Easy Identification of Plastics and Rubbers

183 Pages·3.631 MB·English

by  Verleye, G.A.L., Roeges, N.P.G., De Moor, M.O.

Easy Identification of
Plastics and Rubbers
Guénaëlle A. L. Verleye
Noël P. G. Roeges
Marc O. De Moor
Rapra Technology Limited
Shawbury, Shrewsbury, Shropshire SY4 4NR, United Kingdom
Telephone: [phone] Fax: [phone]
http://www.rapra.net
Easy ID Title Page etc 1 26/11/01, 4:00 pm
Contents
First Published in 2001 by
1. Introduction...........................................................................................................1
Rapra Technology Limited
2. Tests for the Identification of Plastics and Rubbers...............................................3
Shawbury, Shrewsbury, Shropshire, SY4 4NR, UK
2.1 Simple tests ....................................................................................................3
2.1.1 Melting...............................................................................................3
2.1.2 Solubility............................................................................................3
©2001, Rapra Technology Limited
2.1.3 Burning characteristics.......................................................................3
2.1.4 Odour recognition..............................................................................4
2.1.5 Dripping.............................................................................................4
All rights reserved. Except as permitted under current legislation no part
2.1.6 Flotation.............................................................................................4
of this publication may be photocopied, reproduced or distributed in any
2.1.7 Halogen test.......................................................................................4
form or by any means or stored in a database or retrieval system, without
the prior permission from the copyright holder. 2.1.8 Nitrogen- and sulphur-test .................................................................5
2.1.9 Burchfield colour reaction..................................................................5
2.1.10 Liebermann-Storch-Morawski reaction.............................................. 6
Acknowledgements
2.2 Recording an IR spectrum .............................................................................7
Without the kind interest and stimulus of the Belgian Plastics and Rubber Institute (BPRI),
2.2.1 Principles of infrared spectroscopy.....................................................7
this book would never have been published. For this reason, we would like to express our
appreciation to Mr. D. Booth and Mr. R. Dimiaux; the president and secretary of the 2.2.2 Origin of infrared absorption.............................................................7
BPRI. Special mention should also be made of the contributions of Mrs. H. Lauwereys,
2.2.3 Normal vibrations of a molecular fragment....................................... 8
who carried out the necessary language corrections.
Model CX ..........................................................................................8
Model CX2........................................................................................9
A catalogue record for this book is available from the British Library.
Model CX3........................................................................................9
In summary......................................................................................10
ISBINSB: N97: 81--18-589595577-?-?2?6-8?-9 Ring structures.................................................................................10
2.2.4 Sample preparation for recording an IR-spectrum ...........................11
Typeset by Rapra Technology Limited
2.3 The identification flow charts......................................................................12
Printed aPnrdin bteodu anndd b byo Luingdh tbnyin ?g? ?Source Inc.
2.3.1 Flow chart – Melting behaviour.......................................................13
i
Easy ID Title Page etc 2 26/11/01, 4:00 pm
Easy ID Contents 1 26/11/01, 4:00 pm
Contents
1. Introduction...........................................................................................................1
2. Tests for the Identification of Plastics and Rubbers...............................................3
2.1 Simple tests ....................................................................................................3
2.1.1 Melting...............................................................................................3
2.1.2 Solubility............................................................................................3
2.1.3 Burning characteristics.......................................................................3
2.1.4 Odour recognition..............................................................................4
2.1.5 Dripping.............................................................................................4
2.1.6 Flotation.............................................................................................4
2.1.7 Halogen test.......................................................................................4
2.1.8 Nitrogen- and sulphur-test .................................................................5
2.1.9 Burchfield colour reaction..................................................................5
2.1.10 Liebermann-Storch-Morawski reaction.............................................. 6
2.2 Recording an IR spectrum .............................................................................7
2.2.1 Principles of infrared spectroscopy.....................................................7
2.2.2 Origin of infrared absorption.............................................................7
2.2.3 Normal vibrations of a molecular fragment....................................... 8
Model CX ..........................................................................................8
Model CX2........................................................................................9
Model CX3........................................................................................9
In summary......................................................................................10
Ring structures.................................................................................10
2.2.4 Sample preparation for recording an IR-spectrum ...........................11
2.3 The identification flow charts......................................................................12
2.3.1 Flow chart – Melting behaviour.......................................................13
i
i
Easy ID Contents 1 26/11/01, 4:00 pm
Easy Identification of Plastics and Rubbers
Easy Identification of Plastiucs and Rubbers Contents
2.3.2 Flow chart – Sample floats in water .................................................14 3.4.15 PPS (Polyphenylene sulphide)...........................................................67
2.3.3 Flow chart – Sample sinks in water..................................................15 3.4.16 PVC (Polyvinyl chloride)..................................................................70
2.3.4 Flow chart – Sample keeps burning after removal from the flame...... 16 3.4.17 PVDF (Polyvinylidene fluoride)........................................................73
2.3.5 Flow chart – Sample burns but extinguishes after removal 3.4.18 PEI (Polyetherimide).........................................................................76
from the flame..................................................................................17
3.4.19 PEEK (Polyetheretherketone) ...........................................................79
2.3.6 Flow chart – Sample does not burn..................................................18
3.4.20 PAI (Polyamide-imide)......................................................................82
2.3.7 Flow chart – Sample does not dissolve in toluene.............................19
3.4.21 PI (Polyimide)...................................................................................85
2.3.9 Flow chart – Elastomers which burn and keep on burning
3.4.22 PBI (Polybenzimidazole)...................................................................88
after removal from the flame............................................................21
3.4.23 PPO (Polyphenylene oxide)..............................................................91
2.3.10 Flow chart – Elastomers which burn but extinguish on
3.4.24 PTFE (Polytetrafluoroethene; polytetrafluoroethylene)....................94
removal from the flame....................................................................22
3.4.25 EVA (Ethene-vinylacetate copolymer) ..............................................97
3. Thermoplastics....................................................................................................23
3.4.26 SB (Styrene-butadiene copolymer)..................................................100
3.1 What is a thermoplastic?..............................................................................23 3.4.27 ABS (Acrylonitrile-butadiene-styrene terpolymer)..........................103
3.2 Thermoplastic homopolymers......................................................................23
4. Cellulose and Starch ..........................................................................................107
3.3 Thermoplastic copolymers...........................................................................24
4.1 Introduction to biopolymers ......................................................................107
3.4 Characteristics of individual thermoplastic materials...................................25
4.2 Characteristics of individual biopolymers..................................................108
3.4.1 PE (Polyethene; polyethylene)...........................................................25
4.2.1 Cellulose.........................................................................................108
3.4.2 PP (Polypropene; polypropylene) .....................................................28
4.2.2 Starch.............................................................................................111
3.4.3 PS (Polystyrene)................................................................................31
5. Thermosets........................................................................................................115
3.4.4 POM (Polyoxymethylene; acetal).....................................................34
3.4.5 Saturated polyester – PET (Polyethene terephthalate; 5.1 What is a thermoset? .................................................................................115
polyethylene terephthalate................................................................37
5.2 Sample preparation for recording an IR-spectrum.....................................115
3.4.6 PMMA (Polymethyl methacrylate; acrylic).......................................40
5.3 Thermoset materials...................................................................................115
3.4.7 CA (Cellulose acetate)......................................................................43
3.4.8 CN (Cellulose nitrate)......................................................................46 5.4 Characteristics of individual thermoset materials.......................................116
3.4.9 PVAc (Polyvinyl acetate)...................................................................49 5.4.1 Unsaturated polyester resin (UP)....................................................116
3.4.10 PAN (Polyacrylonitrile) ....................................................................52 5.4.2 Epoxy resin ....................................................................................119
3.4.11 PC (Polycarbonate) ..........................................................................55 5.4.3 UF (Urea-formaldehyde resin)........................................................122
3.4.12 PA (Polyamide; nylon)......................................................................58 5.4.4 MF (Melamine-formaldehyde resin) .................................................125
3.4.13 PSU (Polysulphone; PSUL) ...............................................................61 5.4.5 PF (Phenol-formaldehyde resin; phenolic resin) ................................128
3.4.14 PPSU (Polyphenylsulphone)..............................................................64 5.4.6 PUR (Polyurethane) ..........................................................................131
ii iii
ii
Easy ID Contents 2 26/11/01, 4:00 pm Easy ID Contents 3 26/11/01, 4:00 pm
Contents
Easy Identification of Plastiucs and Rubbers Contents
2.3.2 Flow chart – Sample floats in water .................................................14 3.4.15 PPS (Polyphenylene sulphide)...........................................................67
2.3.3 Flow chart – Sample sinks in water..................................................15 3.4.16 PVC (Polyvinyl chloride)..................................................................70
2.3.4 Flow chart – Sample keeps burning after removal from the flame...... 16 3.4.17 PVDF (Polyvinylidene fluoride)........................................................73
2.3.5 Flow chart – Sample burns but extinguishes after removal 3.4.18 PEI (Polyetherimide).........................................................................76
from the flame..................................................................................17
3.4.19 PEEK (Polyetheretherketone) ...........................................................79
2.3.6 Flow chart – Sample does not burn..................................................18
3.4.20 PAI (Polyamide-imide)......................................................................82
2.3.7 Flow chart – Sample does not dissolve in toluene.............................19
3.4.21 PI (Polyimide)...................................................................................85
2.3.9 Flow chart – Elastomers which burn and keep on burning
3.4.22 PBI (Polybenzimidazole)...................................................................88
after removal from the flame............................................................21
3.4.23 PPO (Polyphenylene oxide)..............................................................91
2.3.10 Flow chart – Elastomers which burn but extinguish on
3.4.24 PTFE (Polytetrafluoroethene; polytetrafluoroethylene)....................94
removal from the flame....................................................................22
3.4.25 EVA (Ethene-vinylacetate copolymer) ..............................................97
3. Thermoplastics....................................................................................................23
3.4.26 SB (Styrene-butadiene copolymer)..................................................100
3.1 What is a thermoplastic?..............................................................................23 3.4.27 ABS (Acrylonitrile-butadiene-styrene terpolymer)..........................103
3.2 Thermoplastic homopolymers......................................................................23
4. Cellulose and Starch ..........................................................................................107
3.3 Thermoplastic copolymers...........................................................................24
4.1 Introduction to biopolymers ......................................................................107
3.4 Characteristics of individual thermoplastic materials...................................25
4.2 Characteristics of individual biopolymers..................................................108
3.4.1 PE (Polyethene; polyethylene)...........................................................25
4.2.1 Cellulose.........................................................................................108
3.4.2 PP (Polypropene; polypropylene) .....................................................28
4.2.2 Starch.............................................................................................111
3.4.3 PS (Polystyrene)................................................................................31
5. Thermosets........................................................................................................115
3.4.4 POM (Polyoxymethylene; acetal).....................................................34
3.4.5 Saturated polyester – PET (Polyethene terephthalate; 5.1 What is a thermoset? .................................................................................115
polyethylene terephthalate................................................................37
5.2 Sample preparation for recording an IR-spectrum.....................................115
3.4.6 PMMA (Polymethyl methacrylate; acrylic).......................................40
5.3 Thermoset materials...................................................................................115
3.4.7 CA (Cellulose acetate)......................................................................43
3.4.8 CN (Cellulose nitrate)......................................................................46 5.4 Characteristics of individual thermoset materials.......................................116
3.4.9 PVAc (Polyvinyl acetate)...................................................................49 5.4.1 Unsaturated polyester resin (UP)....................................................116
3.4.10 PAN (Polyacrylonitrile) ....................................................................52 5.4.2 Epoxy resin ....................................................................................119
3.4.11 PC (Polycarbonate) ..........................................................................55 5.4.3 UF (Urea-formaldehyde resin)........................................................122
3.4.12 PA (Polyamide; nylon)......................................................................58 5.4.4 MF (Melamine-formaldehyde resin) .................................................125
3.4.13 PSU (Polysulphone; PSUL) ...............................................................61 5.4.5 PF (Phenol-formaldehyde resin; phenolic resin) ................................128
3.4.14 PPSU (Polyphenylsulphone)..............................................................64 5.4.6 PUR (Polyurethane) ..........................................................................131
ii iii
iii
Easy ID Contents 2 26/11/01, 4:00 pm Easy ID Contents 3 26/11/01, 4:00 pm
Easy Identification of Plastics and Rubbers
Easy Identification of Plastiucs and Rubbers
6. Elastomers .........................................................................................................135
6.1 What is an elastomer?................................................................................135
6.2 Recording an IR-spectrum .........................................................................135
6.3 The Burchfield colour reaction...................................................................135
6.4 The Liebermann-Storch-Morawski reaction ..............................................136
6.5 Elastomeric materials.................................................................................136
6.6 Characteristics of individual elastomers.....................................................137
6.6.1 NR (Poly-cis1,4-isoprene; natural rubber; polyisoprene)................137
6.6.2 IIR (Isobutene-isoprene rubber; butyl rubber)................................140
6.6.3 EPR (Ethene-propene rubber; poly(ethene-propene)) .....................143
6.6.4 EPDM (Ethene-propene-diene rubber;
poly(ethene-propene-diene-methylene))..........................................146
6.6.5 SBR (Styrene-butadiene rubber; poly(styrene-butadiene)................149
6.6.6 CR (Chloroprene rubber, (polychlorobutadiene,
poly-trans-chloroprene)..................................................................152
6.6.7 NBR (Nitrile rubber; poly(acrylonitrile-butadiene)).......................155
6.6.8 Silicone rubber and thermoset........................................................158
6.6.9 PUR (Polyurethane)........................................................................161
7. Chemical Products Required..............................................................................165
7.1 Introduction..............................................................................................165
7.2 Organic solvents and reagents....................................................................165
7.3 Inorganic products, acids and bases...........................................................165
Abbreviations..........................................................................................................167
Symbols...................................................................................................................168
References ...............................................................................................................168
Index .............................................................................................................................171
iv
iv
Easy ID Contents 4 26/11/01, 4:00 pm
Easy Identification of Plastiucs and Rubbers
6. Elastomers .........................................................................................................135 1 Introduction
6.1 What is an elastomer?................................................................................135
6.2 Recording an IR-spectrum .........................................................................135
6.3 The Burchfield colour reaction...................................................................135 The impact of polymers on our way of life is tremendous. In a typical living room there
may be acrylic carpeting, polyester curtains, nylon hooks and curtain rods, urea-
6.4 The Liebermann-Storch-Morawski reaction ..............................................136
formaldehyde electrical fittings, melamine-formaldehyde laminates on marproof table
tops, polyvinyl acetate paint on the walls, polypropylene chairs, polyurethane foam-
6.5 Elastomeric materials.................................................................................136
filled cushions, and so on. An analogous list can be drawn up for a car. The success of
6.6 Characteristics of individual elastomers.....................................................137 polymers is due to their relative low price in combination with outstanding properties.
This often makes polymers the first choice material instead of metals, wood or other
6.6.1 NR (Poly-cis1,4-isoprene; natural rubber; polyisoprene)................137
expensive natural products.
6.6.2 IIR (Isobutene-isoprene rubber; butyl rubber)................................140
6.6.3 EPR (Ethene-propene rubber; poly(ethene-propene)) .....................143 Polymers can be classified into three groups: thermoplastics, thermosets and elastomers.
They are rarely used as pure materials; generally additives are included to improve the
6.6.4 EPDM (Ethene-propene-diene rubber;
poly(ethene-propene-diene-methylene))..........................................146 quality and reduce the price of commercial products.
6.6.5 SBR (Styrene-butadiene rubber; poly(styrene-butadiene)................149
When using a plastic in an application, it is necessary to know the chemical nature of the
6.6.6 CR (Chloroprene rubber, (polychlorobutadiene, constituent polymer. Poor material selection of plastics and rubbers often results in
poly-trans-chloroprene)..................................................................152 technical problems. Usually these problems can be prevented if technicians are able to
6.6.7 NBR (Nitrile rubber; poly(acrylonitrile-butadiene)).......................155 identify and characterise the plastic. Therefore students should be introduced to a simple
chemical identification of plastics during their education.
6.6.8 Silicone rubber and thermoset........................................................158
6.6.9 PUR (Polyurethane)........................................................................161 The numerous polymers cannot be identified by a simple touch and feel exercise, nor
by their visual appearance. For example, in the case of a translucent plastic, the
7. Chemical Products Required..............................................................................165
constituting polymer could be, for instance, polymethyl methacrylate (PMMA),
polycarbonate (PC) or polystyrene (PS). Similarly, a piece of rubber in the interior of a
7.1 Introduction..............................................................................................165
car could perhaps be ethene-propene-diene rubber (EPDM), but styrene-butadiene
7.2 Organic solvents and reagents....................................................................165 rubber (SBR) and other rubbers are not excluded. Simple observation will not reveal
the chemical nature of a polymer.
7.3 Inorganic products, acids and bases...........................................................165
For these reasons, more than thirty years ago, scientists developed identification schemes
Abbreviations..........................................................................................................167
based on simple tests such as the behaviour of polymers in liquids (e.g. dissolving, floating)
or in a flame (e.g. characteristics of burning, smell). In the 1980s, good tables for the
Symbols...................................................................................................................168
identification of plastics became available [1, 2]. The major advantages of these schemes
are that the procedure is quick and only a rudimentary knowledge of chemistry is required
References ...............................................................................................................168
when using them. However, these identification tables are only valuable for a rough
qualitative assessment of simple homopolymers. Copolymers, polymer blends and the
recently developed high performance plastics may not be identified with these schemes.
A complete analysis of a plastic or rubber is a complex, difficult and time-consuming
task, needing not only highly qualified chemists but also expensive equipment.
iv 1
1
Easy ID Contents 4 26/11/01, 4:00 pm Easy ID of P&R 1 26/11/01, 4:00 pm
Easy Identification of Plastics and Rubbers
Easy Identification of Plastiucs and Rubbers
This book offers a more extended version of the classic identification systems. Besides 2 Tests for the Identification of Plastics and Rubbers
thermoplastics the reader will find common thermosets, a few copolymers and elastomers.
Infrared (IR) spectroscopy is also incorporated in the procedure to obtain accurate results.
The preparation of samples for infrared spectroscopy are kept as simple and quick as
possible, but we realise that the operator must have an elementary knowledge of infrared
spectroscopy and have access to an infrared spectrophotometer. However, the identification
process without infrared techniques is still useful for a broad range of polymers. 2.1 Simple tests
The procedures described in this book have been verified by hundreds of students. The For the identification of an unknown piece of plastic, a number of consecutive steps have
original intention was to use this identification system in education to graduate level. to be taken. These steps are shown in the flow charts in Section 2.3. From the flow charts
For two years, workshops were organised for undergraduates. Each student had to look it can be seen that some tests are used frequently. These tests are described below. The
for some samples of different plastics found in waste materials at home. On these samples basic principles can be found in the following references: [1, 2, 3, 4, 5, 6, 7].
they learned the techniques presented in this book. Therefore it is evident that a layman
will learn this method of ‘easy identification of plastics and rubbers’ very quickly.
2.1.1 Melting
Melting behaviour can be checked by touching the sample with a hot needle. Another
method is to heat a little piece of the unknown plastic in a spoon above the flame. It is
important that the flame does not make direct contact with the plastic. When the plastic
becomes viscous and distorted on heating, it is melting. When it becomes brown-black,
the plastic is not melting but carbonising. Keep in mind that some plastics have a very
high melting temperature and it may take a while before they melt.
2.1.2 Solubility
Solubility can be checked by putting ± 0.1 g of the plastic in 3 ml of the specified solvent
and shaking the tube in a flame. Keep in mind that most organic solvents are combustible.
Accept that the sample dissolves when it visibly disappears after 10 minutes. In some
instances a polymer is not dissolving (in the strict scientific sense), but forming a colloid.
The result is some opalescence, which may be interpreted as a visual disappearance.
Some plastics swell in certain solvents, this is not dissolving. A change in colour of the
solvent because of the presence of coloured pigments, is not evidence for dissolution.
Heating the solvent usually aids dissolution.
2.1.3 Burning characteristics
The characteristics of burning are important [3]. Something that burns in the flame may
keep on burning or stop burning after being removed from the flame. To determine this,
2 3
2
Easy ID of P&R 2 26/11/01, 4:00 pm Easy ID of P&R 3 26/11/01, 4:00 pm
Easy Identification of Plastiucs and Rubbers
This book offers a more extended version of the classic identification systems. Besides 2 Tests for the Identification of Plastics and Rubbers
thermoplastics the reader will find common thermosets, a few copolymers and elastomers.
Infrared (IR) spectroscopy is also incorporated in the procedure to obtain accurate results.
The preparation of samples for infrared spectroscopy are kept as simple and quick as
possible, but we realise that the operator must have an elementary knowledge of infrared
spectroscopy and have access to an infrared spectrophotometer. However, the identification
process without infrared techniques is still useful for a broad range of polymers. 2.1 Simple tests
The procedures described in this book have been verified by hundreds of students. The For the identification of an unknown piece of plastic, a number of consecutive steps have
original intention was to use this identification system in education to graduate level. to be taken. These steps are shown in the flow charts in Section 2.3. From the flow charts
For two years, workshops were organised for undergraduates. Each student had to look it can be seen that some tests are used frequently. These tests are described below. The
for some samples of different plastics found in waste materials at home. On these samples basic principles can be found in the following references: [1, 2, 3, 4, 5, 6, 7].
they learned the techniques presented in this book. Therefore it is evident that a layman
will learn this method of ‘easy identification of plastics and rubbers’ very quickly.
2.1.1 Melting
Melting behaviour can be checked by touching the sample with a hot needle. Another
method is to heat a little piece of the unknown plastic in a spoon above the flame. It is
important that the flame does not make direct contact with the plastic. When the plastic
becomes viscous and distorted on heating, it is melting. When it becomes brown-black,
the plastic is not melting but carbonising. Keep in mind that some plastics have a very
high melting temperature and it may take a while before they melt.
2.1.2 Solubility
Solubility can be checked by putting ± 0.1 g of the plastic in 3 ml of the specified solvent
and shaking the tube in a flame. Keep in mind that most organic solvents are combustible.
Accept that the sample dissolves when it visibly disappears after 10 minutes. In some
instances a polymer is not dissolving (in the strict scientific sense), but forming a colloid.
The result is some opalescence, which may be interpreted as a visual disappearance.
Some plastics swell in certain solvents, this is not dissolving. A change in colour of the
solvent because of the presence of coloured pigments, is not evidence for dissolution.
Heating the solvent usually aids dissolution.
2.1.3 Burning characteristics
The characteristics of burning are important [3]. Something that burns in the flame may
keep on burning or stop burning after being removed from the flame. To determine this,
2 3
3
Easy ID of P&R 2 26/11/01, 4:00 pm Easy ID of P&R 3 26/11/01, 4:00 pm