Polyethylene density classification

Table 2.3 Polyethylene density classification according to ASTM D883...

Figure 7.4 Classification and image processing results of a typical situation in polymer waste recycling (a) digital image (b) initial classification result (c) calculation of separation data based on the initial classification result (d) classification result after real-time image processing. A, B Polyethylene terephthalate (PET) bottles with paper labels, C PE bottle with paper label, D PE bottle with PE film label, E PP cup, F PS cup. Classification colour code red high-density PE green PS dark blue PET yellow PP light blue paper.

L. Ballice, Classification of volatile products evolved during temperature-programmed co-pyrolysis of low-density polyethylene (LDPE) with polypropylene (PP). Fuel, 81(9),1233-1240 (2002). 

The American Society for Testing and Materials (ASTM) has also defined various types of polyethylene. An ASTM publication entitled "Standard Terminology Relating to Plastics" (ASTM D 883-00) provides the following classifications based upon density ... 

Polyethylene is manufactured in various polymeric forms, differing by their molecular weight and linearity, or presence of irregularities, or branches, unsaturations, and so on. This in turn determines the density, or specific gravity of the polymer, which is nsed as the principal classification feature of polyethylenes. The main forms of polyethylenes are as follows ... 

Figure 2.1 Classification of polyethylenes according to branching structure and density.

Polyethylene comes in three main classifications based on density low, medium, and high. These density ranges are generally 0.910-0.925, 0.925-0.940, and 0.940-0.965, respectively. Commercially available grades are broken down further by density into ... 

A density-based method has been introduced for polyethylene classification relying on ASTM-standards (Table 2.2). The density-based classification coincides to some extent with that based on the polymerisation processes. Consequently, polyethylene with low density (LDPE) is usually a polyethylene material produced by high-pressure polymerisation and polyethylene with high density (HDPE) is a polyethylene material manufactured by low-pressure polymerisation. Since the end of the 1970s co-... 

The measurement of melt mass-flow rate and density is usually the first step in the specification and identification of polyethylene materials. It should be noted that the density of the base polymer differs from the density of the finished geomembrane mixed with carbon black. The confusion, which can occur in the classification of the PE resin, has briefly been dealt with in Sect. 2.1. As a rule, only geomembianes coloured black by carbon black, and not their natural-coloured resin, reach a density which properly meets the classification of HOPE plastic material (see Sect. 2, Tables 2.2 and 2.3). However, one may not consider these classification limits as strict technical criteria even if the density of the black geomembianes is just below 0.940 g/cm, it may correspond to what is ealled HOPE geomembrane over the whole spectrum of its characteristics. 

As per the Bureau of Indian Standards classification, there are 7 categories of plastics namely PET, high-density polyethylene (HOPE), PVC, low-density polyethylene (LDPE), PP, PS and others (O). 

Classification of low density polyethylene films defines the types, classes, surfaces, and finishes and considers the following properties impact strength,... 

The classification of medium density polyethylene films (Table 20) considers the following properties stiffness, optical properties, coefficient of friction, and surface treatment. 

TABLE 20 Classification of medium density polyethylene films... 

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