Plastics physical characteristics

CPA. Copolymer alloy membranes (CPAs) are made by alloying high molecular weight polymeries, plasticizers, special stabilizers, biocides, and antioxidants with poly(vinyl chloride) (PVC). The membrane is typically reinforced with polyester and comes in finished thicknesses of 0.75—1.5 mm and widths of 1.5—1.8 m. The primary installation method is mechanically fastened, but some fully adhered systems are also possible. The CPA membranes can exhibit long-term flexibiHty by alleviating migration of the polymeric plasticizers, and are chemically resistant and compatible with many oils and greases, animal fats, asphalt, and coal-tar pitch. The physical characteristics of a CPA membrane have been described (15). 

Styrene is a colorless Hquid with an aromatic odor. Important physical properties of styrene are shown in Table 1 (1). Styrene is infinitely soluble in acetone, carbon tetrachloride, benzene, ether, / -heptane, and ethanol. Nearly all of the commercial styrene is consumed in polymerization and copolymerization processes. Common methods in plastics technology such as mass, suspension, solution, and emulsion polymerization can be used to manufacture polystyrene and styrene copolymers with different physical characteristics, but processes relating to the first two methods account for most of the styrene polymers currendy (ca 1996) being manufactured (2—8). Polymerization generally takes place by free-radical reactions initiated thermally or catalyticaHy. Polymerization occurs slowly even at ambient temperatures. It can be retarded by inhibitors. 

A stationary separator element of knitted small diameter wire or plastic material is formed of wire 0.003 in. to 0.016 in. (or larger) diameter into a pad of 4 inches, 6 inches or 12 inches thick and serves as the impingement surface for liquid particle separation. Solid particles can be separated, but they must be flushed from the mesh to prevent plugging. Although several trade name units are available they basically perform on the same principle, and have very close physical characteristics. Carpenter [4] presented basic perform.ance data for mesh units. Figure 4-15 shows a qpical eliminator pad. 

Plastic also refers to a material that has a physical characteristic such as plasticity and toughness. The general term commodity plastic, engineering plastic, advanced plastic, advanced reinforced plastic, or advanced plastic composite is used to indicate different performance materials. These terms and others will be reviewed latter in this chapter. Plastics are made into specialty products that have developed into major markets. An example is plastic foams that can provide flexibility to rigidity as well as other desired properties (heat and electrical insulation, toughness, filtration, etc.). 

Published by the Plastics Design Library, PDLCOM is an exhaustive reference source of how exposure environments influence the physical characteristics of plastics. Data include resistance to thousands of chemicals, weathering and UV exposure (i.e. color change after accelerated weathering or outdoor exposure) sterilization (radiation, ethylene oxide, steam, etc.) thermal air and water aging environmental stress cracking and much more. 

Table I shows the chemical composition limits of various aluminum alloys presently used for packaging applications (3). In general, these alloys have good corrosion resistance with most foods. However, almost without exception, processed foods require inside enameled containers to maintain an acceptable shelf life (4, 5). Moreover, when flexible foil packages are used for thermally processed foods, the foil is laminated to plastic materials that protect it from direct contact with the food and also provide heat sealability as well as other physical characteristics (6,7).

This book focuses on the relationships between the chemical structure and the related physical characteristics of plastics, which determine appropriate material selection, design, and processing of plastic parts. The book also contains an in-depth presentation of the structure-property relationships of a wide range of plastics, including thermoplastics, thermosets, elastomers, and blends. 

The chemical or physical characteristics of solid or liquid additives, such as extenders, white pigments, dispersing agents, plasticizers, or pigment/extender combinations. 

Disazopyrazolone pigments are broad in scope. Depending on their physical characteristics, different types are targeted for the printing ink, paint, or plastics industry. 

Benzimidazolone pigments, especially those covering the red range of the spectrum, were originally developed and used mostly for plastics. None of them were found to adversely affect the physical characteristics of their host medium. Benzimidazolone pigments do not bloom in plasticized PVC and other polymers. They are usually bleed resistant under typical application conditions. 

Plasticization proves to be true by measurements of electro physical characteristics at modified polyethylene terephthalate (figure 4). 

Several types of materials are in use in the preparation of containers and closure systems glass, plastics, metals, and combinations of these materials. However, care should be taken in the selection of appropriate material. These materials should not present any physical or chemical reactivity that could modify drug activity, quality, purity, or physical characteristics of the drug and pharmaceutical preparations. Any minor modification in the pharmacopeial specification is acceptable if it does not present a threat to patient s health. 

The physical characteristics of the plastic input influence the carbonization process. In static conditions, the heating rate of small particles is higher than for large particles. In this case, difficulties could occur for the extrapolation from small-scale carbonization data to pilot- and industrial-scale units. The physical and chemical properties of the material are of great importance in order to be able to evaluate the heat transfer from the reactor inside the material. 

Physical Characteristics. Shortenings are pictured as solid materials but, in reality, are predominantly fluids. A plastic shortening consists of approximately one-quarter crystalhne-solid triglycerides suspended in liquid triglycerides. The ratio of these two phases determines the consistency of a shortening as it relates to firmness, softness, and spreadibUity. Fats and oUs processors change the consistency of a... 

Gelatin capsules are also produced, which contain 5%i Polyethylene glycol (PEG) 4000 as an additional plasticizer. They have improved physical characteristics over standard gelatin capsules and can loose more moisture before they become brittle. They were first developed by Shionogi Qualicaps in Japan, where they are widely used for pharmaceutical products. 

Liquid oral preparations are usually contained in PET or PETG containers. PETG has a different polymeric composition than PET as discussed under Types of Packaging Materials. Physical characteristics are listed in the USP and 21 C.F.R. specifies their composition. Identification of PET and PETG shows that these plastics are distinct and distinguishable from one another by IR spectrum, but the two compounds are similar as evaluated by thermal analysis.f " This type of plastic should be tested for colorant extraction as previously discussed. " ... 

Soft lenses are made of hydrophilic hydrogel polymers that contain 36-74% water. Other plastics and copolymers are added to alter the physical characteristics of the lens. The diameter is 10.5-15.5 mm and the thickness at the center 0.03-20 mm. Soft lenses can correct most optical defects, including myopia, hyperopia, and astigmatism. Bifocal lenses are also available. They can be colored with either transparent hnes or opaque patterns to change apparent eye color or to mask malformations of the cornea or iris. They are available for daily, weekly, and twice-weekly disposable nse, 1-3 months frequent replacement, and annual replacement. 

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