1、PUBLISHED DOCUMENT PD CEN/TR 15351:2006 Plastics Guide for vocabulary in the field of degradable and biodegradable polymers and plastic items ICS 83.080.01 PD CEN/TR 15351:2006 This Published Document was published under the authority of the Standards Policy and Strategy Committee on 30 November 200
2、6 BSI 2006 ISBN 0 580 49611 2 National foreword This Published Document was published by BSI. It is the UK implementation of CEN/TR 15351:2006. The UK participation in its preparation was entrusted to Technical Committee PRI/82, Thermoplastic materials. A list of organizations represented on PRI/82
3、can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Amendments issued since publication Amd. No. Date CommentsTECHNICALREPORT RAPPORTTECHNIQUE TECHNISCHERBERICHT CEN/T
4、R15351 October2006 ICS83.080.01 EnglishVersion PlasticsGuideforvocabularyinthefieldofdegradableand biodegradablepolymersandplasticitems PlastiquesGuidepourlevocabulairedansledomainedes polymresetdesproduitsplastiquesdgradableset biodgradables KunststoffeLeitfadenfrBegriffeimBereichabbaubarer undbioa
5、bbaubarerPolymereundKunststoffteile ThisTechnicalReportwasapprovedbyCENon16January2006.IthasbeendrawnupbytheTechnicalCommitteeCEN/TC249. CENmembersarethenationalstandardsbodiesofAustria,Belgium,Cyprus,CzechRepublic,Denmark,Estonia,Finland,France, Germany,Greece,Hungary,Iceland,Ireland,Italy,Latvia,L
6、ithuania,Luxembourg,Malta,Netherlands,Norway,Poland,Portugal, Romania, Slovakia,Slovenia,Spain,Sweden,SwitzerlandandUnitedKingdom. EUROPEANCOMMITTEEFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruedeStassart,36B1050Brussels 2006CEN Allrightsofexploitatio
7、ninanyformandbyanymeansreserved worldwideforCENnationalMembers. Ref.No.CEN/TR15351:2006:E2 Contents Page Foreword3 Introduction .4 1 Scope 5 2 Analysis of the alteration stages and mechanisms .5 2.1 Alteration stages5 2.2 Degradation mechanisms .6 3 Basic situations to be distinguished .7 3.1 Indivi
8、dualised 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 Vocabulary11 5.1 Axioms for the vocabulary11 5.2 Terms and definitions. 11 Annex A (informative) Terms and definition listed in alphabetical order1
9、5 CEN/TR 15351:20063 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. CEN/TR 15351:20064 Introduction Today, there are several sectors of human activity that can take advantage of degradable and bi
10、odegradable 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
11、 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
12、 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 as
13、sign 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
14、 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 mo
15、re 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 tas
16、k 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 w
17、orth 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
18、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. CEN/TR 15351:20065 1 Scop
19、e 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,
20、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, e
21、nvironmental, 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 bo
22、dy, plant, micro-organisms or the environment itself), one finds different levels of alterations. These various levels are shown in Figure 1. 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
23、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 w
24、ords. This is DIFFERENT LEVELS OF ALTERATIONfragments Solubilized macromolecules Macromolecule fragments CO 2+ H 2 O + biomass or Fragmentation Dissolution Erosion Initial orCEN/TR 15351:20066 important in the case of an animal body because of the retention of high molar mass molecules mentioned abo
25、ve. 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
26、, 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
27、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.
28、 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 bioassimilati
29、on, 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 2+ H 2 O and of some other compounds
30、 occasionally, e.g. CH 4in the case of anaerobic biodegradation. Again, the formation of (CO 2+ H 2 O) and of other inorganic residues that reflect the involvement of biochemistry in the macromolecule degradation should be distinguished from the biomass formation that shows that degradation by-produ
31、cts have been bioassimilated by the degrading cells. It is important to note that photooxidation of some polymers can yield CO 2in 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, n
32、amely mineralisation + biomass formation. Actually, there are two main routes that are shown in Figure 2. Figure 2 The two general routes leading to bioassimilation POLYMERIC COMPOUNDS Enzymes + Cells Chemistry Biochemistry Low molar massby-products Enzymes +Cells CO2 + H2O Biomass CEN/TR 15351:2006
33、7 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
34、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 condit
35、ions 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? Th
36、is 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
37、 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, livi
38、ng 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
39、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
40、 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 so
41、me 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 dissolution of macromolecules alteration of a polymer-based item with macromolecule cleavage due to non-enzymatic chemical phenomena due t
42、o abiotic enzymatic phenomena due to cell-mediated degradation with formation of biostable residues, regardless of the mechanism of degradation CEN/TR 15351:20068 3.2 Correlation to terms There is the need of distinguishing these various stages and phenomena that are usually referred to inconsistent
43、ly as degradation or biodegradation. A means has to be found and accepted to differentiate the physical breakdown of a polymeric item without macromolecule cleavage from the physical breakdown of this polymeric item due to chemical macromolecule cleavage. It is proposed to use the already introduced
44、 axiom saying that for macromolecular materials or systems that deteriorate acceptably in one way or another, degradation means alteration of macromolecules via chemical cleavage of the main chain. To technologists, this normally means “deterioration of technical performance, but to scientists it ge
45、nerally means “decrease of molar mass by chemical cleavage of the main chain”, which may be but not necessarily related to technical performance. The latter definition will be used in the present work. From there, biodegradation is defined as the alteration of macromolecules with chain cleavage caus
46、ed by cells regardless of their type (human or animal, vegetal, microbial or fungal). This biodegradation can result from cell enzymatic activity as well as from chemical reactions that can occur locally below a cell adhering to a polymeric surface because of the presence of some released non-enzyma
47、tic compounds (acids for instance). Under these conditions, degradation in the presence of isolated enzymes under laboratory conditions cannot be considered as biodegradation and the distinction has to be made clearly. The biodegradation of a polymeric item has to be related to a measurable phenomen
48、on. The production of CO 2and CH 4for anaerobic process, or the consumption of O 2are usually considered but they do not take into account the formation of biomass. NOTE It is worth noting that, under the above conditions, the terms degradation and biodegradation give information on the mechanism of
49、 chain cleavage but do not reflect the fate of the degradation by-products. “Fragmentation” can be selected to reflect a degradation observed at the physical level (visually or through physical measurements) which yields fragments of the original material regardless of the mechanism. If fragmentation is caused by cell
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