Types of plastics

Phenolic plastics are based on phenol formaldehyde resins and are often referred to as Bakellte . The material has a limited colour range and is supplied only in dark colours, principally brown and black. 

Phenolics are good electrical insulators and show good resistance to water, acid and most solvents. They are rigid and have low thermal conductivity. The normal operating temperature limit for phenolic mouldings is 150 °C, but grades are available which will operate at up to 200 C for limited periods. Typical uses include handles and electrical plugs and sockets. 

Phenol and urea formaldehyde resins are used in the casting industry to produce cores and moulds and although formaldehydes have not been proven to cause cancer in humans, they can, when heated, irritate eyes, skin and respiratory tract. 

Usually shortened to melamine, melamine formaldehyde is often used in kitchen utensils and tableware and in electrical insulating parts. It is strong and glossy and has good resistance to heat, chemicals, moisture, electricity and scratching, has excellent moulding properties and is available in a range of vibrant colours. 

Melamine resin is the main constituent of high-pressure laminates with a heat-resistant and wipe-clean surface, widely known by the trade name Formica . 

Phenolic plastics are based on phenol formaldehyde resins and are often referred to as 

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Poly(vinylchloride). Cellular poly(vinyl chloride) can be produced from several expandable formulations as well as by decompression techniques. Rigid or flexible products can be made depending on the amount and type of plasticizer used (43). 

Miscellaneous Properties. The acoustical properties of polymers are altered considerably by their fabrication into a ceUular stmcture. Sound transmission is altered only slightly because it depends predominandy on the density of the barrier (in this case, the polymer phase). CeUular polymers by themselves are, therefore, very poor materials for reducing sound transmission. They are, however, quite effective in absorbing sound waves of certain frequencies (150) materials with open ceUs on the surface are particulady effective. The combination of other advantageous physical properties with fair acoustical properties has led to the use of several different types of plastic foams in sound-absorbing constmctions (215,216). The sound absorption of a number of ceUular polymers has been reported (21,150,215,217). 

Plastics and Resins. Plastics and resin materials are high molecular weight polymers which at some stage in their manufacture can be shaped or otherwise processed by appHcation of heat and pressure. Some 40—50 basic types of plastics and resins are available commercially, but HteraHy thousands of different mixtures (compounds) are made by the addition of plasticizers, fillers, extenders, stabilizers, coloring agents, etc. 

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. 

Table 11 shows U.S. production and sales of the principal types of plastics and resins. Some materials are used both as plastics, ie, bulk resin, and in other apphcations. For example, nylon is used in fibers, urethanes as elastomers. Only their use as plastics is given in Table 11 their uses in other apphcations are Hsted with those apphcations. 

Plastics. The fastest-growing use of whiting (microcarbonate fillers) is in the plastics industry where dry, pulverized limestone is used intensively for most types of plastics. Other carbonate fillers, precipitated calcium carbonate, oyster sheU, marble, and wet-ground limestone, are also used. 

Micronized mica and wet ground both used in certain types of plastics. 

Nacreous Pigments. Mica is used as a substrate for coatings (qv) of various metal oxides to obtain a peadescent effect. Mica coated in this fashion is used as filler and as a coloring agent in certain types of plastics. 

Rubbers. Plasticizers have been used in mbber processing and formulations for many years (8), although phthaHc and adipic esters have found Htde use since cheaper alternatives, eg, heavy petroleum oils, coal tars, and other predominandy hydrocarbon products, are available for many types of mbber. Esters, eg, DOA, DOP, and DOS, can be used with latex mbber to produce large reductions in T. It has been noted (9) that the more polar elastomers such as nitrile mbber and chloroprene are insufficiendy compatible with hydrocarbons and requite a more specialized type of plasticizer, eg, a phthalate or adipate ester. Approximately 50% of nitrile mbber used in Western Europe is plasticized at 10—15 phr (a total of 5000—6000 t/yr), and 25% of chloroprene at ca 10 phr (ca 2000 t/yr) is plasticized. Usage in other elastomers is very low although may increase due to toxicological concerns over polynuclear aromatic compounds (9). 

Cell Construction. Nickel—2iac batteries are housed ia molded plastic cell jars of styrene, SAN, or ABS material for maximum weight savings. Nickel electrodes can be of the siatered or pocket type, however, these types are not cost effective and several different types of plastic-bonded nickel electrodes (78—80) have been developed. 

Some of the common types of plastics that ate used ate thermoplastics, such as poly(phenylene sulfide) (PPS) (see Polymers containing sulfur), nylons, Hquid crystal polymer (LCP), the polyesters (qv) such as polyesters that ate 30% glass-fiber reinforced, and poly(ethylene terephthalate) (PET), and polyetherimide (PEI) and thermosets such as diaHyl phthalate and phenoHc resins (qv). Because of the wide variety of manufacturing processes and usage requirements, these materials ate available in several variations which have a range of physical properties. 

By the mid-1990s capacity for polyethylene production was about 50 000 000 t.p.a, much greater than for any other type of plastics material. Of this capacity about 40% was for HDPE, 36% for LDPE and about 24% for LLDPE. Since then considerable extra capacity has been or is in the course of being built but at the time of writing financial and economic problems around the world make an accurate assessment of effective capacity both difficult and academic. It is, however, appeirent that the capacity data above is not reflected in consumption of the three main types of material where usage of LLDPE is now of the same order as the other two materials. Some 75% of the HDPE and LLDPE produced is used for film applications and about 60% of HDPE for injection and blow moulding. 

The PSA formulator can also take advantage of plasticizers. For example, polyether-based plasticizers have both good low-temperature flexibility and good hydrophilicity. Using these properties, acrylic PSAs have been formulated with these types of plasticizers to obtain high adhesion to food packages stored under refrigerated conditions [102]. Similarly, polyether plasticized acrylics have been used to make repulpable PSAs [103]. 

Chemical Reactivity - Reactivity with Water No reaction Reactivity with Common Materials Softens and dissolves many types of plastics Stability During Transport Stable Neutralizing Agents for Acids and Caustics Not pertinent Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

The formation of crevices between dissimilar metals should be avoided. Corrosion at such connections is generally more severe than either galvanic or crevice corrosion alone. Also, crevices between metals and certain types of plastics or elastomers may induce accelerated rates of combined crevice and chemical attack. Testing is recommended prior to establishing final design specifications. 

In this book no prior knowledge of plastics is assumed. Chapter 1 provides a brief introduction to the structure of plastics and it provides an insight to the way in which their unique structure affects their performance. There is a resume of the main types of plastics which are available. Chapter 2 deals with the mechanical properties of unreinforced and reinforced plastics under the general heading of deformation. The time dependent behaviour of the materials is introduced and simple design procedures are illustrated. Chapter 3 continues the discussion on properties but concentrates on fracture as caused by creep, fatigue and impact. The concepts of fracture mechanics are also introduced for reinforced and unreinforced plastics. 

R = Reparability a plant bought some vessels wdth a new type of plastic lining instead of the one they had used for many years. The new material had better temperature resistance than the old, but when it did need repair, the patches would not stick. In time the problems were overcome, but reparability should have been considered before the change was made. 

Represents more than 400 manufacturers of polymers, additives, and machinery as well as all types of plastics processors and fabricators. Membership is divided into 15 Business Groups sharing four Market Sector Groups. 

The most common types of plasticizer are the phthalic acid esters of Cg, Cio alcohols citric acid esters and epoxy aliphatic esters. 

Recycling of unwanted polymers is the best solution, and six types of plastics in common use are frequently stamped with identifying codes assigned by the Society of the Plastics Industry (Table 31.2), After being sorted by type, the... 

Table 1-2 provides estimates of the major types of plastics consumed yearly worldwide that now total 339,990 million lb (154 million tons). About 90% are thermoplastics (TPs) and 10% thermoset (TS) plastics. USA and Europe consumption s are each about one-third of the world total. There are well over 35,000 different type plastic materials worldwide. However, most of them are not used in large quantities they have specific performance and/or cost capabilities generally for specific products by specific processes that principally include many thousands of products (Chapters 6 7). 

The selection of the evaluation method(s) depends on the specific type of plastic, the environment of the evaluation, the effectiveness of the evaluation method, the size of the structure, the fabricating process to be used, and the economic consequences of structural failure. Conventional evaluation methods are often adequate for baseline and acceptance inspections. However, there are increasing demands for more accurate characterization of the size and shape of defects that may... 

Tliere is another type of application where the damping effect of plastic structures can be used to advantage. It has a long although not obvious history. The early airplanes used doped fabric as the covering for wings and other aerodynamic surfaces. The dope was cellulose nitrate and later cellulose acetate that is a damping type of plastic. Conse-... 

Other elements of weather and outdoor exposure can interact with UV radiation to accelerate degradation in degradable types of plastics. They include humidity, salt spray, wind, industrial pollutants, and atmospheric impurities such as ozone, biological agents, and temperature. The wavelengths that have the most effect on plastics range from 290 to 400 nm (2,900 to 4,000 A). 

Fortunately, there are many different types of plastics that can provide all kinds of properties, including specific dimensional tolerances. It can thus be said that the real problem is not with the different plastics or processes but rather with the designer, who requires knowledge and experience to create products to meet the desired requirements. The designer with no knowledge or experience... 

Plastic suppliers can provide the initial information on shrinkage that has to be added to the design shape and will influence its processing. The shrinkage and postshrinkage will depend on the types of plastics and their... 

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