Selecting Plastic

It is unfortunate that plastics do not have all the advantages and none of the disadvantages of other materials but often overlooked is the fact that there are no materials that do not suffer from some disadvantages or limitations. The faults of materials known and utilized for hundreds of years are often overlooked the faults of the new materials (plastics) are often over-emphasized. 

As examples, steel is attacked by the elements of fire [1500 to 2500°F (815 to 1370°C)]. They lose all their strength, modulus of elasticity, etc. Common protective practice includes the use of protective coatings (plastic, cement, etc.) and then forgetting their susceptibility to attack is all too prevalent. Wood and concrete are useful materials yet who has not seen a rotted board (wood on fire, etc.) and cracked concrete. Regardless this lack of perfection does not mean that no steel, wood, or concrete should be used. The same reasoning should apply to plastics. In many respects, the gains made with plastics in a short span of time far outdistance the advances made in these other technologies. 

To significandy extend the life of structural beams, hardwood (thicker than steel, etc.) can be used thus people can escape even though the wood slowly burns. The more useful and reliable structural beams would be using reinforced plastics (RPs) that meet structural performance requirements with even a more extended supporting life than wood. To date these RPs are not used in this type of fire environment primarily because of their high cost. 

For many applications plastics have superseded metal, wood, glass, natural fibers, etc. Many developments in the electronics and transportation industries and in packaging and domestic goods have been made possible by the availability of suitable plastics. Thus comes the question of whether to use a plastic and if so, which one. 

As an initial step, the product designer must know and/or anticipate the conditions of use and the performance requirements of the product, considering such factors as life expectancy, size, condition of use, shape, color, strength, and stiffness. These end use requirements can be ascertained through market analysis, surveys, examinations of similar products, testing, and/or experience. A clear definition of product requirements will often lead direcdy to choice of the material of construction. At times incomplete or improper product requirement analysis is the cause for a product to fail. 

Much of the market success or failure of a plastic product can be attributed to the initial choice of material. Even though the range of plastics has become large and the levels of their properties so varied that in any proposed application only a few of the many plastics will be suitable. 

A compromise among properties, cost, and manufacturing process generally determines the material of construction. Selecting a plastic is very similar to selecting a metal. Even within one class, plastics differ because of varying formulations, just as steel compositions vary (tool steel, stainless steel, etc.). There are, of course, products for which no plastics is satisfactory, and the interests of the producer and consumer alike are best served by using some other material. 

For many applications, however, plastics have superseded metal, wood, glass, natural fibers, etc. Many developments in the elec- 

Whether the product is a new model of an established commodity or a completely new development, a list can be made of the properties the material or group of materials to be employed must possess, and of those that are also most desirable. By reference to the relevant material properties and prices, an analysis can be made to determine the plastic most likely to be suitable from all requirements. 

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Vinyl compares favorably to other packaging materials. In 1992, a lifecycle assessment comparison of specific packages made from glass, paperboard, paper, and selected plastics concluded that vinyl was the material that has the lowest production energy and carbon dioxide emissions, as well as the lowest fossil fuel and raw material requirements of the plastics studied (169). Vinyl saves more than 34 million Btu per 1000 pounds manufactured compared to the highest energy-consuming plastic (170). 

Table 1. Physical Properties of Selected Plastic Building Materiar...

Table 6. 7 -Values vs Insulation Thickness for Selected Plastics ...

Dielectric Constant, Power Factor and Structure 111 Table 6.1 Typical electrical properties of some selected plastics materials at 20°C... 

There are several plastic coatings available commercially, some being more effective than others. However, the selected plastic coating must possess flexibility, resistance against impact, chemical attack, flow of galvanic currents and... 

Colorability is another reason IDs select plastics for many products. Molding color into a product eliminates finishing and painting operations, thus reducing costs. Beyond cost, integral color also masks the nicks, chips and scratches that impair appearance during the life of the product. Color effects are almost limitless. Transparent, translucent, pearlescent, fluorescent, or marbleized colors are readily available for use in plastics. 

Determine tolerance requirements that are expected in the performance of the product. Shrinkage characteristics of the selected plastic should be as small as possible so that tolerances can be anticipated with a reasonable degree of accuracy. 

Some plastics can be worked by many different processes, but others require a specific process (Fig. 10-9). Process selection can take place before material selection, when a range of materials may be available, or made first to meet performance requirements and only then have the applicable process or processes chosen. (Chapter 7, SELECTING PLASTIC and Chapter 8, SELECTING PROCESS) Usually, in the latter situation only one special process can be used to provide the best performance-to-cost advantages. A particular design group may have its own processing capabilities. Unfortunately, some operations use just whatever equipment is available. This situation could either be very unprofitable, limit profitability, or restrict product... 

The plastics properties catalogue includes single-point data, multi-point data, processing data, product description texts and customer service information. You can select plastic products for your specific application by using the query options. The main feature of the CAMPUS philosophy is comparable data. The properties are based on the international standards ISO 10350 for Single-Point data and ISO 11403-1, -2 for Multi-Point data. CAMPUS is available in English, German, Spanish, French and Japanese. 

Finally, other relevant treatment options for plastics waste include landfill and mechanical recycling. Since these options (unlike Vinyloop and cement kiln incineration) are not even similar to feedstock recycling we discuss them here only very briefly. Mechanical recycling of plastics (be it PVC or other plastics), needs dedicated collection of the plastic waste in question. This is only possible for selected plastic flows (high volumes, recognisable products, products consisting mainly of one plastic). Landfill can accept plastic waste in any waste context (pure plastic type, MPW, mixed materials). I will only address the costs of these alternative technologies. 

Isolation of the products from complex matrixes (e.g. polymer and water, air, or soil) is often a demanding task. In the process of stability testing (10 days at 40 °C, 1 h at reflux temperature) of selected plastic additives (DEHA, DEHP and Irganox 1076) in EU aqueous simulants, the additive samples after exposure were simply extracted from the aqueous simulants with hexane [63]. A sonication step was necessary to ensure maximum extraction of control samples. Albertsson et al. developed several sample preparation techniques using headspace-GC-MS [64], LLE [65] and SPE [66-68]. A practical guide to LLE is available [3]. 

The effects of catalyst on the product distribution for selected plastic/residue doublecomponent systems are shown in Table 14.2. The results show that the presence of residue increased the overall conversion in the double-component coprocessing reactions compared to the single-component reactions except in the case of polystyrene [14]. 

Table 14.2 Effect of catalyst on the product distribution for selected plastic/resid double-component systems...

In India, as in the rest of the world, the use of plastics has increased rapidly. It is possible to replace many metals and other scarce materials with plastics. The production of selected plastics is shown in Table XI for the years since independence, along with the percent of utilization of capacity. This table does not include the many existing fabrication plants. 

Table 4.10 Results of analysis of selected plastic materials for listed metals by ICP-AES after microwave acid digestion (A), dry eishing to 650°C with PTSA (B) or high pressure oxygen bomb combustion (C)...

Anagnostou, E., "Effect of Ultraviolet Irradiation on Selected Plastic Films in Vacuum," (1965), NASA TM X-1124. 

Using melt viscosity measurements, Lundberg et al. (107) showed that one could selectively plasticize either the ion-rich phase or the nonpolar hydrocarbon phase of SPS lonomers by varying the chemistry of the diluent used. Fitzgerald et al. (108) studied the effects of dioctyl phthalate (DOP) and glycerol on the dynamic mechanical properties of SPS lonomers. The addition of DOP lowered... 

Eckert [21 ] develops an economic characterization number for various types of packing. Usually, the most suitable choice of packing is dependent on the material of construction of the equipment. In distillation towers when low-carbon steel is used, 2-inch metal rings are often favored because they give a low AP, high capacity, and efficiency. Alternatively, saddles are the most frequently selected plastic and ceramic packing. 

Each of these processes imposes different demands on the packaging materials. Dry heat (temperatures of 160-180°) can only be withstood by glass, metals and a few selected plastics. Glass often uses 320°C or slightly higher for 3 1 min. 

Fluoropolymers are thermoplastic and nonrigid materials while fluoroelastomers have elastomeric properties. See Tables 2.1 and 2.2 for a comparison of physical and mechanical properties of select plastics and elastomers including fluorinated materials. 

Nature and Amount of the Dispersed Rubber Phase. The effect of the nature of the dispersed rubber phase became apparent during our work on selective plasticization of systems containing two resins A and B, a corresponding AB Cop, and a selective plasticizer of polymer A or B (13, 14) where A was polystyrene (PS) and B was poly (methyl methacrylate) (PMM) or poly (vinyl chloride) (PVC). Selective plasticization is a new method of obtaining resin elastomeric systems which have the advantage that the physical properties (e.g., mechanical properties and refractive index) of the rubbery phase can be varied by the nature and amount of the plasticizer. For such systems, impact resistance is maximum when the energy absorption capacity of the rubbery phase is maximum (e.g., for a given amount of plasticizer with respect to the dispersed phase). 

Figure 6. Impact resistance as a function of the amount of plasticizer in a ternary blend PS-PMM-Cop(PS-PMM) with PS selectively plasticized...

A study of various PS-PMM polyblends in which the dispersed PS phase was selectively plasticized demonstrated that the impact resistance, R, varies in the same way as the occupation density, D (see Table III). Since the dispersed rubber particles are practically spherical, a simple relationship for R and D is ... 

Table 6.9. Selected plastic-elastomer thermoplastic IPNs by trade name ...

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