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for a long time, e.g. to manufacture paintsand coatings from natural resins and oils,vitamin B2 from vegetable oils, aminesand acrylates from molasses and canesugar. Use of renewable resources is ac-tively being researched. However, thecompany uses these materials in largeramount only where it makes sense eco-logically and economically. The amountof renewable resources currently pur-chased by BASF accounts for less than 5%of the total purchasing volume.

It’s Also Possible without Bio-based Resources

When it comes to the various possibili-ties for using renewable resources, thesame criteria must be employed as havebeen to date in terms of life cycle assess-ments (LCAs), i. e. the environmentalcompatibility, economic aspects and so-cial impact over the entire life cycle ofproducts, including the associated man-ufacturing processes and disposal meth-ods, must be investigated. Time and againit is found that a product based on bio-mass in not per se ecologically more effi-cient than a petrochemical-based prod-

uct. Each case must be evaluated individ-ually: if renewable resources are readilyaccessible, i.e. short transportation dis-tances, do not require excess amounts ofwater or fertilizers, then use of biomassas a source for material is ecologicallybeneficial. If, however, large amounts offorest must be cleared or processes thatconsume large amounts of energy areneeded to refine the biomass, the ecolog-ical benefit can easily be reversed.

For a correct assessment, aspects suchas energy and water consumption, gener-ation of greenhouse gases and dischargesinto water, e.g. as the result of overfertil-ization, must be taken into consideration,along with the amount of land required

VALENTINE REIMER

ANDREAS KÜNKEL

SABINE PHILIPP

Over the long term, renewable ener-gy sources and biomass can replaceand complement the limited

amount of fossil fuels and raw materialsto some degree.Against this backdrop, re-newable resources will become increas-ingly important in the future. Per se, how-ever, they are not necessarily good as amaterial to be used, just as petroleum isnot necessarily bad as a material to use.The amount of oil, gas and coal on theEarth is limited, but renewable resourcesare not present in limitless amounts ei-ther. On the one hand, they must growagain and on the other hand they have anumber of competitors: wheat, corn (Ti-tle photo) sugar cane and rice are first andforemost foodstuffs. However, they are al-so used to generate electricity and heat.They are used to produce biofuels andserve as raw materials for the chemical in-dustry. BASF has used bio raw material

An Eco-Efficiency Evaluation.

Use of renewable resources is

currently being actively re-

searched. Before they can be

used, the environmental com-

patibility, economic aspects and

social impact over the entire life

cycle, including production and

disposal, must be investigated. If

the results are not positive, there

are alternatives that do not rely

on biomass, since innovative

petrochemical plastic products are saving enormous amounts of energy and thus

lowering CO2 emissions already today – and the potential is not yet exhausted.

According to estimates, the amount of corn needed for bioplastics – in the form of starch andPLA (polylactic acid) – is less than 0.1 % of the corn grown worldwide

� PE104341

Bio – Sense or Nonsense

BASF SEKT/KC – E100D-67056 LudwigshafenTel. +49/6 21/60-43348Fax +49/6 21/60-49497www.basf.de/plastics

Manufactureri

Translated from Kunststoffe 8/2008, pp. 32–36

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for cultivation. On the economic side, thecosts for growing and refining the biomassmust be compared with the price of oil.Experts in the plastics industry know thatthere are ways to reduce fossil fuel con-sumption and CO2 emissions without re-sorting to biomass. Use of innovativepetrochemical-based plastic products isalready saving enormous amounts of en-ergy through efficient insulation of build-ings, lightweight construction of auto-mobiles and in the packing of transport-ed goods and holds even greater potential(Fig. 1). A study conducted by the Asso-ciation for Comprehensive Analyses(Gesellschaft für Umfassende Analysen;GUA) has reached the conclusion [1] thatcompletely eliminating the use of plasticsin Western Europe alone would result ina 26% increase in energy consumptionand 56% higher greenhouse gas emis-sions. Thus, in the opinion of many par-ticipants, setting quotas for biomaterialsin this complex field is more likely to becounterproductive.

Bioplastics versus Feeding the World

Viewed globally, significantly more landwould need to be cultivated than is cur-rently available to meet the demand forfuel in Germany or the EU on the basis ofbiomass. The much lower amount of bio-mass needed for the anticipated amountof bioplastics, on the other hand, can beprovided without difficulty. This alsomeans that bioplastics would not competewith food production: according toBASF’s estimates, the current consump-tion of bioplastics worldwide is max.

80,000 t. Other estimates come up with afigure of 200,000 t. Even with this higherfigure for consumption, the amount ofcorn needed – in the form of starch andPLA (polylactic acid) – for bioplasticsamounts to less than 0.1% of the amountof corn grown worldwide – which is about700 million t.

Biodegradable versus Bio-based

As a result of the growing interest in re-newable resources and the omnipresentterm “bio”, a misunderstanding has aris-en that often leads to mix-ups. However,it should be made clear that the proper-ties “biodegradable” and “bio-based” donot necessarily have anything to do withone another (Fig. 2). “Bio-based” indi-cates the origin of the material, whether

from renewable or fossil resources. Incontrast, “biodegradability“ addresseswhere the material ends up at the end ofits life. And since the origin and destina-tion need not necessarily be coupled, it ispossible that a bio-based plastic part isdisposed of in a waste incinerator or ablast furnace, while a biodegradable bag(as defined in DIN EN 13432) derivedfrom a classical petrochemical sourceends up in a composting plant.

Doubly Bio-based

Production of plastics from bio-basedpolymers is a new field and still requiresintense research and development. Thecommon bio-based polymers today arePLA and PHB (polyhydroxy butyrates).PLA is produced from lactic acid via poly-condensation; the lactic acid, in turn, isobtained from the fermentation of starch.PHBs are polyesters that are obtainedfrom sugar through the action of mi-croorganisms. Compared to convention-al plastics, the properties and perform-ance capabilities of both polymers arelimited. A different approach is involvedwhen not the polymer itself is obtainedfrom nature, but rather its chemical con-stituents, which otherwise have their ori-gin in petrochemistry. Plastics producedin this way offer the same capabilities asthe fossil-based analogs. Polyethylene(PE) is a representative of this group inwhich exactly the same material is ob-tained from bio-based components: theresource (ethanol) can be obtained fromsugar cane, so that the resultant productcan be called bio-based PE.

The BASF products Ultramid Balance,a PA 6 10 based on sebacinic acid that is

Worldwide Petroleum Consumption in 2005

Fig. 1. More than 80% of the petroleum consumed worldwide is “burned” for heating and driving;only a small percentage of the fossil resource oil is used for production of plastics (source: ExxonMobil,

Wintershall)

Fig. 2. The plastics family: bioplastics as defined here include biodegradable and

bio-based plastics

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obtained from castor oil, and LupranolBalance, a polyol used for production ofpolyurethane and also based on castor oil,are members of this group. In the case ofsuch special products, the use of compo-nents from renewable resources can makesense, and not primarily because theyoriginate in nature, but because they per-mit production of a product with specialproperties. With regard to PA 6 10 incomparison to PA 6, this means consid-erably less water uptake: this predestinesthis product for new applications. Ac-cording to BASF, use of renewable re-sources must lead to a combination ofeco-efficiency and improved perform-ance of polymeric materials. To distin-guish excellent from inappropriate appli-cations of bio-based/biodegradable plas-tics, eco-efficiency analysis, a kind of LCAthat was co-developed by BASF, is themeans of choice. With the aid of such ananalysis, various product and process al-ternatives can be compared on the basisof the entire life cycle – including aspectssuch as energy effects, environmental and

social impact associated with production,transportation, use and disposal. Such ananalysis must be conducted for each in-dividual application and cannot be trans-ferred from one application to another –from a plastic bag to agricultural film ora hamburger container – without an ex-act calculation.

Focus on Biodegradability

About ten years ago, BASF was one of thefirst companies to introduce a plasticthat, like other conventional plastics, wasbased on fossil raw materials, but wascompletely biodegradable. Biodegrad-able means that the material can be me-tabolized by living microorganisms. Un-der composting conditions, ideally in anindustrial composting facility with opti-mized conditions – a high temperature,high humidity, defined oxygen level(DIN EN 13432) – the material is con-verted completely to water and CO2 byfungi or bacteria (Figs. 3 and 4). For thisplastic, with the trade name Ecoflex and

a property profile very similar to that ofclassic polyethylene, there is, in contrastto PE or PP (polypropylene), a uniquemethod for disposal after use: compost-ing. This is a major difference in com-parison to the packaging materials men-tioned, but not the only one: as a high-grade material, Ecoflex also offers specialbarrier properties, e.g. its high water va-por permeability, which predestines it forfruit and vegetable packaging, where ithelps to prevent growth of mold. Ac-cordingly, its barrier properties and,above all, its compostability (and fer-mentability) must be taken into consid-eration when assessing optimal use: inwhat applications is it beneficial to havea compostable plastic that is tear-resist-ant, waterproof, puncture-resistant,printable and water vapor-permeable? Itis beneficial in carrier bags that – ideallyafter being used several times – serve asgarbage bags for organic waste, in agri-cultural film (where it can be plowed un-der) and in food packaging that can beplaced in the container for organic waste

Fig. 3. Fossil-based biodegradable plastic Ecoflex satisfies the stringent requirements of the most important international standards for biodegradabilityand compostability: the figure shows, from left to right, decomposition of an Ecoflex film within four weeks in compost at a temperature of 55°C

Time

100

80

60

40

20

0

%

0

Biol

ogic

al d

egra

datio

n (th

eor.

CO2)

20 40 60 80 d 100

EcoflexCellulose

Biological Degradation

Fig. 4. The degradation curve shows that Ecoflex is more than 90% decom-posed after 80 days and thus biodegrades completely much faster than re-quired by the Standard EN13432-Part 2

© Kunststoffe

Elongation at break

4,000

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Ecoflex/starch

Ecovio L

Ecoflex

PLA

PHBPSPET

PP

PE-HD

PBSPCL

PE-LD

Biodegradable plasticsConventional plastics

Physical Properties

Fig. 5. Ecoflex and Ecovio (= Ecoflex/PLA blends) offer a wide range of ma-terial properties: depending on the proportion of Ecoflex or PLA, the plasticbecomes stiffer (modulus of elasticity) or flexible (elongation at break)

© Kunststoffe

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along with food remains. These are – rap-idly growing – niche markets, and a plas-tic that can occupy such niches offers ad-ditional benefits over PE and PP.

Biodegradable and Bio-based

The growing use of renewable resourcesto manufacture products has opened upan additional field of application forEcoflex. Since the plastic exhibits goodcompatibility with starch,cellulose, lignin,PLA and PHB, it is possible to create var-

ious blends that, on the one hand, arecompletely biodegradable, and, on theother, contain a high proportion of re-newable resources. For this reason, BASFcalls Ecoflex an “enabling polymer”or ”en-abler”, which means that the materialmakes it possible to use renewable re-sources. Most renewable raw materialssuch as corn starch do not have good phys-ical properties and are often neither wa-terproof nor puncture-resistant. PLA,which is produced from corn starch, isbrittle in its pure state and thus more dif-ficult to process than conventional plas-tics.

To process biomaterials on high-per-formance machines efficiently, and con-vert them into high-grade end productsthat are still biodegradable, an effectiveblend component is required. As Fig. 5shows, various stiffness/flexibility profilescan be achieved by mixing starch or PLAwith Ecoflex, so that stiff shells as well asflexible pouches and film are feasible(Fig. 6).

Why Composting?

Use of biodegradable plastics is of inter-est especially if the products can provideeconomical and/or ecological benefits be-yond simply “disappearing from view”bybeing buried in the soil or incorporatedinto the organic waste stream.

If conventional plastic garbage bags fororganic waste are not to be separated fromtheir contents in a time-consumingprocess, then incineration remains theonly possibility for disposing of the filledbags. This makes no sense from the ener-gy standpoint, since organic waste isabout two-thirds water. If, however, abiodegradable garbage bag is used, sepa-ration is not necessary – the organic wastetogether with the bag undergoes organicdisposal. There are various possibilitiesfor this approach: first of all, compost-ing; secondly, anaerobic fermentationduring which the biomass is converted in-to biogas (methane), providing a sourceof energy.

Composting is important especially insome southern European countries wheresoil erosion poses a serious problem.Biodegradable plastics assist in this regardby providing a clean sorting mechanismfor organic waste for production of high-grade compost as a soil improvement. Inthis way, biodegradable plastics representnot only a cost-effective disposal solution,but can also make an important contri-bution to efficient management of or-ganic waste. Biodegradable carrier bagscan make a similar contribution: aftershopping, they can be used for collectionand disposal of organic waste; the bag seesdouble use – as a shopping bag and as agarbage bag (Fig. 7).

Conclusions

Experts as well as the interested publicand even politicians, who can sendthe right or wrong signals through sub-sidies and quotas, must remember onething when it comes to the complex top-ic of renewable raw materials in generaland so-called bioplastics in particular:only consideration on a case by case ba-sis provides information on efficientuse of resources. A polyethylene shop-ping bag is not bad per se nor is vegetablepackaging made of starch necessarilygood. ■

REFERENCES

1 GUA – Gesellschaft für umfassende Analysen:The Contribution of Plastic Products to ResourceEfficiency. Vienna 2005.

THE AUTHORS

DR. VALENTINE REIMER, born in 1971, works inthe plastics and the environment competence centerat BASF SE, Ludwigshafen, Germany.

PROF. DR. ANDREAS KÜNKEL, born in 1969, worksin market development for biodegradable plastics atthe same company.

DR. SABINE PHILIPP, born in 1964, is responsiblefor contact with the plastics press at the same com-pany; sabine.philipp@basf.com

Fig. 7. A biodegradable carrier bag (left) can be used after shopping as a garbage bag to collectorganic waste

Fig. 6. Film made of Ecovio becomes waterproof and tear-resistant by its share of Ecoflex

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