Polyethylene classifications

Polyethylene polymers history of, 17 701-702 simulations of, 16 747 Polyethylene products, Ziegler-Natta catalysts for, 26 540-543 Polyethylene resins, 17 700-703 applications for, 17 703 Polyethylenes, classification of, 17 701t. 

Table 1.2 provides a summary of commonly used classifications in the polyethylene industry. A brief note is warranted here to conclude the survey of polyethylene classifications and nomenclature. In the early 1990s, several types of polyethylene manufactured with metallcxiene catalysts (a type of single site catalyst, see Chapter 6) were introduced to the market. To differentiate polyethylene produced with metallocenes from polyethylene manufactured using older conventional catalysts, metallocene grades are sometimes abbreviated mVLDPE, mLLDPE, etc. 

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-... 

Table 2.2. Polyethylene classification and PE resin nomenclature as per ASTM D1248-84 Standard Specification for Polyethylene Plastics Moulding and Extrusion Materials (formerly) and ASTM D883-96 Standard Terminology Relating to Plastics (currently)...

The limiting oxygen index of Tefzel as measured by the candle test (ASTM D2863) is 30%. Tefzel is rated 94 V-0 by Underwriters Laboratories, Inc., in their burning test classification for polymeric materials. As a fuel, it has a comparatively low rating. Its heat of combustion is 13.7 MJ/kg (32,500 kcal/kg) compared to 14.9 MJ /kg (35,000 kcal/kg) for poly(vinyHdene fluoride) and 46.5 MJ /kg (110,000 kcal/kg) for polyethylene. 

Iodine is packed in double polyethylene-lined fiber dmms containing 10, 25, and 50 kg. There is no specific freight classification. 

More frequentiy, alkyd resias are described by a combiaed classification ia terms of thek oil length, the type of fatty acids, and any unusual kigredients. Such descriptions as an isophthaUc, very long tall oil alkyd a medium oil dehydrated castor-PE ( pentaerythritol, not polyethylene) alkyd or a short oil lauric-ben2oic alkyd, immediately project the general properties of the reski. 

A classification by chemical type is given ia Table 1. It does not attempt to be either rigorous or complete. Clearly, some materials could appear ia more than one of these classifications, eg, polyethylene waxes [9002-88 ] can be classified ia both synthetic waxes and polyolefins, and fiuorosihcones ia sihcones and fiuoropolymers. The broad classes of release materials available are given ia the chemical class column, the principal types ia the chemical subdivision column, and one or two important selections ia the specific examples column. Many commercial products are difficult to place ia any classification scheme. Some are of proprietary composition and many are mixtures. For example, metallic soaps are often used ia combination with hydrocarbon waxes to produce finely dispersed suspensions. Many products also contain formulating aids such as solvents, emulsifiers, and biocides. 

Shipping and Storage. MSA is shipped in tank tmcks and in plastic 55-gaHon dmms or smaller containers with polyethylene inserts. The freight classification is Alkyl Sulfonic Acid, Liquid 8 Corrosive Material, UN 2586, Chemical NOIBN. 

Sodium borobydride is available as a 12% solution in caustic soda and in soHd form either as powder or pellets (3). The predominant form produced is the solution, the DOT shipping classification for which is corrosive Hquid. Forms of packaging are 18.9-L pails, 208.2-L dmms, and either tank tmck or tank car for bulk shipments. 1991 pricing for the solution form was 40.34/kg of borobydride contained. SoHd sodium borobydride, a white powder packaged in polyethylene bags in metal containers, was priced at 48.39/kg. 

The chemical and physical properties of the polymers obtained by these alternate methods are identical, except insofar as they are affected by differences in molecular weight. In order to avoid the confusion which would result if classification of the products were to be based on the method of synthesis actually employed in each case, it has been proposed that the substance be referred to as a condensation polymer in such instances, irrespective of whether a condensation or an addition polymerization process was used in its preparation. The cyclic compound is after all a condensation product of one or more bifunctional compounds, and in this sense the linear polymer obtained from the cyclic intermediate can be regarded as the polymeric derivative of the bifunctional monomer(s). Furthermore, each of the polymers listed in Table III may be degraded to bifunctional monomers differing in composition from the structural unit, although such degradation of polyethylene oxide and the polythioether may be difficult. Apart from the demands of any particular definition, it is clearly desirable to include all of these substances among the condensation... 

For films. Table 4.1 proposes an arbitrary classification of the polyethylene subfamilies (where m indicates metallocene catalysis). 

The WetOx process can concentrate radioactive contaminants, causing a shift in classification from class A to class B waste. This will have an impact on the selection of solidification media and could effect burial surcharges. The following materials cannot be processed by the WetOx process spent oil, ammonia, polyvinyl chloride, polyethylene, and rubber. 

Abbreviations. PEG, polyethylene glycol PVP, polyvinylpyrrolidone PVA, polyvinylalcohol HPMC, hydroxypropylmethylcellulose CMEC, carboxymethylethylcellulose, BCS, biopharmaceutical classification system Y, Yes. 

The application areas of bimodal polyethylenes are the same as for corresponding uni-modal resins. However, improved product property combinations, such as stiffness-impact balance, result in products with higher performance. For example, without bimodal polyethylene and control over the MWD and comonomer incorporation, development of HDPE pipe materials with higher pressure classification would not have been possible [15, 16]. Another new opportunity is material reduction (source reduction) without compromising the properties of the ready-made plastic products. Depending on the end use, e.g. in film application a thickness reduction of 10-30% is possible. 

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). 

Whereas UL 94 delivers only a classification based on a pass-and-fail system, LOI can be used to rank and compare the flammability behavior of different materials. In Figure 15.2 the increasing LOI values are presented for different polymers as an example POM = poly(oxymethylene), PEO = poly(ethyl oxide), PMMA = poly(methyl methacrylate), PE = polyethylene), PP, ABS, PS, PET = polyethylene terephthalate), PVA = poly(vinyl alcohol), PBT, PA = poly(amide), PC, PPO = poly(phenylene oxide), PSU, PEEK = poly(ether ether ketone), PAEK = poly(aryl ether ketone), PES, PBI = poly(benzimidazole), PEI = poly(ether imide), PVC = poly(vinyl chloride), PBO = poly(aryl ether benzoxazole), PTFE. The higher the LOI, the better is the intrinsic flame retardancy. Apart from rigid PVC, nearly all commodity and technical polymers are flammable. Only a few high-performance polymers are self-extinguishing. Table 15.1 shows an example of how the LOI is used in the development of flame-retarded materials. The flame retardant red phosphorus (Pred) increases... 

The broadest classification for plastics is the old thermoplastic and thermosetting . Examples of the former group are polyethylene, polystyrene, and poly-(methyl methacrylate) examples of the latter are urea-formaldehyde condensation polymers, powder coatings based on polyesters, epoxy resins, and vulcanized synthetic elastomers. 

DOT CLASSIFICATION Forbidden SAFETY PROFILE Poison by ingestion and intraperitoneal routes. Moderately toxic by inhalation. Irritating to skin, eyes, and mucous membranes. Inhalation can cause headache and nausea. Causes mild narcosis. A very dangerous explosion hazard explodes when heated rapidly. Dissolution is exothermic and solutions of more than 50% can explode. Mixtures of 90% trinitromethane + 10% isopropyl alcohol in polyethylene bottles have exploded. Frozen mixtures with 2-propanol (10%) explode when thawed. Can explode during distillation. Mixtures with divinyl ketone can explode at 4°C. When heated to decomposition it emits toxic fumes of NOx. See also NITRO COMPOUNDS. 

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