Tough plastic

Commercially produced elastic materials have a number of additives. Fillers, such as carbon black, increase tensile strength and elasticity by forming weak cross links between chains. This also makes a material stilfer and increases toughness. Plasticizers may be added to soften the material. Determining the effect of additives is generally done experimentally, although mesoscale methods have the potential to simulate this. 

These rubbers are now also being blended on a large scale with polyolefin plastics, particularly polypropylene, to produce a range of materials which at one extreme are tough plastics and at the other the so-called thermoplastic polyolefin rubbers (TPORs) (.see Section 11.9.1). 

Nobel invented gelatinous dynamite in 1875 by accident. He investigated the effect of nitroglycerine on the collodion (nitrocellulose in a mixture of ether and alcohol) that he used to treat a cut finger and found that it produced a tough plastic material with adjustable viscosity and high water resistance. 

ABS has a specific gravity of 1.03 to 1.06 and a tensile strength in the range of 6 to 7.5 X 10 psi. These polymers are tough plastics with outstanding mechanical properties. A wide variety of ABS modifications are available with heat resistance comparable to or better than polysulfones and polycarbonates (noted later in this section). Another outstanding property of ABS is its ability to be alloyed with other thermoplastics for improved properties. For example, ABS is alloyed with rigid PVC for a product with better flame resistance. 

Those with transparency capabilities provide many different products that include toys, protective shields (high heat resistance, gunfire, etc.), transportation vehicle lighting, camera lenses, eyeglasses, contact lenses, etc. When transparency is needed in conjunction with toughness, plastic materials are the preferred candidates. Add to the capability of providing simple to very complex shapes. 

When packaging problems are tough, plastics often are the answer and sometimes the... 

Obturator Pad. Pad of tough plastic material, forming part of an Obturator (qv)... 

Polyunsaturated fats can combine easily with oxygen at the points where there is a double bond between two carbon atoms. This is why they make good antioxidants they combine with the oxygen free radicals so they don t damage other molecules. It is also how oils harden, and is thus important to painters. Oil paints made with linseed oil are almost three-quarters trilinolein. They dry to form a tough plastic film that incorporates the pigments and holds them onto the surface to be painted. 

Figure 7.1 Typical stress-strain curves for (a) a brittle plastic and (b) a tough plastic with yield point, showing the parameters used for the evaluation of degradation in tests...

Although the materials studied in this research program lack optimization, they already compare satisfactorily to commercial materials in many respects. With reasonable further research and development studies, high quality tough plastics and reinforced elastomers may be anticipated. 

ABS (30% acrylonitrile, 20% butadiene, and 50% styrene) is a tough plastic with outstanding mechanical properties ABS is one of the few plastics that combines both toughness and hardness. So the applications include ballpoint pen shells, fishing boxes, extruded pipes, and space vehicle mechanical parts. There s more than 20 pounds of ABS molded parts in an automobile. 

Polyvinyl chloride (PVC) is a tough plastic often used in construction and plumbing. It is also used in some food, shampoo, oil, and household product containers. 

Periodic system disassembly allows more extensive CDS procedures to be undertaken. Most columns are manufactured from glass, or more usually, tough plastic or stainless steel. After a thorough cleaning of all disassembled components, sterilization by autoclaving is usually undertaken prior to re-assembly. Most chromatographic media likewise can be autoclaved before column re-pouring. 

Ultrafiltration membranes are usually manufactured from tough plastic-based polymers, such as polyvinyl chloride or polycarbonate. A range of membranes are available which display different cut-off points (Figure 3.20). Membranes displaying cut-off points of 3, 10, 30, 50 and 100 kDa are most commonly used. Thus, if the protein of interest displays a molecular mass of 70kDa, it may be concentrated effectively by using an ultrafilter membrane displaying a molecular mass cut-off point of 50 kDa. Ultrafiltration is a popular method of concentration because ... 

Other addition polymers are created by using different monomers. The only requirement is that the monomer must contain a double bond. The monomer propylene, for example, yields polypropylene, as shown in Figure 12.28. Polypropylene is a tough plastic material useful for pipes, hard-shell suitcases, and appliance parts. Fibers of polypropylene are used for upholstery, indoor-outdoor carpets, and even thermal underwear. 

At a considerably later date. Frankland prepared ethyl methacrylate and methacrylic acid from ethyl a-hydroxyisobutyrate and phosphorus trichloride. Tollen prepared aciylate esters from 2,3-dibromopropionate esters and zinc. Otto Rohm, in 1901. described the structures of the liquid condensation products (including dimers and timers) obtained from the action of sodium alkoxides on methyl and ethyl acrylate. Shortly after World War 1, Rohm introduced a new acrylate synthesis, noting that an acrylate is formed in good yield from heating ethylene cyanohydrin and sulfuric acid and alcohol. A major incentive for the development of a clear, tough plastic acrylate was for use in the manufacture of safety glass. 

Polyvinylidine chloride (Saran) is a tough plastic which is extensively used in laboratory drainpipes. This form of the plastic is rigid, but flexible transparent films are used widely in food packaging. Polyvinylidine chloride becomes brittle at 10°C and loses most of its strength at 77°C. It has unusually low permeability... 

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