Plasticity, defined

Colorants are typically defined as pigments and dyes that, when added to plastics, define a specific color. The subject of colorants has been discussed in numerous books and papers. However, in the context of this chapter, a dye is defined as a substance that is soluble in the resin system and produces color only by the absorption of light and no scattering of light. Pigments are not soluble in the resin system and therefore must be mixed into the resin by one of many dispersion processes. Factors such as pigment particle size and ease of mixing or dispersion directly influence their... 

The Second Edition has 11 terms concerning cellular plastics defined in English and French. 

For a possibility to use the fire retardant coatings, we need to solve a problem concerned with providing the required adhesion between the coating and protected material. The adhesive strength of the coatings to fiberglass plastic defined as the shear strength of a joint. 

The optimum degree of crystallinity that is characteristic of a particular plastic (defined in percentage terms) may only be attained through slow cooling of the moulded part in the mould cavity. This means that heated and thermostatically-controlled moulds have to be used. Although this lengthens the cycle time, it is a basic pre-condition for the manufacture of quality products with stabilised dimensions and good mechanical and use properties. 

Pressure-area isotherms for many polymer films lack the well-defined phase regions shown in Fig. IV-16 such films give the appearance of being rather amorphous and plastic in nature. At low pressures, non-ideal-gas behavior is approached as seen in Fig. XV-1 for polyfmethyl acrylate) (PMA). The limiting slope is given by a viiial equation... 

Film and sheet are defined as flat unsupported sections of a plastic resia whose thickness is very thin ia relation to its width and length. Films are generally regarded as being 0.25 mm or less, whereas sheet may range from this thickness to several centimeters thick. Film and sheet may be used alone ia their unsupported state or may be combined through lamination, coextmsion, or coating. They may also be used in combination with other materials such as paper, foil, or fabrics. 

A cellular plastic has been defined as a plastic the apparent density of which is decreased substantially by the presence of numerous cells disposed throughout its mass (21). In this article the terms cellular plastic, foamed plastic, expanded plastic, and plastic foam are used interchangeably to denote all two-phase gas—soHd systems in which the soHd is continuous and composed of a synthetic polymer or mbber. 

Maximum Service Temperature. Because the cellular materials, like their parent polymers (204), gradually decrease in modulus as the temperature rises rather than undergoing a sharp change in properties, it is difficult to precisely define the maximum service temperature of cellular polymers. The upper temperature limit of use for most cellular polymers is governed predominantly by the plastic phase. Fabrication of the polymer into a... 

Fig. 4. (a) The crack tip plastic zone and (b) the Dugdale plastic zone model. Terms are defined in text. 

The distance from the crack tip, along the X-axis, at which the von Mises equivalent stress falls below the yield stress, defines the size of the plastic zone, r. For the plane stress case of unconstrained yielding, which corresponds to the free surface of the specimen in Figure 4, this gives... 

The use of the single parameter, K, to define the stress field at the crack tip is justified for brittle materials, but its extension to ductile materials is based on the assumption that although some plasticity may occur at the tip the surrounding linear elastic stress field is the controlling parameter. 

High density polyethylene (HDPE) is defined by ASTM D1248-84 as a product of ethylene polymerisation with a density of 0.940 g/cm or higher. This range includes both homopolymers of ethylene and its copolymers with small amounts of a-olefins. The first commercial processes for HDPE manufacture were developed in the early 1950s and utilised a variety of transition-metal polymerisation catalysts based on molybdenum (1), chromium (2,3), and titanium (4). Commercial production of HDPE was started in 1956 in the United States by Phillips Petroleum Company and in Europe by Hoechst (5). HDPE is one of the largest volume commodity plastics produced in the world, with a worldwide capacity in 1994 of over 14 x 10 t/yr and a 32% share of the total polyethylene production. 

ASTM D883 defines a filler as "...a relatively inert material added to a plastic to modify its strength, permanence, working properties, or other quaHties or to lower costs." EiHers (qv) that modify the properties and characteristics of epoxies are employed in epoxy resins for a variety of reasons. Then principal functions are to control viscosity, reduce shrinkage and the coefficient of thermal expansion, effect a cost reduction, and color the epoxy resins. 

Numerous toxicological studies have been conducted on a variety of plasticizers. However, because di-(2-ethylhexyl) phthalate (DEHP) is the most widely used plasticizer and is a well-defined single substance, it is the plasticizer that has been most thoroughly investigated in terms of its toxicology and has often been considered as a model for the other phthalates (36). 

Performance Characteristics Polyester resins undergo a rapid transformation from a viscous Hquid to a soHd plastic state that comprises a three-dimensional cross-linked polymer stmcture. The level of polyester polymer unsaturation determines essential performance characteristics (Table 7), although polymer components can influence subtle features that affect thermal, electrical, and mechanical performance as defined by ASTM procedures. 

---