Polymer foam classification

A rigid foam is defined as one in which the polymer matrix exists in the crystalline state or, if amorphous, is below its Tg. Following from this, a flexible cellular polymer is a system in which the matrix polymer is above its Tg. According to this classification, most polyolefins, polystyrene, phenolic, polyycarbonate, polyphenylene oxide, and some polyurethane foams are rigid, whereas rubber foams, elastomeric polyurethanes, certain polyolefins, and plasticized PVC are flexible. Intermediate between these two extremes is a class of polymer foams known as semirigid. Their stress-strain behavior is, however, closer to that of flexible systems than to that exhibited by rigid cellular polymers. 

Uses Dispersant emulsifier for latex polymerization, wastewater treatment foam-able hydrophilic prepolymer for wound dressings, biocompalible coatings, dmg delivery vehicles absorbent foam, carrier food-contact PU, rubber articles Manuf/Distrib. Air Prods. Bayer Chemtura Cylec Conap DSM NeoResIns Huntsman Polyurethanes Monomer-Polymer Dajac Labs Polyurethane Coqp. of Am. Soluol Vertellus Perf. Materials Polyurethane resin Synonyms Polyurethane polymer PU Classification Urethane... 

To illustrate some commonly encountered classification methods, a data set obtained from a series of polyurethane rigid foams will be used.55 In this example, a series of 26 polyurethane foam samples were analyzed by NIR diffuse reflectance spectroscopy. The spectra of these foams are shown in Figure 8.25. Each of these foam samples belongs to one of four known classes, where each class is distinguished by different chemistry in the hard block parts of the polymer chain. Of the 26 samples, 24 are selected as calibration samples and 2 samples are selected as prediction samples. Prediction sample A is known to belong to class number 2, and prediction sample B is known to belong to class number 4. Table 8.8 provides a summary of the samples used to produce this data set. 

In the case of cellular rubber, the ASTM uses several classifications based on the method of manufacture [11,12]. Cellular rubber is a general term covering all cellular materials that have an elastomer as the polymer phase. Sponge rubber and expanded rubber are cellular rubbers produced by expanding bulk rubber stocks, and are open-cell and closed- cell, respectively. Latex foam rubber, which is also a cellular rubber, is produced by frothing a rubber latex or liquid rubber, gelling the frothed latex, and then vulcanizing it in the expanded state. 

DOT CLASSIFICATION 8 Label Corrosive SAFETY PROFILE Moderately toxic by ingestion, skin contact, and subcutaneous routes. A corrosive irritant to eyes, skin, and mucous membranes. Dangerous fire hazard when exposed to heat, flames, oxidizers. To fight fire, use alcohol foam. When heated to decomposition it emits toxic fumes of NOx. Used as an intermediate in production of petroleum and polymer additives, and surfactants. See also AMINES. 

This classification of foamed materials only formally resembles the classification based on the cell concept proposed by A. A. Berlin more than a quarter of a century ago it is based on quite different morphological notions about the spatial structure of foamed polymers. 

Shutov, F. A The gas-structure element and a new classification of plastic foams. All-Union Conference on Gas-Filled Polymers, Vladimir/USSR, 1974 (in Russian)... 

Most common fluids of simple structure are Newtonian (i.e., water, air, glycerine, oils, etc.). However, fluids with complex structures (i.e., high polymer melts or solutions, suspensions, emulsions, foams, etc.) are generally non-Newtonian. Examples of non-Newtonian behavior include mud, paint, ink, mayonnaise, shaving cream, polymer melts and solutions, toothpaste, etc. Many two-phase systems (e.g., suspensions, emulsions, foams, etc.) are purely viscous fluids and do not exhibit significant elastic or memory properties. However, many high polymer fluids (e.g., melts and solutions) are viscoelastic and exhibit both elastic (memory) as well as nonlinear viscous (flow) properties. A classification of material behavior is summarized in Table 5.1 (in which the subscripts have been omitted for simplicity). Only purely viscous Newtonian and non-Newtonian fluids are considered here. The properties and flow behavior of viscoelastic fluids are the subject of numerous books and papers (e.g., Darby, 1976 Bird et al., 1987). 

Polyurethanes are produced by the chemical action of di-isocyanate and polyol. The properties can be varied by the type of isocyanate used and the proportion of the two monomers. There are four main groups of classification for the thermoplastic groups of polyurethane, i.e. rigid foam, flexible foam, non-cellular and cellular polymers. Two main isocyanates used are toluene di-isocyanate (TDI) and diphenylmethane diisocyanate (MDI). Polyurethanes have limited application in the pharmaceutical or medical industries. Polyurethane is used as an adhesive for laminations (thermosetting material). Like thermosetting polyurethane, thermoplastic polyurethanes can be found as esters and ethers. 

Classification Tertiary amine Empirical C12H27N Formula CH3(CH2)9N(CH3)2 Properties M.w. 185.36 dens. 0.778 (20/4 C) b.p. 234 C ref. index 1.431 cationic Storage Keep under argon sensitive to air Uses Intermediate for quat. ammonium compds., amine oxides, betaines for household prods., disinfectants, sanitizers, industrial hand cleaners, cosmetics, bubble baths, deodorants, polymer additives, PU foam catalysis, epoxy curing agent Manuf./Distrib. Fluka http //www.sigma-aldrich.com... 

Ethylene oxide, ethyl-. See 1,2-Epoxybutane Ethylene oxide polymer CAS 9002-90-8 Classification Polymer Properties Vise. 1500 cps min. (1% aq.) Hazardous Decomp. Prods. Heated to decomp., emits acrid smoke and irritating fumes Uses Foam stabilizer in fermented malt beverages... 

Classification Polymer synthetic elastomer Definition Unsaturated polymer of chloroprene Empirical (C4HsCI)x Formula [CH2CH=CCICH2]x Properties As solid, latex, or flexible foam m.w. 100,000-300,000 dens. 1.23-1.35 brittle pt. -35 C softens. 80 C ref. index 1.5512 (20 C) high tens, str. resilient resistant to oils, oxygen, ozone, elec, current, abrasion... 

Table 35-1. Classification of Polymer Plus Additive Mixtures. Closed Areas Give the Regions of Foams ( ... 

In Chapter 1 the importance of the various classes of colloidal systems to modern science and technology was indicated in a general way. Because of the wide variety of colloidal systems one encounters, each having certain unique features that distinguish it from the others, it is convenient to discuss each major classification separately. For that reason, chapters have been devoted to specific systems such as solid dispersions, aerosols, emulsions, foams, lyophilic colloids (i.e., polymer solutions), and association colloids. There is a great deal of overlap in many aspects of the formation, stabilization, and destruction of those systems, and an effort will be made not to repeat more than is necessary. However, for purposes of clarity, some repetition is unavoidable. 

As is the case in most discussions of interfacial systems and their applications, definitions and nomenclature can play a significant role in the way the material is presented. The definition of an emulsion to be followed here is that they are heterogeneous mixtures of at least one immiscible liquid dispersed in another in the form of droplets, the diameters of which are, in general, greater than 0.1 (.m. Such systems possess a minimal stability, generally defined rather arbitrarily by the application of some relevant reference system such as time to phase separation or some related phenomenon. Stability may be, and usually is, enhanced by the inclusion of additives such as surfactants, finely divided solids, and polymers. Such a definition excludes foams and sols from classification as emulsions, although it is possible that systems prepared as emulsions may, at some subsequent time, become dispersions of solid particles or foams. 

Although there are numerous minor classification schemes for polymers, depending on how one wishes to categorize them, nearly all polymers can be placed in one of two major classifications—thermosetting materials (or thermosets) and thermoplastic materials. Likewise, foams, adhesives, embedding resins, elastomers, and so on, can be subdivided into thermoplastic and thermosetting classifications. 

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