Reveals the potential of cereals

19/08/10

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Tereos

logo TEREOS Syral

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Meriplast®

A novel protein-based bioplastic

Revealing the potential of wheat proteins

Wheat gluten is unique amongst vegetable proteins due to its specific visco-elastic properties, which are notably essential for quality in bread making. Tereos Syral has developed a process which enables to maintain the visco-elasticity of wheat gluten into a novel flexible and elastic biomaterial.

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Sustainability

Meriplast® is 100% based on renewable raw materials (wheat and oilseeds such as rapeseed or sunflower) and 100% biodegradable. The production process is very mild and fully complies with the principles of green chemistry.

Mechanical and physical properties

Meriplast® has unique flexibility & elasticity properties. It shows a good resistance to torsion and folding. It is not soluble in water but a prolonged immersion in water will affect the materials’ mechanical properties.

Sensory

Meriplast® displays outstanding sensory properties. It has a very good touch, a good grip without stickiness, it is permeable and absorbs water. It has a pleasant cereal smell.

Safety

Meriplast® is not toxic when degraded in farmland soil. It does not burn in normal atmospheric conditions: it has a limited oxygen index (LOI) above 21% (22 and 26% for Meriplast® N60 and N50 respectively).

A novel flexible and elastic biomaterial

Meriplast® is a novel bioplastic entirely made from raw materials derived from agriculture and is fully biodegradable. This material has specific flexibility and elasticity properties, which makes it unique amongst the biodegradable and renewable materials currently available. Meriplast® is fully bio-based, it is both renewable and biodegradable.

ApplicationsThe targeted applications of Meriplast® are moulded objects for interior such as toys, leather imitation for office products (covers), design articles, pieces of furniture. Applications are still in the development phase.

ProcessabilityMeriplast® can be processed on standard rubber processing machinery (injection moulding, calandering).

The rangeDifferent grades that vary in extensibility and tensile strength can be produced. The material’s natural colour is light brown but it can be coloured into a wide variety of tints.

Why use Meriplast®?

Meriplast® life cycle

AgriculTurAl ProducTion

wheat oilseeds

coproduct coproduct

Te r e o s S y r a lPAT e n T e d P r o c e S S

Meriplast®

Bio-ethanol Bio-diesel

b i o d e g r A d AT i o n1 0 0 %Figure 1: The natural colour

of Meriplast® is light brown.

Figure 2: Prototypes of finished products made of Meriplast®

Mechanical properties

The mechanical properties of Meriplast® are similar to elastic materials such as natural rubber or thermoplastic elastomers up to 100% elongation. Ultimate tensile strength and elongation are however lower (Table 2).

A visco-elastic behaviour

Meriplast® exhibits a complex visco-elastic behaviour with dominant elastic features, as demonstrated by relaxation tests (Figure 6). The figure shows changes in the tensile modulus over time under a constant extension ratio of 100 %. The behaviour of the material is in between a purely elastic and a purely viscous material: the linear decrease on a double logarithmic plot has a slope of -0.13, compared to 0 for a purely elastic material and 1 for a purely viscous material.

Moreover, Meriplast® displays a unique, slow elasticity as shown by measures of residual elongation of the samples after removal from the testing machine (Figure 7). For example, after stretching the material to an elongation of 100% for 1h, the material retracts to 30% of its initial length after 30 minutes and to 4% after 7 days.

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Figure 6: Relaxation test for Meriplast® N60 at extension ratio of 100%1,E+05

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Figure 7: Residual elongation of Meriplast® N60 after relaxation test

Table 2: Physical and mechanical properties of Meriplast®

a According to ISO 527-2 type 5A, b Rubber Technology, Compounding and Testing for performance By John S. Dick Hanser, c Technical data sheet from API, d ASTM D 2240

Physical and mechanical properties

DensityHardness

(Shore A-15’’)d

Strength at 100% elongationa

Strength at break (MPa)a

Elongation at break (%)a

Meriplast® N60 1.30 69 2.3 4.5 350

Meriplast® N50 1.32 75 2.6 4.8 320

Natural rubber (thread)b - 70 3 30 500

API (TPE from APINAT)c - 65-83 2 – 4.5 10-14 700-800

Mechanical response to variations of humidity and temperature

Increasing temperature or humidity causes plastification of Meriplast®, hence decreasing elastic modulus.

Under standard ambient conditions (50% relative humidity and 25°C), the material has a moisture content of approximately 11% and a stress at break of 4.3 MPa. At a relative humidity of 70%, moisture content increases to 24% and stress at break decreases to 1.6 MPa (Figure 8). This is reversible when the material is put back to the initial conditions.Meriplast® is not designed for prolonged immersion in water. As an example, after a 24-hour immersion in water, the material adsorbs up to 1.5 times its own weight. Drying of the swollen material will result in the loss of mechanical properties in terms of flexibility and elasticity.

Temperature affects mechanical properties of Meriplast® in a steady way, with no sharp transitions. Dynamic mechanical thermal analysis shows that the material has a transition from glassy state (at -100°C) towards a rubbery state plateau (at 100°C), which occurs over a very broad range of about 200°C (Figure 9). For natural rubber, this transition typically occurs over 40 to 60°C. That makes Meriplast® unique amongst elastic materials.

Slow relaxation and resilience of Meriplast® also influence response to compression, which is different from that of rubber. Meriplast® N50 has a compression set value of 65% after a release time of 30 min, compared to 10% for natural rubber and

30% for SBR rubber. However, after a prolonged release time of 7 days, the material almost retrieves its original shape (Table 3).

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Figure 8: Influence of relative humidity on stress at break

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Figure 9: Dynamic moduli (Storage Modulus, Loss Modulus and Tan Delta) as a function of the temperature for Meriplast® N60

Table 3: Compression set value (%) (ASTM D395 Method B type 1 for 24hr at 25°C)

compression time at 25°CMeriplast® N50 Meriplast® N60

after 30 min release after 7 days release after 30 min release after 7 days release

1 hour 31 1 25 <1

1 day 65 8 62 <1

2 days 67 10 59 3

1 week 77 32 80 37

Packaging and storageMeriplast® is available in 15 kg reels with endless strands of 13-14 mm diameter (Figure 3). Different packaging is available on request. The product should be stored in a cool, dry place with good ventilation.

Figure 4: Equipment used for testing Meriplast® processing

Figure 3: Meriplast® packaging

Processing conditionsMeriplast® is thermosetting and has a processing viscosity similar to uncured rubbers. Consequently, it can be shaped using traditional rubber injection technology, for example on REP machinery (REP International, 69960 Corbas, France) (Figure 4).

Recommended temperature settings are 60°C in the extrusion section, 70°C in the injection chamber and 140-150°C in the mould. Examples of moulded articles such as plates (120 x 120 x 2 mm) or conical frustums (60 and 47 mm for the diameters, 25 mm height) are shown in Figure 5. Typical mould shrinkage is 2.5%, as determined with a calibrated plate mould.

Conical frustum

Two plates obtained with one injection: one being injected in parallel and the other one by one point

Figure 5: Examples of moulded articles

Moulding temperature (°C) Moulding time (min)

Plate140 6

150 2

Conical frustum 140 10

Table 1: Optimal processing conditions for two moulded objects

Similarly to other natural materials such as leather or wood, Meriplast® adsorbs water but it is not soluble in water. Prolonged contact with water (e.g. dishwasher) should be avoided.

Meriplast® shows full degradation after 36 days in aerobic fermentation (according to ISO 14852 based on the modified Sturm test) and 50 days in farmland soil. Meriplast® and its

degradation metabolites are not toxic as tested by microbial inhibition tests.ISO 14852: Determination of the ultimate aerobic biodegradability of plastic materials in an aqueous medium - Method by analysis of evolved carbon dioxideDomenek S., Feuilloley P., Gratraud J., Morel M.H., Guilbert S. (2004) Biodegradability of wheat gluten based bioplastics Chemosphere 54: 551–559

Product stability and degradation

The company

Tereos Syral is the 3rd European starch producer and is the starch activity of the international agro-industrial group Tereos. Tereos Syral transforms 3 million tons of wheat and corn in its 6 European factories into 1,800,000 tons of starch and starch-based products, 180,000 m3 of alcohol and bioethanol, 200,000 tons of vegetable proteins, and by-products for animal feed. The firm has 1,280 employees and has a pro forma yearly turnover of 1.2 billion €.

The success of starch products is linked to their versatility and to their renewable as well as biodegradable nature. Current starch manufactures can already be described as bio-refineries. Fibre, protein and starch from the cereals are separated by mostly mechanical means and further transformed in specific lines combining a wide range of technologies: enzymatic or chemical hydrolysis and modifications, hydrogenation, refining, fermentation, drying, crystallisation.

Tereos Syral received the special award of R&D for Meriplast® at the Biowerkstoff-Kongress in Stuttgart in October 2009.

Zone Industrielle et PortuaireF-67390 MARCKOLSHEIMTel : +33 (0)3 88 58 60 60Fax : + 33 (0)3 88 58 60 61info-syral@tereos.comwww.tereos-syral.com

19/08/10

CMJN

-

-

-

-

-

-

-

-

-

-

-

-

-

-

Tereos

logo TEREOS Syral

- 100%

---

• Pic

ture

s cre

dits

: Pat

rick

Bogn

er, s

hutt

erst

ock

• Dec

embe

r 201

1 • T

he in

form

atio

n m

entio

ned

here

in re

mai

n th

e pr

oper

ty o

f Ter

eos S

yral

or i

ts c

onta

ctor

s. A

lthou

gh T

ereo

s Syr

al u

ses r

easo

nabl

e en

deav

ours

to e

nsur

e th

e ac

cura

cy a

nd c

ompl

eten

ess o

f sai

d in

form

atio

n, T

ereo

s Syr

al w

aive

s all

liabi

lity

in re

latio

n to

thei

r use

by

the

addr

esse

e.