reverte masterbatches – degradation kinetics....biodegradation to carbon dioxide, water and...

TECHNICAL INFORMATION SHEET 18

Reverte masterbatches – Degradation kinetics.

1. Introduction Previous Technical Information Sheets (TIS 9, TIS 9B and TIS 16) have described the degradation characteristics of films containing Reverte masterbatches when subjected to heat and/or light. This Technical Information Sheet has been raised to address a question raised regarding the photo-initiation stage of Reverte containing films.

2. Theoretical considerations. Reverte masterbatches are designed to introduce an oxo-biodegradable characteristic into certain polymers. This means that products made from polymers containing Reverte will, in the presence of oxygen and energy, undergo oxidative chain scission until the polymer’s molecular weight is sufficiently reduced to allow microbial-based biodegradation. The rate of this initial oxidation stage is controlled by the presence of sacrificial free radical scavengers (“energy absorbers”) that prematurely remove the energy required for the oxidation, hence preventing it happening until they are exhausted. However, in addition to this, Reverte products have been formulated to have an extra level of protection against premature oxidation through the inclusion of a photosensitive, but very efficient free radical scavenger. This package is deactivated by a small exposure to natural light which means that the initial breakdown reaction only occurs at a very low rate until it is phototriggered. The level of photoexposure required, which has to be natural rather than artificial light, is around 6 to 10 hours of outdoor exposure in a typical Northern European climate and should not be regarded as a “bullet” but as a gradual “topping-up” procedure. It should be understood that the oxidation reaction will still occur in the absence of any light exposure, but it will take between 18 and 24 months to initiate. This gives extra confidence against premature degradation as without any outdoor light exposure the product will have an 18 to 24 month shelf life before the onset of oxidation. The graph below helps to clarify the kinetics of the reaction.

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0

20

40

60

80

100

120

140

160

180

200

-24 -18 -12 -6 0 6 12 18 24 30 36 42 48

Time in Months at 20oC

Deg

ree o

f E

mb

ritt

lem

en

t (%

)

Control film

1% Reverte

No Trigger

Embrittlement point

3. The breakdown kinetics of a PE film containing 1% Reverte BD 92845.

The curves were obtained from ageing the specimens in accelerated ageing cabinets with and without photo-exposure and measuring their rate of degradation or “degree of embrittlement”. Arrhenius principles were used to calculate their respective behaviors in “real-time” at 20oC. The blue curve represents a film that has not experienced any photoexposure. For this curve the time starts at -24 months. It can be seen that it has exhibited a dwell time of around 18 to 24 months followed by a steady development of embrittlement over the next 48 months. The red curve shows the behavior of a Reverte specimen. Point zero on the graph indicates the time of photoexposure and this film shows a characteristic dwell time of around 4 months following the phototriggering and a rapid development of embrittlement over the next 8 months. The green curve represents a control sample without any Reverte additive. It has been aged alongside the red curve specimen. It can be seen that there has not been any significant development of embrittlement over a four year timescale.

The blue curve specimen will be transformed into the red curve specimen at any point along its lifetime by an appropriate level of phototriggering. Andrew Barclay Technical Director

Wells Plastics Limited, Emerald Way, Stone. Staffordshire. ST15 0SR UK

www.wellsplastics.com

This information is correct to the best of our knowledge, but we would recommend that users make their own assessment to confirm that the material meets their requirements. We accept no liability for any damage, loss or injury resulting from

the use of this information. Freedom from patent rights must not be assumed.

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Reverte masterbatches – Recycling Quantified.

1. Introduction Reverte oxo-biodegradable additive masterbatches are added to polyolefin products such as polyethylene packaging to impart an oxo-biodegradable property to the final article. The special technical characteristics of the Reverte additive ensure that the product has a useful, pre-programmed, fit-for-purpose lifetime followed by a post disposal breakdown process that consists of embrittlement, microfragmentation and, finally, complete biodegradation to Carbon dioxide, water and biomass. However, before their final disposal, products made from polymers, such as polyethylene bags, may be required to enter a recycling stream. A large part of this re-use is through in-plant recycling of plastic waste generated in the production process, but some post consumer waste also finds its way into the recyclate stream. Waste products such as these that contain Reverte oxo-biodegradable additive masterbatches are suitable for recycling as the additive will not normally be triggered before disposal and even post consumer waste is unlikely to be significantly degraded before re-use. This Technical Information Sheet has been compiled to demonstrate the suitability of Reverte containing products for recycling.

2. Overview of Experimental Procedure Polyethylene film recyclate consisting of in-house production waste was obtained from a packaging film manufacturer. The same grade of polyethylene film, but in this case containing 1% by weight of oxo-biodegradable additive masterbatch additive was also obtained from the same source. Samples of film were manufactured using the standard in-house recyclate plus varying levels of the oxo-biodegradable film recyclate. Generally the level of re-introduction of such recyclate in industry is thought to be not more than 10% by weight. However, for the purposes of this study, levels of 10 and 20% were investigated. Physical, mechanical and ageing properties of the resultant films were determined to quantify the effect of the addition of the oxo-biodegradable feedstock.

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3. Results 3.1 Effect of Addition on Physical Properties

Oxo-biodegradable film in final product

(%)

Final MFI

(g/dmin)

Elongation at break

(%)

Tensile Modulus

(MPa)

Tensile Strength

(MPa) 0 0.9 150 82 11.8 10 0.8 185 74 12.2 20 0.8 193 71 12.4

3.2 Effect of Addition on Degradation Properties

Oxo-biodegradable film in final product (%) Relative Embrittlement Time

Virgin PE film 100 Recycled film with 0% OB additive 87

Recycled film with 10% OB additive 86 Recycled film with 20% OB additive 79

4. Discussion It can be seen that the addition of quite large amounts of in-process oxo-biodegradable scrap to the normal polymer stream utilised has had a negligible effect on the physical properties of the films produced. Generally the Melt Flow Index of a polymer would be expected to increase if the product is degraded. Inspection of the above results shows that in this case the MFI did not significantly change – in fact it slightly decreased, not indicating any premature degradation. In comparison, the Elongation to Break would be expected to decrease as the polymer is degraded and this property was found to slightly increase with the level of OB additive. This is again indicative of no premature degradation taking place. The Modulus (stiffness) and the Tensile Strength values obtained were also not significantly changed in a way that would indicate any degradation of properties. It would be expected that a recycled polymer feedstock would give somewhat inferior ageing properties to a virgin feedstock. This small deterioration in time to embrittlement would not be expected to be of any consequence in the fit-for-purpose lifetime of the final product (film). It can be seen that in this case the recycled feedstock gave a 13% reduction in the time to embrittlement after ageing in an accelerated ageing light cabinet at 50oC. it can be seen that the film containing 10% recycled oxo-biodegradable film did not significantly alter the accelerated ageing properties, giving a 14% reduction compared with the virgin polymer control, virtually the same as the sample without any oxo-biodegradable recyclate.

4. Discussion (continued) The film containing 20% oxo-biodegradable recyclate gave a 21% reduction in time to embrittlement compared with the virgin product and a 9% reduction when compared with the 100% recycled product. Whilst these results are slightly higher than those obtained from the 10% addition samples, they are not thought to be such as to significantly detract from the useful working life of the polymeric product.

5. Conclusion The addition of high levels of oxo-biodegradable film recyclate has not significantly affected the immediate physical properties of a recycled polyethylene film and has had a minimal and insignificant effect on the film’s ageing properties. Andrew Barclay Technical Director





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TECHNICAL INFORMATION SHEET 25B

Food Safety of Reverte masterbatches. 1. Introduction Reverte oxo-biodegradable additive masterbatches have been designed to impart an oxobiodegradable characteristic in a number of polymers including polyethylenes, polypropylenes certain polyolefinic copolymers and PET. Reverte oxobiodegradable products are formulated using a number of additives chosen to give the products their characteristic properties. All of the Reverte grades use a similar additive package, but the individual components may be present in varying amounts to impart specific oxo-biodegradable properties. However, all Reverte grades have been formulated to be suitable for food contact applications. 2. Food Safety Certification Bodies Major food contact specification bodies include the European Community (through EC directive 2002/72/EC), Canada (through their Food Inspection Agency / Bureau of Chemical Safety) and, in America, the FDA (through their positive listings and “Chapter” suitability). Various Reverte grades have been independently verified for food contact suitability under the European 2002/72/EC specification and all ingredients are appropriately listed. Reverte grades’ details have also been submitted to the Canadian Bureau of Chemical Safety and they have issued letters of non-objection clarifying their suitability for a range of food contact applications. In addition, all of the ingredients in Reverte products are present in the FDA positive listings and are suitable for use in food contact applications to FDA §177.1520 when added to PE, PP, other olefin copolymers and PET within the recommended addition levels found in the relevant Reverte Technical Data sheets. Copies of some relevant certifications may be found in appendices 1/1 through to 2/2 of this Technical Information Sheet. Reverte products have been developed to benefit the environment and should be used with the confidence that this brings. Andrew Barclay Technical Director





Appendix 1/1 – EC/FDA Approval for BD 92845

Appendix 2/1 – Canadian Approval for BD 93172

Bureau of Chemical Safety 251 Sir Frederick Banting Driveway

Tunney’s Pasture 1st floor East, AL: 2201 C

Ottawa, Ontario

K1A 0K9

May 25, 2009

Our file: KS09011302

John James Wells Plastics Limited

Emerald Way

Stone Business Park Stone, Staffordshire

ST15 0SR, UK

[email protected]

Dear Mr. James:

RE: Reverte BD 93172

This is in reference to your e-mail of May 11, 2009, advising us about some

changes in the formulation of the subject product and seeking acceptance

for use of the subject masterbatch in the manufacture of polyethylene terephthalate (PET) bottles at the maximum level of 1.5% in final products,

which are intended to be used for water and soft drinks.

Based on available information on the subject masterbatch, we see no reason

to object to its use as proposed, provided that it is technically suitable

for the intended end-uses.

It should be noted that Mr. Dallaire of the Canadian Food Inspection Agency

(CFIA) will be advised of our comments by copy of this letter.

Yours truly,

Elena Emelianova, Ph.D. Scientific Evaluator

Food Packaging Materials and Incidental Additives Section

Chemical Health Hazard Assessment Division

cc Mr. Dallaire (CFIA)

[email protected]

Appendix 2/2 – Canadian Approval for BD 92845, BD 92771 and BD 93470

Emerald Way, Stone Business Park,

Stone. Staffordshire. ST15 0SR. UK

Tel : +44 (0)1785 817421

Fax : +44 (0)1785 817771

e-mail : technical;@wellsplastics.com


Wells’ Reverte products and their compliance with RoHS, CONEG and Packaging Waste Legislations.

The Restriction of Hazardous Substances in Electrical and Electronic Equipment (ROHS) Directive (2002/95/EC) affects manufacturers, sellers, distributors and recyclers of electrical and electronic equipment containing lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls or polybrominated diphenyl ethers.

From 1 July 2006 new electrical and electronic equipment must not contain lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBBs) or polybrominated diphenyl ethers (PBDEs).

The US CONEG legislation (Confederation of North Eastern Governors) aims to reduce the problems faced by the authorities of disposing of their increasing waste mountains. In particular, it seeks to minimise the use of heavy metals and their compounds in packaging. The model CONEG legislation suggests that the total content of lead, cadmium, mercury and hexavalent chromium in packaging and packaging components must not exceed 100ppm. The European Parliament and Council Directive 94/62/EC on packaging and packaging waste requires the sum of concentration levels of lead, cadmium, mercury and hexavalent chromium present in packaging or packaging components shall not exceed 100ppm. All of these requirements apply to the final articles and not to individual additives used in the manufacture of the article. To the best of our knowledge we can certify that lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls and polybrominated diphenyl ethers are not present in Wells’ Reverte products and so compliance with any of the above directives should not be compromised through their use. However, they do not form part of our manufacturing specification and so we do not routinely analyse for the presence of these substances. Independent testing for the presence of lead, cadmium, mercury and hexavalent chromium has been carried out on Reverte masterbatches and these results are available on request. Signed……………………………. Position : Technical Director Dated : 16/04/10

Originated by Wells Plastics Limited, Emerald Way, Stone Staffordshire. ST15 0SR UK. Tel: 01785 817421, Fax: 01785 817771. Information contained in this document or as otherwise supplied to you by Wells is believed to be accurate and is given in good faith, but it is for you to satisfy yourself of the suitability of the Product for your own particular purposes. Accordingly Wells gives no warranty as to the fitness of the product for any particular purpose, and any implied warranty or condition, (statutory or otherwise) is excluded except to the extent that such

exclusion is prevented by law. Wells accepts no liability for loss or damage whatsoever or howsoever (other than that arising from death or personal injury caused by the negligence of Wells if proved) resting from reliance on this.

TECHNICAL INFORMATION SHEET 29A

Wells’ Reverte® products and their compliance with ASTM D 6954.

1. Introduction Polymers such as polyethylene and polypropylene are not generally regarded as biodegradable as their high molecular weight renders them too hydrophobic and, therefore, very resistant to microbial attack.

Reverte®

is an additive masterbatch designed to be added to these polymers in order to impart a controlled

oxobiodegradable characteristic. Oxobiodegradability is a two stage process. The first stage is catalytic oxidative chain scission of the polymer causing a serial reduction in molecular weight which results in acute embrittlement and microfragmentation. The second stage takes place when the molecular weight has been sufficiently reduced to render it available for microbial attack. This microbial attack (or biodegradation) biotically breaks down the degraded residues to carbon dioxide, water and biomass. 2. The ASTM D 6954-04 test method. A number of oxobiodegradable test methods and standards have been developed to enable oxobiodegradation to be quantified, but at the time of writing the above method is the one of choice because it has been in the public domain since 2004 and has set the standard for demonstrating, evaluating and quantifying oxobiodegradability in polymeric products. ASTM D 6954 has a set of testing criteria laid out in three tiers. Tier 1 measures the initial degradation through molecular weight reduction, Tier 2 measures the biodegradation of the preoxidised Tier 1 material through test methods such as ASTM D 5338 (aerobic biodegradation under controlled composting conditions) and Tier 3 measures toxicity (through the absence of proscribed heavy metals) and eco-toxicity through germination and growth tests. 3. Results from Tier 1 and Tier 2 Testing. Polyethylene check-out bags containing 1% Reverte are being tested at an independent test house according to ASTM D 6954 and testing to Tiers 1 and 2 has been undertaken. Definitive results, demonstrating the oxobiodegradability of PE containing Reverte, may be found below : 3.1 Fragmentation / Degradation of Bag. The bags were aged in a UV / heat ageing cabinet according to a modified ASTM D 5208 cycle C test method at 50

oC.

Figure 1 : Bag during ageing.

14 weeks14 weeks14 weeks

7 weeks

StartStart

It can be seen that the bag has degraded to powder during the ageing process.

3.2 Tier 1 : Molecular Weight Reduction The molecular weight change during ageing was as follows :

Molecular Weight reduction results for Reverte PE bags

tested to Tier 1 ASTM 6954.

0

40000

80000

120000

160000

0 500 1000 1500 2000

Ageing time in hours at 50oC

Mo

lec

ula

r W

eig

ht

PE Carrier bag + 1% Reverte

Source : Independent testing

to ASTM 6954 by RAPRA UK

It can be seen that the molecular weight rapidly fell to the level of �5000 required within the ASTM 6954 test method. 3.3 Tier 2 : Mineralisation (Biodegradation).

The preoxidised carrier bag was tested according to a modified ASTM D 5338 (aerobic degradation under controlled composting conditions) to determine its biodegradability.

The preoxidised bag rapidly underwent biodegradation and achieved >95% mineralisation in just under 10 weeks. This demonstrates the efficacy of the Reverte additive in rendering the product oxobiodegradable ; in other words catalysing the catalytic oxidative cleavage of the polymer molecule (the “oxo” stage) and then enabling

the resultant low molecular weight polymer to be mineralised (the “biodegradation” stage).

Biodegradation results from Reverte PE bags.

0

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100

0 2 4 6 8 10

Composting time in weeks

Deg

ree

of

Min

era

lis

ati

on

(%

)

Source : Independent testing to a

modified ASTM D 5338 method by

Biosystems Atlanta

4. Tier 3 Testing (ecotoxicity). Testing to this final Tier has now been completed and the Reverte PE bag has been shown to pass the requirements of Tier 3 of the test standard both for short term toxicity (10 days) and long term toxicity (30 days). 4.1 Sediment (terrestrial) short term toxicity - Amphipod, Hyalella azteca Survival and Growth Test.

Assay % Survival Weight mg pH Cond Mho DO mg/l Reverte sample 90 1.81 6.7 162 7.4 Negative control 100 1.64 6.5 157 7.4

4.2 Long-term (30-day) Toxicity Test Earthworm (OECD 207). Mortality Data

Assay % Survival Reverte sample 100

Negative control 100 4.3 Long-term (30-day) Toxicity Test Plant Germination (OECD 208). Mortality Data Oat.

Assay % Survival

Reverte sample 97

Negative control 100 4.4 Long-term (30-day) Toxicity Test Plant Germination (OECD 208). Mortality Data Radish.

Assay % Survival Reverte sample 100 Negative control 100

4.5 Long-term (30-day) Toxicity Test Plant Germination (OECD 208). Mortality Data Mung Bean.

Assay % Survival

Reverte sample 100 Negative control 100

5. Summary. These independently derived test results have conclusively demonstrated the oxobiodegradability of HDPE film containing 1% Reverte according to ASTM D 6954-04. The initial oxidation, subsequent biodegradation and ecotoxic standards have all been shown to meet the appropriate criteria within the ASTM D 6954-04 test method which is currently the method of choice to demonstrate, measure and quantify oxobiodegradation. The product submitted has successfully passed Tier 1 (oxidative molecular weight reduction), Tier 2 (biodegradation) and Tier 3 (ecotoxicity) of the ASTM D 6954-04 standard. Reverte has again been shown to be the product of choice when a proven oxo-biodegradable property is required.

Signed……………………………. Position : Technical Director Dated : 10/03/11

Originated by Wells Plastics Limited, Emerald Way, Stone Staffordshire. ST15 0SR UK. Tel: 01785 817421, Fax: 01785 817771. Information contained in this document or as otherwise supplied to you by Wells is believed to be accurate and is given in good faith, but it is for you to satisfy yourself of the suitab ility of the Product for your own particular purposes. Accordingly Wells gives no warranty as to the fitness of the product for any particular purpose, and any implied warranty or condition, (statutory or otherwise) is excluded except to the extent that such

exclusion is prevented by law. Wells accepts no liability for loss or damage whatsoever or howsoever (other than that arising from death or personal injury caused by the negligence of Wells if proved) resting from reliance on this.

Selected extracts from report : 1. Graph of molecular weight reduction from RAPRA report CTR51223

Appendix 1 – Report of Tier 1 Oxidation.

2. “Pass” statement from RAPRA report CTR51223

Appendix 2 – Pass certificate for Tier 2 biodegradation.

Appendix 3 – Pass certificate for Tier 3 Ecotoxicity.

Appendix 4 – Extract from report for Tier 3 Ecotoxicity.

reverte masterbatches – degradation kinetics....biodegradation to carbon dioxide, water and...

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