Biodegradable plastics from renewable resources Sergio Bocchini
Innovation in the field of polymeric materials: research on new materials The driving force for research in biopolymers are: the fear of a possible significant rise in prices of petroleum products law enforcement that can made obligatory (for some applications) or encouraging their use the growing issues related to the waste recovery generated by fossil polymers
WASTE RECOVERY ISSUES Fossil fuels Convent. polymers (PP, PE, PS, PVC) Use Dispersion in the environment Not degradable wastes Landfill Waste combustion Global environmental issue Recycling Development of green polymeric materials
Landfill disposal It was used in the past because simple and economic. In the 1999 (APME 2002) 8,4 millions of tons were disposed using landfills Because of hygienic problems and landfill exhaustion, CEE is trying to disincentivate this methodology (Landfill Directive European Commission 1999/31/EC In the case of biopolymers, there are some problems due to methane emission (a gas far more harmful than CO 2 from environmental point of view) in anaerobic biodegradation J.H.Song et al. Puil. Trans. R. Soc. B 2009 364, 2127
Waste combustion for energy recover In 2002 in EU 40 million tons were burned with energy recovery in 230 incinerators It is considered quite good view because the plastic material has a GCV (gross calorific value) is comparable to or greater than that of coal This system, however, is widely criticized In principle it should be good also for biopolymers however there are no data of GCV of biopolymers. J.H.Song et al. Puil. Trans. R. Soc. B 2009 364, 2127
Recycling This technique is growing in the field of polymers from fossil resources. The goal is to "dignify" the waste, to make them suitable for applications including high-level in substitution of the virgin polymers Biopolymers can be recycled using traditional technique Actually the lack of specific plants, can create problems in the cycle of recycling petrochemical polymers
Biopolymers Taking into account the previous argument the biopolymers are an area with great potential development potential because they combine high Technical potential Eco-sustainability, form the resource point of view and the end of life
Biopolymers Based on a marker analyses of Hannover University (Dept. of Bioprocess Engineering), it was estimated that in the 2007 there were already 26 commercial producer of biopolymers and many other were active from the R&D point of view. About 60 society were active in the biopolymers sector (Bioplastics Magazine (03/07) Vol.2 pag 31) In a more recent study (2009) of bioplastics24.com 32 producers of biopolymers were reported (Bioplastics 09/10: processing parameters and technical characteristics a global overview) On Material Data Center (www.materialdatacenter.com) about 50 producer are cited
Biopolymers Despite the growing interest in the market for biopolymers, there is still some confusion regarding the definition of "biopolymer. This can lead to misunderstandings and errors in objective assessment on the market prospects and also, from the legislative point of view. therefore it is appropriate to give some definitions.
Biopolymers - Definition On the basis of European Bioplastics Association Biodegradable Polymers with compostability approved on the basis of EN 13432 The source (renewable or fossil fuel) is not important Polymers based on renewable source They should be biodegradable or not
Biopolymers Both categories presents some environmental benefits: Biodegradable polymers allow the disposal of products in composting plants without leaving residues and fragments The polymers from natural resources are "zero carbon foot print". All the CO 2 released at the end of the life cycle is "captured" by the new cultures in the following season
GLOBAL CARBON CYCLING THE ECO DRIVER CO 2 Biomass/Bio-organics Bio-chemical Industry 1-10years > 10-6 years Polymers, Chemicals & Fuels Chemical Industry Fossil Resources (Petroleum, Natural gas) Renewable Carbon CO 2 & Biomass Polymers Biochemical Industry Small, entreprenuerial business Green Polymers & Chemicals
Carbon foot print: kg CO 2 for 100 kg of plastics Intrinsic value proposition for bio feedstock R.Narayan 1^PLA World Congress, Munich 2008
Biodegradation ad legislation There are specific regulations, set by major international organisations (ISO, CEN, ASTM, DIN, Green PLA) for different applications and systems at the end of life
Biodegradation and Standards Knowledge of regulations on the biodegradation and compostable is very important for the development of biopolymers because: biodegradation can occur in very different environments This could generate errors and misunderstandings between manufacturers, customers, Associations Unlike other applications, the manufacturer finds it hard to carry out controls.
Standards as a communication tool Authorities Standards Producers Users
Biodegradation and Standards Biodegradation is a process in which substances and materials can be assimilated by microorganism and be so placed in the natural cycle. (according to Standard UNI CEN/TR 15351-07) The microorganisms that are present in every environment and assimilate organic waste play an important role in the biodegradation.
Biodegradation and Standards PRODUCT USE/DISPOSAL CONTROLLED UNCONTROLLED WASTEWATER SOLID WASTE OPEN WATER SOIL MARINE AEROBIC TREATMENT ANAEROBIC TREATMENT ANAEROBIC STABILIZATION COMPOSTING BIOGASIFICATION LANDFILL USE OF COMPOST IN SOIL C.Bastioli Handbook of Biodegradable Polymers, RAPRA
Biodegradability Order of aggression with regard to biodegradation in different environments Compost Soil Fresh Water Marine Water T + fungi + fungi + bacteria diluite bacteria bacteria bacteria C.Bastioli Handbook of Biodegradable Polymers, pag 165, RAPRA
Biodegradability The conversion reactions of organic carbon are different depending on whether the degradation occurs in aerobic or anaerobic environment Aerobic Biodegradation C POLIMER + O 2 CO 2 + H 2 O + C RESIDUE + C MICROBIC Anaerobic Biodegradation C POLIMER CH 4 + CO 2 + C RESIDUE + C MICROBIC Nota: C MICROBIC carbon incorporated in the (chemical compound, molecoles) of cells C RESIDUE carbon not yet degraded C.Bastioli Handbook of Biodegradable Polymers, pag 151, RAPRA
For regulation a material is biodegradable if : 1. It can be biodegraded in a microbiologically active environment 2. It does not introduce toxic substances in the environment 3. The concentration of heavy metals of tested material is less than one half of the corrisponding limit for the compost The biodegradation tests should be performed in parallel to the tests of biodegradation of a reference sample consisting of pure microcrystalline cellulose or from polycaprolactone
Biodegradation curve
Biodegradability - definitions Regulations give different definition of biodegradability taking into account Primary and last Biodegradability Presence of oxygen (aerobic and anaerobic biodegradability)
Biodegradability - definitions Primary Biodegradability (ISO regulation) : structural change (transformation) of a chemical compound by microorganisms, resulting in the loss of a specific property last Biodegradability (EN 13432) : Decomposition of an organic compound by microorganism, in presence of oxygen, in carbon dioxide, water and mineral salts and whatever other element (mineralization) and new biomass or, in absence of oxigen, in carbon dioxide, methan, mineral salts and new biomass.
Biodegradation It is a process than happen, usually, in two different phases: 1. Degradation Fragmentation: the action of moisture, heat, UV, and/or enzimes riduce molecular chains and the resistance of the polymer, the compounds are fragmented 2. Biodegradation: the fragments are consumed by the microorganisms as food source and energy and converted in CO 2 and H 2 O, the speed should be compatible with the environment times: Plastic Fragments CO 2 Plastic Plastic Fragments Microbs H 2 O Plastic Fragments Humus BPI Biodegradable Product Institute confused by the terms Biodegradable & Biobased
Biodegradation The rate and level of biodegradation is highly dependent on the environment in which the material is deposited : Moisture content (from waster with high water content) Oxygen presence ( aerobic or anaerobic environment) Temperature (high for compost, low for soil or in water) Microorganism concentration (high in waste treatment plants, low in sea water) Salt concentration Rules which provide all of these cases have been drafted
Overview of the main ISO standards Biodegradation standards Aerobic Tests Anaerobic tests In acqueous media soil In acqueous media ISO 14853 High solid ISO 15985 CO 2 developed ISO 14852 O 2 Demand ISO 14851 Developed CO2 Compost ISO 14855 Mineral bed Composting ISO 14855 emenda Soil ISO 17556 Other tests: marine environment (solo ASTM 5437 e 6691)
Other biodegradation rules There are specific rules (especially ASTM) to simulate the process of biodegradation in different environments landfill (ASTM D 5526-94). In landfill the biological activity is very low compared to compost and substrates for the production of biogas (for the lowest concentration of microorganisms) In Sea (ASTM D5437-93 o ASTM D 6691-01 ASTM D 5209). These rules are interesting for specific applications (such as fishing lines, nets, disposable materials for boats and so on..) Resistance to mushrooms, bacteria
Recapitulation of the main ISO standards Of great significance are the standards for assessing the biodegradability in solids, both in compost that in soil, to evaluate the possibility of disposal is composting plants directly on the ground (mulch film, home composting, etc.). The biodegradation levell is independent from the shape and the dimension of the material for testing. However, the time to reach the level required by the rules of biodegradation depends on these factors. Consequently, if tests are conducted on different types of materials it is necessary that the shape and size of the samples are similar. In the case of powder particle size should be the same.
Compostability Compostability can be defined as a specific form of degradation that occurs in both industrial and home composting facilities. It is particularly important for the possibility of disposing of waste, especially from those derived from packaging or agricultural use. In particolar:
Compostability The composting process is the transformation of organic wastes in carbon dioxide, water, biomass and heat By action of microorganism normaly present in the environment (biodegradation). The process happens in dedicated plants that should insure the right developing of the process During the process the compost reaches 60-70 C, with a moisture content of about 50-60%RH.
Composting At the end of the process the initial waste is transformed in a substance called compost, The smell and the appearance is of a fertile soil sanitized and stabilized as it has no pathogenic microbes (for humans and plants, insect larvae and weed seeds) and putrescible material, through the action of temperature
Composting In the composting plants this phenomenon is controlled and optimized in order to : Obtain high conversion rate, Effluent control, Final compost quality control, and so on
Composting To ensure a good composting process certain factors should be stable : Size of composting material: pregrinding is used to have good areation and easy release of CO 2 (average particle diameter between 0.5 and 5 cm) C/N Ratio Low ratio the process releases an high amount of NH 3 and there is a reduction in performance, For too high value the process slows down or stops for lack of elements necessary for microbial growth. (ISO 16929 between 20 and 30, according Piemonte Region between 15 and 40). The moisture content should be higher than 50%
Compostabily During the grinding, packaging and other objects in biopolymer present in compost should not interfere with the machinery and processes commonly used in composting plants. The size of the fragments obtained must be appropriate for the composting process
Composting Composting is a process that leads to significant benefits: Use of waste materials, derived from agriculture, urban and industrial waste, which, if not reused, can be harmful to the environment Return to the soil of organic matter that allows a return in terms of fertility in the medium and long term Allows a significant saving of chemical fertilizers by using the content of nutrients (N, P, K) in the compost
Level of biodegradability and compostability UNI EN Biodegradability 13432 (ISO 14855. or ISO 14852 and ISO 14851) The acceptance level is 90% to be achieved in less than 6 months Disintegrability * Samples of the test material is composted together with organic waste for 3 months. The mass of the residues of the test material with size> 2 mm must be less than 10% of the initial mass. * See ISO 14045
Compost quality Should not discharge toxic substances into the environment The compost is analyzed in the typical physical and chemical parameters as ph, salt content, density, N2, ammonium nitrogen, P, Mg and K Tests with life forms : Determination of germination by the method described in- UNI 10 780 Annex K Determination of acute toxicity on earthworms by the method described in ISO 11268-1
Final biodegradability Standard ISO 14855 ASTM D 6002 JIS K 6953 ASTM D 5338 (ISO 14855)
Test method to determin compost quality Standard EN 13432 ASTM D 6400 Test method Ecotoxicity test with not less than two types of plants. In accordance with OECD Guideline 208. Ecotoxicity test with cress and at least two other types of plant is to be conducted in accordance with OECD Guideline 208 Chemical characterisation of the compost: Volumetric weight, total dry solids, volatile solids, salt content, ph-value Nutrient content (N, NH 4 - N, P, Mg, Ca)
Major Production Systems of Biopolymers from Renewable Source 1. Use natural polymers that can be modified, but remain basically unchanged (eg. Polymers from starch, cellulose) 2. Fermentation to produce biomonomers which are then polymerized (eg. PLA) 3. Produce biopolymers directly in microorganisms (eg. PHA). 4. Produce monomers and polymers from bio-monomers fossil The second of these systems is gaining importance, the third, although there are first experimental productions, seems to be still far away from mass production. In the quarter, many companies are investing (eg. BioPET coca-cola)
Some examples of biodegradable material from renewable raw material(1) Starch Collection treatment of corn to extract the starch Starch destructuration and addiction of a polyester to increase mechanical properties ACIDE POLYLACTIQUE (PLA) Starch destructuration to form glucose Collecti on treatment of corn to extract the starch Convesion of glucose to form lactic acid Lactic acid polymerisation
Some examples of biodegradable material from renewable raw material (2) POLYHYDROXYALCANOATES (PHA) Bacteria «Ralstonia eutropha» Use of biopolymer as energy stock Fermentation of sugar into polyesters Cell disintegration, formation drying polymer extraction with solvents Object made in PHA CELLULOSE ACETATE
Biopolymers / Biobased Polymer Renewable Resource-based Microbial syntetized Petro-based syntetic Petro-Bio (mixed) Sources Polylactic acid, PLA Starch plastics Cellulosic plastic Soy-based plastic Polyhydroxy alkanoates, PHA Polyhydroxybutyrate co-valerate, PHBV Aliphatic polyesters Aliphaticaromatic polyesters Polyester- PTT Biobased Polyurethane Biobased epoxy amides Blends etc Polyvinyl alcohols
Hybrid Polymers The increasing demand for biopolymers and the lack of capacity to meet demand is pushing towards the production of hybrid materials, that is obtained by mixing a biopolymer and a polymer fossil.
Hybrid Polymers This approach, according to the manufacturer, allows substantially reduce the use of petrochemical raw materials and environmental benefits in terms of reducing CO 2 emissions in the life cycle of the product Toyota and other Japanese companies are developing this concept for parts that require higher performance are not intended for composting. This approach must be carefully evaluated because, even if it favors the development of polymers from natural resources, can create problems at the end of life. These materials, in fact, are not compostable nor recyclable if it can create problems with the existing lines
Hybrid Polymers Society Trade mark Biopolymer Petro-polymer Cereplast Cereplast Hybrid ResinTM TPS PP Cerestech Cereloy Eco TPS HDPE,LDPE, LLDPE, PP CardiaBiopolymers Cardia Biohybrid TPS Polyolefins Bayer Makroblend BC PLA PC PMTC EcoHybrid PLA/PHB PP, PTU, PETG RTP RTP Hybrid PLA PC, PMMA, or ABS PolyOne Resound PLA/PHA Poliesteri Different
Exaple Cerestech Cereloy ECO PP 50% PP 50% Starch PP 0,9-0,915 165-160 1300-1500 30-40 > 50 41-38 Ref. www.cerestech.com
A bit of history It 's interesting to underline that the biopolymers are on the market for a long time, some dating back to the origins of the development of this sector. The "celluloid" was invented in 1868. The first synthetic polymers were based on natural resources. Among the biopolymers from renewable resources "historic" include the types of cellulose, nylon 11, and the natural gums. Polycaprolactones and EVOH among biodegradable polymers have been developed since many years.
A bit of history With the development of cheaper technologies based on fossil resource, biopolymers had gradually lost its importance. In the '70s, after the first oil crisis, a new game was intense R & D to develop new classes of biopolymers, mainly for the packaging industry.
STARCH Collect Extraction of starch from corn Destrutturation of starch for recombination with a biodegradable polyester
Starch Starch is a carbohydrate (polysaccharide) found in many plants (corn, potatoes, wheat, etc..),widely available in nature. The annual production of starch is about 35 Million Tons of Half of U.S. Commercial use of starch hydrolyzed not food use food use
Amylose a): linear polysaccharide; Amylopectine b): branced polysaccharide
Structure and composition of starch particles in fuction of different vegetables K. Morawietz Bioplastics Conference 28/07/2007 Alessandria Italy
Starch Starch is present in the form of granules due to the strong intermolecular bonds between the hydroxyl groups. These supramolecular structure should be destroyed in order to use the starch as a thermoplastic material through different types of reaction. In most cases, the starch is then mixed with other polymers to obtain materials that are easily processable.
Starch plasticization
Polymers derived from Starch As a consequence, the polymers from starch can be very different : Polymers from pure starch (used as filler); Polymers from partially fermented starch; Polymers from destructured starch; Polymers from modified starch (sostitution of OH grups with ester or ether groups); Polymers from blend of starch with other polymers (polyesters, CPL, CA, PVOH). The blends obtained could be da flexible such as come PE or rigid such as PS. This makes it very difficult to make a comparison between the different grades or give indications of the properties. The differences between the different types are extremely high.
Blending with other polymers requires a careful study for formulation in order to obtain a good dispersion between phases (see picture below)
Main producers Producer Product Capacity [ton] Espansion Novamont Mater-Bi 35.000 80.000 Biotec / Sphere Bioplast 15.000 50.000 (up to 200.000) Biop Biopar 17.000 65.000 (2012) 95.000 (2015) Rodenburg Solanyl 40.000 Végéplast Végémat 10.000 50.000 (2010) Plantic Plantic 3.000 10.000 Biograde CardiaBioplastics? Cereplast Cereplast Compostable 10.000
Other producers Producers Ever Corn (Japan Corn Starch) Limagrain Ventura Supol Potatopack Harbin Livan Biodegradable Product Product Ever Corn Biolice Floralat Supol Potatoes Livan
TPS with natural fibres Ventura produces a material called "Floralat" based on starch reinforced with natural fibers. In this way they can reach values of form about 4,000 MPa. Elastic Modulus [MPa] Floralat + 10% filler 4022 Floralat + 30% filler 4234 Stress at break [MPa] 34,8 33,5 Strain at break[%] 1,5 1,6 Density [g/cm 3 ] 1,34 1,34
Polymers from Starch The 75% of polymers from starch is used for packaging the other 25% in agricolture The quote of polymers from starch with respecto to the other biopolymers was evaluated as 75-80% (Ref. Utrecht University/Fraunhofer ISI) An interesting application is the use of starch as a filler in tire manufacturing (partial substitution of C black). The benefits in terms of noise reduction and less friction, resulting in lower consumption.
Other properties of polymers from starch Low barrier to water vapour Sensible to contact withh 2 O Low resistance to solvents Good barrier to oils and fat The barrier properties are highly variable depending on the formulation.
Polymers from starch processability The polymers from pure starch can be processed on thermoplastic lines after addition of plasticizers The modified polymers have better processability characteristics (depending on the degree of substitution, but lost in biodegradability) The blend with starch (usually polyester aliphatic / aromatic, PCL, CA, EVOH) and have better processability. It is processed in standard machines with minor modifications, eg. extrusion, thermoforming, blow film, injection molding, foaming
FILM PROPERTIES Low gloss, but discreet transparency Weldability on themselves or with other biopolymers, similar to that of PE and can be made at the same speed (Novamont) Excellent printability. According Novamont you can use water based inks or solvents without corona treatment Can be use for FFS (Form, Fill, Seal) Food approved Can be laminated on paper (hot glue, coating, extrusion coating or lamination) Possible lamination or extrusion coating
Barrier properties of films by litterature Novamont presents the data reported not to specific products, but the range in general. As you can see the permeability to O 2 covers the range from PET to HDPE C.Bastioli EPF School, Gargnano maggio 2009
Barrier properties Very interesting are the data submitted by Plantic. The TPS has been produced starting from high-amylose starch (80%), according to a patented technology.
MATER BI NF Film properties Temp melting C 110 Density gr/cm 3 1,29 MFI gr/10 min 3 σt MPa 22 Strain at break % 340 E t MPa 210 Res lacer MD/TD N/mm 36/46 Haze % 95 WVTR g30μ/m 2 24hr/90RH 850
Foam trays from starch polymer A very important application is that of the foam trays. They are soft and flexible with a density of 80-120 g/l. The packaging can be realized with stretch film machine using up Automac HFFS film, laminates, films of cellulose (UCB Naturflex).
Foam trays TPS L. Garavaglia AIM Polimeri da fonti rinnovabili Bologna 2005
Foam trays TPS L. Garavaglia AIM Polimeri da fonti rinnovabili Bologna 2005
L. Garavaglia Foam trays TPS
TPS applications Bags for solid waste collection and composting A. Castellanza AIM Polimeri da fonti rinnovabili Bologna 2005
TPS applications FOOD PACKAGING MADE IN MATTER B Nets for fruits and vegetables Bags for bread Transparent windows for bags Rigid foam trays
TPS APPLICATIONS
TPS APPLICATIONS Application in the agricultural field film mulching A. Castellanza AIM Polimeri da fonti rinnovabili Bologna 2005
M.Malinconico Mulching films
World consumption of plastic materials (tons) in agriculture M.Malinconico
M.Malinconico
TPS applications Pots for nursery
Starch destructuration (glucose formation) PLA Collect Estraction of starch from corn Fermentation production of lactic acid from glucose Lactic acid Polymerization
PLA (Polylactic acid) It was one of the first commercially produced biopolymers is available from several manufacturer it is a polymer with application versatility with performance comparable to those of petrochemical polymers (PP, PS, etc...) It is, however, a brittle material with low resistance to temperature It is easy to recycle with different technique (mechanic, chemical).
Biodegradability of manufact made in PLA The PLA is compostable, or biodegradable in composting conditions : temperature di 50 60 C in presence of high moisture level and microorganism in about 45 90 days At room temperature and out of the composting conditions, PLA is chemically and physically resistant to degradation, such as traditional plastic materials (PE, PP, PS, PET, etc....) When used in normal conditions PLA made objects are equally stable and free from contamination by biodegradation, as the objects made by traditional plastics.
PLA production For PLA there are suppliers of technology for production of the monomer and polymerization The groups Uhde Inventa-Fischer can provide technology and engineering for the construction of a plant for the production of PLA. The production cost is estimated at 1,4 1,7 / Kg (depending on the cost of raw material) for a capacity of 20,000 tons per year of PLA. Lactic acid polymerisation grade is produced by Purac, and Galactic
Lactic acid Lactic acid, the monomer for the production of PLA, is a natural compound present in all animals. It is used in food, cosmetics, pharmaceutical, It is included in the positive list of permitted monomers for plastics approved for food contact. It is produced by sugar fermentation
Lactic acid Acidification, Purification
Lactic Acid Lactic acid is chiral thus there are two diastereoisomet L- or D- Lactic acid obtained by chemical synthesis it is a racemic mix (50% D and 50% L) Fermentation, instead, is very specific and essentially allows the production of a stereoisomer (99.5% di L-isomer and 0.5% of D-isomer) As a consequence, the polymers may have a different relationship between the two stereoisomers and therefore different characteristics and crystallinity
PLA
Lactic acid Lactic acid polymerisation grade is produced from Purac, with a market share of 70%, and from Galactic. Purac has built a 110,000-ton plant in Thailand. Purac recently developed technology for the production of D-lactide (plant from 5000 t / y in Spain from August 2008) In 2007, Galactic has created a J.V. with Total Petrochemicals (Futerro) with the aim of building a plant for PLA production.
PLA production- 1 There are two main methods for producing polylactic acid from lactic acid monomer, which differ both in terms of chemical / equipment, and from that of the type of polymer obtained : Direct condensation polymerization ring-opening polymerization
PLA production- 2 Direct condensation polymerization : Waterremoval of water through condensation 1) with the use of a solvent 2) under high vacuum 3) at high temperature has the great disadvantage of producing only the value of a molecular weight polymers with low to moderate, due to the difficulty of completely eliminating water and other impurities.
PLA production- 3 However, there are studies for improvement of the limitations presented by this technique, the Japanese Mitsui Chemicals has in fact developed a new process based on the direct polycondensation of L-lactic acid to allow the production of PLA with high molecular weight without the use of solvents.
PLA production 4 ring-opening polymerization catalytic
PLA production - 5 As mentioned above, lactic acid is a chiral molecule, and subsequent ring-opening polymerization can produce different types of polymers, each with different properties : e.g. : in the case of high concentration of L lactide can be obtained crystalline polymers, while in the opposite case we obtain a more amorphous material.
PLA main producers Producer Product Production Capacity [ton] Expansion NatureWorks LLC Natureworks 140.000? Mitsui Lacea 500 Misun Biomaterial Revoda 5.000 Toyobo Bioecol 200 Futerro**?? 1.500 (2009) Unitika* Terramac compounding Teijin Biofront 200 10.000 Pyramid Bioplastics Pyramid 60000 (2010) Hycail Hycail PLA Pilot plant sell to Tate&Lyle Toyota Motors Toyota Ecopla 1.000 sell in the2008 a Teijin * Unitika is a compounder ** jv Total and Galactic
Manufact producers Manufact type Producer Fibers Kanebo Gohsen Teijin Unitika Films Treofan EarthFirst Film Mitsubishi Unitika Tohcello Laminated Kanebo Kasei
PLA producers Interesting developments are expected in Europe : In Italy in 2007 that created the Bio-on who is investigating the production of PLA from molasses and juices full of sugar cane and beet byproducts of other processes. The advantage is the low cost of these materials and their availability, not being used as food. Bio-On is also exploring the production of PHA An important agreement was reached between Total (through Petrofina) and Galactic (producer of lactic acid) to develop a production technology of PLA in a joint venture (Futerro).
PLA properties The properties can be modulated using the racemic form or co-lactic acid with other monomers Mechanical properties Tensile strength 50 60 MPa Modulus 3500 4000 MPa Strain 1 5 % Izod 12 20 J/m Thermal properties Tg ~ 60 C, Tf 140-180 C, Tc 95-120 C Vicat 65 C Above 60 C tends to degrade in the presence of moisture
PLA properties: a comparison
PLA properties Density 1,25 g/cm 3 Trasparent, with high gloss Good resistance to UV Good barrier properties for smell moderate to O 2, CO 2, acqua, Weldable with different technique (hot, with ultrasounds, with RF ) Excellent behavior in permanent torsion and bending (dead fold) Can be used in contact with food
Trasparency (%) Comparison PLA vs. Competitors Trasparency 100 98 96 94 92 90 88 86 84 82 PP alta trasp. SBS OPS A-PET PLA Materiale Luc Bosiers AIM 14 gennaio 2005 Bologna
PLA critical points As mentioned above, the critical points of PLA are: The low thermal resistance which makes it impossible to use for use with hot drinks, microwave, and ironing because of deformation of the artifacts in the transport The weakness that creates problems in thermoforming and film technology (breaks in the cutting, trimming, etc.). The low melt strength, which creates problems in blown film and in the process of foaming
Thermal resistance The PLA crystallizes very slowly and is therefore difficult to raise the level of crystallinity at speeds of conventional process. As a result, the thermal resistance remains low (around 60 C). The thermal resistance can be improved: accelerating the rate of crystallization nucleating heterogeneous or through the use of d-lactide, which acts as a seed of crystallization (stereocomplex), resulting in reduced molding cycles with the addition of natural fibers
THERMAL RESISTANCE According to Purac * d-lactide is much more effective than talc as nucleating agent and can considerably enhance The temperature of crystallization, Crystallinity level Crystallization rate. Consequently it improves the moulding cycle, that, according to Mazda, can be reduced to 1/5, and thermal resistance (T m 220-230 C) The same advantages can be obtained, according Unitika ** who developed this technique, with a heterogeneous nucleating agent. *1 European Bioplastics Conference, Bruxelles 21 novembre 2006 ** 2 European Bioplastics Conference, Parigi, 21 novembre 2007
THERMAL RESISTANCE The developed technology developed from Purac is based on: Mixing PDLA with a standard PLA resin with the formation of crystallites sterocomplex. The mixture can be made standard for compounding machines (extruders, internal mixers) even if the rotating twin screw extruders are recommended. Purac Application data
After mixing THERMAL RESISTANCE It has a rapid formation of steroecomplex crystallites which act as nucleating agents and accelerate the solidification of PLA during processing (molding, extrusion..). It is important to operate at a higher temperature than the melting point of the PLA but less than that of steroecomplex Itis important precristallize the sterocomplex before transformation. In injection molding is necessary to have the temperature of the mold 90-110 C (annealing) to promote the crystallization Purac Application data
Relative Cristallinity Effect of heterogeneous nucleating agent Isothermal crystallization of PLA 1,0 from 200 C to 130 C @ -500 C/min 0,8 0,6 0,4 0,2 0,0 0 1 10 100 1000 Time (min) S.Murase 2^ European Bioplastics Conference, Paris 21-22/11/2007
Properties of TE-7300 and TE-8300
The effect of fiber reinforce T. Yanagisawa 2^ European Bioplastics Conference, Paris 21-22/11/2007
Poor impact resistance To improve the impact resistance of PLA have been developed impact resistance agents, compatible with the same PLA. Some of the producers are Arkema (Biostrength), DuPont (Biomax) e Rohm and Haas (Paraloid). As an example we report the data obtained with a polyacrylate:
14 [%] 12 Impact resistance effect of a polyacrylate 3,5 3 [J] 10 2,5 8 6 2 1,5 Haze [%] Dart Drop Impact [J] 4 1 2 0,5 0 0 2 3 4 5 7,5 10 % BPM 500 in PLA B.Azimipour 2^ European Bioplastics Conference, Paris 21-22/11/2007 0
PLA 3051 + 5% Impact Modifier Formulation Temp. mould ( C) Resilience (KJ/m 2 ) PLA 3051D 60 13,10 PLA 3051D + BIOSTRENGTH 130 60 18,91 PLA 3051D + BIOSTRENGTH 150 60 22,87
Low melt strength The use of chain extenders modify the rheologic behaviour of PLA Source: Bioplastics Magazine 03/2008 pg. 35