paul bullock & dr. jens spirgatis session 14.2 / 7691€¦ · paper 7691 paul bullock / dr....

New Developments in the extrusion of biopolymers

Paul Bullock & Dr. Jens SpirgatisSession 14.2 / 7691

Paper 7691 Paul Bullock / Dr. Jens Spirgatis 2


• What are biopolymers? • What are the differences bio to biodegradeable?• What advantages can these resins offer? • Can they be processed like oil-based polymers?



• 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



• 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



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%)



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



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



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



Compounding: reactive extrusion

Die-face air granulation / under water pelletizing



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)



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)



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)



• 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



3-layer Blown Film Line with IBC



Extruder with AC-driveand high output barrierscrew



3-layer Blown Film Die Headbasic lay-out 1:1:1 up to 1:3:1



High performanceair cooling ring



• 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



Extrusion

Casting Unit

Blending



• 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



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



Casting Unit• motorised positioning

of casting unit in height and longitudinal direction

• high accurancy(± 1 °C) of thecasting roll‘s surface


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


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


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.

paul bullock & dr. jens spirgatis session 14.2 / 7691€¦ · paper 7691 paul bullock / dr....

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