Identification of plastics

Identification of plastics can be as simple as finding the resin identification code (typically on the bottom of the component) or as complex as separating the base resin from the filler, reinforcements, and colorants to analyze via infrared (IR) spectroscopy. The resin identification codes developed by the Society of Plastics Industry in 1998 are shown in Table 1.5. Despite the desire of many individuals to recycle, many communities recycle often only recycle plastics polyester (polyethylene terephthalate (PET)) and high-density polyethylene (HDPE). In fact, local recycling companies in the United States will often bury plastics in a landfill, either with the rest of the waste or in separate locations, ostensibly to mine at a later date. Collected recyclables are also shipped from the United States as baled 

Society of Plastics Industry Resin Identification Codes 

Resin PET-Polyester Symbol Alternative Symbol PET Recycled Uses Beverage bottles, shreded bevaage bottles becomes carpet and mats 

Other-resin other than 1-6 or combination of resins OTHER Plastic lumber 

The most reliable (time-consuming and costly) identification method is to use infrared spectroscopy measurements to determine the material. The Rapra Collection of Infrared Spectra of Rubbers, Plastics, and Thermoplastic Elastomers can be used to compare the spectrum of a test material to reference spectra. The transmission spectra in this reference are obtained either from cast or molded thin film or in the case of cross-linked materials by pyrolysis of the material in a Pyrex tube. 

A precondition for the bonding of plastics is the knowledge of the adhesive characteristics. Trade names and product marking according to Table 9.1 help identify the adhesive in the case of missing indications, it is difficult or almost impossible for laymen. The following two criteria may serve to distinguish between thermoplastic and thermoset material  

It is important to identify the types of plastics present in objects to understand how, when and why they were produced, and to identify the optimal conservation strategies for them. Methods of identification may be divided into simple tests, based on measuring their appearance, mechanical and chemical properties, 

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Braun, D., Simple Methods for the Identification of Plastics, 2nd ed. Hanser Publishers, Munich, 1986, p. 21. 

Rapid identification of plastics by spectroscopic and x-ray methods were reviewed [17]. Several books are available [2,11]. 

G.A.L. Verleye, N.P.G. Roeges and M.O. de Moor, Easy Identification of Plastics and Rubbers, Rapra Technology Ltd, Shawbury (2001). 

D. Brown, Simple Methods for Identification of Plastics, Hanser-Gardner Publishers, Cincinnati, OH (1999). 

The high sensitivity of XRF for elements of higher atomic weight (e.g. Br, Cl) is of advantage in the identification of plastics in postconsumer waste, and is being used in practice only for separating PVC ... 

D. Wienke, W. van den Broek and L. Buydens, Identification of plastics among nonplastics in mixed waste hy remote sensing near-infrared imaging spectroscopy. 2. Multivariate rank analysis for rapid classification. Anal. Ghent., 67, 3760-3766 (1995). 

The uses of IR spectra in identification, classification and mechanistic studies have been well documented. Tests for the identification of plastics utilized in Naval ordnance weaponry are discussed in Ref 21. Correlations between polymeric structure and ablative properties using IR spectroscopy have been obtained by monitoring changes in functional group absorption,properties.(Ref 12). The application of IR spectroscopy to the detection of more than 40 of the most common constituents of primers, tracers, igniters, incendiaries,... 

Wienke, D. van den Broek, W. Buydens, L., Identification of Plastics among Nonplastics in Mixed Waste by Remote Sensing Near-Infrared Imaging Spectroscopy. 2. Multivariate Rank Analysis for Rapid Classification Anal. Chem. 1995, 67, 3760-3766. 

Anon., Solar Hot Water Heating Systems Identification of Plastic Materials for Low Cost Glazings, PolyNEW, Inc., Subcontract TAR-9-29449-02 Report, National Renewable Energy Laboratory, Golden, CO, 2002. 

Scott R A (2000), Textiles in defence , in Handbook ofTechnical Textiles. Horrocks A R and Anand S C (eds), Woodhead Publishing, Cambridge. UK. Chapter 16, 425-460. Verleye A L, Roeges P G and Moor M O (2001), Easy Identification of Plastics and Rubbers,... 

Figure 1.16 Codes for the identification of plastic objects by resin.

Wahl HG, Hoffinarm A, Haring H-U, et al. 1999. Identification of plasticizers in medical products by a combined direct thermodesorption-cooled injection system and gas chromatography-mass spectrometry. J Chromatogr A847 1 -7. 

Identification of plastics [34] is carried out by a systematic procedure preliminary test, detection of elements, determination of characteristic values, and, finally, specific tests. For an exact identification, however, the test sample should first be purified so that it contains no additives (plasticizers, fillers, pigments, etc.) that may affect the results of an analysis. Purification is achieved by solvent extraction either the material is dissolved out and polymer is obtained by reprecipitation or evaporation of the solvent, or the pure polymer remains as the insoluble residue. The solvent varies, and a general method cannot be given. However, for many materials particularly for those in which additives do not interfere, the unpurified material can be investigated and qualitative preliminary tests used. 

Simple methods for identification of plastics / Dietrich Braun. - - 5th edition. 

For more recent synthetic polymers, interviews with the artist can provide information about materiak and technique used, although they do not always replace analysis. The date of manufacture or, if unavailable, the date of collection, can provide a starting point in the identification of plastics. If a plastic was manufactured before around 1905, it is likely to be a semi-synthetic or natural material, rather than a fully synthetic plastic. The period between 1939 and 1960 saw a dramatic increase in production of polystyrene, poly (vinyl chloride), nylon, acrylics and polyethylene and the phasing out of semi-synthetics. If a plastic was manufactured before the 1940s, it could not have been shaped by injection moulding, recognized by a small imperfection due to the filling hole. 

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