CEN/TR 15351:2006

SLOVENSKI STANDARD
01-april-2007
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Plastics - Guide for vocabulary in the field of degradable and biodegradable polymers
and plastic items
Kunststoffe - Leitfaden für Begriffe im Bereich abbaubarer und bioabbaubarer Polymere
und Kunststoffteile
Plastiques - Guide pour le vocabulaire dans le domaine des polymeres et des produits
plastiques dégradables et biodégradables
Ta slovenski standard je istoveten z: CEN/TR 15351:2006
ICS:
83.080.01 Polimerni materiali na Plastics in general
splošno
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL REPORT
CEN/TR 15351
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
October 2006
ICS 83.080.01
English Version
Plastics - Guide for vocabulary in the field of degradable and
biodegradable polymers and plastic items
Plastiques - Guide pour le vocabulaire dans le domaine des Kunststoffe - Leitfaden für Begriffe im Bereich abbaubarer
polymères et des produits plastiques dégradables et und bioabbaubarer Polymere und Kunststoffteile
biodégradables
This Technical Report was approved by CEN on 16 January 2006. It has been drawn up by the Technical Committee CEN/TC 249.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,
Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2006 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 15351:2006: E
worldwide for CEN national Members.

Contents Page
Foreword.3
Introduction .4
1 Scope .5
2 Analysis of the alteration stages and mechanisms .5
2.1 Alteration stages.5
2.2 Degradation mechanisms .6
3 Basic situations to be distinguished .7
3.1 Individualised situations.7
3.2 Correlation to terms.8
4 The actual situations .8
4.1 Heterogeneous degradation.8
4.2 Formulated plastics.9
4.3 Qualifiers .9
5 Vocabulary.11
5.1 Axioms for the vocabulary.11
5.2 Terms and definitions. .11
Annex A (informative) Terms and definition listed in alphabetical order.15

Foreword
This document (CEN/TR 15351:2006) has been prepared by Technical Committee CEN/TC 249 “Plastics”, the
secretariat of which is held by IBN/BIN.
Introduction
Today, there are several sectors of human activity that can take advantage of degradable and biodegradable
polymers, polymeric materials and items, namely the sectors of biomedical, pharmaceutical, packaging,
agricultural, and environmental applications. Although they appear very much different at first sight, these
applications have some common characteristics:
 the necessity to deal with the polymeric wastes when a macromolecular material or compound is
to be used for a limited period of time,
 the fact that living systems have some similarities in the sense that they function in aqueous
media, they involve cells, membranes, proteins, enzymes, ions, etc…,
 the fact that living systems can be dramatically perturbed by toxic chemicals, especially low
molar mass ones,
Another characteristic of degradable polymeric compounds is that each sector of applications has developed
its own science and thus its own terminology. In particular, surgeons, pharmacists and environmentalists do
not assign the same meaning to a given word. For instance, “biomaterial” means “therapeutic material” for
people working in the biomedical sector whereas it means material of renewable origin for specialists working
in the sector of exploitation of renewable resources. The field of norms is another source of examples. Norms
related to degradation, and/or biodegradation in these different sectors, have introduced definitions
independently. The resulting mismatching and inappropriate use often lead to misunderstanding and
confusion.
Because human health and environmental sustainability are more and more interdependent and, because
science, applications, and norms are developed in each of these sectors, it is urgent to harmonise the
terminology or to define a specific terminology when a general one is not available, so that they can be
proposed to international normative organisations.
Such a task should be based on scientific and mechanistic considerations. The present technical report is an
attempt to set up a common and simple terminology applicable in the various domains where degradation,
biodegradation, bioassimilation, and biorecycling are major academic and industrial goals.
It is worth noting that elimination from the human (or animal) body of high molecular weight compounds is not
possible unless macromolecules are degraded to low molar mass molecules. Indeed, skin, mucosa and
kidney are very efficient barriers that keep high molar mass molecules entrapped in the parenteral
compartments. As for the environmental life, eliminating a waste from the planet is not possible, so far.
Therefore, any product or chemical that is not recycled or biorecycled is going to be stored in one way or
another, i.e. as such or as biostable residue of degradation.
1 Scope
This guide provides the vocabulary to be used in the field of polymers and plastic materials and items.
The proposed terms and definitions are directly issued from a scientific and technical analysis of the various
stages and mechanisms involved in the alteration of plastics up to mineralization, bioassimilation and
biorecycling of macromolecular compounds and polymeric products; i.e polymeric items.
NOTE The proposed vocabulary is intended also to be in agreement with a terminology usable in various domains
dealing with time limited plastic applications, namely biomedical, pharmaceutical, environmental, i.e., in surgery, medicine,
agriculture, or plastics waste management.
2 Analysis of the alteration stages and mechanisms
2.1 Alteration stages
If one looks carefully at what can happen when a polymeric item is in contact with a living system, regardless
of the living system (animal body, plant, micro-organisms or the environment itself), one finds different levels
of alterations. These various levels are shown in Figure 1.

DIFFERENT LEVELS OF ALTERATION
Initial
fragments
Fragmentation
or
Solubilized
macromolecules
Dissolution
or
Macromolecule
Erosion
fragments
CO + H O + biomass
2 2
Figure 1 — The levels of alteration for a polymeric device
From this schematic presentation it appears that the formation of tiny fragments or dissolution does not
necessarily correspond to macromolecule breakdown. Actually it reflects the disappearance of the initial
device only. Whether the macromolecules that formed the original polymer-based item remain intact or are
chemically cleaved with decrease of molar mass needs to be distinguished by specific words. This is
important in the case of an animal body because of the retention of high molar mass molecules mentioned
above. In the environment, solid fragments of a polymeric device (regardless of whether the particles are
visible or not) may also be recalcitrant. Similarly, macromolecules that are dispersed or dissolved in outdoor
water may be absorbed by minerals and stored there, or may reach the underground water, thus resulting in
dispersion as long lasting waste in Nature.
Macromolecule breakdown to “biostable” (i.e. could not be biodegraded further to minerals and biomass) small
molecules is a third stage of degradation where low molar mass molecules may be generated that can be
much more toxic than the original high molar mass ones. This remark raises the problem of the interactions of
the degradation products with living systems. This problem is solved in the biomedical field by the use of the
term “biocompatibility”. In the case of the environmental applications, there is not an equivalent word. One
could extend the use of the term “biocompatibility” to express that degradable polymeric items and their
degradation products have no detrimental effect on relevant living systems. Whether the generated low molar
mass degradation by-products can be bioprocessed further, i.e. up to bioassimilation, or their breakdown
stops at intermediate stages where the generated degradation by-products are biostable needs also to be
distinguished by specific words.
The last stage of degradation is complex in the sense that it includes the formations of biomass, of CO +
H O and of some other compounds occasionally, e.g. CH in the case of anaerobic biodegradation. Again, the
2 4
formation of (CO + H O) and of other inorganic residues that reflect the involvement of biochemistry in the
2 2
macromolecule degradation should be distinguished from the biomass formation that shows that degradation
by-products have been bioassimilated by the degrading cells. It is important to note that photooxidation of
some polymers can yield CO in the absence of microorganisms.
2.2 Degradation mechanisms
Another fundamental discussion concerns the routes that can lead from a polymeric item to the ultimate stage,
namely mineralisation + biomass formation.
Actually, there are two main routes that are shown in Figure 2.
POLYMERIC
COMPOUNDS
Enzymes Chemistry
+
Cells
Low molar mass
by-products
Enzymes
Biochemistry
+
Cells
CO2 + H2O
Biomass
Figure 2 —The two general routes leading to bioassimilation

a) Cell-mediated polymer degradation
The left-hand side route corresponds to the attack of cells on a polymeric item or macromolecule followed by
biochemical processing of the degradation products as a result of enzymatic reactions. This route requires the
presence of appropriate enzymes and thus of specific cells under viable conditions (atmosphere, water,
nutrients). In nature, enzymes cannot be found without the presence of living cells. In other words, no life-
allowing conditions, no degradation by living systems. This raises the problem of degradation tests carried out
under lab conditions with commercially available isolated enzymes. Are these isolated enzymes to be
considered as causing degradation by a living system (despite the absence of the microorganisms that the
enzymes are issued from) or by simple chemical degradation in the presence of a non-viable catalytic
system? This question is fundamental. It has to be solved by appropriate terminology in order to avoid
confusion in literature.
b) Chemistry-mediated polymer degradation
The right hand side route differs from that of the left-hand side in the sense that the breakdown of polymer-
based items and macromolecules depends on chemical processes. Therefore, only the generated small
molecules have to be eliminated through biochemical pathways. Here the conditions required to trigger
chemical degradation are necessary (light, water, oxygen, heat…). No triggering phenomenon, no degradation.
On the other hand, living cells have to be present to ensure the biochemical processing of the low molar mass
molecules formed from the macromolecules of the original polymeric item. Therefore, words are necessary to
distinguish these routes.
c) Combination
If one combines the several levels of degradation with these two different routes, it is again obvious that a
number of specific words are required to distinguish the various possibilities.
It is worth noting that, any material is unstable when in contact with living systems for a long period of time
and therefore, the terminology has to be limited to the desired degradation of polymeric items in contrast to
the undesired degradation that any material eventually undergoes under the influence of use and ageing.
3 Basic situations to be distinguished
3.1 Individualised situations
Let us first consider each possibility separately, though they can overlap to some extent:
 alteration of a polymeric item with or without disappearance in the absence of macromolecule
cleavage
 due to breakdown to small solid fragments
 due to dissolut
...