Plastic and Thermoplastic Materials

Plastics are highly resistant to a variety of chemicals. They have a high strength per unit weight of material therefore, they are of prime importance to the designer of chemical process equipment. Their versatility in properties has provided new and innovative designs of equipment. They are excellent substitutes for expensive nonferrous metals. 

Plastics are high-molecular-weight organic compounds of natural or mostly artificial origin. In fabrication, plastics are added with fillers, plasticizers, dyestuffs and other additives, which are necessary to iower the price of the material, and give it the desired properties of strength, elasticity, color, point of softening, thermal conductivity, etc. 

Plastics are subidivided into two types thermoplastic and thermosetting. The thermoplastics can be softened by heat and hardened again by subsequent cooling. This process is reversible and can be repeated many times. By contrast, the thermosetting resins are first softened and melted and, at subsequent heating to a definite temperature, they are irreversibly hardened, becoming insoluble [53]. 

The physical and mechanical properties of the principal thermoplastics of interest for process plant applications are listed in Table 3.42. Table 3.43 gives typical hydrostatic design stresses for different types of thermoplastic pipe. Plastics wideiy employed in piping systems are described briefly below. 

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By analogy between thermosetting plastics and thermoplastic materials whose granulation is well developed and brought to a commercial level in many countries, two main directions may be conventionally defined as follows4 ... 

Plastic and thermoplastic material, as PVC, PE, rubber and thermosetting plastics. 

The EVAs make it possible to produce compounds with high filler levels and are compatible with many elastomers, plastics and other materials SBR, butyl rubber, EPDM, nitrile rubber, Hypalon, thermoplastic elastomers, epoxies, PVC, PVDC, bitumen. 

Just as in the manufacture of sheet natural rubber and the asphaltic sheet linings, the basic material as the sheet lining manufacturer receives it from the plantation (rubber) or from the refiner or importer (asphalt), the manufacturer of the synthetic lining materials will receive his synthetic elastomer, thermoplastic or other basic resin from the company that produces it-and will have to blend it with fillers, stabilizers, plasticizers, and other materials to make a suitable compound which will-as a lining—perform its function satisfactorily under the anticipated conditions, and for an economical length of time. The actual amount of the basic resinous material in the compound may be as low as 70% of the total weight. 

Extrusion is a cost effective manufacturing process. Extrusion is popularly used in large scale production of food, plastics and composite materials. Most widely used thermoplastics are processed by extrusion method. Many biopolymers and their composite materials with petroleum-based polymers can also be extruded. These include pectin/starch/poly(vinyl alcohol) (Fishman et al. 2004), poly(lactic acid)/sugar beet pulp (Liu et al. 2005c), and starch/poly(hydroxyl ester ether) (Otey et al. 1980), etc. In this study, composite films of pectin, soybean flour protein and an edible synthetic hydrocolloid, poly(ethylene oxide), were extruded using a twin-screw extruder, palletized and then processed into films by compression molding process or blown film extrusion. The films were analyzed for mechanical and structural properties, as well as antimicrobial activity. 

Plastics can be disposed of by standard methods after washing with water or an oxidizing solution. Reinforced plastics and thermoplastics such as PVC, PP, and the like can be washed by high-pressure water jet, with sufficient containment to prevent the spread of metallic mercury. The effectiveness of washing other materials in baths improves with the addition of detergent or acid plus free chlorine. 

Ihere is a growing trend to use natural fibers as fillers and/or reinforces in plastic composites as thermosetting and thermoplastic materials. Ihe use of lignocellulosic materials as reinforcements has received increasing attention due to the improvements that natural fibers can provide such as low density, biodegradabihty and highly specific stiffness, as well as the fact that these materials are derived from renewable and less expensive sources [11-... 

Reprocessed plastic n. Thermoplastic material that has been left over from molding, extrusion, or thermoforming, such as sprues and runners, sheet, trim, trim between ther-moformed parts, and rejected parts, then molded, extruded, or thermoformed again into useful articles by other than the original processors. 

This chapter reviews the main results obtained in the fields of starch-filled plastics and thermoplastic starch, paying particular attention to the concepts of gelatinization, destructurization, extrusion cooking, and the use of com-plexed starch in specific synthetic polymers. Aspects such as processability, the physicochemical and physicomechanical properties and the biodegradation behaviour of starch-based materials on the market are briefly considered. 

Intended for the student of materials and engineering, this book presents a concise survey of thermosetting plastics and thermoplastics, indicating the more important techniques of plastics fabrication and component assembly. 

The world demands for thermoplastic elastomers are forecast to expand by 7.5% per year to 2.6 million metric tons in 2006. TPEs will continue to find the majority of their applications as replacements for natural and synthetic rubbers, as well as rigid thermoplastics and metals. The global TPE industry will remain heavily concentrated in the USA, Western Europe and Japan, particularly for specialty materials, such as polyester elastomers. Prom the two trends of application of polyester elastomers as engineering plastics and functional materials, the second one is prioritized. In terms of engineering applications, the PEE production will remain closely related to the motor vehicle industry, sporting goods, hoses, and small household goods. 

At first glance, the difference between thermosetting plastic materials and thermoplastic materials seems pretty simple one you can heat and melt and reprocess, the other you cannot. But there are some additional differences between them, some of which are subtle, and some not. To understand those differences, we need to look at these materials on a molecular level. 

The most reliable (time-consuming and costly) identification method is to use infrared spectroscopy measurements to determine the material. The Rapra Collection of Infrared Spectra of Rubbers, Plastics, and Thermoplastic Elastomers can be used to compare the spectrum of a test material to reference spectra. The transmission spectra in this reference are obtained either from cast or molded thin film or in the case of cross-linked materials by pyrolysis of the material in a Pyrex tube. 

Nylon A class of synthetic fibres and plastics, polyamides. Manufactured by condensation polymerization of ct, oj-aminomonocarboxylic acids or of aliphatic diamines with aliphatic dicarboxylic acids. Also rormed specifically, e.g. from caprolactam. The different Nylons are identified by reference to the carbon numbers of the diacid and diamine (e.g. Nylon 66 is from hexamethylene diamine and adipic acid). Thermoplastic materials with high m.p., insolubility, toughness, impact resistance, low friction. Used in monofilaments, textiles, cables, insulation and in packing materials. U.S. production 1983 11 megatonnes. 

The air-coupled ultrasonic probes are essentially built up by the piezo-composite plate and a front side matching layer, made of air bubbles filled plastic materials. By using a thermoplastic material as matrix material of the composite, the transducer can easily be shaped by heating up, forming and cooling down to realize focusing transducers. Because of the low... 

The two primary types of plastics, thermosets and thermoplastics, are made almost exclusively from hydrocarbon feedstocks. Thermosetting materials are those that harden during processing (usually during heating, as the name implies) such that in their final state they are substantially infusible and insoluble. Thermoplastics may be softened repeatedly by heat, and hardened again by cooling. 

In the eady 1920s, experimentation with urea—formaldehyde resins [9011-05-6] in Germany (4) and Austria (5,6) led to the discovery that these resins might be cast into beautiful clear transparent sheets, and it was proposed that this new synthetic material might serve as an organic glass (5,6). In fact, an experimental product called PoUopas was introduced, but lack of sufficient water resistance prevented commercialization. Melamine—formaldehyde resin [9003-08-1] does have better water resistance but the market for synthetic glass was taken over by new thermoplastic materials such as polystyrene and poly(methyl methacrylate) (see Methacrylic polya rs Styrene plastics). 

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