air are passed
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 37
1192011
3
5
Fillers To impart valuable service properties such as
strength resistance finish and workability
Reducing cost shrinkage on setting and brittlenessExample Wood flour asbestos china clay talc
gypsum saw dust
Fillers form 60 of plastics
Lubricants To facilitate the moulding operations
Gives glossy finish
Example Waxes soaps Oleates stearates
Catalystaccelerators To accelerate the
polymerisation (added only in thermosetting resins)Example Hydrogen peroxide Benzoyl peroxide
Metals (Ag Cu amp Pb)
6
Difference between Thermoplastics amp Thermosetting plastics
SNo THERMOPLASTICS THERMOSETTING PLASTICS
1 Formed by addition Polymn Formed by condensation Polymn
2 Long chain linear polymers Three dimensional network
structure joined by strong covalent
bonds
3 Soften on heating and stiffen on
cooling
Do not soften on heating
4 Can be remoulded Cannot be remoulded
5 Usually soft weak amp less brittle Usually hard strong amp more brittle
6 Can be reclaimed from wastes Cannot be reclaimed from wastes
7 Soluble in organic solvents Insoluble in organic solvents
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 47
1192011
4
7
INJECTION MOULDING (for Thermoplastics)bullMaterials of definite quantity at Hi Temp is injected into a cold mould under P
bullIn cold mould the polymer solidifies
bullPolymer is fed as granules pellets powder through hopperbullPolymer get softened in horizontal cylinder
bullHydraulic piston pushes the molten material into mould
bullUniform spreading inside the hot cylinder is ensured by torpedo
bullMolten plastic is injected through a nozzle into moulded cavity
Mould
bullConsists of movable amp stationary parts
bullMolten plastic is injected at a P of
15000kgcm2
bullProper flow of material is ensured by
preheating the mould to appropriate T
bullMould is cooled by circulating water
and then opened to eject the moulded
article
8
BLOW MOULDING (for thermoplastics) [for hollow plastic articles]bullTo produce soft drink bottles containers using Polyethylene PVC Polystyrene
bullPARISON ndash hot softened thermoplastic made by injection extrusion moulding
bullParison is placed inside a two piece hollow mould (as 2 halves)
bullParison kept between two halves encloses a blowing pin at one end
bullOther end pinches and closes
bullParison is blown using pressurized air through the blow pin
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 57
1192011
5
9
BLOWMOULDING ContinuedhelliphellipbullParison kept under hot condition is inflated and expands until it comes in
contact with inner area of the cold hollow mould
bullUnder pressure
bullParison acquires the shape of hallow cavity of mould
bullMould is cooled and the thermoplastic article is removed from the mould by
opening the mould
10
EXTRUSION MOULDING
bullFor producing common plastic materials
bulleg films filaments hoses sheets amp coating wires and cables with PVCbullPlastic material as powder granules is fed into a cylinder thru hopper
bullCylinder is with the provision for heating
bullHot plastic is pushed thru cylinder by helically revolving screw
bullDue to friction the Temperature increases
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 67
1192011
6
11
EXTRUSION MOULDING (Continueshellip)
bull Plastic material passes through three zones
1 Feed zone2 Compression zone
3 Metering zone
12
EXTRUSION MOULDING (Continueshellip)
bull In compression zone powder charge is melted by heating element
bull It is compressed by revolving screw
bull Polymer flows at a constant rate due to helical movement of screwbull Pressure in this zone enables plastic to be in melted stage amp enters the die
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 77
1192011
7
13
EXTRUSION MOULDING (Continueshellip)
bull From die moulded plastic is coming out in desired profile
bull Extrudated material from die is hot and hence it is cooled rapidly to
avoid any deshaping
bull Cooling by passing extrudate over a conveyor belt through which
tubes of cold watercold air are passed
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 47
1192011
4
7
INJECTION MOULDING (for Thermoplastics)bullMaterials of definite quantity at Hi Temp is injected into a cold mould under P
bullIn cold mould the polymer solidifies
bullPolymer is fed as granules pellets powder through hopperbullPolymer get softened in horizontal cylinder
bullHydraulic piston pushes the molten material into mould
bullUniform spreading inside the hot cylinder is ensured by torpedo
bullMolten plastic is injected through a nozzle into moulded cavity
Mould
bullConsists of movable amp stationary parts
bullMolten plastic is injected at a P of
15000kgcm2
bullProper flow of material is ensured by
preheating the mould to appropriate T
bullMould is cooled by circulating water
and then opened to eject the moulded
article
8
BLOW MOULDING (for thermoplastics) [for hollow plastic articles]bullTo produce soft drink bottles containers using Polyethylene PVC Polystyrene
bullPARISON ndash hot softened thermoplastic made by injection extrusion moulding
bullParison is placed inside a two piece hollow mould (as 2 halves)
bullParison kept between two halves encloses a blowing pin at one end
bullOther end pinches and closes
bullParison is blown using pressurized air through the blow pin
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 57
1192011
5
9
BLOWMOULDING ContinuedhelliphellipbullParison kept under hot condition is inflated and expands until it comes in
contact with inner area of the cold hollow mould
bullUnder pressure
bullParison acquires the shape of hallow cavity of mould
bullMould is cooled and the thermoplastic article is removed from the mould by
opening the mould
10
EXTRUSION MOULDING
bullFor producing common plastic materials
bulleg films filaments hoses sheets amp coating wires and cables with PVCbullPlastic material as powder granules is fed into a cylinder thru hopper
bullCylinder is with the provision for heating
bullHot plastic is pushed thru cylinder by helically revolving screw
bullDue to friction the Temperature increases
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 67
1192011
6
11
EXTRUSION MOULDING (Continueshellip)
bull Plastic material passes through three zones
1 Feed zone2 Compression zone
3 Metering zone
12
EXTRUSION MOULDING (Continueshellip)
bull In compression zone powder charge is melted by heating element
bull It is compressed by revolving screw
bull Polymer flows at a constant rate due to helical movement of screwbull Pressure in this zone enables plastic to be in melted stage amp enters the die
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 77
1192011
7
13
EXTRUSION MOULDING (Continueshellip)
bull From die moulded plastic is coming out in desired profile
bull Extrudated material from die is hot and hence it is cooled rapidly to
avoid any deshaping
bull Cooling by passing extrudate over a conveyor belt through which
tubes of cold watercold air are passed
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 57
1192011
5
9
BLOWMOULDING ContinuedhelliphellipbullParison kept under hot condition is inflated and expands until it comes in
contact with inner area of the cold hollow mould
bullUnder pressure
bullParison acquires the shape of hallow cavity of mould
bullMould is cooled and the thermoplastic article is removed from the mould by
opening the mould
10
EXTRUSION MOULDING
bullFor producing common plastic materials
bulleg films filaments hoses sheets amp coating wires and cables with PVCbullPlastic material as powder granules is fed into a cylinder thru hopper
bullCylinder is with the provision for heating
bullHot plastic is pushed thru cylinder by helically revolving screw
bullDue to friction the Temperature increases
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 67
1192011
6
11
EXTRUSION MOULDING (Continueshellip)
bull Plastic material passes through three zones
1 Feed zone2 Compression zone
3 Metering zone
12
EXTRUSION MOULDING (Continueshellip)
bull In compression zone powder charge is melted by heating element
bull It is compressed by revolving screw
bull Polymer flows at a constant rate due to helical movement of screwbull Pressure in this zone enables plastic to be in melted stage amp enters the die
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 77
1192011
7
13
EXTRUSION MOULDING (Continueshellip)
bull From die moulded plastic is coming out in desired profile
bull Extrudated material from die is hot and hence it is cooled rapidly to
avoid any deshaping
bull Cooling by passing extrudate over a conveyor belt through which
tubes of cold watercold air are passed
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 67
1192011
6
11
EXTRUSION MOULDING (Continueshellip)
bull Plastic material passes through three zones
1 Feed zone2 Compression zone
3 Metering zone
12
EXTRUSION MOULDING (Continueshellip)
bull In compression zone powder charge is melted by heating element
bull It is compressed by revolving screw
bull Polymer flows at a constant rate due to helical movement of screwbull Pressure in this zone enables plastic to be in melted stage amp enters the die
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 77
1192011
7
13
EXTRUSION MOULDING (Continueshellip)
bull From die moulded plastic is coming out in desired profile
bull Extrudated material from die is hot and hence it is cooled rapidly to
avoid any deshaping
bull Cooling by passing extrudate over a conveyor belt through which
tubes of cold watercold air are passed
8102019 Thermosets amp thermoplastics
httpslidepdfcomreaderfullthermosets-thermoplastics 77
1192011
7
13
EXTRUSION MOULDING (Continueshellip)
bull From die moulded plastic is coming out in desired profile
bull Extrudated material from die is hot and hence it is cooled rapidly to
avoid any deshaping
bull Cooling by passing extrudate over a conveyor belt through which
tubes of cold watercold air are passed
Top Related