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New Developments in the extrusion of biopolymers
Paul Bullock & Dr. Jens SpirgatisSession 14.2 / 7691
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 2
New Developments in the extrusion of biopolymers
• What are biopolymers? • What are the differences bio to biodegradeable?• What advantages can these resins offer? • Can they be processed like oil-based polymers?
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 3
New Developments in the extrusion of biopolymers
• Bioplastics are generally understood as either: • Plastics made of renewable raw materials (converted to
biodegradable or non biodegradable products) or biodegradable plastics made of renewable or fossil raw materials
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 4
New Developments in the extrusion of biopolymers
• In Europe the biodegradability of products is defined by the standard EN 13 432, according to which the degradation process takes place between 6 and 12 weeks and meets the current requirements of composting plants
• Not all bioplastics are biodegradable but have otheradvantages. e.g. weight saving in reinforced plastics(automotive), improved mechanical and physicalproperties
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 5
New Developments in the extrusion of biopolymers
Internal structure of BIOPAR® materials: influence of formulationComparison of structure and morphology inside BIOPAR®- pellets in dependence on content of compatibilizer and plasticizer
BIOPAR® - Compound: potato starch in combination with Ecoflex
With compatibilizerHigh content of plasticizer (> 15wt%)
BIOPAR® - Compound: potato starch in combination with Ecoflex
No compatibilizerLow content of plasticizer (< 8wt%)
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 6
New Developments in the extrusion of biopolymers
Compound:
• potato starch in combination with Ecoflex
• No compatibilizer
• Low content of plasticizer (< 8wt%)
Film formed from the Compound
• a lot of cracks inside the material
• no adhesion between starch and Ecoflex-phase
• Tear resistance: 2.100 – 2.700cN/mm
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 7
New Developments in the extrusion of biopolymers
Compound:
• potato starch in combination with Ecoflex
• with compatibilizer
• high content of plasticizer (> 15wt%)
• Film formed from the Compound
• a lot of layers of starch and Ecoflex
• good adhesion between starch and Ecoflex-phase
• Tear resistance: 26.000 – 28.000cN/mm
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 8
New Developments in the extrusion of biopolymers
BIOPar®
• Compounding: production process by a reactive extrusion•
Native potato starch
Synthetic, biodegradable
Polymer,e.g.
Polyester
Compatibilizer and additives
extruder
mixing / chemical reaction
catalyst
BIOPAR®- granulate
• direct gravimetric dosing of components • reactive extrusion using twin screw extruder• processing temperatures: between 120 and 180°C
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 9
New Developments in the extrusion of biopolymers
Compounding: reactive extrusion
Die-face air granulation / under water pelletizing
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 10
New Developments in the extrusion of biopolymers
Mechanical properties of the filmsProduct form: blown filmThickness: 15 – 200µm
Mechanical properties:Tensile strength 20 – 30MPaElongation at break 300 – 1200%E-Modulus 50 – 250MPaTear resistance 15.000 – 30.000cN/mm
Dart impact strength (Dart-Drop) up to 12J/mm²
Film stretched in monoaxial direction: LDPE
Mechanical properties, MDTensile strength 60 – 80 Mpa (DIN 53 455) 22MPaElongation at break 200 – 250 % (DIN 53 455) 300%E-Modulus 30 – 50 Mpa (DIN 53 455)
Mechanical properties, CDTensile strength 20 – 25 Mpa (DIN 53 455) 15MPaElongation at break >1000% (DIN 53 455) 700%E-Modulus 40 – 60 Mpa (DIN 53 455)
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 11
New Developments in the extrusion of biopolymers
Permeation properties of the films
Sample Water Vapour Transmission Rate
(WVTR) (g/m2.day.100µm at
60%RH)
Oxygen - permeation(cm³/m².d.bar)
Mono film70 – 100 2 – 12 (23°C, 40% RH)
540 – 700 (23°C, 85% RH)
Multi layer film10 – 35 30 – 200 (23°C; 40%RH)
540 – 620 (23°C; 85%RH)
Ecoflex FBX 7011 40 700
LDPE 0,7 - 1) 2000 (23°C, 85% RH)
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 12
New Developments in the extrusion of biopolymers
Applications1. Films for packaging (shopping bags,
magazine packaging)
2. Films for garbage bags for compostablewaste
3. Films for agriculture (mulch films)
4. Yarns for nets (for fruit and vegetable packaging)
5. Binding strings for farming and Geotextiles
6. Coating for paper, cardboard, textiles
7. Injection moulded components for agriculture and forestry (plant pots, trays)
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 13
New Developments in the extrusion of biopolymers
• The resin can be run on conventional equipment withlittle modification
• Extrusion temperatures much lower than normal forPE/PP
• Barrier screws give best results – 3-zone screws not so good
• Conventional blown film dies and air cooling rings work• Very high throughputs can be reached: 390 kg/ with
300mm die insert, die factor around 1,40
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 14
New Developments in the extrusion of biopolymers
3-layer Blown Film Line with IBC
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 15
New Developments in the extrusion of biopolymers
Extruder with AC-driveand high output barrierscrew
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 16
New Developments in the extrusion of biopolymers
3-layer Blown Film Die Headbasic lay-out 1:1:1 up to 1:3:1
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 17
New Developments in the extrusion of biopolymers
High performanceair cooling ring
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 18
New Developments in the extrusion of biopolymers
• Barrier screws give best results in cast film extrusion• Conventional die and feed blocks give good results• Pressure must rise constantly along screw length –
pressure drops are fatal!• The „damp“ nature of the film means special attention
must be paid to edge pinning• Controlled cooling down to processing temperature
required – deposits, frozen polymer
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 19
New Developments in the extrusion of biopolymers
Extrusion
Casting Unit
Blending
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 20
New Developments in the extrusion of biopolymers
• low-noise operation due to watercooling
• no raising of dust because of watercooling system
• almost maintenance-free
• allows almost every desired fittingposition
• about 30 % less space requirement
• energy savings approx. 5-10 %
• screw extraction from the front orthrough the motor
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 21
New Developments in the extrusion of biopolymers
Coextrusion Feed Block• inline gap adjustment for the
middle and core layer
• inline profiling of each layer
• all adjustments are possibleduring production
• central adjustment forparallel gap adjustment
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 22
New Developments in the extrusion of biopolymers
Casting Unit• motorised positioning
of casting unit in height and longitudinal direction
• high accurancy(± 1 °C) of thecasting roll‘s surface
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 23
New developments in the extrusion of biopolymers
Chances in processing of BIOPAR®
• High outputs are possible on existing extruders• The extruded films have good mechanical properties• The films can be converted easily into end products• The resin has in principle excellent barrier properties
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 24
New Developments in the extrusion of bioploymers
Risks in processing the resin
• Risks include• Problems to stabilise the extrusion process• Danger of gels• Die lip build-up in cast extrusion• Capacitive thickness measurement not possible in
blown film lines• Unresolved challenge of finding tie layer resins for
coextrusion to LDPE or L-LDPE – varying melttemperatures
Paper 7691 Paul Bullock / Dr. Jens Spirgatis 25
New Developments in the extrusion of biopolymers• Summary
• This biopolymer runs well on conventional extruders
• The resin uses about 2/3 less energy
• It has good barrier to oxygen and gases
• It biodegrades according to DIN 13432
Special thanks to BIOP, Dresden for helping to createthis paper.