1. Using Advanced Materials and Advanced Processing Technologies to
provide solutions

2. Savings through Understanding and Controlling Energy Usage in Polymer
Processing
Gerry McNally, CSci MSc FIOMM FSPE
Facilitator/Director of Polymer Research, Innovation and Competence
Northern Ireland Polymers Association

3. Challenges for the NI Polymer Industry Sector
NIPA/ Invest NI Collaborative Programme
1. Materials – costs and lack of substitutions, green polymers, materials availability
2. Energy Costs – issues associated with costs and availability and improved energy
management within companies – NI 2nd highest energy costs in Europe (Montenegro)
3. Collaboration – Issues directly addressing the B2B industry/academia interface inhibiting
collaboration - particularly inhibiting SME involvement
4. People – Issues associated with staff recruitment, lack of qualified graduates, staff retention,
training and up-skilling
5. Processing – Issues related to new processes, challenges of using new materials, improved
process control - inhibiting innovation
6. Legislation - recycling, REACH, WEEE and H&S
7. Marketing, end user demands, trading conditions, imports.

4. Current Sources of Energy Usage in Polymer Processing
Operation of machinery and ancillary equipment – 90% total energy bill
Heating a polymer materials (which have excellent insulation properties) and conveying the polymer melt at
correct viscosity to forming tools to high quality for a wide range of applications manufacture products.
Mission To manufacture products with excellent performance and appearance
at most competitive cost
Vitally important to gain more knowledge on processing & polymer viscosity
Challenges –we use a wide range of processing machines and polymers – with different
melting temperatures- different viscosities- processes -
5.

5. Challenges for the NI Polymer Industry Sector
NIPA Initiative for Energy Cost Savings
1. Energy Costs – issues associated with costs
(a) Established BPF Climate Change Levy reductions for NIPA companies
(b) NIPA Energy Basket - Bergen Energy –
2.. Improved Energy Management within NIPA Companies
(a) 1st
Energy workshop in Jan 2014 inhibiting
(b) 2nd
Cost saving workshop today
3. Establish NIPA Innovation Vouchers with PPRC on additives and process monitoring
with automatic control for energy reduction
4. NIPA/Invest NI Planned activities over next 1-2 months –
(a) Immediate- assistance available to establish Energy management strategies within
selected NIPA Companies
(b) Establish a range of demonstration plants in firms to bench mark and improve on energy
efficiency –

6. Polymer processing -Complex Science and Engineering Field
To manufacture products with performance and appearance at most competitive cost
Use correct polymer and process using optimum processing conditions
To achieve optimum processing conditions involves knowledge of engineering and scientific disciplines
1. Solids Handling and Solids feeding
2. Design -- wide variety of dies, IM tools, extruder screw designs etc
3. Heat transfer -
4. Fluid flow -
5. Aerodynamics -
6. Cooling and development of morphology and crystallinity
7. Micro structural development will affect mechanical performance
8. Development of crystalline structure simultaneously during cooling, cooling rate orientation biaxial
9. Understanding of the effect of additives on crystalline development
10. We use a wide variety of processing technologies
We use Advanced Processing technologies to process advanced materials

7. Advanced Polymer Processes
Blown Film
Profile Extrusion
Tube and Pipe
Sheet Extrusion
Cast Film
Extrusion blow moulding
Multilayer co-extrusion
Compounding
Injection moulding
Multi-shot moulding
Mesh/Netting

8. Typical of Energy Cost in Polymer Processing Site
Operation of machinery and ancillary equipment – 90% total energy bill

9. Energy Usage In Extrusion Blow Moulding Unit Processes

10. Energy Usage in Sheet Extrusion Unit Processes

11. Energy Usage in Injection Moulding Unit Processes
All Electric – 30% Energy savings over Hydraulic

12. Energy Use at a typical Profile Extrusion Plant

13. Comparison of Average Specific Energy Consumption, kWhr/kg /hr
SEC dependent on;
Unit Processes
Production rate
Polymer Type

14. Current Sources of Energy Usage in Polymer Processing
Operation of machinery and ancillary equipment – 90% total energy bill
Materials and energy costs are greatest expense to companies
Polymer Processing (motors and barrel heating ) 66%
Compressed air 10%
Chillers 10%
NIPA Invited Speakers today on;
Chillers, Heaters, Smart heat barrels and screws
Challenges –we use a wide range of polymers – with different melting temperatures- different
viscosities- processes -

15. Polymer Materials
To manufacture products with performance and appearance at most competitive cost
We process correct polymer using optimum processing conditions.
In order to achieve this we use a wide variety of polymers with different chemical structures and additives
1. Commodity polymers -- PEs PP PS PVC
2. Engineering polymers --PA ABD POM PC Peek PPS PET PBT PVdf
3. Thermoplastic Elastomers -- (TPEs) TPOs PU Silicones
4.. Co-polymers -- LLDPEs, block and random PP/PE copolymers, ABS
5. Polymer Blends
6. Wide range of additives to improve processing and product performance and appearance
7. Wide range of different molecular weight polymers and MWD( catalyst type)
8. These polymers have different melting temperatures
9. Wide range of melt viscosities
We use Advanced Materials to provide solutions

16. Melting/Processing Temperatures Commodity Polymers
Polymer Melting Temp Processing
Temperature
LDPE 110ºC 190ºC
LLDPE 120ºC 210ºC
HDPE 135ºC 220ºC
PP 165ºC 230ºC
EVA 100ºC 170ºC
PP/PE Copolymers 120ºC 200ºC
PVC 180ºC 190ºC

17. Melting/Processing Temperatures Engineering Polymers
Polymer Melting Temp Processing
Temperature
Nylon 6 180ºC 260ºC
PET 230ºC 270ºC
PEEK 265ºC 360ºC
PC 150ºC 280ºC
PBT 220 ºC 270ºC
PA 66 230ºC 275ºC
PPS 190ºC 350ºC

18. Specific Energy Consumption of Polymers
Dependent on Polymer thermal characteristics
Heat transfer coefficients, thermal conductivity, specific heat, enthalpy of
melting etc.
Semi -crystalline Polymers
PP, PEs, Nylons, PET etc.
Amorphous Polymers
Polystyrene, PVC, PC etc.

19. Heat transfer to the polymer in an extruder
• Extruder Motor
• Screws
• Barrel
• Heater bands
• Breaker Plate
• Screen Packs
• Melt temperature/ pressure
• Heat Transferred by both conduction and extruder screw shear
.cγ
Heater bands Screw
Breaker Plate
and
Screen Pack
Die
Meterin
g
section
Compres
sion
section
Feed
section
Feed
Hop
per
Drive
Barrel

20. Extruder zones
Feed section
This zone accepts the granules from the hopper, preheats them and conveys them to the next section. The screw depth in this
section is constant
Compression section
The screw depth decreases in this section squeezing any air back out through the hopper and giving a melt free from porosity.
Metering section
This section homogenises the melt and meters it through to the die at a constant rate, with uniform temperature and pressure.
The screw depth is constant.

21. Mechanism of Polymer Flow in a single screw extruder
Feed Section
In the first, or solids conveying, zone of the extruder the solid polymer particles are compacted together in the screw channel by the
rotating action of the screw to form a solid bed of material.
Compression Section
At the start of the next extruder section, the plastication (melting) zone, the barrel heaters cause a thin film of molten polymer to
form in the gap between the solid bed and the barrel wall. The melt film is subjected to intense shearing in the thin gap, causing a
rapid temperature rise in the material.
The generated heat melts the solid bed within a short distance of the start of melting.
Metering Section
In the last zone of the extruder, the metering section, the polymer melt flow is stabilized in the shallow screw channels, and finally the
material passes out through the die on the end of the machine
The extruder conveys a well mixed polymer melt with a constant viscosity to forming dies tools etc.

22. Barrier Screws
Barrier screws have a second flight added which splits the channel into two; a solids channel and a melt channel. The screw’s feed
channel connects to the solids channel and the melt channel connects to the metering section.
At the beginning of the barrier section a barrier flight is introduced into the screw channel. The clearance between the barrier flight
and the barrel is generally larger than the clearance between the main flight and the barrel. The barrier clearance is large enough
so the polymer melt can flow over the barrier; but it is too small for solid particles to pass over. This causes a phase separation
with the solid bed on one side and the melt pool on the other.
This design ensures better melting and also increases mixing capabilities

23. Polymer Melts are non-Newtonian Fluids
Many fluids not ideal.
Viscosity varies with shear rate
Therefore the term viscosity must be related to a particular shear rate
Polymer melts are pseudoplatic Fluids (Time independent)
1.Viscosity decreases with increasing shear rate. *
2.Examples.
3.Shear Thinning – (Explanation)
4.Various flow regimes in pseudoplastic fluids.
•Apparent viscosity μa read from rheogram.
Polymer Melt Flow

24. Typical rheogram showing the effect of shear rate on polymer viscosity
( shear thinning)
Typical shear rates
Rotational 0 sec-1
Extrusion 100-300 sec-1
Injection 1000-4000 sec-1
•

25. Experimental Characterisation of Non – Newtonian Fluids
1. Tube Viscometry.
2. Rotational viscometry.
- Cone and plate.
- Concentric cylinders.
3. Melt flow indexer (MFI).
4. Melt rheometer - Single barrel -- Dual barrel.
5. Torque rheometer.
6. Dynamic rheometer.

26. Melt Flow Indexers
1. Description of equipment.
2. Different operating conditions for different polymers.
3. MFI is defined as the weight in grams extruded in 10 minutes g/10min
4. Extruded through a standard capillary at standard temperature and load.
5. Limitations but useful for grading polymers.
6. 190oC PEs -- 210oC PP --300 PC

27. Dual Capillary Rheometers
The most versatile of all rheometer for polymer rheology; shear rate range up to 10-6
sec-1
.
Description of equipment.
Shear stress, shear rate and temperature control.
Shear rate
Shear stress
Viscosity
Single capillary – corrections. Rabinowitch and Bagley correction factors
Therefore if you know (i) dimensions of your die/tool channels
(ii) Pressure (p) and (iii) Throughput (Q gms /sec) then you know viscosity of the polymer melt
3
4
r
Q
π
γ =
L
pr
2
=τ
LQ
rp
Q
r
L
rp
842
43
ππ
γ
τ
µ ===

28. Factors Affecting Viscosity
1. Temperature.
2. Pressure.
3. Molecular weight.
4. Molecular weight distribution.
5. Additives.
Effect of temperature on viscosity
Viscosity decreases with increasing temperature – density lower – more intermolecular space
available.
1. Some polymers are more sensitive to temperature change than others – activation energy
of flow.
2. Arrhenius relationship: U = A eE/RT
.
3. Williams Landel and Ferry – Viscosity of a polymer at a certain temperature is related to
Tg.
1. See Activation Energy table.
•
( )
( )
EquationWLFLog
g
g
TT
TT
U
−+
−
−=
66.51
44.17
13

29. Effect of Molecular Weight on Viscosity.
1. The most important effect controlling viscosity.
2. The longer the chain, the more intermolecular contact and entanglements.
3. Beuche Relationship between melt viscosity and molecular weight ;: Uo = K mw
3.4
.
4. With increasing shear rate, 3.4 decreases as increases
5. Molecular weight distribution

30. Effect of Additives on Viscosity
Plasticisers and flow promoters ( liquids waxes ) decrease the viscosity of polymer melts
Viscosity decreases with increasing content – density lower – more intermolecular space available
Flow promoters - 1- 3%
Plasticised PVC 5- 40% -plasticiser level related to shore hardness

31. Extrusion processing conditions
Vitally import to achieve correct viscosity of polymer melt before the die
Normally achieved by in house trails to establish SOP
Barrel and die temps and barrel pressures
Melt temperature/ pressure
Well established SOP conditions so no change ??
However perhaps we can still achieve correct viscosity in a much more energy efficient way
.cγ
Heater bands Screw
Breaker Plate
and
Screen Pack
DieDrive
Barrel

32. Mica Band Heaters (used on dies)
They consist of a nickel chromium resistance wire
(80% nickel, 20% chromium) wound onto a mica sheet
and protected by a metal sheath made of brass, steel or stainless steel.
Ceramic heaters (used on barrels)
A nickel chromium resistance wire (80% nickel, 20% chromium)
or any other adequate resistive material is coiled and inserted
into articulated ceramic knuckles. A heat shield located in between ceramic
knuckles and the outside metal sheath protects the outside structure
of the band heater while directing the heat to the centre of the heater.
Aluminium or bronze cast band heaters
One or more tubular heaters are coiled into a cylindrical or
half-cylinder shape and cast into bronze or aluminium.
Those heaters are designed for applications in difficult environments
and applications requiring very good reliability and good heat distribution.
Cartridge heaters
are used when it is not possible to use band or cast heaters,
i.e. in clamp rings, adaptors Care should be taken that the heater fits tightly
into the slot otherwise it can easily burn out
Conventional Heaters

33. Conventional temperature thermocouples
• Melt temperature is usually measured by thermocouples situated
• against the actual melt in ports drilled through the barrel and die walls.
• The tip of the probe is flush with the barrel and die surface
• in order to reduce hang-up degradation and wear on the
• thermocouple.
• It should be noted that the melt temperature reading
• will be related to the temperature of the surrounding
• metal surface.
• The melt temperature towards the centre of the
• melt stream will usually be a few degrees higher.
• Must be well positioned and mounted
• Pressure transducers
• Melt pressure is usually measured by transducers situated against
• the actual melt in ports drilled through the barrel and die walls.
• By fitting pressure probes before and after the breaker plate
• it is possible to constantly measure the differential pressure
• and hence the degree of blocking or contamination of the screens.
• Alarms can be set to shut down the machine in cases of high pressure

34. Energy saving in extrusion heater bands
Barrel and die heaters most important condition controlling viscosity
RMG USA New Mica Heater bands with ceramic fibre filled insulation-
less heat escapes to air savings of approx
20-30% on power consumption
New - Rex TCS products
Bonded ceramic fibre insulation
savings of 60% on energy
Induction heating Xalloy RMG USA
Injection moulding not yet on extrusion

35. Reducing energy in extrusion processes new developments locally
1. By Improved on-line automatic Extrusion Control system
2. Preliminary system funded by and developed at PPRC 2011 -2012 (Bo Kha, Clarke, McNally )
- real time using pressure measurements and algorithms to develop software and automatic control
3. By Supercritical additives to reduce processing temps by up to 20-30oC
NIPA Innovation Voucher – commencing January 2014 – NIPA Process capability SIG

36. Summary
Commence company Energy strategy and monitoring protocols immediately
Investigate improved energy efficient barrel heater bands
Improve overall insulation of barrel and dies
Formation of NIPA Energy SIG to research develop improved energy efficient processing
Industrial R&D programme Invest NI

37. Closing Information